Ch. 7 Review

Question 1

What holds the lipid bilayer together?

Answer 1

Hydrophobic interactions

Question 2

Where are the hydrophobic and hydrophilic regions of a transmembrane protein?

Answer 2

Hydrophilic- sides facing extracellular matrix and cytosol, interior of protein

Hydrophobic- outside facing lipid bilayer

Question 3

The membrane is _______

Answer 3

FLUID

Question 4

Phospholipids move _____ not _______

Answer 4

Laterally, they don’t FLIP-FLOP

Question 5

Why don’t phospholipids flip-flop?

Answer 5

The phospholipids would have to then invert themselves, this requires more energy then lateral movement and it’s rare

Question 6

Do proteins in the membrane move?

Answer 6

Yes, only laterally for the same reasons as phospholipids

Question 7

Fluidity is essential for cells, what are the two reasons?

Answer 7

1. for permeability (slight!)
2. so the membrane proteins can function (ex. ETC in mitochondria for fluidity)

Ex homeostasis

Question 8

What factors influence fluidity?

Answer 8

1. temperature- High temp more fluid, low temp less fluid
2. type of fatty acids- saturated vs. unsaturated (more fluid)

Question 9

At a high temp there are more _______ fatty acids, at a low temp there are more _______ fatty acids

Answer 9

saturated, unsaturated

Question 10

Single celled life can ______ which types of fatty acids are present?

Answer 10

alter

Question 11

Membranes are mosaics that ______

Answer 11

1. contain a diverse set of proteins
2. some are embedded, some are not
   -integral vs peripheral proteins

Question 12

Membranes also contain 4 things

Answer 12

1. glycoproteins (oligosaccharide attached to amino acide side chain)
2. glycolipids (oligosaccharide and lipid)
3. oligosaccharides
4. receptors

Question 13

Proteins have a specific _______ which determines its _______

Answer 13

orientation, function

Question 14

What are the 6 types of membrane proteins mentioned in lecture?

Answer 14

1. transport
2. enzymatic activity
3. signal transduction
4. cell to cell recognition
5. intercellular signaling (cell junctions)
6. attached to the cytoskeleton

Question 15

What do cells need from the environment?

Answer 15

1. nutrients for energy, vitality and growth
   -sugars, amino acids, fatty acids
   -Na+ K+, vitamins allow us to do biochemistry
2. Gases (ex. O2)
3. Need to eliminate waste

Question 16

Membrane proteins maintain what and accommodate for what?

Answer 16

Must maintain internal environment, membrane proteins accommodate for the diversity of needs and nutrients

Question 17

What are the barriers to getting nutrients into the cell? What is the solution?

Answer 17

PROBLEM
1. nutrients are polar and charged, proteins need to help

2. The cell membrane has a hydrophobic core

SOLUTION
Membranes are selectively permeable

Question 18

What does selective permeability depend on?

Answer 18

1. permeability of a pure phospholipid bilayer
2. the presence of transport proteins

Question 19

What can cross the bilayer? What can’t?

Answer 19

CAN
small, nonpolar molecules (ex. O2)
small, polar molecules are partially blocked but can cross (ex. H2O)

CAN’T
large, polar molecules are totally blocked (ex. glucose)
charged substances of ANY size are totally blocked (ex. Na+ or K+)

Question 20

What are the two types of transport?

Answer 20

passive and active

Question 21

Is energy involved in passive transport?

Answer 21

There is no NET energy, BUT there is POTENTIAL energy

Question 22

Is energy involved in active transport?

Answer 22

YES, ATP is used

Question 23

What are the two types of passive membrane transport?

Answer 23

1. simple diffusion (small nonpolar substances)
2. Facilitated diffusion
   -channel and carrier proteins for polar and charged substances

Question 24

Transport and channel proteins are _______

Answer 24

SPECIFIC

Question 25

Define channel proteins

Answer 25

1. integral membrane protein completely spanning the membrane 2.Contains a HYDROPHILIC CORE, that recognizes ONE type of solute

Question 26

How do channel proteins recognize one specific solute?

Answer 26

based on specific shape, size, and polarity. The channel protein is used by individual atoms.

Question 27

What is an example of a channel protein?

Answer 27

ion channels (Na+, K+, Ca++) aquaporins

Question 28

What is osmosis? Why is it special?

Answer 28

Osmosis is the diffusion of water water VIOLATES high to low water diffuses from high to low concentration, the solutes remain constant

Question 29

What are examples of osmoregulation?

Answer 29

protists- contractile vacuoles bacteria- cell walls plants- cell walls animals- solute balancing

Question 30

Plants prefer which osmoregulation state? Animals prefer which one?

Answer 30

plants- hypotonic animals-isotonic

Question 31

Carrier proteins change _______ to allow _______ solute to pass through

Answer 31

shape, ONE

Question 32

Channel proteins are ______ and _______ change shape

Answer 32

static, DON'T

Question 33

Carrier proteins can transport

Answer 33

monomers like amino acids or glucose

Question 34

Why active transport?

Answer 34

1. so solutes can move AGAINST the concentration gradient to concentrate things within the cell 2. requires INPUT of ENERGY 3. requires a CARRIER protein

Question 35

What are the two types of active transport?

Answer 35

primary- used to concentrate ions via ion pumps, driven by ATP secondary- involves movement of TWO substances, COTRANSPORT, driven by the ion gradient

Question 36

What pump is essential for osmoregulation in animal cells?

Answer 36

Sodium potassium pump, which MAINTAINS the gradient 3 Na+ out, 2 K+ in

Question 37

What is an example of a secondary active transport?

Answer 37

Na+ driven glucose transport protein Glucose transport doesn't need ATP BUT it needs Na+, Na+ comes from active transport of sodium potassium pump, glucose transport needs ATP SECONDARILY

Question 38

Vesicles transport ______

Answer 38

transport macromolecules, particles, and small cells

Question 39

What are the two types of vesicle transport

Answer 39

exocytosis- secretion, out of cell endocytosis- phagocytosis, into cell

Question 40

Phagocytosis is ________ while receptor-mediated endocytosis is ________

Answer 40

nonspecific, specific