Quiz 4 BIOL 111

Question 1

How are secondary structures formed?

Answer 1

Hydrogen bonding in peptide backbone

Question 2

Tertiary structure

Answer 2

• highest level of structure for a single protein
• Stabilized by interactions between the R-groups of the amino acids

Question 3

Electrostatic interactions

Answer 3

H-bonds and ionic bonds between R-groups

Question 4

Disulfide bridges

Answer 4

SH groups of cysteine can form covalent bonds called disulfide (S-S) bridges

Question 5

Van der Waals Interactions

Answer 5

weak interactions between nonpolar molecules due to charge fluctuations in the electron clouds of atoms

Question 6

Hydrophobic interactions

Answer 6

hydrophobic R groups fold to the interaction of the protein to avoid contact with the aq environment

Question 7

Domains

Answer 7

subunits within a protein that carry out specific functions

Question 8

Activating the transcription of a gene requires

Answer 8

transcriptional activation domain (TAD) to attract/interact w/ RNA polymerase

Question 9

function of a protein depends on

Answer 9

what domain it has

Question 10

Quaternary structure

Answer 10

interaction of 2 or more proteins to form a multi-protein complex

Question 11

Chaperone proteins

Answer 11

enzymes that help proteins fold/refold into the proper shape

Question 13

Epigenetic Modifications

Answer 13

modifications that change the expression of genes w/ out changing the DNA sequence of the gene
* Often change the chromatin structure of a gene
* Epigenetic modifications can change how tightly DNA and histones bind to each other

Question 14

Euchromatin

Answer 14

DNA & histones are loosely associated and DNA very accessible to transcription factors/RNA pol. binding

Question 15

Heterochromatin

Answer 15

DNA & histones are tightly associated and DNA is not very accessible to transcription factors/RNA pol.

Question 16

Histone acetylation

Answer 16

acetyl groups are covalently bound to lysines located in the amino-terminal tails of histones

Question 17

Histones are acetylated

Answer 17

HATs

Question 19

Histones are deacetylated

Answer 19

by (HDACs)

Question 20

Methyl group

Answer 20

physical barrier to binding of transcription factors (inhibits gene transcription)

Question 21

Cytosines methylated by

Answer 21

DNMTs

Question 22

Cytosines demethylated

Answer 22

DNA demethylases

Question 23

fertilization membrane

Answer 23

lifts off the surface of the egg soon after the first sperm makes contact

Question 25

polyspermy

Answer 25

the entrance of more than one sperm into the egg.

Question 26

holoblastic

Answer 26

Cleavage in the sea urchin

Question 27

How do sea urchin eggs show polarity?

Answer 27

* nucleus is away from the bottom and close to the top. * The nucleus is offset toward the animal pole.

Question 28

How do amphibian (frog) eggs show polarity?

Answer 28

they have a distinct animal vegetal polarity, have * more yolk that is concentrated in the vegetal hemisphere than in the animal hemisphere, and * the nucleus is also offset towards the vegetal pole. There is no cell division in the animal pole.

Question 29

How do chicken eggs show polarity?

Answer 29

small portion of the cell is at animal polarization of yolk

Question 30

2. Cell division is a major event during development. How does the amount of yolk in echinoderm, frog and chicken eggs influence cell division?

Answer 30

*having less yolk allows the eggs to develop quicker * Echinoderms develop the quickest, then frogs, and then chicken eggs.

Question 31

3. What do the blastulas of echinoderms, frogs and chickens have in common? In terms of the blastocoel, how are they different?

Answer 31

hollow space and develop the notochord and have blastocoel

Question 32

4. On the cellular level, how is gastrulation accomplished in echinoderms, amphibians, and birds? In general terms what does gastrulation accomplish?

Answer 32

Echinoderms → cells of vegetal plate migrate to the center of the embryo Amphibians → cells at ventral margin of gray crescent migrate to center of embryo Birds → initiated by separation of cells from the lower surface of the blastoderm