Unit 3 Packet Carolyn Student
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Chapter 3 Part 1
TEST PREPARATION CHECKLIST BIOLOGY:
Name: _________________________________ Date: __________________________________
Gather Information Subject of Test: _Cell Structure and Function (pt.1) ___________________ Date of Test: ______________ Chapters/Concepts to Study: Chapter 3 (3.1,3.3, 3.4, and 3.5) _______________________ Other Information covered (videos, handouts, labs, quizzes, assignments, etc.):
What types of questions will be on the test? Check all that will be on the test. ___True/False
__Multiple Choice _35
_____Labeling
____Fill-in-the-blank
Total Number of Questions ____35_______
_Matching _____Essay
__Short Answer _ _____Other
Total Number of Points Possible ____100______
Plan From the list below, check any study strategy that you believe will be of use to you in preparing for this test. Add any strategies you use that are not listed below. _____Compete the chapter reviews in Biology McDougal Littell for the chapters covered on the test. _____Complete the online activities for the concepts covered on test and answer the online activity questions. www.classzone.com
_____ Update lecture notes with a friend’s notes (especially if you have been absent during the unit). _____ Update lecture notes with information from your textbook. _____ Reread textbook and paraphrase the material.
_____ Complete the practice test sheet. _____ Define key terms from each concept covered on the test. _____ Practice vocabulary by making flashcards _____ Outline textbook chapters. _____ Complete the online chapter assessments for the chapters covered on test. www.classzone.com
_____ Make a test including a variety of questions and types of questions.
_____ Review guided reading packets for each chapter covered on test.
_____ Teach material to someone else. _____ Draw a picture or diagram of what you are studying.
_____ Record or take notes from test review session. _____ Make a timeline. _____ Reread lectures notes aloud. _____ Study with a friend. _____ Rewrite lecture notes. _____ Highlight lecture notes. _____ Summarize lecture notes (find and note main ideas) _____ Explain lecture notes to a friend or relative.
_____ Meet with teacher before or after school to discuss material for the test. _____ Utilize the Resource Room (RSP) to ask questions and prepare for test.
Study Log When you study for a test, make sure you do something other than just read. For example, write, draw, read aloud, tape, talk, highlight, make flash cards, etc. Be creative. When you are actively involved in your study strategy, you will remember more of the material and understand it better. When did you study?
How long did you study?
How did you study? What did you do?
Analysis Complete this section after you have received your graded test back. Points Earned/Points Possible
______________
Percentage/Letter Grade on Test
______________
What worked well for you in preparing for this test?
What will you do differently next time (besides “study more”)? Be specific.
ASSIGNMENT LOG CHAPTER 3 (Part 1) You may find it helpful to keep up with your daily grade in this class by using the following sheet. Record the due date for the assignment. Each day an assignment is due the teacher or T.A. will go around and stamp workbooks. Workbooks will be collected and graded the week before grade checks or the day of your test. Before you turn in your workbook check whether you completed an assignment or not. When your workbook is returned record the points that you earned. Your average is determined by dividing the points you have earned by the points possible. Remember that assignments turned in late will not receive higher than an 80%. Incomplete assignments may receive no credit and is up to the discretion of the teacher. When you are out of school it is your responsibility to make up assignments and get them stamped the following day. If you do not understand an assignment it is your responsibility to ask for help. Copying workbooks is not allowed and is considered cheating. You must complete your own work. Lastly, cheating will result in a grade of zero for all those involved including the owner of the completed workbook.
GOOD LUCK! ASSIGNMENT DATE COMPLETED? POSSIBLE POINTS DUE POINTS EARNED Starters 10 Test Prep Checklist:Plan 10 Study Log 10 Chapter 3 Pt 1 Vocabulary 20 3.1 Power Notes 15 3.1 Reading Questions 20 Cell Theory Mapping/Summary 25 3.3 Power Notes 15 3.3 Reading Questions 20 Cell Membrane Diagrams 15 Cell Membrane 25 Mapping/Summary 3.4 Power Notes 15 3.5 Power Notes 15 Passive Vs. Active Venn 25 Diagram and Summary Transport Mapping/Summary 25 Practice Quiz 30 Chapter 3 (Part 1) Exam 100 Total 395
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Chapter 3 Key Vocabulary (Part 1)
Word
Cell Theory
Cytoplasm
Organelle
Prokaryotic Cell
Eukaryotic Cell
Definition
Picture
Cell Membrane
Phospholipid
Fluid Mosaic Model
Selectively Permeable
Receptor
Passive Transport
Diffusion
Concentration Gradient
Osmosis
Isotonic
Hypertonic
Hypotonic
Facilitated Diffusion
Active Transport
Endocytosis
Phagocytosis
Exocytosis
chapter
7
Cellular Structure and Function
2 section ●
Structure of the Plasma Membrane You have learned that lipids are large molecules made up of glycerol and three fatty acids. A phospholipid (fahs foh LIH pid) is made up of glycerol, two fatty acids, and a phosphate group. The plasma membrane is made up of two layers of phospholipids arranged tail-to-tail in what is called a phospholipid bilayer. The phospholipid bilayer allows the plasma membrane to survive and function in its watery environment.
The Plasma Membrane
-!). )DEA
A cell’s plasma membrane helps maintain homeostasis.
What You’ll Learn how the cell’s plasma membrane functions ■ the role of proteins, carbohydrates, and cholesterol in the plasma membrane ■
Before You Read A window screen in your home allows air to pass through while keeping insects out. In this section, you will learn about a cell structure that has the same basic function. On the lines below, list some things you think would be allowed to pass into a cell and some things that would be kept out.
What is the structure of the phospholipid bilayer?
1. Highlight the items in the figure that enter the cell through the plasma membrane. Circle the items that exit the cell.
A cell’s survival depends on maintaining balance, called homeostasis. The plasma membrane is the cell structure primarily responsible for homeostasis. It is the thin, flexible boundary between the cell and its watery environment. Nutrients enter the cell and wastes leave the cell through the plasma membrane. Selective permeability (pur mee uh BIH luh tee) of the plasma membrane allows some substances to pass through while keeping others out. The figure below shows selective permeability of the cell’s plasma membrane. The arrows show common substances that enter and leave the cell. The plasma membrane controls how, when, and how much of these substances enter and leave the cells. /UTSIDE THE CELL /XYGEN 0LASMA MEMBRANE
Chapter 7 Cellular Structure and Function
7ASTES
7ASTES 7ATER
72
'LUCOSE
#ARBON DIOXIDE )NSIDE THE CELL
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Picture This
Function of the Plasma Membrane Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
a flash card for each question heading in this section. On the back of the flash card, write the answer to the question. Use the flash cards to review what you have learned.
the phospholipid bilayer.
Each phospholipid has a polar head and two nonpolar tails. The phosphate group in the phospholipid makes it polar. The polar head is attracted to water because water is also polar. The nonpolar tails, made of the fatty acids, are repelled by water. The phospholipid bilayer is arranged so that the polar heads can be closest to the water that is inside and outside the cell. Likewise, the nonpolar tails are farthest from the water because they are inside the phospholipid bilayer, as shown in the figure below. This bilayer structure is important for the formation and function of the plasma membrane.
Read to Learn Make Flash Cards Make
2. Explain the purpose of
-EMBRANE PROTEIN
/UTSIDE THE CELL
Picture This 3. Identify Circle one phospholipid. Label its head and tails.
#ARBOHYDRATE CHAIN
0OLAR HEADS
.ONPOLAR TAILS
#HOLESTEROL )NSIDE THE CELL 4RANSPORT PROTEIN
How does the phospholipid bilayer function? The phospholipid bilayer forms a barrier that is polar on the surface and nonpolar in the middle. Substances that can dissolve in water will not pass through the plasma membrane because they are stopped by the nonpolar middle. This allows the plasma membrane to separate the environment inside the cell from the environment outside the cell. Reading Essentials
Chapter 7 Cellular Structure and Function
73
chapter
What else is found in the plasma membrane?
7
-!). )DEA
What are transport proteins?
Cellular transport moves substances in and out of a cell.
4 section ●
Proteins also create tunnels through the plasma membrane. These proteins, known as transport proteins, move needed substances or waste materials through the plasma membrane. Transport proteins contribute to the selective permeability of the plasma membrane. Cholesterol molecules are nonpolar. They move among the tails of the phospholipids. Cholesterol helps prevent the fatty-acid tails from sticking together, keeping the plasma membrane fluid. Cholesterol also helps maintain homeostasis in a cell.
Carbohydrates and proteins might stick out from the plasma membrane. They help the cell identify chemical signals from the environment. For example, carbohydrates in the plasma membrane might help disease-fighting cells identify and attack a potentially harmful cell.
What is the fluid mosaic model?
5. Name three substances that move among the phospholipids of the plasma membrane.
74
Cellular Structure and Function
the process of diffusion, facilitated diffusion, and active transport ■ effect of hypotonic, hypertonic, or isotonic solutions on a cell ■ how large particles enter and exit a cell ■
How does cholesterol help cells?
What substances help identify chemical signals?
All the components of the plasma membrane are in constant motion. Phospholipids can move sideways within the plasma membrane. Proteins, carbohydrates, and cholesterol molecules move among the phospholipids. The phospholipid bilayer creates a sea in which all the other molecules float. As the individual molecules move around, a pattern, or mosaic, is formed on the surface of the plasma membrane. This organization of the plasma membrane is called the fluid mosaic model. It is fluid because the molecules are moving and being rearranged. It is called a mosaic because scientists can observe clear patterns on the surface of the plasma membrane. biologygmh.com
Before You Read Describe on the lines below how you would move a large box that weighs more than you do. Then read the section to learn how large particles move in and out of cells.
Read to Learn Create a Quiz As you read this section, write quiz questions based on what you have learned. After you write the questions, answer them.
Record Information Make a three-pocket Foldable from an 11 ⫻ 17 sheet of paper. As you read, record information about cellular transport on quarter sheets of notebook paper and store them in the appropriate pocket.
Diffusion Substances dissolved in water move constantly and randomly. Imagine you place a drop of red ink on the left side and a drop of blue ink on the right side of a dish of water. The ink moves randomly through the water and turns the water purple as the colors mix. The ink has diffused in the water. Diffusion is the net movement of particles from an area where there are more particles of the substance to an area where there are fewer particles. Diffusion does not require additional energy because the particles are already in motion. Concentration is the amount of a substance in an area. Diffusion continues until the concentrations are the same in all areas of the water. The dish of water has reached dynamic equilibrium, in which the particles continue to move randomly, but the overall concentration does not change.
What affects the rate of diffusion?
Diffusion
80
Active Transport
Passive Transport
Chapter 7 Cellular Structure and Function
Concentration, temperature, and pressure affect the rate of diffusion. Diffusion occurs more quickly when the concentration, temperature, or pressure are high because the particles collide more often. The size and charge of a substance also affects the rate of diffusion. Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
transport proteins.
Cellular Transport
What You’ll Learn
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
4. Define the role of
Cellular Structure and Function
Cholesterol, proteins, and carbohydrates move among the phospholipids in the plasma membrane. Proteins are found on both the inner surface and the outer surface of the plasma membrane. Proteins on the outer surface are called receptors because they send signals to the inside of the cell. Proteins on the inner surface anchor the plasma membrane to the cell’s internal support structure. These proteins give the cell its shape.
What is facilitated diffusion?
How do hypotonic solutions and hypertonic solutions differ?
Water can diffuse across the plasma membrane. However, other ions and molecules that cells need to function cannot diffuse across the plasma membrane. Molecules such as sugars and chlorine need help to move from outside the cell’s environment to inside the cell. Facilitated diffusion uses transport proteins to help move some ions and small molecules across the plasma membrane. One type of facilitated diffusion is shown in the figure below.
move into a cell placed in a hypotonic solution?
Picture This 1. Explain Use this figure to
)NSIDE
(IGHER #ONCENTRATION
explain facilitated diffusion to a partner.
,OWER #ONCENTRATION
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Diffusion of water and facilitated diffusion of ions and small molecules occur without additional energy because the particles are already moving. When no energy is added, the transport is referred to as passive transport.
Active Transport Substances might need to move from an area of lower concentration to an area of higher concentration. Transport proteins help move substances across the plasma membrane against the normal flow. This movement against the normal flow requires energy and is called active transport.
Osmosis: Diffusion of Water Water passes in and out of the cell through the plasma membrane. The diffusion of water across a selectively permeable membrane is called osmosis (ahs MOH sus). Osmosis helps the cell maintain homeostasis.
Transport of Large Particles Some substances are too large to move by diffusion or active transport. Endocytosis is the process by which a cell surrounds a substance in the outside environment with a portion of the plasma membrane, then pinches off the substance, leaving it inside the cell. Exocytosis is the process by which large substances exit the cell. Both processes, as shown in the figure below, require energy. As with other forms of transport, endocytosis and exocytosis help cells maintain homeostasis.
What is the result of osmosis? Most cells undergo osmosis because they are surrounded by watery solutions. These solutions have different concentrations than the inside environment of the cell. Before osmosis, the concentration inside and outside the cell have not reached dynamic equilibrium. After osmosis, the concentrations are the same on both sides of the membrane, and dynamic equilibrium has been reached.
2. Explain Why is the cell at equilibrium in an isotonic solution?
What happens to a cell in an isotonic solution?
%NDOCYTOSIS )NSIDE THE CELL
4. Label the cell structure
A cell in an isotonic solution has the same concentration in its cytoplasm as its surrounding watery environment. Water continues to move through the plasma membrane, but water enters and leaves the cell at the same rate. The cell is at equilibrium with its surrounding environment. Reading Essentials
Picture This through which substances pass as they leave the cell during exocytosis.
Chapter 7 Cellular Structure and Function
81
82
Chapter 7 Cellular Structure and Function
0LASMA MEMBRANE
6ACUOLE
%XOCYTOSIS /UTSIDE THE CELL
6ESICLE
)NSIDE THE CELL
biologygmh.com
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
/UTSIDE
/UTSIDE THE CELL
4RANSPORT PROTEIN
3. Analyze Why does water
If a cell is placed in a solution that has a lower concentration of dissolved substances, the cell is in a hypotonic solution. There is more water outside the cell than inside the cell. Osmosis moves water into the cell. As water moves into an animal cell, the plasma membrane swells. If the solution is too hypotonic, pressure builds inside the cell, and it might burst. In a plant cell, the cell wall keeps it from bursting. As the central vacuole fills with water, the plasma membrane pushes against the cell wall. The plant cell becomes firmer. In a hypertonic solution, the concentration of dissolved substances outside the cell is higher than inside. There is more water inside the cell. During osmosis, more water moves out of the cell than into it. Animal cells shrink in hypertonic solutions. The loss of water in plant cells causes wilting.
CELL THEORY
3.1
Power Notes
Scientists who contributed to the cell theory:
CHAPTER 3 Cell Structure and Function
SECTION
The principles of cell theory: 1.
2.
3. Important technological advances:
Copyright © McDougal Littell/Houghton Mifflin Company.
The cell theory is:
This is a
This is a
cell.
cell. All cells have:
Unit 2 Resource Book McDougal Littell Biology
Power Notes
3
Chapter 3 Reading Guide Questions 3.1 (pg 70-72) 1. How did the following scientists contribute to the cell theory: Hooke-
Leeuwenhoek-
Schleiden-
Schwann-
Virchow-
2. How did improvements with the microscope form the cell theory?
3. What are the 3 major principles of the cell theory?
4. What is cytoplasm?
5. What are organelles?
6. Cells can be divided into 2 categories. What are they and how do they differ?
7. What structural differences suggest that eukaryotic cells evolved from prokaryotic cells?
8. Suppose a certain poison kills human cells by blocking pores in the nuclear membrane. Explain why it would not kill bacteria?
CELL MEMBRANE
3.3
Power Notes
Functions:
Fluid mosaic model:
CHAPTER 3 Cell Structure and Function
SECTION
Phospholipids:
Cell Membrane Other molecules: • • •
Sketch a semipermeable membrane.
Selective permeability: •
Copyright © McDougal Littell/Houghton Mifflin Company.
• • •
Receptors: • Intracellular
• Membrane
Unit 2 Resource Book McDougal Littell Biology
Power Notes
11
Chapter 3 Reading Guide Questions 3.3 (pg 81-84) 1. What is the function of the cell membrane?
2. What is a phospholipid?
3. The structure of a phospholipids causes them to organize into a bilayer in the presence of water. Explain.
4. What part of the membrane is nonpolar?
5. Why do scientists describe the arrangement of molecules that make up a cell membrane a fluid mosaic model?
6. What is selective permeability in your own words.
7. Describe a selectively permeable membrane that you see in everyday life.
8. How do molecules cross membranes and how is it based on size?
9. How do receptors transmit messages across cell membranes?
10. How do intracellular membrane receptors differ from membrane receptors?
11. If proteins were rigid why would the make poor receptors?
DIFFUSION AND OSMOSIS
3.4
Power Notes
Sketch molecules diffusing into a cell.
1. outside
CHAPTER 3 Cell Structure and Function
SECTION
Passive transport:
3. inside 2. Diffusion:
Osmosis:
How do different solutions affect cells?
Copyright © McDougal Littell/Houghton Mifflin Company.
Label the type of solution each red blood cell is in. Draw arrows on each cell to show the direction of osmosis.
1.
3.
5.
2.
4.
6.
Sketch molecules entering a cell by facilitated diffusion. 1. outside
Facilitated diffusion:
3. inside
2.
Unit 2 Resource Book McDougal Littell Biology
Power Notes
15
ACTIVE TRANSPORT, ENDOCYTOSIS, AND EXOCYTOSIS
3.5
Power Notes
Sketch molecules entering a cell by active transport. 1. outside
CHAPTER 3 Cell Structure and Function
SECTION
Active transport:
3. inside 4.
2.
Endocytosis:
Copyright © McDougal Littell/Houghton Mifflin Company.
1.
2.
3.
2.
3.
Exocytosis:
1.
Unit 2 Resource Book McDougal Littell Biology
Power Notes
19
Topic / Concept: Active Transport Vs. Passive Transport
Venn Diagram
Summary Paragraph . . .
TEST PREPARATION CHECKLIST BIOLOGY:
Name: _________________________________ Date: __________________________________
Gather Information Subject of Test: _Cell Structure and Function (pt.1) ___________________ Date of Test: ______________ Chapters/Concepts to Study: Chapter 3 (3.1,3.3, 3.4, and 3.5) _______________________ Other Information covered (videos, handouts, labs, quizzes, assignments, etc.):
What types of questions will be on the test? Check all that will be on the test. ___True/False
__Multiple Choice _35
_____Labeling
____Fill-in-the-blank
Total Number of Questions ____35_______
_Matching _____Essay
__Short Answer _ _____Other
Total Number of Points Possible ____100______
Plan From the list below, check any study strategy that you believe will be of use to you in preparing for this test. Add any strategies you use that are not listed below. _____Compete the chapter reviews in Biology McDougal Littell for the chapters covered on the test. _____Complete the online activities for the concepts covered on test and answer the online activity questions. www.classzone.com
_____ Update lecture notes with a friend’s notes (especially if you have been absent during the unit). _____ Update lecture notes with information from your textbook. _____ Reread textbook and paraphrase the material.
_____ Complete the practice test sheet. _____ Define key terms from each concept covered on the test. _____ Practice vocabulary by making flashcards _____ Outline textbook chapters. _____ Complete the online chapter assessments for the chapters covered on test. www.classzone.com
_____ Make a test including a variety of questions and types of questions.
_____ Review guided reading packets for each chapter covered on test.
_____ Teach material to someone else. _____ Draw a picture or diagram of what you are studying.
_____ Record or take notes from test review session. _____ Make a timeline. _____ Reread lectures notes aloud. _____ Study with a friend. _____ Rewrite lecture notes. _____ Highlight lecture notes. _____ Summarize lecture notes (find and note main ideas) _____ Explain lecture notes to a friend or relative.
_____ Meet with teacher before or after school to discuss material for the test. _____ Utilize the Resource Room (RSP) to ask questions and prepare for test.
Study Log When you study for a test, make sure you do something other than just read. For example, write, draw, read aloud, tape, talk, highlight, make flash cards, etc. Be creative. When you are actively involved in your study strategy, you will remember more of the material and understand it better. When did you study?
How long did you study?
How did you study? What did you do?
Analysis Complete this section after you have received your graded test back. Points Earned/Points Possible
______________
Percentage/Letter Grade on Test
______________
What worked well for you in preparing for this test?
What will you do differently next time (besides “study more”)? Be specific.
ASSIGNMENT LOG CHAPTER 3 (Part 1) You may find it helpful to keep up with your daily grade in this class by using the following sheet. Record the due date for the assignment. Each day an assignment is due the teacher or T.A. will go around and stamp workbooks. Workbooks will be collected and graded the week before grade checks or the day of your test. Before you turn in your workbook check whether you completed an assignment or not. When your workbook is returned record the points that you earned. Your average is determined by dividing the points you have earned by the points possible. Remember that assignments turned in late will not receive higher than an 80%. Incomplete assignments may receive no credit and is up to the discretion of the teacher. When you are out of school it is your responsibility to make up assignments and get them stamped the following day. If you do not understand an assignment it is your responsibility to ask for help. Copying workbooks is not allowed and is considered cheating. You must complete your own work. Lastly, cheating will result in a grade of zero for all those involved including the owner of the completed workbook.
GOOD LUCK! ASSIGNMENT DATE COMPLETED? POSSIBLE POINTS DUE POINTS EARNED Starters 10 Test Prep Checklist:Plan 10 Study Log 10 Chapter 3 Pt 1 Vocabulary 20 3.1 Power Notes 15 3.1 Reading Questions 20 Cell Theory Mapping/Summary 25 3.3 Power Notes 15 3.3 Reading Questions 20 Cell Membrane Diagrams 15 Cell Membrane 25 Mapping/Summary 3.4 Power Notes 15 3.5 Power Notes 15 Passive Vs. Active Venn 25 Diagram and Summary Transport Mapping/Summary 25 Practice Quiz 30 Chapter 3 (Part 1) Exam 100 Total 395
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Chapter 3 Key Vocabulary (Part 1)
Word
Cell Theory
Cytoplasm
Organelle
Prokaryotic Cell
Eukaryotic Cell
Definition
Picture
Cell Membrane
Phospholipid
Fluid Mosaic Model
Selectively Permeable
Receptor
Passive Transport
Diffusion
Concentration Gradient
Osmosis
Isotonic
Hypertonic
Hypotonic
Facilitated Diffusion
Active Transport
Endocytosis
Phagocytosis
Exocytosis
chapter
7
Cellular Structure and Function
2 section ●
Structure of the Plasma Membrane You have learned that lipids are large molecules made up of glycerol and three fatty acids. A phospholipid (fahs foh LIH pid) is made up of glycerol, two fatty acids, and a phosphate group. The plasma membrane is made up of two layers of phospholipids arranged tail-to-tail in what is called a phospholipid bilayer. The phospholipid bilayer allows the plasma membrane to survive and function in its watery environment.
The Plasma Membrane
-!). )DEA
A cell’s plasma membrane helps maintain homeostasis.
What You’ll Learn how the cell’s plasma membrane functions ■ the role of proteins, carbohydrates, and cholesterol in the plasma membrane ■
Before You Read A window screen in your home allows air to pass through while keeping insects out. In this section, you will learn about a cell structure that has the same basic function. On the lines below, list some things you think would be allowed to pass into a cell and some things that would be kept out.
What is the structure of the phospholipid bilayer?
1. Highlight the items in the figure that enter the cell through the plasma membrane. Circle the items that exit the cell.
A cell’s survival depends on maintaining balance, called homeostasis. The plasma membrane is the cell structure primarily responsible for homeostasis. It is the thin, flexible boundary between the cell and its watery environment. Nutrients enter the cell and wastes leave the cell through the plasma membrane. Selective permeability (pur mee uh BIH luh tee) of the plasma membrane allows some substances to pass through while keeping others out. The figure below shows selective permeability of the cell’s plasma membrane. The arrows show common substances that enter and leave the cell. The plasma membrane controls how, when, and how much of these substances enter and leave the cells. /UTSIDE THE CELL /XYGEN 0LASMA MEMBRANE
Chapter 7 Cellular Structure and Function
7ASTES
7ASTES 7ATER
72
'LUCOSE
#ARBON DIOXIDE )NSIDE THE CELL
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Picture This
Function of the Plasma Membrane Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
a flash card for each question heading in this section. On the back of the flash card, write the answer to the question. Use the flash cards to review what you have learned.
the phospholipid bilayer.
Each phospholipid has a polar head and two nonpolar tails. The phosphate group in the phospholipid makes it polar. The polar head is attracted to water because water is also polar. The nonpolar tails, made of the fatty acids, are repelled by water. The phospholipid bilayer is arranged so that the polar heads can be closest to the water that is inside and outside the cell. Likewise, the nonpolar tails are farthest from the water because they are inside the phospholipid bilayer, as shown in the figure below. This bilayer structure is important for the formation and function of the plasma membrane.
Read to Learn Make Flash Cards Make
2. Explain the purpose of
-EMBRANE PROTEIN
/UTSIDE THE CELL
Picture This 3. Identify Circle one phospholipid. Label its head and tails.
#ARBOHYDRATE CHAIN
0OLAR HEADS
.ONPOLAR TAILS
#HOLESTEROL )NSIDE THE CELL 4RANSPORT PROTEIN
How does the phospholipid bilayer function? The phospholipid bilayer forms a barrier that is polar on the surface and nonpolar in the middle. Substances that can dissolve in water will not pass through the plasma membrane because they are stopped by the nonpolar middle. This allows the plasma membrane to separate the environment inside the cell from the environment outside the cell. Reading Essentials
Chapter 7 Cellular Structure and Function
73
chapter
What else is found in the plasma membrane?
7
-!). )DEA
What are transport proteins?
Cellular transport moves substances in and out of a cell.
4 section ●
Proteins also create tunnels through the plasma membrane. These proteins, known as transport proteins, move needed substances or waste materials through the plasma membrane. Transport proteins contribute to the selective permeability of the plasma membrane. Cholesterol molecules are nonpolar. They move among the tails of the phospholipids. Cholesterol helps prevent the fatty-acid tails from sticking together, keeping the plasma membrane fluid. Cholesterol also helps maintain homeostasis in a cell.
Carbohydrates and proteins might stick out from the plasma membrane. They help the cell identify chemical signals from the environment. For example, carbohydrates in the plasma membrane might help disease-fighting cells identify and attack a potentially harmful cell.
What is the fluid mosaic model?
5. Name three substances that move among the phospholipids of the plasma membrane.
74
Cellular Structure and Function
the process of diffusion, facilitated diffusion, and active transport ■ effect of hypotonic, hypertonic, or isotonic solutions on a cell ■ how large particles enter and exit a cell ■
How does cholesterol help cells?
What substances help identify chemical signals?
All the components of the plasma membrane are in constant motion. Phospholipids can move sideways within the plasma membrane. Proteins, carbohydrates, and cholesterol molecules move among the phospholipids. The phospholipid bilayer creates a sea in which all the other molecules float. As the individual molecules move around, a pattern, or mosaic, is formed on the surface of the plasma membrane. This organization of the plasma membrane is called the fluid mosaic model. It is fluid because the molecules are moving and being rearranged. It is called a mosaic because scientists can observe clear patterns on the surface of the plasma membrane. biologygmh.com
Before You Read Describe on the lines below how you would move a large box that weighs more than you do. Then read the section to learn how large particles move in and out of cells.
Read to Learn Create a Quiz As you read this section, write quiz questions based on what you have learned. After you write the questions, answer them.
Record Information Make a three-pocket Foldable from an 11 ⫻ 17 sheet of paper. As you read, record information about cellular transport on quarter sheets of notebook paper and store them in the appropriate pocket.
Diffusion Substances dissolved in water move constantly and randomly. Imagine you place a drop of red ink on the left side and a drop of blue ink on the right side of a dish of water. The ink moves randomly through the water and turns the water purple as the colors mix. The ink has diffused in the water. Diffusion is the net movement of particles from an area where there are more particles of the substance to an area where there are fewer particles. Diffusion does not require additional energy because the particles are already in motion. Concentration is the amount of a substance in an area. Diffusion continues until the concentrations are the same in all areas of the water. The dish of water has reached dynamic equilibrium, in which the particles continue to move randomly, but the overall concentration does not change.
What affects the rate of diffusion?
Diffusion
80
Active Transport
Passive Transport
Chapter 7 Cellular Structure and Function
Concentration, temperature, and pressure affect the rate of diffusion. Diffusion occurs more quickly when the concentration, temperature, or pressure are high because the particles collide more often. The size and charge of a substance also affects the rate of diffusion. Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
transport proteins.
Cellular Transport
What You’ll Learn
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
4. Define the role of
Cellular Structure and Function
Cholesterol, proteins, and carbohydrates move among the phospholipids in the plasma membrane. Proteins are found on both the inner surface and the outer surface of the plasma membrane. Proteins on the outer surface are called receptors because they send signals to the inside of the cell. Proteins on the inner surface anchor the plasma membrane to the cell’s internal support structure. These proteins give the cell its shape.
What is facilitated diffusion?
How do hypotonic solutions and hypertonic solutions differ?
Water can diffuse across the plasma membrane. However, other ions and molecules that cells need to function cannot diffuse across the plasma membrane. Molecules such as sugars and chlorine need help to move from outside the cell’s environment to inside the cell. Facilitated diffusion uses transport proteins to help move some ions and small molecules across the plasma membrane. One type of facilitated diffusion is shown in the figure below.
move into a cell placed in a hypotonic solution?
Picture This 1. Explain Use this figure to
)NSIDE
(IGHER #ONCENTRATION
explain facilitated diffusion to a partner.
,OWER #ONCENTRATION
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Diffusion of water and facilitated diffusion of ions and small molecules occur without additional energy because the particles are already moving. When no energy is added, the transport is referred to as passive transport.
Active Transport Substances might need to move from an area of lower concentration to an area of higher concentration. Transport proteins help move substances across the plasma membrane against the normal flow. This movement against the normal flow requires energy and is called active transport.
Osmosis: Diffusion of Water Water passes in and out of the cell through the plasma membrane. The diffusion of water across a selectively permeable membrane is called osmosis (ahs MOH sus). Osmosis helps the cell maintain homeostasis.
Transport of Large Particles Some substances are too large to move by diffusion or active transport. Endocytosis is the process by which a cell surrounds a substance in the outside environment with a portion of the plasma membrane, then pinches off the substance, leaving it inside the cell. Exocytosis is the process by which large substances exit the cell. Both processes, as shown in the figure below, require energy. As with other forms of transport, endocytosis and exocytosis help cells maintain homeostasis.
What is the result of osmosis? Most cells undergo osmosis because they are surrounded by watery solutions. These solutions have different concentrations than the inside environment of the cell. Before osmosis, the concentration inside and outside the cell have not reached dynamic equilibrium. After osmosis, the concentrations are the same on both sides of the membrane, and dynamic equilibrium has been reached.
2. Explain Why is the cell at equilibrium in an isotonic solution?
What happens to a cell in an isotonic solution?
%NDOCYTOSIS )NSIDE THE CELL
4. Label the cell structure
A cell in an isotonic solution has the same concentration in its cytoplasm as its surrounding watery environment. Water continues to move through the plasma membrane, but water enters and leaves the cell at the same rate. The cell is at equilibrium with its surrounding environment. Reading Essentials
Picture This through which substances pass as they leave the cell during exocytosis.
Chapter 7 Cellular Structure and Function
81
82
Chapter 7 Cellular Structure and Function
0LASMA MEMBRANE
6ACUOLE
%XOCYTOSIS /UTSIDE THE CELL
6ESICLE
)NSIDE THE CELL
biologygmh.com
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
/UTSIDE
/UTSIDE THE CELL
4RANSPORT PROTEIN
3. Analyze Why does water
If a cell is placed in a solution that has a lower concentration of dissolved substances, the cell is in a hypotonic solution. There is more water outside the cell than inside the cell. Osmosis moves water into the cell. As water moves into an animal cell, the plasma membrane swells. If the solution is too hypotonic, pressure builds inside the cell, and it might burst. In a plant cell, the cell wall keeps it from bursting. As the central vacuole fills with water, the plasma membrane pushes against the cell wall. The plant cell becomes firmer. In a hypertonic solution, the concentration of dissolved substances outside the cell is higher than inside. There is more water inside the cell. During osmosis, more water moves out of the cell than into it. Animal cells shrink in hypertonic solutions. The loss of water in plant cells causes wilting.
CELL THEORY
3.1
Power Notes
Scientists who contributed to the cell theory:
CHAPTER 3 Cell Structure and Function
SECTION
The principles of cell theory: 1.
2.
3. Important technological advances:
Copyright © McDougal Littell/Houghton Mifflin Company.
The cell theory is:
This is a
This is a
cell.
cell. All cells have:
Unit 2 Resource Book McDougal Littell Biology
Power Notes
3
Chapter 3 Reading Guide Questions 3.1 (pg 70-72) 1. How did the following scientists contribute to the cell theory: Hooke-
Leeuwenhoek-
Schleiden-
Schwann-
Virchow-
2. How did improvements with the microscope form the cell theory?
3. What are the 3 major principles of the cell theory?
4. What is cytoplasm?
5. What are organelles?
6. Cells can be divided into 2 categories. What are they and how do they differ?
7. What structural differences suggest that eukaryotic cells evolved from prokaryotic cells?
8. Suppose a certain poison kills human cells by blocking pores in the nuclear membrane. Explain why it would not kill bacteria?
CELL MEMBRANE
3.3
Power Notes
Functions:
Fluid mosaic model:
CHAPTER 3 Cell Structure and Function
SECTION
Phospholipids:
Cell Membrane Other molecules: • • •
Sketch a semipermeable membrane.
Selective permeability: •
Copyright © McDougal Littell/Houghton Mifflin Company.
• • •
Receptors: • Intracellular
• Membrane
Unit 2 Resource Book McDougal Littell Biology
Power Notes
11
Chapter 3 Reading Guide Questions 3.3 (pg 81-84) 1. What is the function of the cell membrane?
2. What is a phospholipid?
3. The structure of a phospholipids causes them to organize into a bilayer in the presence of water. Explain.
4. What part of the membrane is nonpolar?
5. Why do scientists describe the arrangement of molecules that make up a cell membrane a fluid mosaic model?
6. What is selective permeability in your own words.
7. Describe a selectively permeable membrane that you see in everyday life.
8. How do molecules cross membranes and how is it based on size?
9. How do receptors transmit messages across cell membranes?
10. How do intracellular membrane receptors differ from membrane receptors?
11. If proteins were rigid why would the make poor receptors?
DIFFUSION AND OSMOSIS
3.4
Power Notes
Sketch molecules diffusing into a cell.
1. outside
CHAPTER 3 Cell Structure and Function
SECTION
Passive transport:
3. inside 2. Diffusion:
Osmosis:
How do different solutions affect cells?
Copyright © McDougal Littell/Houghton Mifflin Company.
Label the type of solution each red blood cell is in. Draw arrows on each cell to show the direction of osmosis.
1.
3.
5.
2.
4.
6.
Sketch molecules entering a cell by facilitated diffusion. 1. outside
Facilitated diffusion:
3. inside
2.
Unit 2 Resource Book McDougal Littell Biology
Power Notes
15
ACTIVE TRANSPORT, ENDOCYTOSIS, AND EXOCYTOSIS
3.5
Power Notes
Sketch molecules entering a cell by active transport. 1. outside
CHAPTER 3 Cell Structure and Function
SECTION
Active transport:
3. inside 4.
2.
Endocytosis:
Copyright © McDougal Littell/Houghton Mifflin Company.
1.
2.
3.
2.
3.
Exocytosis:
1.
Unit 2 Resource Book McDougal Littell Biology
Power Notes
19
Topic / Concept: Active Transport Vs. Passive Transport
Venn Diagram
Summary Paragraph . . .
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