Bio1 Reviewer Part1.docx

Discovery of Cells:  1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.  He described the cells as tiny boxes or a honeycomb  He thought that cells only existed in plants and fungi Anton van Leuwenhoek  1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms

 He called them “animalcules”  He also observed blood cells from fish, birds, frogs, dogs, and humans  Therefore, it was known that cells are found in animals as well as plants Development of Cell Theory  1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells  1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.  1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells. The Cell Theory  1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)  2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)  3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

Selective permeability - regulates chemical composition of the cell, it selects what enters into the cell Phospholipids - are lipids that help control the substances that enters and leaves the cell Phosphor - phosphate head; water-loving (hydrophilic) Lipid - fatty acid tail; water-fearing (hyrophobic); stores energy for longer period of time Bi - 2 Proteins - important/essential biological molecules that is a product of a cell’s genetic translation

Cells with more than one nucleus include muscle cells and liver cells, largely because of the massive volume of cytoplasm and number of organelles that need controlling. Nucleic Acid: contains hereditary or genetic information Deoxyribose nucleic acid (DNA) – genetic materials are found Ribonucleic acid (RNA) – carries order issued by the DNA concerning protein synthesis Chromosomes-long thin thread of chromatin, 46 found in human body (blueprint) controls all cellular activity such as growth and cell division.

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“Powerhouse of the cell” Cellular respiration occurs here to release energy for the cell to use Bound by a double membrane Has its own strand of DNA

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Production of ATP (adenosine triphosphate) – Chief energy storing molecule used by the organisms; needed for growth and repair; energy

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A.k.a. “ER” Connected to nuclear membrane Highway of the cell Rough ER: studded with ribosomes; it makes proteins Smooth ER: no ribosomes; it makes lipids

The cells conveyor belt, transports materials Stores, modifies and packages proteins

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Found only in plant cells Contains the green pigment chlorophyll Site of food (glucose) production Bound by a double membrane

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Chloroplasts absorb light energy, which is the catalyst for photosynthesis.

Actin, also found in muscle cells, mainly help maintain cell shape in their cytoskeletal role. Microtubules mostly move organelles around the cell. Intermediate filaments also provide structural support.

RIBOSOMES   

Site of protein synthesis, helps in the production of proteins Found attached to rough ER or floating free in cytosol Produced in a part of the nucleus called the nucleolus

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A polypeptide is a chain of amino acids. In this diagram, you can see the ribosome is making a polypeptide, also known as a protein. Protein examples= (support) collagen, elastin, keratin, (transport) hemoglobin, (hormones) insulin,(movement) actin, myosin, (defense) antibodies and enzymes

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LYSOSOMES  

Garbage disposal of the cell Contain digestive enzymes that break down wastes

CELL WALL    

Found in plant and bacterial cells Rigid, protective barrier Located outside of the cell membrane Made of cellulose (fiber)

CENTRIOLES   

Aids in cell division Usually found only in animal cells Made of microtubules and is part of the cytoskeleton  Organizing Chromosomes. Every animal-like cell has two small organelles called centrioles. They are there to help the cell when it comes time to divide. They are put to work in both the process of mitosis and the process of meiosis.

VACUOLES       

Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes, wastes, pigments, etc Disposal sites for metabolic byproducts Produces pigments that color the cells, that help attract pollinating insects to flowers Protects the plant against predators by producing poisonous or unpalatable to animals Growth of plant cells

Prokaryotes  Pro = before  Karyose = kernel, which represents the nucleus  So prokaryotes don’t have a distinct nucleus  Ex. Bacteria Eukaryotes  Eu = true  Karyose = kernel, the nucleus  So eukaryotes are the cells with a true nucleus  Ex. Found in animals, plants, and fungi (yeast)

What they have in common  DNA  Cell (plasma) membrane  Ribosomes  Simple in Prokaryotic, complex in Eukaryotic  Cytoplasm  Allow the flow of nutrients and wastes to enter and leave the cell  Have similar metabolic ( life processes) like photosynthesis and respiration  Require a supply of energy  Made from the same basic chemicals  Carbohydrates, proteins, nucleic acid, fats, minerals, and vitamins Differences  That’s what they have in common, but there are significant differences too.  The two main ones are age and structure. Age Differences  Scientists believe that prokaryotic cells (in the form of bacteria) were the first life forms on earth. They are considered “primitive” and originated 3.5 billion years ago. That is 2 billion years before eukaryotic cells and billions of years before our earliest ancestor, the hominids.  4.6 billion years ago – Earth was formed  3.5 billion years ago – the first life arose: prokaryotic bacteria  1.5 billion years ago – eukaryotic cells arose  500 million years ago – multi-celled eukaryotes arose  3 million years ago – our earliest ancestor, the hominids, appeared Structural Differences  Eukaryotic cells contain two important things that prokaryotic cells do not:  A nucleus  Membrane bound organelles

Eukaryotic and Prokaryotic Cell Structure

Cell Structure

Prokaryotic Cell

Typical Animal Eukaryotic Cell

Cell Membrane

Yes

Yes

Cell Wall

Yes

No

Cilia or Flagella

Yes, simple

Yes, complex

Endoplasmic Reticulum

No

Yes

Golgi Complex

No

Yes

Lysosomes

No

Yes

Mitochondria

No

Yes

Nucleus

No

Yes

Ribosomes

Yes, simple

Yes, complex