Membrane structure and function

Question 1

Membrane def

Answer 1

Selectively permeable barrier that seperate the inside of a cell from the outside

Question 2

Inside of an organelle

Answer 2

Lumen

Question 3

outside of an organelle

Answer 3

cytosol

Question 4

Phospholipid bilayer def

Answer 4

component of cell membranes forming barrier between cell interior and external environment
- hydrophilic heads face water on both sides and tails inwards

Question 5

Plasma membrane def

Answer 5

structure that surrounds the cell and controls what gets into and out

Question 6

Components of plasma membrane

Answer 6

phospholipids and proteins

Question 7

Do proteins and lipids move?

Answer 7

Yes

Question 8

What are the ways phospholipids move? What about proteins?

Answer 8

Lateral diffusion(side to side) for phospholipid and protein, flip-flop(inside to outside) for phospholipid

Question 9

What is the fluid mosaic model?

Answer 9

Membranes are a mosaic of lipids, proteins and carbohydrates

Question 10

Characteristics of fluid mosaic model

Answer 10

fluid nature(lateral diffusion),Mosaic(various proteins are embedded in bilayer) => different lids and proteins in membrane

Question 11

Describe the experiment that showed membranes are fluid

Answer 11

Mouse cell and Human fused

Question 12

The main types of membrane proteins?

Answer 12

Peripheral and Integral

Question 13

Characteristics of peripheral membrane protein

Answer 13

not embedded in membrane, easy to remove, lacks hydrophobic sequences

Question 14

Characteristics of integral membrane protein

Answer 14

Across the membrane,difficult to remove, hydrophobic regions interact with interior of membrane

Question 15

True or False? Integral Proteins can extend all the way through membrane or only partway into interior

Answer 15

True

Question 16

True or False? Integral Proteins have hydrophobic parts and hydrophilic parts

Answer 16

True

Question 17

Functions of membrane functions

Answer 17

Transport(ex: aquaporin allowing passage water)
Enzymatic reactions(ATP synthase produces atp)
Signal transduction(insulin receptor => binds = glucose)’
Cell-Cell recognition(blood type)
Intercellular joining
Stabilizing of membranes

Question 18

Glycoprotein def

Answer 18

membrane proteins with carbohydrate groups attached to them

Question 19

Glycolipids def

Answer 19

membrane lipids with carbohydrates attached to them

Question 20

feature of Cholesterol in membranes

Answer 20

important component of phospholipid bilayer

Question 21

Describe asymmetry in membranes

Answer 21

inner layer not same as outer layer, so sideness

Question 22

What does cholesterol do related to membrane fluidity

Answer 22

Keeps membranes from becoming too fluid when temp rises, and from becoming too rigid when temp decrease

Question 23

True or False, Heat increases fluidity

Answer 23

True

Question 24

True or False? Shorter and unsaturated phospholipids do NOT increase fluidity

Answer 24

False:
shorter = more flexible, and unsaturated = create space, so prevents becoming solid

Question 25

Where are membrane proteins and lipids synthesized?

Answer 25

Endoplasmic reticulum

Question 26

How do glycolipids get formed?

Answer 26

Glycoproteins undergo carbohydrate modification in golgi apparatus

Question 27

What can enter biological membranes?

Answer 27

Hydrophobic molecules and small uncharged polar molecules

Question 28

What cannot enter biological membranes?

Answer 28

Large uncharged polar molecules, ions

Question 29

What types of molecules use simple(passive) diffusion?

Answer 29

Hydrophobic molecules, small polar molecules

Question 30

What type of transport do large polar molecules and ions use?

Answer 30

facilitated diffusion(passive) and active transport(active)

Question 31

What type of molecule uses bulk trasnport?

Answer 31

Large macromolecules, Large amounts of smaller molecules

Question 32

3 Types of membrane transport

Answer 32

Diffusion,facilitated diffusion, active transport

Question 33

Explain the basis of diffusion

Answer 33

No energy required, substances move down their concentration gradient from high to low

Question 34

Characteristics of facilitated diffusion

Answer 34

Does not require energy, needs a channel or carrier(integral protein)

Question 35

What is usually transported by facilitated diffusion?

Answer 35

Ionic compounds and polar compounds

Question 36

What is water transported by?(facilitated diffusion)

Answer 36

aquaporin

Question 37

Characteristics of active transport

Answer 37

Solutes move from low-high, integral protein needed, energy needed

Question 38

What do active transport transport?

Answer 38

Polar and charged/ionic molecules

Question 39

Osmosis def

Answer 39

diffusion of water across a semi permeable membrane

Question 40

Where does water flow to during osmosis?

Answer 40

Area of higher solute concentration(lower water concentration)

Question 41

isotonic def

Answer 41

same solute concentration

Question 42

Why is Osmosis important?

Answer 42

water balance, excess water flow will be dangerous for cell

Question 43

How do plant cells prevent water flow excess?

Answer 43

cell wall which provides structural support

Question 44

True or False? Animal cells have cell wall

Answer 44

False

Question 45

Hypertonic def

Answer 45

having a higher solute concentration(COMPARE)

Question 46

Hypotonic def

Answer 46

Having a lower solute concentration(COMPARE)

Question 47

What happens when a cell placed in hypertonic solution?

Answer 47

Cell shrinks, water flows out of the cell

Question 48

What happens when a cell placed in a hypotonic solution?

Answer 48

Cell expands, water flows into cell(burst)

Question 49

What happens when a cell placed into isotonic solution?

Answer 49

Nothing

Question 50

What happens for plant cells when cell placed into hypotonic solution?

Answer 50

Cell walls prevent damage breakdown

Question 51

What happens for plant cells when cell placed into hypertonic solution?

Answer 51

Plasma membrane pulls away from cell wall

Question 52

What happens for plant cells when cell placed into isotonic solution?

Answer 52

Cell not damaged but lacks structural support(flaccid)

Question 53

Types of bulk transport

Answer 53

endocytosis(move into cell),exocytosis(secreted out of cell)

Question 54

How does endocytosis work?

Answer 54

Plasma membrane changes shape to form a pocket around molecules, then closes off

Question 55

Phagocytosis def

Answer 55

particle engulfed by pseudopodia and digested after fusion with lysosome

Question 56

Pinocytosis

Answer 56

extracellular fluid containing solutes is gulped(cell drinking)

Question 57

pseudopodia def

Answer 57

temporary,cytoplasmic extensions of a cell membrane used for engulfing food

Question 58

How does exocytosis work

Answer 58

Proteins synthesized in ER and packaged into transport vesicles => vesicle fuses with PM and releases contents