Exam 2

Question 1

In general, which form of secondary structure is least stable?

Answer 1

parallel beta sheets

Question 2

In a protein, the most conformationally restricted amino acid is ____; the least conformationally restricted is _____.

Answer 2

proline pro: glycine gly

Question 3

Of the following, which amino acid is least likely to be found on the surface of a single-subunit protein?

Answer 3

Trp

Question 4

list the amino acids in proteins that sugars are commonly linked to and briefly describe the linkage.

Answer 4

Asn - N-linked

Ser/Thr - O-linked

Question 5

A molecule that s critical in regulating membrane fluidity in animal cells is

Answer 5

cholesterol

Question 6

steroid hormones are

Answer 6

derivatives of cholesterol

Question 7

the three dimensional structure of a protein is determined by

Answer 7

the sequence of amino acids

Question 8

which of the following is not an example of a super-secondary structural element?

Answer 8

B-helix

Question 9

The protein Data Bank is a database that primarily contains information about?

Answer 9

protein structure

Question 10

A protein that contains 3 domains has which levels of protein structure?

Answer 10

Primary, secondary, and tertiary only

Question 11

Which of the following can play a role in stabilizing overall protein structure?

Answer 11

metal ions, disulfide bonds, hydrogen bonds

Question 12

unmodified carbohydrates are typically ________.

Answer 12

aldehydes or ketones with multiple hydroxyl groups

Question 13

a ketone and alcohol can react to form a _________.

Answer 13

hemiketal

Question 14

which of the following include only 3 carbon carbohydrates?

Answer 14

dihydroxyacetone and D- and L-glyceraldehyde

Question 15

Galactose prefers to cyclize into a

Answer 15

pyranose ring

Question 16

The amino sugars are aldose derivatives in which a hydroxyl functional group has been modified to an _______.

Answer 16

amine

Question 17

The storage form of glucose in animals includes

Answer 17

glycogen

Question 18

The monosaccharides above are examples of which type of isomer?

Answer 18

D

Question 19

They are fisher projections of

Answer 19

glucose and mannose

Question 20

glycoproteins are normally

Answer 20

found in membranes, secreted as extracellular proteins, more protein mass and less sugar mass

Question 21

The main component of a bacterial cell wall is a _______, which is composed mostly of ________.

Answer 21

proteoglycan, sugars

Question 22

Which of the following statements does not apply to fatty acids?

Answer 22

they usually have an odd number of carbons

they contain an ester functional group

Question 23

rank the melting point f the following fatty acids from lowest to highest:
cis-oleate (18:1)
palmitoletic acid (16:1)
linoleate (12:1)

Answer 23

3 > 2 > 1

Question 24

which of the following lipid types contains a sugar substituent?

Answer 24

gangliosides

Question 25

Which of the following membranes would be the most fluid?

Answer 25

a bilayer made of lipids with polyunsaturated 16-carbon fatty acids

Question 26

ceramides contain which of the follwing?

Answer 26

sphingosine and a sugar (no phosphate)

Question 27

The packing of subunits into larger protein complexes in keratin and collagen result in what unique characteristic

Answer 27

fibrous structure which gives great strength

Question 28

Define the term topological switch point that is used to describe a characteristic of protein structure.

Answer 28

point where consecutive secondary structures don't interact with each other

Question 29

what info can be taken from a Ramachandran diagram/plot?

Answer 29

what phi and angles are allowed in secondary structures

Question 30

mRNA

Answer 30

codes for protein

Question 31

rRNA

Answer 31

protein synthesis machinery

Question 32

tRNA

Answer 32

carries amino acid in protein synthesis

Question 33

Upon heating DNA strands do not separate starting at one end and separate sequentially like a zipper. Describe how two strands separate and what causes this type of separation?

Answer 33

DNA strands separate at many regions b/c A:T has 2 H-bonds & G:C has 3 H-bonds.

Question 34

What is lectin?

Answer 34

sugar binding proteins

Question 35

Hydrogen substituents in the pyranose ring preferentially occupy _____ positions in the chair conformation.

Answer 35

axial

Question 36

glycogen is most similar to the plant polysacharide

Answer 36

amylopectin

Question 37

Only B(1->4) bonds can be found in the plant product _______.

Answer 37

cellulose

Question 38

4 roles sugars can play in a living system:

Answer 38

energy source, carbon supplier, structural role, energy storage, signaling molecule

Question 39

a protein has 100 amino acids and is only composed of Lys and Glu. what is the most likely type of secondary structure that would occur in this protein?

Answer 39

alpha helix. charged residues repel in B-sheet structures and are less favored.

Question 40

a protein has 100 amino acids and is only composed of Lys and Glu. describe the interactions that will play a major role in stabilizing this secondary structure.

Answer 40

h-bonds between the backbone.