Gene regulation

Question 1

Demands for the synthesis of certain proteins may change, for instance in development, during which the degree of expression of several genes can vary according to the precise _____ of the cell and also w/ _____.

Answer 1

location; time

Question 2

Immediately upstream of the gene is the _____, which is involved in the binding of RNA polymerase II to the DNA template strand.

Answer 2

promoter

Question 3

Promoters for RNA polymerase II are usually several hundred nucleotides long and often contain a consensus sequence called the _____.

Answer 3

the TATA box (TATAAA)

Question 4

The TATA box, usually located around _____ upstream of the transcriptional start site, binds, via the so - called ____ subunit of TFIID, to a series of general transcription factors which are relatively abundant proteins used to initiate the transcription of nearly all mRNAs.

Answer 4

25 bp; TATA – binding protein (TBP)

Question 5

These are relatively abundant proteins used to initiate the transcription of nearly all mRNAs.

Answer 5

Transcription factor

Question 6

The TATA box, usually located around 25 bp upstream of the transcriptional start site, binds, via the so - called TATA-binding protein subunit of _____, to a series of general transcription factors which are relatively abundant proteins used to initiate the transcription of nearly all mRNAs.

Answer 6

TFIID

Question 7

Basal transcriptional efficiency is commonly aided by the presence of other upstream _____ within the promoter region.

Answer 7

short consensus regulatory sequences

Question 8

Short consensus regulatory sequences include multiple copies of the so - called _____, which binds the ubiquitous transcription factor SpI, and the _____, which is typically located 75 bp upstream of the transcriptional start site and binds the transcription factors CTF and CBF.

Answer 8

GC box;CAAT box

Question 9

What does the short consensus regulatory sequence GC box recognize?

Answer 9

TF SpI

Question 10

What does the short consensus regulatory sequence CAAT box recognize?

Answer 10

TF CTF and CBF

Question 11

CAAT box, which is typically located _____ bp upstream of the transcriptional start site and binds the transcription factors CTF and CBF.

Answer 11

75

Question 12

The activity of many promoters is modulated by one or more _____.

Answer 12

enhancers

Question 13

Enhancers are generally short sequences, with a length of _____ bp, that bind specific transcription factors.

Answer 13

less than 20-30

Question 14

T/F. Most enhancers function whether on the coding or non - coding strand of DNA and can be located, in either orientation, up to several kilobases from their target promoter.

Answer 14

True

Question 15

Most enhancers are active only in specific cell types and thus play a central role in _____ of gene expression.

Answer 15

regulating tissue specificity

Question 16

_____ are similar to enhancers but, in contrast, inhibit transcription of the associated gene.

Answer 16

Silencers

Question 17

The large number of specific transcription factors and their interaction at individual enhancers allows complex patterns of gene activation in response to particular circumstances including _____ and _____.

Answer 17

tissue differentiation; physiological or pathological receptor signaling

Question 18

Interactions between the proteins bound to enhancers and those bound to the promoter sequences are probably permitted by _____.

Answer 18

loop formation of the intervening sequences

Question 19

About _____ percent of genes are only expressed at specific times and places (e.g. insulin in the pancreatic islet β - cells). The other _____ percent, which are called _____, are expressed in all tissues, generally fulfill basic metabolic needs and account for _____or more of the genes expressed in any particular cell type.

Answer 19

80%; 20%; housekeeping genes; 90%

Question 20

The majority of housekeeping genes and about 40% of tissue - specific genes have _____ near their 5 ′ ends.

Answer 20

CpG islands (indicated as C, p for phosphate, G, to distinguish them from G hydrogen bonded to C in opposite DNA strands)

Question 21

The CpG islands are about _____ in length and contain a high proportion of 5 ′ - CG - 3 ′ dinucleotide pairs.

Answer 21

1 kb

Question 22

The _____ are about 1kb in length and contain a high proportion of 5 ′ - CG - 3 ′ dinucleotide pairs.

Answer 22

CpG islands

Question 23

The CpG islands are about 1kb in length and contain a high proportion of _____ dinucleotide pairs.

Answer 23

GC

Question 24

T/F. Generally, cytosine residues in CpG dinucleotides are methylated, but in CpG islands associated with active neighbouring gene expression, there is usually a lack of methylation.

Answer 24

T

Question 25

Although the bulk of regulation probably occurs at the transcriptional level, regulation of a gene ’ s activity may also occur later with:

Answer 25

alteration of the rate of protein translation or degradation

alternative splicing of the mRNA to produce different gene products (e.g. calcitonin or calcitonin gene - related neuropeptide).

Question 26

Mutations within a gene ’ s regulatory sequences can occur and may result in:

Answer 26

no gene product, e.g., beta-thalassemia

abnormal persistence of a fetal gene product, e.g., hereditary persistence of a-fetoprotein or hemoglobin F

anomalous patterns of gene expression, e.g., ectopic expression of creatine kinase