Cellular Physiology

Question 1

this is your sign to go familiarize yourself with parts of the cell!

Answer 1

thank you! I’m going to look at a diagram now (the one on slide 12 of lecture 2 is great!)

Question 2

4 basic concepts of cell theory

Answer 2

1. cells are building blocks of all life
2. cells are produced by division of pre-existing cells
3. cells are the smallest units that perform all vital physiological functions
4. each cell maintains homeostasis at the cellular level

Question 3

4 main types of biomolecules

Answer 3

proteins
carbohydrate
lipids
nucleic acids

Question 4

proteins

Answer 4

polymers of amino acids
functions: cell structure, function

Question 5

carbohydrates

Answer 5

precursors to many other carbohydrates, hydrated carbon
function: cell recognition, energy metabolism

Question 6

lipids

Answer 6

hydrophobic
functions: energy metabolism, cell structure and signalling

Question 7

nucleic acid

Answer 7

DNA + RNA
functions: coding, transmitting and expressing genetic information

Question 8

cell membrane functions

Answer 8

composed of lipids, carbs and proteins
anchoring to, and physical isolation from the environment
recognition
regulation of environment exchange
sensitivity to environment (receptors)
structural support
organelle organization

Question 9

which membrane proteins are classified by position?

Answer 9

integral (transmembrane) proteins
peripheral proteins

Question 10

which membrane proteins are classified by function?

Answer 10

anchoring
recognition
enzymes
receptors
carriers
leak channels
gated channels

Question 11

transmembrane/integral proteins

Answer 11

structural components of membrane

Question 12

peripheral proteins

Answer 12

attached to inner or outer surface of the membrane,

Question 13

anchoring proteins

Answer 13

attach cell membranes to one another, or to attach membrane to internal/external structures

Question 14

recognition proteins

Answer 14

identify cell, and prevent immune system attack

Question 15

enzymes

Answer 15

catalyze reactions in and out of the cell

Question 16

channel proteins include:

Answer 16

enzymes
leak channels
gated channels

Question 17

receptor proteins

Answer 17

bind to specific ligands in extracellular fluid

Question 18

carrier proteins

Answer 18

move solutes across membrane, may or may not require ATP

Question 19

leak channels

Answer 19

permit continuous or passive movement of water and ions

Question 20

gated channels

Answer 20

close or open to regulate ion movement

Question 21

passive movement across the membrane

Answer 21

molecules move along the concentration gradient from high to low

Question 22

active movement across the membrane

Answer 22

molecules move against concentration gradient (requires energy from ATP)

Question 23

diffusion

Answer 23

example of passive transport

lipid solid molecules can diffuse across the membrane
simple: large molecules cannot diffuse through unless transported through carrier mechanism
facilitated: requires a channel protein. small water soluble molecules and ions diffuse through membrane channels

Question 24

simple diffusion

Answer 24

concentration gradients provide chemical driving force for diffusion. drives overall movement of solute from regions of high to low concentration until uniformly distributed

Question 25

flux

Answer 25

rate of movement per time. diffusion continues until there is no net flux
net flux is 0 at equilibrium

Question 26

Fick’s Equation

Answer 26

net diffusion or flux (J) across a membrane

J= DA(ΔC)/Δx

D=diffusion coefficient, influenced by permeability of the molecule in specific environment
A= membrane surface area
C= concentration (looking for difference in C)
x= distance (looking for difference in distance)

flux is proportional to concentration gradient and inversely proportional to cross-sectional distance

Question 27

what 3 carriers are involved in facilitated diffusion

Answer 27

ion channels
porins
permeases

Question 28

which molecules use facilitated diffusion?

Answer 28

hydrophilic molecules

Question 29

ion channels

Answer 29

small pores for specific ions
open and close (gated) in response to cellular conditions, but some can be constantly open (leak)

Question 30

porins

Answer 30

like ion channels, but for large molecules

Question 31

permeases

Answer 31

function like enzymes
carries molecules across membrane

Question 32

3 kinds of gated channel proteins

Answer 32

voltage gated
ligand gated
mechanogated

Question 33

voltage gated

Answer 33

open in response to change in voltage

Question 34

ligand gated

Answer 34

open in response to a binding chemical cue (ligand)

Question 35

mechanogated

Answer 35

open in response to stretch on the membrane

Question 36

what is an example of primary active transport

Answer 36

the sodium potassium pump

Question 37

the sodium potassium pump

Answer 37

3 Na+ move OUT, 2 K+ move IN.
needs ATP to bind, which becomes ADP and leaves after transport

Question 38

secondary active transport

Answer 38

uses energy in electrochemical gradient from one molecule to drive movement of another molecule.
ex. sodium-glucose cotransporter

OR
cells also use exchange carriers where the molecules move in opposite directions.

Question 39

isotonic

Answer 39

same osmotic concentration in/outside cell. net flux=0

Question 40

hypotonic

Answer 40

more water outside the cell, water rushes in, resulting in swelling

Question 41

hypertonic

Answer 41

low water outside the cell, so water leaves the cell

Question 42

why are enzymes important physiologically

Answer 42

most biochemical reactions would occur too slowly to be meaningful without enzymes. they catalyze reactions

Question 43

3 facts about enzymes as biochemical catalysts

Answer 43

enzymes are active at low concentrations
enzymes increase the rate of reactions without being altered themselves in the process
enzyme activity is influenced by the environmental conditions such as temperature, pH

Question 44

how do enzymes affect reaction rates

Answer 44

they lower the activation energy, acting as catalysts. this allows the reaction to occur at a useful rate.

Question 45

why might solely relying on pH or temperature to activate reactions be a problem?

Answer 45

need excess heat, or too harsh of a pH shift, can cause damage.

Question 46

where does the substrate bind to the enzyme?

Answer 46

the active site

Question 47

what happens once the activation energy is met?

Answer 47

the substrate adopts a transition state, and changes into the product.

Question 48

are enzymatic reactions reversible?

Answer 48

yes! can go in both directions, usually

Question 49

draw out the enzyme complex diagram!

Answer 49

yes! (slide 28 for cellular physio)

enzyme available, substrate binds creating an enzyme-substrate complex, is converted to product, product is released, and enzyme is available again