CHAPTER 3 - STRUCTURE & FUNCTION OF THE CELL
CELL = Basic unit of life
I. MEMBRANES - surrounds cells & many organelles
A. FLUID-MOSAIC MODEL (p. 60)
1. "Proteins in a sea of phospholipids"
2. AMPHIPATHIC - 2 natures
a. HEAD - HYDROPHYLLIC - CHARGED - POLAR
b. TAIL - HYDROPHOBIC - NEUTRAL - NON-POLAR
B. BILAYER
1. FAT SOLUBLE
2. WATER INSOLUBLE
3. PORES, CHANNELS, CARRIERS
4. CONSTANT ENERGY INPUT TO MAINTAIN
C. GLYCOCALYX - "SUGAR COATING" - FOOD/FRIEND/FOE
1. GLYCOPROTEINS & GLYCOLIPIDS
II. INTRACELLULAR STRUCTURES (Fig. 3.1, p. 57 & Tab. 3.1, p. 58-59)
A. PROTOPLASM = all material of cell
B. P.M. = PLASMA/CELL MEMBRANE - surrounds
C. CYTOPLASM/CYTOSOL = FLUID MATRIX
D. CYTOSKELETON (p. 77)
1. MICROTUBULES - flagella, cilia, division
2. MICROFILAMENTS - ACTIN, muscle, structure, microvilli
3. INTERMEDIATE FILAMENTS - strength
E. ORGANELLES
1. NUCLEUS - DNA, control & regulation
2. RIBOSOMES - protein synthesis
3. ENDOPLASMIC RETICULUM - network, transport, communication.
a. ROUGH - protein syn. for export
b. SMOOTH - lipid syn, detox, Ca storage
4. GOLGI - packaging for export
5. VESICLES - product, waste
6. LYSOSOME - digestion, contain enzymes
7. MITOCHONDRIA - powerhouse, ATP prod.
8. CENTRIOLES - spindle during division
III. MOVEMENT THROUGH P.M. (Tab. 3.3, p. 67)
A. PASSIVE - [HI]è [LO]
- NO ENERGY REQUIRED
1. DIFFUSION - random (p. 68)
2. FACILITATED DIFFUSION - w/carrier or mediator (Frig. 3.20,p. 72)
3. OSMOSIS - diffusion of H2O across SELECT. PERM. MEMBRANE
- HI [H2O] è LO [H2O] (p. 69)
a. HYPERTONIC - HI [ ] of solute (p. 71)
b. HYPOTONIC - LO [ ] of solute
c. ISOTONIC - equal [ ]
4. FILTRATION - movement forced by pressure difference
B. ACTIVE - [LO] è [HI] (p. 73-74)
- ENERGY REQUIRED
- CARRIER or MEDIATOR REQUIRED
1. ENDOCYTOSIS - movement INTO cell (p. 75)
a. PHAGOCYTOSIS - cell eating
b. PINOCYTOSIS - cell drinking
c. RECEPTOR-MEDIATED - very specific
2. EXOCYTOSIS - movement OUT of cell (p. 76)
a. WASTES, SECRETORY PRODUCTS - horm., enzy., etc.
IV. CELL METABOLISM - requires ATP
A. GLYCOLYSIS – Glucose è pyruvic acid; cytoplasm
B. ANAEROBIC RESPIRATION è cytoplasm, 2 ATP
C. AEROBIC RESPIRATION è mitochondria, 36-38 ATP
V. PROTEIN SYNTHESIS = GENE EXPRESSION (Fig 3.40, p. 87)
A. TRANSCRIPTION - mRNA from DNA (p. 88)
1. NUCLEUS
2. DNA uncoils
3. RNA polymerase reads DNA, assembles RNA
4. A-U, T-A, C-G, G-C
B. TRANSLATION - protein from mRNA (p. 90)
1. CYTOPLASM, mRNA codes for protein
2. TRIPLET CODE - CODON - 3 bases = 1 AMINO ACID
3. STEPS: ribosome, mRNA, A.A. & energy
a. CHARGING - aa to tRNA, requires ATP!
b. INITIATION - ribosome binds to mRNA, reads codon
- tRNA brings correct A.A.,
- ANTICODON on tRNA attaches to CODON
c. ELONGATION - A.A.s added to chain-PEPTIDE bond
d. TERMINATION - STOP CODON
4. CODE is a. UNIVERSAL b TRIPLET c. DEGENERATE
VI. CELL DIVISION
A. CELL LIFE CYCLE: (p. 91)
1. INTERPHASE - DNA replication – in NUCLEUS, normal cell activities
2. MITOSIS = division of nucleus (p. 94)
a. PROPHASE
b. METAPHASE
c. ANAPHASE
d. TELOPHASE
3. CYTOKINESIS = division of cytoplasm
(p. 99)
B. MITOSIS (p. 94) vs. MEIOSIS = REDUCTION DIV.
1. ASEXUAL - 1 SEQUENCE SEXUAL - 2 SEQUENCES
2. 2 IDENTICAL CELLS 1 or 4 DIFFERENT CELLS
3. SOMATIC, 2n è 2n GERM, 2n è 1n
MITOSIS: MEIOSIS: SYNAPSIS & CROSSING
OVER DURING PROPHASE I