Biomembranes II (Lecture 8)

Question 1

______ can be used to solubilize lipids

and membrane proteins.

Answer 1

Detergents

Question 2

_____ contain a charged group and tend to denature proteins.

Answer 2

Ionic detergents

Question 3

______ detergents lack a charged group and can extract protein in active form .

Answer 3

Non-ionic detergents

Question 4

WHat are the two types of ionic detergents?

Answer 4

Sodium deoxycholate
Sodium dodecylsulfate (SDS)

Question 5

What are the two types of non-ionic detergents?

Answer 5

Triton X-100

Octylglucoside

Question 6

______ proteins purify and biochemically characterize as-is.

Answer 6

Soluble

Question 7

______ proteins are most soluble in water; remove from membrane with high salt concentration to disrupt ionic bonds or with divalent ion chelators (eg. EDTA)

Answer 7

Peripheral

Question 8

______ proteins might remove anchor and study as a soluble protein.

Answer 8

Membrane-anchored

Question 9

______ membrane proteins are hydrophobic membrane-spanning regions tend to aggregate and precipitate when removed from membranes; need to solubilize with non-ionic detergent

Answer 9

Integral

Question 10

______ is caused when the concentration is above the CMC and you cannot interact with the protein

Answer 10

Micelles

Question 11

Light energy capture occurs in ______ of chloroplasts

Answer 11

Thylakoid membrane

Question 12

The soluble portion of the chloroplast is the ______.

Answer 12

Stroma

Question 13

The interior of the thylakoid vesicles is the ______

Answer 13

Thylakoid lumen

Question 14

What is the difference between chlorophyll a and chlorophyll b

Answer 14

CHO group for b instead of methyl group for a

Question 15

What are the four stages of photosynthesis?

Answer 15

1. Light absorption, generation of high-energy
   electrons, and O2 formation from H2O
   — Photosystem core proteins maintain chlorophyll in orientation & position optimal for light absorption
2. Electron transport leading to reduction of NADP+ to NADPH and PMF generation
3. Synthesis of ATP
4. Carbon fixation (conversion of CO2 into carbohydrates)

Question 16

You attempted to isolate chloroplasts, and tested the results using DCPIP. If purification of chloroplasts was ineffective, so that there was very little PSII present, what result would you expect?

Answer 16

DCIP would remain blue

Question 17

True or False: For fatty acid biosynthesis, you always need an even number of carbons from 14-20 carbons for phospholipid and 26 carbons for sphingolipids.

Answer 17

True

Question 18

______ are fatty acids have no carbon-carbon double bonds (saturated with hydrogen) and ______ are fatty acids that DO have at least one carbon-carbon double or triple bond.

Answer 18

Saturated, unsaturated

Question 19

Unesterified fatty acids (not linked to CoA) are transported by ______ in the cytosol.

Answer 19

Fatty acid binding proteins (FABP)

Question 20

Where can active FABPs be found?

Answer 20

Adipose tissue and active muscle

Question 21

Where are phospholipids synthesized?

Answer 21

Cytosolic face of ER membrane (usually smooth ER)

Question 22

______ is made in the ER from palmitoyl CoA and serine.

Answer 22

Sphingolipids

Question 23

Where is cholesterol usually made?

Answer 23

Animal cells only, mainly in liver, ER cytosol and membrane

Question 24

What are the 3 types of lipid transport between organelles?

Answer 24

Vesicle transport
Membrane “bridges”
Lipid-transfer proteins

Question 25

What are the 4 types of lipoproteins that transfer larger fats in the bloodstream.

Answer 25

Chylomicrons Very low density lipoproteins (VLDL) Low Density lipoproteins (LDL) High-density lipoproteins (HDL)

Question 26

What type transfers the most triglycerides?

Answer 26

Chylomicron

Question 27

WHat type transfers the most protein?

Answer 27

HDL

Question 28

WHat type transfers the most cholesterol

Answer 28

LDL

Question 29

Where are most lipids synthesized?

Answer 29

Liver