Chapter 11 Flashcards

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1
Q

Constitutive Genes

A

Actively expressed all the time

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2
Q

Inducible Genes

A

Expressed only when their proteins are needed by the cell.

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3
Q

Selective Gene transcription

A

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

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4
Q

Transcription factors

A

Control whether or not a gene is active

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5
Q

Repressor

A

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

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6
Q

Activator

A

(Positive regulation) Binds near promoter to stimulate transcription.

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7
Q

Virus

A

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

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8
Q

Lytic life cycle

A

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

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9
Q

Lysogenic phase

A

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.

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10
Q

HIV (Human Immunodeficiency virus

A

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

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11
Q

Retrovirus

A

virus whose genome is a single stranded RNA

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12
Q

reverse transcriptase

A

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

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13
Q

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

A

3 proteins

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14
Q

Inducer

A

switches on expression in inducible genes

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15
Q

structural genes

A

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

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16
Q

Operon

A

cluster of genes with a single promoter

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17
Q

operator

A

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

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18
Q

lac Operon

A

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

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19
Q

trp operon

A

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.

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20
Q

Summary of inducible systems

A

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

21
Q

Summary of Repressible systems

A

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

22
Q

Sigma Factors

A

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

23
Q

TATA Box

A

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

24
Q

RNA Polymerase II

A

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

25
Q

General Transcription Factors

A

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.

26
Q

Enhancers

A

DNA sequences that bind activators to initiate translation.

27
Q

Silencers

A

DNA sequences that bind repressors to restrict translation.

28
Q

How do Enhancers and Silencers work?

A

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.

29
Q

Epigenetic changes

A

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

30
Q

DNA Methylation

A

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

31
Q

DNA Methyltransferase

A

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

32
Q

CpG Islands

A

DNA regions rich in C and G residue doublets

33
Q

Maintenance methylase

A

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

34
Q

Demethylase

A

Catalyzes the removal of the methyl group from cytosine.

35
Q

Euchromatin

A

Uncondensed transcribable DNA. Unmethalated.

36
Q

Heterochromatin

A

Condensed untranscribable DNA. Methylated.

37
Q

How is DNA methylation involved in the X chromosomes in females

A

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

38
Q

Chromatin remodeling

A

Large amounts of DNA are packed within the nucleus with histones

39
Q

Histones

A

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

40
Q

Histone acetyltransferases

A

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

41
Q

Histone deacetylase

A

Can remove the acetyl groups from histones and repress transcription.

42
Q

How can epigenetic changes be induced by the environment?

A

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

43
Q

Alternative splicing

A

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

44
Q

MicroRNA (miRna)

A

tiny rnA molecules that can inhibit and degrate mRNA.

45
Q

How can translation of mRNA be regulated?

A

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

46
Q

translational repressor proteins

A

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

47
Q

Ubiquitin

A

a 76-amino acid involved in the destruction of proteins

48
Q

Proteosome

A

a huge protein complex that targets proteins to be destroyed.