Membranes

Question 1

What is the function of the plasma membrane?

Answer 1

To allow the passage of necessary molecules, protecting the cell

Question 2

What are the four components of cellular membranes

Answer 2

Phospholipid bilayer, transmembrane proteins, interior protein network, cell surface markers

Question 3

What are integral membrane proteins?

Answer 3

Span the lipid bilayer, nonpolar regions are embedded in the interior, polar regions protrude

Question 4

What do integral proteins do?

Answer 4

playing critical roles in movement of molecules across bilayer and the transduction of energy and signals.

Question 5

What is the 6 major functions of membrane proteins

Answer 5

transport,
enzymatic activity,
Receptor proteins (signal transduction)
cell-cell recognition,
intercellular joining (tight junctions)
attachment to the cytoskeleton and extracellular matrix
desmodomes
gap junctions

Question 6

Why is membrane fluidity important?

Answer 6

for permeability and enzyme function

Question 7

What factors impact the membrane fluidity?

Answer 7

Membrane composition and temperature

Question 8

What roles do unsaturated fatty acids have in membranes

Answer 8

unsaturated fatty acids make membranes more fluid, and the kinks from the double bonds keep them from packing tightly

most membranes contain steroids like cholesterol which can increase or decrease membrane fluidity based on temperature

Question 9

How does cholesterol act as a temperature buffer?

Answer 9

At cool temps; cholesterol maintains fluidity by preventing tight packing via double bonds

at warm temps: cholesterol restrains the movements of phospholipids, making it less fluid

Question 10

How does selective permeability regular cells molecular traffic

Answer 10

small, nonpolar molecules can cross the membrane directly

large, polar molecules do not cross the membrane easily

Question 11

what are the types of passive transport?

Answer 11

simple diffusion, osmosis, facilitated diffusion

Question 12

what are the types of active transport?

Answer 12

Primary active, secondary active

Question 13

What are the types of transport proteins

Answer 13

can be channel, carrier, pump, or cotransporter

Question 14

What are 2 energy sources Active Transport:

Answer 14

ATP and the electrochemical gradient

Question 15

What is passive transport

Answer 15

it is the movement of molecules down the concentration gradient (no energy)

Question 16

what is osmosis

Answer 16

osmosis is the net diffusion of water across a membrane toward a higher solute concentration

Question 17

what is tonicity

Answer 17

the ability of a solution to cause a cell to gain or lose water

depends on concentration of non-penetrating solutes

Question 18

what is an isotonic solution

Answer 18

it is when the solute concentration is the same on the inside of the cell, therefore no net water movement occurs across the membrane

Question 19

what is a hypertonic solution

Answer 19

it is when the solute concentration is greater on the outside than the inside of the cell; causing water to rush out and shrink

Question 20

what is hypotonic solution

Answer 20

when the solution solute concentration is less than the inside of the cell; causing water to rush in and gain size

Question 21

what is facilitated diffusion?

Answer 21

they are passive carrier mechanisms that move molecules from higher to lower concentrations

Question 22

What is active transport?

Answer 22

they are energy dependent carrier mechanisms that move charged or polar molecules against their concentration gradient

Question 23

what are channel proteins

Question 24

What are membrane carbohydrates

Answer 24

they are either glycolipids or glycoproteins and face the extracellular side of the membrane

they are important for cell-cell recognition and communication

Question 25

Most lipid and some proteins move:

Answer 25

laterally

Question 26

what are the 3 conditions that detemne the direction of flow in a membrane

Answer 26

relative concentration on either side, voltage differences, and gated channels that may be opened or closed

Question 27

What drives the diffusion of K + through its channel (not the pump)

Answer 27

there is a higher concentration on the inside of the cell which drives the K+ out. However, the excessive positive charge on the outside of the cell impedes the diffusion of K+ out of the cell

Question 28

what do peripheral proteins do

Answer 28

cell-cell recognition, acting as enzymes, transportation

Question 29

what is a membrane pore

Answer 29

b-sheet barrel, allows water and small polar molecules to pass throguh

Question 30

what are the membrane components that move substances by facilitated diffusion

Answer 30

channel proteins, carrier proteins, porin (aquaporin)

Question 31

what is a co-transporter?

Answer 31

is a form of active transport because it is using the energy from one concentration gradient to transport another molecule across the membrane against its concentration gradient

Question 32

What are three specific protein types that transport sodium and what type of transport are they?

Answer 32

Na+ Channel: Facilitated diffusion (passive)

Na+/K+ Pump: Primary Active Transport

Na+/ glucose cotransporter: Seconary Active Transport

Question 33

Is ATP required for movement of glucose in a glucose transporter

Answer 33

no

Question 34

Is ATP required for the movement of glucose in a Na+/Glucose Transporter

Answer 34

no, its energy is supplied by the electrochemical gradient

Question 35

true or false: phospholipids and integral membrane proteins can move laterally along the plane of the plasma membrane

Answer 35

true

Question 36

true or false: in simple diffusion, the concentration of one substance affects the diffusion of another

Answer 36

false

Question 37

true or false: alpha helices and beta-sheets describe the tertiary structure of proteins

Answer 37

false, it describes the secondary

Question 38

True or false: DNA is found in the nucleus, mitochondria,and chloroplasts of eukaryotic cells

Answer 38

True

Question 39

what is the role of the ecm in animals

Answer 39

support, adhesion, movement, regulation