Last final pre

Question 1

Explain and describe the GPCRs with comparison/contrast to RTKs. How does this differ from
other receptor proteins we discussed previously? (Eg. Voltage-gated?)

Answer 1

GPCRs indirectly activate a signal transduction pathway via a G protein, while RTKs directly activate a pathway without G protein mediation.
Indirect

Question 2

o Explain/Draw the kinetochore structure of the centromere of the chromosome, noting
important proteins and enzymes of the complex.

Answer 2

Disc shaped protein- inner bound to chromosomal DNA. Outer connects to spindle fibers (PROTEINS AND ENZYMES?)

Question 3

o Describe the three main motifs, including similarities and differences, and key
parts/sections of each motif
▪ HLH
▪ Zinc-finger
▪ Leucine zipper

Answer 3

HLH- 2 alpha helixes and a loop. Basic, positively charged side chains that contact DNA
ZF-a zinc ion of each finger is coordinated between two cysteines (on beta sheet) and two histidines (short alpha helix)
LZ- Leucines every 7th AA, 2 a helixes coil together. Basic AA on one side of alpha helix

Question 4

List the ways that histone-DNA complex disruption can allow or prevent transcription

Answer 4

Histones compacting DNA reduces its accessibility and therefore its transcription. Histone modifications (EG acetylation, which loosens) affect transcription as well.

Question 5

o What functional groups can be added? What do they do to the histones and/or DNA?

Answer 5

Methyl- Lowers gene expression
acetyl- Increases gene expression
phosphoryl- Generally increases
lysine-arginine-Serve as potential sits for other modifications

Question 6

o What is a chromatin remodeling complex, and how does it work?

Answer 6

Modifies chromatin by using ATP to modify and move nucleosomes. SWI/SNF are recruited to promoters by recognizing epigenetic changes.

Question 7

Explain the miRNA versus the siRNA response in cells. How is translation effected? How is
transcription effected?

Answer 7

miRNA end is cleaved. Dicer cleaves it in cytoplasm, passenger strand is removed. Binds to target, slows translation. partially complementary
Ends of siRNAs are cleaved, binds to pre-RISC, binds to complementary RNA. Degrades

Question 8

o Explain how piwi-RNAs differ from other RNAs

Answer 8

Small, move transposons, do epigenetic and post transitional silencing

Question 9

Describe or draw the nucleus – Include the various structural proteins found in and around both
the inner and outer nuclear membrane

Answer 9

Outer- Nesprins. FIbrous proteins that bind nuclear envelope to cytoskeleton
IF- Provice support
Inner-
NPC- membrane transport
Lamina- structural support

Question 10

o What imports/exports/energy molecules are involved in NPC

Answer 10

Importins, exportins

Question 11

Describe the nuclear pore complex, including how it can determine what RNAs and proteins can
move in which directions through the complex. What importins/exports/energy molecules are
involved?

Answer 11

Donut shaped complex of nucleoporins that. They must have a nuclear localization signal. Importin alpha/beta brings stuff in by interacting with FG domains of nucleoporins

Question 12

How do chromatids know when to
separate into their migrating chromosome forms?

Answer 12

Cohesin is cleaved

Question 13

What signals and enzymes are needed to start each phase?
Explain how the Ras-MAPK cascade can be altered to cause some forms of cance

Answer 13

CDK- Involved in M phase, start most phases