Chapter 11

Question 1

Constitutive Genes

Answer 1

Actively expressed all the time

Question 2

Inducible Genes

Answer 2

Expressed only when their proteins are needed by the cell.

Question 3

Selective Gene transcription

Answer 3

The cell has control over when it wants specific genes to be expressed.

Question 4

Transcription factors

Answer 4

Control whether or not a gene is active

Question 5

Repressor

Answer 5

(Negative regulation) Binds near the promoter to prevent transcription.

Question 6

Activator

Answer 6

(Positive regulation) Binds near promoter to stimulate transcription.

Question 7

Virus

Answer 7

Injects its genetic material into a host cell, and often turns that cell into a virus factory.

Question 8

Lytic life cycle

Answer 8

The host cell immediately begins producing new viral particles after being infected

Question 9

Lysogenic phase

Answer 9

Dormant phase found in some life cycles. The viral genome becomes incorporated into host cell. Replicated along with the host genome. Later triggered by environmental signal to start virus production.

Question 10

HIV (Human Immunodeficiency virus

Answer 10

Infective agent that causes Aquired immunodeficiency syndrome (AIDS) in humans

Question 11

Retrovirus

Answer 11

virus whose genome is a single stranded RNA

Question 12

reverse transcriptase

Answer 12

After infection, this makes a DNA strand that is complementary to the HIV RNA while also degrading it and making a second DNA.

Question 13

Number of proteins involved in the uptake of lactase by E. Coli

Answer 13

3 proteins

Question 14

Inducer

Answer 14

switches on expression in inducible genes

Question 15

structural genes

Answer 15

The genes that encode the three enzymes for processing lactose in E. Coli

Question 16

Operon

Answer 16

cluster of genes with a single promoter

Question 17

operator

Answer 17

in lac operon, is near the promoter and controls transcription of the structural genes.

Question 18

lac Operon

Answer 18

The lac operon is not transcribed unless latose (or other B galactoside) is the predominant sugar. This rmoves the repressor normally bound to the operator

Question 19

trp operon

Answer 19

Typ operon is switched off when its repressor is bound to the operator. In this case, the repressor beinds to the DNA only in the presence of a corepressor. Tryptophan functions as the corepressor in this case.

Question 20

Summary of inducible systems

Answer 20

the substrate of metabolic pathway (inducer) interacts with a transcription factor (The repressor), releasing the repressor from the operator, allowing transcription

Question 21

Summary of Repressible systems

Answer 21

The product of a metabolic pathway (corepressor) binds to the repressor protein which then binds to the operator, blocking transcription.

Question 22

Sigma Factors

Answer 22

Special proteins in prokaryotes called Sigma factors that can bind to RNA polymerase and direct the polymerase to specific promoters.

Question 23

TATA Box

Answer 23

The most common core promoter. Rich in A-T base pairs.

Question 24

RNA Polymerase II

Answer 24

The polymerase that transcribes the protein-coding genes in eukaryotes,

Question 25

General Transcription Factors

Answer 25

Certain factors must bind to the promotor before the RNA Polymerase II. First TFIID binds to TATA box, followed by Polymerase and other transcription factors.

Question 26

Enhancers

Answer 26

DNA sequences that bind activators to initiate translation.

Question 27

Silencers

Answer 27

DNA sequences that bind repressors to restrict translation.

Question 28

How do Enhancers and Silencers work?

Answer 28

After repressors or activators bind to the enhancers and silencers, they cause the DNA to bend. This bending along with other transcription factors, determines the initiation of transcription.

Question 29

Epigenetic changes

Answer 29

Regulating transcription of DNA by reversible, non sequence specific alterations to the DNA in the nucleus. These are heritable alterations.

Question 30

DNA Methylation

Answer 30

Chemically modifying cytosine in DNA that use repressors, inactivating the DNA.

Question 31

DNA Methyltransferase

Answer 31

The enzyme that catalyzes the covalent addition of the methyl group to cytosine.

Question 32

CpG Islands

Answer 32

DNA regions rich in C and G residue doublets

Question 33

Maintenance methylase

Answer 33

When DNA is replicated, this catalyzes the formation of 5-methylcytosoine in the new DNA strand, because it is heritable.

Question 34

Demethylase

Answer 34

Catalyzes the removal of the methyl group from cytosine.

Question 35

Euchromatin

Answer 35

Uncondensed transcribable DNA. Unmethalated.

Question 36

Heterochromatin

Answer 36

Condensed untranscribable DNA. Methylated.

Question 37

How is DNA methylation involved in the X chromosomes in females

Answer 37

One of the X chromosomes is heterochromatin, and so cannot be transcribed

Question 38

Chromatin remodeling

Answer 38

Large amounts of DNA are packed within the nucleus with histones

Question 39

Histones

Answer 39

The proteins that wind around the DNA, tightening it, and repressing it, not allowing it to transcribe.

Question 40

Histone acetyltransferases

Answer 40

Can add acetyl groups to the histones to neutralize charges and loosening the DNA and allowing it to transcribe. It activates transcription.

Question 41

Histone deacetylase

Answer 41

Can remove the acetyl groups from histones and repress transcription.

Question 42

How can epigenetic changes be induced by the environment?

Answer 42

Health, toxins, and the settings humans can affect their DNA, slightly altering it. This is way twins differ as they age.

Question 43

Alternative splicing

Answer 43

Can be a deliberate mechanism for removing introns and splicing them together in different ways, often removing exons as well.

Question 44

MicroRNA (miRna)

Answer 44

tiny rnA molecules that can inhibit and degrate mRNA.

Question 45

How can translation of mRNA be regulated?

Answer 45

By inhibiting translation with miRNAS, modifying the 5' cap, and translational repressor proteins

Question 46

translational repressor proteins

Answer 46

proteins that block translation by binding to mRNAs and preventing their attachment to the ribosome.

Question 47

Ubiquitin

Answer 47

a 76-amino acid involved in the destruction of proteins

Question 48

Proteosome

Answer 48

a huge protein complex that targets proteins to be destroyed.