week 12

Question 1

gene expression

Answer 1

process by which info stored in a gene is used to create a functional product ( a protein)

Question 2

operon

Answer 2

A set of adjacent genes that are transcribed in a polycistronic mRNA and are thus coordinately regulated; an operon is generally considered to include associated regulatory sequences (e.g., promoter, operator, etc.). Primarily found in bacteria and archaea.

Question 3

positive transcriptional control

Answer 3

Condition where binding of an activator protein to a regulatory DNA sequence stimulates transcription of a gene or a cluster of genes.

Question 4

negative transcriptional control

Answer 4

Condition where binding of a repressor protein to a regulatory DNA sequence prevents transcription of a gene or a cluster of genes.

Question 5

inducible

Answer 5

a gene/operon that is normally inactive but can be activated by a specific molecule or stimulus&raquo_space;> inducer

Question 6

repressible

Answer 6

Operon that is expressed under one set of environmental conditions, but whose transcription is repressed under an alternative environmental condition (i.e., the trp operon).

Question 7

inducer

Answer 7

An accessory molecule that binds to a protein that leads to activation of gene expression. The inducer can bind to a repressor protein and prevent its function or bind to an activator protein and stimulate its function.

Question 8

corepressor

Answer 8

An accessory molecule required for a repressor protein to exert its function.

Question 9

repressor

Answer 9

A transcription factor that binds to regulatory sequences associated with a gene and represses that gene’s expression.

Question 10

activator

Answer 10

A transcription factor that binds to regulatory sequences associated with a gene and upregulates that gene’s expression.

Question 11

promoter

Answer 11

A regulatory sequence of DNA near the end of a gene that acts as the binding location of RNA polymerase and directs RNA polymerase to the start of transcription.

Question 12

operator

Answer 12

Regulatory DNA sequences to which repressor or activator proteins bind. Term used in bacterial systems.

Question 13

constitutive

Answer 13

the continuous or constant transcription of a gene, meaning it’s always “on” and producing a protein.

Question 14

feedback inhibition

Answer 14

the process of products going back in the pathway to inhibit products to prevent excessive production

Question 15

structural genes

Answer 15

the process by which a gene’s information is used to create functional products, often proteins, within a cell

Question 16

describe why prokaryotes need to regulate gene expression

Answer 16

They need to regulate gene expression to conserve energy & resources. As well as in response to environmental changes and stimuli.

Question 17

lacZ

Answer 17

encodes B-galactoside, breaks down lactose into glucose and galactose

Question 18

lacY

Answer 18

encodes lac permease, which facilitates import of lactose into the cell.

Question 19

lacI

Answer 19

repressor protein, Contains two binding sites, one for the operator and one for allolactose, the inducer

Question 20

operator

Answer 20

LacO, binds repressor protein to block transcription of operon genes

Question 21

promoter

Answer 21

lacP, binds RNA polymerase

Question 22

mRNA stability

Answer 22

how long an mRNA molecule persists before being degraded, longer can produce more protein , while shorter allow for more rapid changes in gene expression

Question 23

RNA processing

Answer 23

modifications for RNA before it becomes mRNA(splicing, capping, and a-poly tail), ensures mRNA is mature source of regulation

Question 24

transcription

Answer 24

DNA being copied into RNA, primary control point for gene expression, determines how much mRNA is produced from a gene

Question 25

chromatin remodeling

Answer 25

modification of the chromatin structure, which is essential for regulating which genes are expressed in different cell types and different conditions.

Question 26

translation

Answer 26

mRNA >>> protein, controls the amount of protein produced from a given mRNA molecule

Question 27

post-translational modifications

Answer 27

changes after made to a protein (phosphorylation), can alter protein’s activity

Question 28

chromosome territory

Answer 28

The region within an interphase nucleus occupied by a particular chromosome during interphase.

Question 29

enhancer

Answer 29

A eukaryotic cis-acting DNA regulatory sequence to which trans-acting factors bind and stimulate transcription.

Question 30

silencer

Answer 30

A eukaryotic cis-acting DNA regulatory sequence to which trans-acting factors bind to repress transcription

Question 31

activator

Answer 31

A transcription factor that binds to regulatory sequences associated with a gene and upregulates that gene’s expression.

Question 32

repressor

Answer 32

A transcription factor that binds to regulatory sequences associated with a gene and represses that gene’s expression.

Question 33

transcription factor

Answer 33

Proteins that bind promoters and are functional in transcription.

Question 34

cellular differentiation

Answer 34

the process by which a cell with less specificity develops and matures into a specialized cell type with a distinct structure and function.

Question 35

differential gene expression

Answer 35

the process where different genes are turned on or off in different cells or under different conditions, leading to the development of diverse cell types and functions

Question 36

alternative splicing

Answer 36

a cellular process in which exons from the same gene are joined in different combinations, leading to different, but related, mRNA transcripts

Question 37

siRNA

Answer 37

Single-stranded 21- to 24-nucleotide RNA molecules derived from either endogenous or exogenous double-stranded RNA molecules that are incorporated in RISC to mediate RNAi. Endogenously produced siRNAs are most often from nongenic regions (e.g., repetitive RNA or products of an RNA-dependent RNA polymerase). Exogenously produced siRNAs are often derived from invading nucleic acids (e.g., transposons and viruses).

Question 38

miRNA

Answer 38

Small (21–24 nuts) regulatory RNAs produced by Dicer and acting in a RISC complex to either repress translational or cleave target mRNA molecules. Compare with RNA interference (RNAi).

Question 39

RISC

Answer 39

Complex containing Argonaute protein that binds small RNA molecules and targets complementary RNA molecules for degradation or translational repression

Question 40

RITS complex

Answer 40

RISC-like complex that mediates small RNA-induced transcriptional gene silencing.

Question 41

CpG islands

Answer 41

Region in which the frequency of CpG dinucleotides is higher than the average for the genome; commonly found near the transcription start sites of animal genes. The cytosines are often methylated when the gene is inactive and demethylated when the gene is transcriptionally active.

Question 42

lactose

Answer 42

Induces the expression of lac operon genes by inactivating the repressor.

Question 43

glucose

Answer 43

Suppresses lac operon expression when present in high concentrations by lowering cAMP levels.

Question 44

cAMP

Answer 44

Activates CAP to enhance transcription of lac operon genes in low glucose conditions.

Question 45

CAP

Answer 45

Enhances transcription of lac operon genes in response to low glucose levels by forming a complex with cAMP.

Question 46

Explain how differential gene expression results in the structural and functional differences between two cell types (ex: a skin cell and a white blood cell)

Answer 46

Differential gene expression allows genetically identical cells to become highly specialized in structure and function by controlling which genes are active in each cell type.

Question 47

Explain how chromatin is altered by modifying histones, using chromatin remodeling complexes, and DNA methylation