Exam 2 (Ch.18)

Question 1

basis for development, cellular differentiation, and physiological cellular responses

Answer 1

differential gene expression

Question 2

Although transcriptional control is the major type of regulation in eukaryotes, what also plays an important role

Answer 2

Posttranscriptional regulation such as alternative splicing, mRNA stability, and translation

Question 3

Pre-mRNA introns are cut out by the spliceosome in a reaction involving the formation of a lariat structure.

Answer 3

splicing

Question 4

refers to the fact that pre-mRNA can be spliced in different ways

(An important biological advantage of introns)

Answer 4

alternative splicing

Question 5

Gene that encodes a-tropomyosin
- protein functions in the regulation of cell contraction
- Found in smooth and striated muscle cells

Answer 5

alternative splicing example

Question 6

Different cells of a multicellular organism regulate contraction in subtly different ways:

produce different forms of ______ by alternative splicing

Answer 6

alpha-tropomyosin

Question 7

• A spliceosome recognizes the 5’ and 3’ splice sites and removes the intervening intron
• This is not a random event, the specific pattern of splicing is regulated in a given cell

Answer 7

process of alternative splicing

Question 8

Proteins that modulate the ability of spliceosomes to recognizes or choose splice sites

Answer 8

splicing factors

Question 9

found in the mature mRNA from all cell types

Answer 9

constitutive exons

Question 10

not found in all mature mRNAs

Answer 10

alternative exons

Question 11

primary mechanism for regulating mRNA processing

Answer 11

alternative splicing

Question 12

The ___ of Eukaryotic mRNA varies considerably

Answer 12

stability
(mRNA stability)

Question 13

the stability of mRNA can be regulated so that it’s _____

Answer 13

half life is shortened or lengthened

Question 14

factors that affect mRNA stability

Answer 14

• length of the polyA tail
• destabilizing elements

Question 15

• decapping pathway
• deadenylation pathway
• endonucleolytic pathway

Answer 15

pathways for degradation of eukaryotic mRNAs

Question 16

mRNA can be degraded by removal of the 5’-cap (____), shortening of the 3’-polyA tail (___), or internal endonucleolytic cleavage

Answer 16

decapping; deadenylation

Question 17

what can repress transcription by altering chromatin

Answer 17

RNA-induced gene silencing

Question 18

microRNAs (miRNAs):

• are short (21-24 nt) ________ molecules involved in RNA ___
• are encoded in the ___ ___ and transcribed by RNA poly II

Answer 18

double stranded RNA; silencing; nuclear genome

Question 19

miRNA-mediated gene silencing affects ____ and/or ____ of specific mRNAs

Answer 19

translation; stability

Question 20

Example: miRNA function in limb development

Answer 20

Mutants without normal miRNA function show developmental defects

Question 21

• ____ ____ recognize substrate proteins and catalize the addition of ubiquitin (Ub) to create a long chain.

Answer 21

Ubiquitin ligases

Question 22

post-translational modifications regulate ____ ___

Answer 22

protein activity

Question 23

a 76 amino acid protein

Answer 23

ubiquitin (Ub)

Question 24

The ___ removes ubiquitin tags, unfolds the protein, and cleaves it into small peptides.

Answer 24

proteasome

Question 25

- Ubiquitinated proteins are recognized by the ____

Answer 25

proteasome

Question 26

- Phosphorylation - Acetylation - Hydroxylation - Methylation

Answer 26

Types of post-translational modification

Question 27

the process of covalently adding a chemical group to an amino acid in a protein after the protein has been synthesized.

Answer 27

Posttranslational modification (PTM)