Macromolecules and Membranes

Question 1

Glycosidic bonds

Answer 1

Bond between carbohydrate monomers, forms through condensation.

Question 2

α-glycosidic bonds vs β-glycosidic bonds

Answer 2

α - hydroxyl group below the sugar plane (starch and glycogen)
β - hydroxyl group above the sugar plane (cellulose)

Question 3

Oligosaccharides

Answer 3

Small chains of 3-10 saccharides covalently attached to lipids or proteins

Question 4

Amylose/Starch vs glycogen function

Answer 4

chemical energy storage in plants vs animals

Question 5

Starch and glycogen main and side chain bond type

Answer 5

α(1-4)
side chains connect via α(1-6)

Question 6

Cellulose main to side chain bond type

Answer 6

β(1-4)

Question 7

Fats (triglycerides), formation and bond type

Answer 7

1 glycerol + 3 fatty acids, ester linked

Question 8

Saturated vs unsaturated fats

Answer 8

No double bonds - solid at room temp, vs double bonds - liquid at room temp cause they can’t pack well.

Question 9

Plant and fish oils are generally ————- fats

Answer 9

Cis unsaturated fats (e.g. olive oil)

Question 10

Hydrogenation of vegetable oil

Answer 10

Forms saturated fats or TRANS unsaturated fats which are thought to be worse for health.

Question 11

Steroids

Answer 11

Amphipathic, such as cholesterol, estradiol, testosterone with a hydroxyl group.
Low density - bad high cholesterol levels associated with coronary artery disease.

Question 12

Formation of bonds between amino acids

Answer 12

Form peptide bods though condensation reactions from the carbonic group to the amino.

Question 13

Nonpolar amino acid characteristics

Answer 13

Hydrophobic, associate via Van der Waals forces and hydrophobic interactions.
Glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline.

Question 14

Polar-uncharged amino acid characteristics

Answer 14

Partial charges at physiological pH - form hydrogen bonds with other molecules.
Serine, threonine, cysteine, tyrosine, asparagine, glutamine.

Question 15

Polar-charged amino acid characteristics

Answer 15

have a full charge at physiologic pH, having the ability to form IONIC bonds with other charged species.
Aspartame and glutamate - acidic.
Lysine, arginine, histadine - basic.

Question 16

Glycine characteristics

Answer 16

TINY! Can by both hydrophilic and hydrophobic.

Question 17

Cysteine characteristics

Answer 17

Will form covalent bonds with another systemic to forma disulfide bond

Question 18

Proline characteristics

Answer 18

Will form a disruptive kink in a polypeptide

Question 19

Beta sheet

Answer 19

Carbonyl oxygens H-bond with the amino hydrogens of another peptide between TWO REGIONS of the same polypeptide and backbones are adjacent, parallel/antiparallel.

Question 20

Alpha helix

Answer 20

Carbonyl oxygens H-bond with amino hydrogens within the SAME REGION of a polypeptide. Across 4 amino acid intervals.

Question 21

Interactions of side chains (tertiary structure)

Answer 21

Disulfide bonds, H-bonds, ionic bonds, Van der Waals and hydrophobic interactions.

Question 22

Determining tertiary structure

Answer 22

X-ray crystallography, NMR

Question 23

Location of fibrous vs globular proteins

Answer 23

Outside the cell (collagens, keratins), vs found inside the cell.

Question 24

Pyruvate dehydrogenase multi-protein complex

Answer 24

Many segments with distinct structures and predictable functions, domains working in a semi-independent manner. “molecular machine”

Question 25

Christian Afinsen

Answer 25

1956, unfolded proteins with urea and mercaptoethanol, but reformed.

Question 26

Hsp70, BiP

Answer 26

Hsp70 - cytoplasm, Bip - ER. Binds new proteins as they are translocated into the ER using ATP hydrolysis and facilitate proper folding by preventing aggregation (inappropriate interactions)

Question 27

Chaperonin

Answer 27

Polypeptide enters cylinder, causing the cap to attach and the chaperonin conformationally changes to create a hydrophilic environment for proper folding.

Question 28

Membrane diameter

Answer 28

5-10 nm thick.

Question 29

Polar head group of phosphoglycerides

Answer 29

Includes a choline and phosphate group.

Question 30

Sphingolipids structure

Answer 30

No glycerol backbone, instead a sphingosine with one fatty acid attached, generally longer FA tails.

Question 31

Garter and Grendel

Answer 31

1925 Phospholipid bilayers will spontaneously form in water.

Question 32

3 movements of lipids in the membrane

Answer 32

Transverse diffusion (flip-flop between leaflets), rotation, lateral diffusion.

Question 33

Cholesterol on membrane fluidity

Answer 33

Pretty even distribution between leaflets. Increases rigidity at warmer temps by preventing movement, and increases fluidity at smaller temps due to its bumpy shape preventing tight packing.

Question 34

Characteristics of membrane carbohydrates

Answer 34

Always attached, and always face AWAY from the cytoplasm, important in: - cell to cell interactions - Sorting of proteins

Question 35

N-linked glycoproteins

Answer 35

Asparagine

Question 36

O-linked glycoproteins

Answer 36

Serine or threonine

Question 37

Glycoproteins determine cell type

Answer 37

O - absence. A - GalNAc. B - Gal.

Question 38

Integral membrane proteins

Answer 38

Asymmetric shape, amphipathic, α-helix. Use nonpolar amino acids to penetrate the membrane.

Question 39

Peripheral membrane proteins

Answer 39

Electrostatic bonds and hydrogen bonds to connect to integral membrane proteins. Dynamic and asymmetrical distribution.

Question 40

Lipid anchored membrane proteins

Answer 40

GPI - always facing away form the cytoplasm, attach directly to a polar head. Others attach directly to the lipid itself.

Question 41

GPI

Answer 41

Glyco-Phosphatidyl Inositol

Question 42

Larry Frye and Michael Edidin

Answer 42

Cultured mice/human cells, formed hybrid by virus-induced fusion, labelled proteins with specific fluorescent antibodies, begin to mix in 5 mins, completely mixed in 40 mins.

Question 43

Fluorescence Recover After Photobleaching

Answer 43

To study membrane protein fluidity. Membrane molecules labeled with a fluorescent dye, laser beam bleaches an area of the surface. Fluorescent molecules slowly diffuse into the bleached area as lipids move laterally.

Question 44

Restriction of movement (A-F)

Answer 44

- Random diffusion - Immobilised by underlying membrane skeleton - Interaction with motor proteins - Restricted by other integral proteins - Restricted by protein fences in the membrane skeleton - Restrained by extracellular materials

Question 45

4 features of lipid rafts

Answer 45

Tightly packed, sphingolipids, cholesterol, receptor proteins bind external chemical signal to move rafts.

Question 46

Globular proteins vs fibrous proteins

Answer 46

Compact globs, most proteins in the cell with several domains. Remain elongated, small specific group such as collagen as keratins that weave together structural uses no enzyme activity.