2. Cell physiology

Question 1

Cell Structure:

 3 major subdivisions

Answer 1

o Plasma memb. that encloses cell
o Nucleus which contains DNA
o Cytoplasm liquid environment of inner cell

Question 2

Plasma Membrane

Answer 2

Lipid molecules and proteins which enclose cell and act as selective barrier between ICF and ECF

Question 3

Nucleus

Answer 3

Largest organized cell component; contains DNA, which directs protein synthesis and serves as genetic blueprint during cell replication

Question 4

RNA

Answer 4

 Messenger (mRNA) copies code
 Ribosomal (rRNA) makes up ribosomes, large and small subunit
 Transfer (tRNA) delivers amino acids to peptide

Question 5

Cytoplasm

Answer 5

Compartment between membrane and nucleus

Filled with cytosol (gel liquid), organelles, and cytoskeleton

Question 6

Organelles

Answer 6

Membranous vs nonmembranous

Question 7

ER

Answer 7

 Site of protein synthesis
 Rough ER- contains ribosomes
 Smooth ER- lacks ribosomes, processes and packs protein, and stores calcium for release as second messenger

Question 8

Golgi

Answer 8

 Completes protein modifications and sorts, packs, and directs proteins to organelles or exocytosis
 Exocytosis
o Protein called clathrin helps to form a vesicle; this protein is useful for moving proteins and vesicles in and out of cells, esp. within synapses
 Endocytosis
o Pinocytosis: simple fluid uptake
o Receptor-mediated endocytosis: uses surface proteins to activate clathrin, which in turn enables pinching and vesicle formation
o Phagocytosis: large particle uptake (eating)

Question 9

Metabolism

Answer 9

Lysosomes: Large, uses hydrolytic enzymes to break peptides, destroys things
 Peroxisomes: Small, uses oxidative enzymes and produces H2O2, detoxifies things

Question 10

Mitochondria

Answer 10

 Converts food energy into ATP, which is cell’s energy currency
 2 membranes- inner one is folded into cristae, inside of which is the matrix

Question 11

Cytoskeleton

Answer 11

Cell support and structure

Question 12

Plasma membrane–phospholipid bilayer

Describe phospholipid structure

Answer 12

Glyceral molecules form the backbone.

To each glyceral is bound 2 fatty acids and a phospholipid head group

Question 13

Cholesterol

Answer 13

tucked between phospholipids, it contributes to membrane fluidity and stability

Question 14

Membrane Proteins

Answer 14

Form channels across membrane, Carrier molecules, Docking-marker acceptors, Membrane-bound enzymes, Receptor sites, Cell adhesion molecules (CAMs), Cell recognition

Question 15

Membrane Carbohydrates

Answer 15

glycolysis of Erythrocytic membrane groups plays large part in determining blood groups

Question 16

ECM made up of

Answer 16

o Collagen - multiple forms of connective protein
o Elastin - thin, shimmery membrane
o Fibronectin

Question 17

Desmosomes

Answer 17

 Made of keratin intermediate filaments which are very flexible and stretchy in the extracellular state (over the intracellular state)
 Anchors close, non-touching cells in stretchy tissues

Question 18

Tight junctions

Answer 18

 Used to separate compartments
 Prevent movement of substances between cells by firmly bonding cells together
 This forces substances through the cells, which is more selective
 Esp. important in digestive tract

Question 19

Gap junctions

Answer 19

small connecting tunnels made of connexon proteins
Allows free passage of very small ions and/or membrane potentials to pass between cells w/o an action potential
Each cell assembles half of a channel

Question 20

Diffusion:

Answer 20

 Uniform spreading out of molecules
 Dependent on Brownian motion and conc. gradients
 Critical for muscle contractions, nervous signaling, exchange of O2 and CO2, and movement of substances across kidney tubules

Question 21

Fick’s Law of Diffusion

Answer 21

 > conc. grad. inc. diff.
 ECF is large, so conc. changes very slowly
 Substances move freely between blood and ECF, but not ECF and ICF
 > permeability inc. diff.
 > S.A. inc. diff.
 > Mol. Weight dec. diff.
 > distance of diff. dec. diff.

Question 22

Osmosis: Net diffusion of water down its conc. gradient

Answer 22

 Hydrostatic pressure prevents infinite movement to side with higher conc. gradient
 Tonicity: osmolarity of solution in comparison to the cell
 Isotonic solution: Cell stays the same size
 Hypotonic solution: cell will swell (> water conc.)
 Hypertonic solution: cell will shrink (< water conc.)
 This generally initiates apoptosis