Lecture 15 Membrane Structure (ch11)

Question 1

What is more abundant, proteins or lipids in the cell membrane? (and by how much)

Answer 1

Lipids are 50x more than proteins

Question 2

What makes up 50% of the membrane mass and does most of the cell membrane’s functions?

Answer 2

Protiens! Because they are bigger they take up more mass

Question 3

What is an example of an anchor protein?

Answer 3

Integrin

Question 4

What is an example of an ion channel proteiN?

Answer 4

K + leak channel (K+ can leave cell)

Question 5

Which portion of the membrane associated proteins are hydrophobic?

Answer 5

The part that is inside the membrane.

Question 6

Which portion of the membrane associated proteins are hydrophillic?

Answer 6

The part that is in the cytosol or outside the cell (interstitial space)

Question 7

What type of protein is peripheral?

Answer 7

Protein attached protein (1 protein attached to another)

Question 8

Which protein is integral but not in the membrane?

Answer 8

Lipid linked protein

Question 9

What conformation is a protein that crosses the cell membrane (most cases)? What is this protein called?

Answer 9

Alpha helical; transmembrane protein

Question 10

A multipass transmembrane protein with multiple alpha helices is oriented how? If this is the case it is called a ____ ___

Answer 10

Each of the pieces face their hydrophobic side in and hydrophilic side out; a nuclear pore

Question 11

If there is a multipass transmembrane protein with beta sheets, what does it form? What is an example?

Answer 11

A beta barrel; porin proteins

Question 12

What do porin proteins form?

Answer 12

Channels holding water in the outer membrane of bacteria

Question 13

How can we take out a protein forma membrane to study its function? What is the con?

Answer 13

Detergent; Can disrupt the protein structure :(

Question 14

What is an alternative to detergent?

Answer 14

Cryonelectromicroscopy- study proteins while still IN membrane

Question 15

What are two commonly used detergents?

Answer 15

SDS and triton X100

Question 16

What do detergents from?

Answer 16

Micells (little balls that look like dandelions)

Question 17

What is the main component of the RBC cortex? Mutations of this would cause ___

Answer 17

Spectrin; anemia

Question 18

How is spectrin attached to the RBC membrane?

Answer 18

Actin moves transmembrane proteins to connect spectrin — membrane

Question 19

What side foes the protein cortex attach to of the membrane? WHat is its job?

Answer 19

Protein cortex —cytosol side of membrane; biconcave disc shape

Question 20

Other than RBCs, other human and animal cells have a cortex composed of ____ and ___

Answer 20

actin and myosin

Question 21

What organisms have a cell wall instead of a cortex?

Answer 21

Plants, yeasts, and bacteria

Question 22

What did the mouse -human hybrid cell experiment tell us?

Answer 22

Proteins can move laterally in each single layer of the bilayer (most proteins)

Question 23

What is it called when a membrane protein is ‘grounded’ to its spot?

Answer 23

A membrane domain

Question 24

Give examples of how a cell can be restricted movement by tethering?

Answer 24

To the cortex, the extracell matrix, to to other proteins of another cell’s surface

Question 25

How do diffusion barriers work?

Answer 25

They make a (tight junction) barrier between the apical and basal laminas in epithelium

Question 26

The tight junctions (diffusion barriers) in the gut ET are important for __ ___

Answer 26

nutrient absorption

Question 27

What is the surface of the cell coated with? What do they do?

Answer 27

A layer of carbs; they help cells recognize each other, attract water ->slimy, and protect from damage

Question 28

If a lipid has a sugar added on it, it is called a ___

Answer 28

glycolipid

Question 29

If a protein has a sugar added on it, it is either a __ or ___

Answer 29

glycoprotein (attach to short chains oligosach) or proteoglycan (to long chains polysach)

Question 30

What is cell to cell recognition and adhesion mediated by? Give 2 examples

Answer 30

Lectin proteins; sperm reognizes egg or WBC recognizes where an infection is