ANATOMY & PHYSIOLOGY NOTES CH 3

I.Environ of the cell

AExtracellular Environment ECF

water, proteins, vitamins, hormones, salts

1.Interstitial fluid

a.fluid between cells

b.pathway for materials btwn cells

c.matrix--dense mat of protein strands where little fluid is exchanged

B.Intracellular Environment ICF

a. protoplasm: water, protein, carbohydrates, fats, nucleotides, electrolytes,

b.separated frm ECF by plasma membrane

c.protoplasm contains cytoplasm w/ organelles, nucleus, plasma membrane, considered alive

II.Cell Structure and Function

A.Plasma Membrane

1.Structure

a.lipid-protein bilayer

(1)lipid--hydrophilic head and hydrophobic tail

(a)substances must dissolve in oil to pass

(b)cholesterol provides mechanical strength

(2)protein

(a)provide channels for transport, regulated and unregulated

(b)glycoproteins--carbohydrate + protein--receptors and signals

2.Modifications to membrane

a.microvilli --small, slender projections for increased surface area

(1)cells that absorb and release

b.cilia --longer than cilia,

(1)microtubles-- organized proteins for support (2)move body fluids

c.flagella --one single long extension for movmnt

3.Functions

a.passive processes

(1)diffusion --high [ ] to low [ ] by kinetic energy

(a) along [ ] gradient until equilibrium

(2)facilitate diffusion --integral proteins provide a pathway for molecules too big to cross membrane

(a)glucose, also coupled with Na

(3)Osmosis --mvmnt of water acrss selectively permeable membrane, [ ] gradient determines movmnt

(a)isotonic solution

(b)hypertonic --ECF contains mre solutes, H2O mvs out--crenation

(c)hypotonic --ECF contains less solutes H2O moves in hypertrophy

(4)Filtration --mvmnt along pressure gradient, mainly small molecules in kidneys

b.active processes

(1)active transport --requires ATP and carrier protein

(1)against [ ] gradient, lrg molcles,

(2)cytosis --large volumes or particles

(1)endocytosis--phagocytosis and pinocytosis

(2)exocytosis--excretion vs. secretion

B.Cytoplasm

1.endoplasmic reticulum

2.Golgi apparatus

3.Mitochondria

4.lysosomes

5.peroxisomes

6.cytoskeleton--not membrn bound, provide structure

a.microtubles

b.centrioles

c.microfilaments

C.Nucleus large structure, easily seen w/ cmpd microscope, control center

1.nuclear membrn --double membrane, w/ pores to allow substancs to move between nucleoplasm and cytoplasm

2.Nucleoplsm--similar to cytoplasm, contains nucleoli and chromatin which change during cll life

a.nucleoli--composed of RNA and protein, maybe site of ribosome synthesis

b.chromatin--composed of single DNA strand, condense into chromosomes, contain genes

DProtein Synthesis 2 processes

1.genetic code --directs protein synthesis by AA sequence

a. message contained in sequence of nucleotides in DNA

b.triplet code --3 nucleotides code for each AA, 20 AA+ start and stop codes

c.gene --code for entire polypeptide

2.transcription --message transcribed from DNA to mRNA

a.all RNA formed this way, mRNA, tRNA, rRNA

b.codon--each nucleotide triplet that codes for 1 AA

3.translation --tRNA brings specific AA to mRNA, matches codon w/ its anticodon

a.AA are joined, tRNA released to find mre AA

b.continues until stop message than releases polypeptide

III.Cell Division

A.Mitosis division of nuclear material, increase cell #

1.interphase --cell growth and chromosome replication

2.prophase --chromo thicken, centromeres cnnct chromatids, nucleus disappears

3.metaphase --chromatids line up, membrane gone

4.anaphase --chromatids separate, cytokinesis begins

5.telophase

B.Meiosis reduction of chromsme #, for sexual reprod