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Cell Biology Final Exam > Regulation of Gene Expression > Flashcards

Regulation of Gene Expression Flashcards

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1
Q

Gene Expression

A

lets cells be different

  • mainly controlled through transcriptional regulation
  • additional controls: postranscriptional, translational, and posttranslational
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2
Q

Operon

A

A cluster of prokaryotic genes and DNA regulatory sequences

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3
Q

Transcriptional unit

A

cluster of genes

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4
Q

Operator

A

regulatory DNA sequences in operon

-regulatory proteins bind the operator

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5
Q

Repressor proteins

A

prevent operon genes from being expressed

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6
Q

Activator proteins

A

turn on expression of genes from operon

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7
Q

Lac Operon

A

lactose metabolism in E.Coli requires three genes: lacZ, lacY, and lacA (lac operon contains all three)
lac operon sequence is between promoter and lacZ

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8
Q

What happens when lactose is absent?

A

stops lac operon expression
encoded by lacI, synthesized in active form
binds operator
prevents transcription

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9
Q

What happens when lactose is present?

A

Allolactose- made from lactose. it is the inducer of lac operon by binding to lac repressor
therefore inducible operon because inducer increases expression

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10
Q

Catabolite Activator Protein

A
  • activator that stimulates gene expression
  • CAP activated by cAMP
  • cAMP only abundant when glucose levels are low
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11
Q

trp Operon

A

default state is expression since trp repressor is inactive
trp operon is repressible operon
lac and trp operons both exhibit negative gene regulation

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12
Q

Gene regulation in eukaryotes

A

more complex, no operon, genes are scattered, chromatin has histones, different types of cells, nuclear envelope

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13
Q

Transcriptional Regulation

A
  1. initiation of transcription
  2. methylation of DNA
  3. chromatin structure
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14
Q

Three DNA binding activators motifs

A
  1. helix turn helix
  2. zinc finger
  3. leucine zipper
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15
Q

Coactivators

A

bridge enhancer and promoter which increases transcription to maximal rate

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16
Q

Respressors

A

oppose the effect of activators and decrease transcription

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17
Q

Combinatorial gene regulation

A

high gene regulation with low numbers of activators

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18
Q

Hormones

A

signal molecules activate all cells with specific hormone receptors
-all genes regulated by a specific hormone contain a steroid hormone response element

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19
Q

DNA methylation

A

adds methyl group to cytosine

-gene silencing occurs when DNA methylation is located in promoters

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20
Q

Genomic imprinting

A

permanent silencing of a maternal/paternal allele

  • inherited methylated allele is silenced
  • methylation maintained as DNA is replicated
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21
Q

Nucleosomes

A

Eukaryotic DNA + histones= nucleosomes

22
Q

Chromatin remodeling

A
  1. activators recruit remodeling complexes that displace nucleosomes
  2. activators recruit histone acetyltransferase enzyme that acetylates and loosens histone association with DNA
    - makes gene promoters more accessible
23
Q

Posttranscriptional regulation

A

controls the availability of mRNA to ribosomes

24
Q

Micro-RNA

A

regulates gene expression through RNA interference

miRNA binds to any complementary mRNA sequence and silences it

25
Q

Small interfering RNA

A

from RNA encoded outside the cell’s genome

-often used by viruses

26
Q

Translational regulation

A

controls rate at which mRNAs are used in protein synthesis

increasing length of poly(A) tail increases translation of mRNA

27
Q

Posttranslational regulation

A

controls functional proteins:

  • chemical modification alters activity of protein
  • processes inactive precursers to active proteins
  • rate of degradation, ubiquitin
28
Q

Epigenetic gene regulation

A

persists through cell or organismal generation

-does not result from changes in DNA nucleotide sequence

29
Q

Two epigenetic mechanisms

A
  1. Feedback loops: self-sustaining regulatory loop

2. Chromatic packaging- regulation of packaging of DNA and its associated proteins

30
Q

Tumor

A

a mass of cells due to dedifferentiation

31
Q

Oncology

A

branch of medicine for the study, treatment and prevention of cancer

32
Q

Carcinoma

A

tumor in cells of epithelial origin eg breast

33
Q

Sarcoma

A

tumor in cells of connective tissue

34
Q

Leukemia

A

tumor in cells of the blood

35
Q

Lymphoma

A

cells of the immune system

36
Q

Tumor grade (1-3)

A

resemblance of tumor to normal tissue

37
Q

Tumor stage (1-4)

A

degree of tumor invasion

38
Q

Prognosis

A

probability of survival five years after diagnosis

39
Q

Pronto-oncogenes

A

encode proteins that stimulate cell division

40
Q

Oncogenes

A

are altered pronto-oncogenes that cause a cell to be cancerous

41
Q

Tumor suppressor genes

A

genes encode proteins that inhibit cell division

-in cancer, tumor suppressor genes can be mutated

42
Q

BRCA1 and BRCA2

A
  • both tumor suppressor genes
  • both involved in DNA damage repair
  • mutated genes are risk factors for breast cancer
  • 60% breast cancers have BRCA1 or 2 mutation
  • up to 85% risk
43
Q

Tumor angiogenesis

A

tumor cells signal the formation of new blood vessels

44
Q

Intravasation

A

cancer cells enter blood vessels

45
Q

Extravasation

A

cancer cells exit the blood vessels

46
Q

Surgery

A

removal of tumor and lymph nodes

47
Q

Chemotherapy

A

chemical that are selective and non-selective to cancer cells

48
Q

Radiotherapy

A

radiation treatment of cancer

49
Q

Targeted therapy

A

specific to cancer cells

50
Q

Herceptin

A

targeted therapy against Her2

- specifically binds Her2 receptor and stops cell division

Cell Biology Final Exam (6 decks)

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