Topic 14

Question 1

Normally the rate of mutation can be affected by which of the following?

Answer 1

genome size, exposure to mutagens, ionizing radiation, & infections

Question 2

Is a type of regulatory protein that decreases the frequency of transcription when binding to DNA?

Answer 2

repressors

Question 3

The control of gene expression occur through which of the following?

Answer 3

regulatory proteins & promoters

Question 4

Gene expression is converting information from the genotype into the ____?

Answer 4

phenotype

Question 5

Is a type of regulatory protein that increases the frequency of transcription when binding to DNA?

Answer 5

activators

Question 6

Is a type of mutation that causes conversion to a STOP codon?

Answer 6

nonsense mutations

Question 7

Is a type of mutation that is changes the amino acid of a protein?

Answer 7

missense mutation

Question 8

Is a type of mutation that causes a shift in the codons, and thus changes a large amount of the amino acids downstream?

Answer 8

frameshift mutation

Question 9

What is the relationship between mutations and evolution?

Answer 9

mutations can create new alleles

Question 10

Is a type of mutation that does NOT cause any change to the amino acid?

Answer 10

silent mutation

Question 11

Regulatory proteins

Answer 11

act by modulating the ability of RNA polymerase to bind to the promoter.

RNA polymerase binding to the promoter is the key to transcription creating the mRNA and protein synthesis.

Regulatory proteins can either block or facilitate the binding of RNA polymerase.

Regulatory proteins are able to interact with specific sequences of bases.

Question 12

Repressor/Downregulation

Answer 12

Negative control – decreases the frequency of initiating transcription, mediated by proteins called repressors that bind to regulator sites on DNA.

Question 13

Activator/Upregulation

Answer 13

Positive control – increases the frequency of initiating transcription, mediated by proteins called Activators

Question 14

DNA-binding motifs

Answer 14

are the key structure within the DNA-binding domains of these proteins, most common motif is the helix-turn helix motif

Helix-turn helix motif – is the most common DNA-binding motifs, contructured from two alpha-helical segments of protein, linked by a short, nonhelical segment.
Interacts with the major groove.

Zinc finger motif – protein structural motif containing zinc ions, which interacts with the major groove, with multiple finger-like protrusions that make tandem contacts with the DNA molecule.

Leucine Zipper motifs – is created where a region on one subunit containing several hydrophobic amino acids (usually leucines) interacts with a similar region on the other subunit

Question 15

locus

Answer 15

A specific fixed position on a chromosome, where a particular gene or genetic marker is located. The plural form is loci

Question 16

Initiation/Transcription factor complex

Answer 16

Transcription factor complexes – bind to promoter regions upstream from genes, in the genetic code itself.

RNA polymerase I transcribes rRNA (Ribosome RNA)
RNA polymerase II transcribes mRNA (Messenger RNA)
RNA polymerase III transcribes tRNA (Transfer RNA)

Question 17

operons

Answer 17

consisting of a single promoter, and multiple genes that are transcribed together

Question 18

lac operon

Answer 18

consists of the regulatory region with promoter, repressor and Operator, and genes necessary to utilize lactose

consist of a Regulatory region, and Coding region with multiple genes coding for enzymes necessary for Lactose utilization

Operator – Binding site for repressor protein (lac repressor), controlling the transcription of the coding region by blocking RNA polymerase (Negative regulator

Question 19

TRP Operon

Answer 19

consists of the promoter, repressor, and Operator, and genes necessary to synthesize tryptophan

consist of a Regulatory region, and Coding region with multiple genes coding for enzymes necessary for tryptophan synthesize

Operator – Binding site for repressor protein (Trp repressor), controlling the transcription of the coding region by blocking RNA polymerase (Negative regulator)

Question 20

lac repressor (protein)

Answer 20

is removed by the binding of allolactose, allowing for a conformational change in structure.

Question 21

trp repressor

Answer 21

binds to the operator under the presence of Trypotophan, and is removed in the absence of tryptophan

Question 22

promoter regions

Answer 22

binding site for RNA polymerase.

Question 23

CAP (catabolite activator protein)

Answer 23

affects RNA polymerase from binding to the promoter, and activated by increasing levels of cAMP (Positive regulator), becomes available in low-glucose levels in the cell/Environment.

Question 24

regulatory regions

Answer 24

a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism

Question 25

coding region

Answer 25

also known as the coding sequence (CDS), is the portion of a gene’s DNA or RNA that codes for protein

Question 26

epigenetics

Answer 26

the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.

Question 27

DNA methylation

Answer 27

affect the structure of the chromatin

epigenetic alteration, affecting gene expression, by using methylase, to add a methyl group to cytosine.

High level of DNA methylation correlates with inactive genes and is seen in genomic imprinting in allele-specific expression, as DNA methylation is heritable, as the semiconservative replication of DNA, produces hemi-methylated DNA that becomes fully methylated by methylase.

Question 28

histone modification

Answer 28

affect the structure of the chromatin

changing the conformation of histones and altering the structure of chromatin, includes forms of acetylation, and methylation of lysine, and phosphorylation of serine, threonine, and tyrosine.

Depends on the type of modification and location, can activate or deactivate the transcription of gene expression.

Question 29

X-Chromosome Inactivation

Answer 29

in female mammals, one X chromosome will become inactivated, due to proper dosage compensation, having equal genes being expression between males and females.

X-inactivation-specific transcript – a specific region of the X Chromosome that inactivates process.

Question 30

Post-translation regulation

Answer 30

protein degradation through proteases and ubiquitin

proteins are turned over in a controlled manner, as proteins are continually being synthesized and degraded.

Question 31

Ubiquitin

Answer 31

(76-amino acid protein), is used by eukaryotic cells for marking proteins for destruction by proteases, ubiquitin can be added in chains, with ubiquitin ligase, creating polyubiquitinated chain, to signal to destroy protein

Question 32

Compare and contrast the types transcription factors

Answer 32

General Transcription factors – are factors necessary to recruit RNA polymerase II to a promoter region and assemble of an initiation complex for productive initiation.

Specific Transcription factors – are tissue specific or time dependent factors that stimulate higher levels of transcription than the base level.

Question 33

Proteases

Answer 33

is an enzyme that breaks down proteins into smaller polypeptides or single amino acids

Question 34

Understand the difference in gene expression in Prokaryotes and Eukaryotes, with respect to number of genes per translation, and regulatory regions within DNA

Answer 34

In prokaryotes, the processes of transcription and translation occur almost simultaneously in the cytoplasm. The regulation of gene expression occurs primarily at the transcriptional level. Prokaryotic transcription often covers more than one gene and produces polycistronic mRNAs that specify more than one protein.

In eukaryotes the processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus in the cytoplasm. The regulation of gene expression can occur at all stages of the process, including transcriptional, post-transcriptional, translational, and post-translational levels.

In prokaryotes, the number of genes involved in translation is relatively small, with only about 55 genes required for the process. In contrast, eukaryotes have a much larger number of genes involved in translation, with estimates ranging from 2000 to 3000 genes.

Question 35

Compare and contrast the types of regulatory factors

Answer 35

activators, repressors, enhancers (DNA sequences that bind to activator & increase the rate of transcription of genes), silencers (DNA sequencers that bind to repressor & decrease the rate of transcription of genes, and Transcription factors (are necessary for initiation of transcription, required for RNA polymerase enzyme to bind to the promoter region, and initiate gene expression.
Transcription factors interact with RNA polymerase to form the initiation/transcription complex at the promoter region (TATA box) upstream from a gene)