Biology 100 Review

BIOLOGY 100 CELL DIVISION AND CELL CYCLE Types of Cell: 1. SOMATIC  Make up the bulk of the body. 2. GERMINAL/REPRODUCTIVE  The egg and sperm cells. CHROMOSOMES  

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CHARACTERISTICS  Darkly-staining finite bodies within the nucleus of eukaryotic cells. COMPOSITION  DNA  RNA  Protein PARTS  Chromonemata  Two thread-like, consists of major and minor coils.  Centromere  Point of attachment of chromosomes to the spindle fiber.  Chromatid  One-half of the chromosomes or the duplicated chromosomes.  Mitotic Spindle  A system of microtubules (spindle fibers) that both guide and “pull” products of chromosome replication.  After cell division, the spindle microtubules disappear

TYPES OF CELL DIVISION 1. AMITOSIS  Direct  Cell simply constricts and finally divides into two daughter cells. 2. MITOSIS  Indirect  Cell passes through several stages.

STAGES OF MITOSIS 1. Prophase (PREPARE)  Nucleolus disappears  Chromatin condenses into chromosomes  Separation of entrosomes  Formati on of the mitotic spindle 2. Prometaphase  Nuclear membrane breaks down  Kinetochore microtubules invade nuclear space, and attach to kinetochores.  Polar microtubules push against each other, moving centrosomes apart

3. Metaphase (MIDDLE)  Chromosomes line up along metaphase plane (imaginary plane) 4. Anaphase (AWAY)  Chromosomes break at centromeres, and sister chromatds move to opposite ends of the cell 5. Telophase  The chromosomes reach the opposite poles of the cell and begin to lengthen.  The spindle fibers dissolve and a nuclear membrane forms around each mass of chromatin.  Telophase is followed by cytokinesis, the division of the cytoplasm. 6. Interphase  During interphase, the cell increases in size.  The DNA of the chromosomes is replicated.  The centrosome is duplicated. SIGNIFICANCE OF UNDERSTANDING MITOSIS  Preserves the continuity of life  Allows organisms to grow, repair, and reproduce  Important in unlocking the mysteries of embryonic development and stem cells  Important in understanding how cancer develops and could someday provide clues in stopping cancer. GENE STRUCTURE COMPOSITION OF GENES 1. NUCLEOPROTEINS  Made up of nucleic acids and proteins 2. NUCLEIC ACID  Made up of nucleotides 3. NUCLEOTIDES  Basic unit of a DNA molecule ARCHITECTURE OF DEOXYRIBOSE NUCLEIC ACID (DNA) 1. BASES/NITROGEN COMPOUNDS  PURINES i. (G)uanine ii. (A)denine iii. Made up of larger molecules  PYRIMIDINES i. (C)ytosine ii. (T)hymine iii. Made up of small molecules 2. SUGAR  RIBOSE i. In RNA  DEOXYRIBOSE i. In DNA 3. PHOSPHATES

BIOSYNTHESIS OF THE NUCLEIC ACID DNA 1. Template 2. Primer 3. Four (4) deoxyribose triphosphates i. dATP ii. dCTP iii. dGTP iv. dTTP 4. Enzymes of DNA polymerase III MODERN CONCEPTS OF REPLICATION 1. COMPLEMENTARY COPYING

THE CELL CYCLE - The sequence of regular repetitive physical and chemical processes taking place within the cell. FOUR PHASES 1. GAP 1 i. Cell growth ii. Normal functions 2. SHYNTHESIS PHASE OF INTERPHASE i. Copies DNA 3. GAP 2 i. Additional growth 4. MITOSIS PHASE i. Division of the cell nucleus (MITOSIS) ii. Division of the cell cytoplasm (CYTOKINESIS) = Mitosis occurs only if the cell is large enough and the DNA undamaged. MEIOSIS

2. DISCONTINUOUS MECHANISM

1. CHROMOSOMES FROM PARENTS 2. CHROMOSOMES REPLICATE  During meiosis, chromosomes from both parents are copied and paired to exchange portions of DNA. 3. LIKE CHROMOSOMES PAIR UP 4. CHROMOSOMES SWAP SECTIONS OF DNA  This creates a mix of new genetic material in the offspring’s cells. 5. CHROMOSOME PAIRS DIVIDE 6. CHROMOSOMES DIVIDE  Daughter nuclei have single chromosomes and a new mix of genetic material.

DIFFUSION - Dispersion of molecules of one substance over those of another. DIFFERENCE MITOSIS  Involves one division of the genetic information, followed by cytokinesis, and produces two diploid cells

TYPES 1. OSMOSIS i. Diffusion of a solvent or gas through a selective permeable membrane from greater to lesser concentration.

MEIOSIS  Involves two nuclear divisions, which makes four haploid cells  Meiosis 1 is different from Mitosis SIMILARITIES  Chromosomes duplicate once  Both make it possible for cells to inherit genetic information

EXCHANGE OF MATERIALS 1. ACTIVE i. Needs energy within the cell ii. Needs oxygen iii. Lesser to greater concentration iv. FASTER FLOW 2. PASSIVE i. No need for energy ii. No need for oxygen iii. Greater to lesser concentration iv. SLOWER FLOW

2. DIALYSIS i. Diffusion of dissolved substances (solutes) from greater to lesser solute concentration.

OSMOTIC PRESSURE - Pressure exerted by the molecules of solute is directly proportional to the no. of particles or molecules. ISOTONIC SOLUTION - A solution whose concentration is EQUAL within the cell. ISOSMOTIC SOLUTION - A solution whose osmotic pressure is EQUAL to that within the cell.

FACTORS THAT AFFECT THE DEGREE OF PERMEABILITY 1. 2. 3. 4.

SIZE OF MOLECULES SIZE OF PORES SOLUBILITY ELECTRICAL CHARGES