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Biology > Gene Expression > Flashcards

Gene Expression Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

T or F. All the cells in the human body contain the exact same genome and it is only what genes are expressed that differs

A

True

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2
Q

Each cell is programmed in a way to express only a specific subset of these genes at specific times, and in response to specific stimuli

A

Gene expression

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3
Q

The process by which stem cells differentiate into different tissues and specialized cell types in the body during development

A

Cell differentiation

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4
Q

T or F. Stem cells are cells during embryonic stage of development

A

False. Adults also have stem cells known as somatic stem cells

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5
Q

Somatic stem cells include

A

Hematopoietic stem cells - generate blood cells of the body
Intestinal stem cells
Mesenchymal stem cells- produce fat, bone, and liver cells

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6
Q

Stem cell potency

A

Refers to their limits on cell differentiation

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7
Q

Totipotent cell

A

Can differentiate into any type of cell

In humans, this only applies to early embryos, up to morula or 16-cell stage

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8
Q

Pluripotent

A
  • Can differentiate into any cells of the ectoderm, mesoderm, or endoderm
  • Cannot differentiate into cells of the placenta
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9
Q

Multipotent

A

Can differentiate into a limited subset of cell types within a germ layer
(Ex. Adult stem cells)

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10
Q

Totipotent and pluripotent cells- target of biomedical research

A

Can be used to generate tissue and organ grafts for transplant from a patient’s own stem cells which can be used to replace failing organ or repair degenerative tissue like damaged heart muscle

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11
Q

Dilemma of stem cells from embryo

A

Totipotent cells can only be found from the embryos, therefore much research now is focused on making adult stem cell Totipotent or pluripotent

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12
Q

Programmed cell death

A

Apoptosis

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13
Q

Apoptosis in embryonic development

A

It helps define the boundaries of organs and tissues
(Ex. Developing embryos- webbed fingers and toes - coordinated apoptosis cause the disappearance of these webbed structures during embryogenesis)

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14
Q

Apoptosis as checkpoint

A

The body would rather sacrifice a cell than let it persist with serious organelle dysfunction or DNA mutations that could lead to cancer

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15
Q

T or F. Cell differentiation is irreversible

A

Cell differentiation usually does not reverse in normal human physiology. However, cancer cells can become less differentiated, and pluripotency can be artificially induced

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16
Q

As cell potency move from Totipotency to multipotency these qualities increase

A
  1. Expression of lineage-specific genes: as pluripotent cells develop into multipotent cell, they express a greater percentage of lineage-specific genes due to specialization
  2. Methylation of genes required for differentiation into other lineages: DNA methylation “turns off” genes. It is expected that a differentiated cell would methylate genes required for differentiation into other lineages
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17
Q

Genetic system used by prokaryotes to regulate the expression of specific genes

A

Operon

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18
Q

Operon can be either ___________ or ___________ controlled genes

A

Positive or negative

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19
Q

Genes expressed when activator present

A

Positively controlled gene

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20
Q

Genes expressed unless repressor present

A

Negatively controlled gene

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21
Q

Binds and stimulate transcription in prokaryotes

A

Activator

22
Q

Repressor binds to what in the Operon. What does it mean for transcription and when repressor is bound?

A

It binds to the operator in the Operon. Transcription cannot occur when repressor is bound to the operator.

23
Q

Two examples of operons that are under negative control which means that repressor can inhibit transcription

A

Lac operon and trp operon

24
Q

Negative inducible operon definition and example

A

No transcription is the default position. But gene expression can be induced by a specific signal or change in the environment that removes the repressor, allowing transcription to occur

Ex. lac operon

25
Q

Negative repressible operon definition and example

A

The default is the “on” position (transcription occurs), but gene expression can be repressed by binding of the repressor in certain conditions.

Ex. trp operon

26
Q

Lac operon

A

Contains genes for enzymes that metabolize lactose. Only activated when glucose levels are low.

27
Q

3 structural genes of lac operon

A

Lac Z, lac Y,and lac A
Also includes promoter where RNA polymerase binds to initiate transcription
Also includes operator and CAP binding sequence

28
Q

Inactive LAC repressor

A

Usually bound to the operator of lac operon, preventing the transcription of RNA polymerase bound to the CAP binding site of the promoter

29
Q

When lactose is present, its isomer ____________ binds the repressor and prevents it from interacting with the operator

A

Allolactose

30
Q

cAMP when glucose levels are low

A

cAMP binds to the CAP-binding site to really ramp up transcription in times of need - this is an example of positive control (which is when an activator stimulates transcription)

31
Q

T or F. Lac operon is under both negative inducible control and positive control

A

True

32
Q

Contains genes for the synthesis of the amino acid, tryptophan.

A

Trp operon- an abundant amount of tryptophan represses expression of these genes (negative feedback on its own synthesis)

33
Q

A short sequence upstream of its target gene that serves as the initial binding site for RNA polymerase to initiate transcription

A

Promoter- in eukaryotes most contain the TATA box which is about 30bp upstream of the coding sequence
The GC and CAAT boxes, up to 10 to 150 bp upstream of the TATA box

34
Q

Proteins that bind to specific DNA sequences to regulate gene expression, recruiting other regulatory proteins that might affect gene transcription or that make chemical modifications to the DNA

A

Transcription factors

35
Q

Play a critical role in determining the activity and the identity of a given cell

A

Transcription factors

36
Q

Sequences that promote enhanced expression of genes in response to appropriate stimuli. May be located upstream or downstream of their target genes and even thousands of bp away from the coding sequence

A

Enhancers

37
Q

Enhancers bind transcription factors known as _____________ and these help twist the DNA into a hairpin loop back onto itself to bring the enhancer region closer to the gene sequence in order to facilitate the initiation of transcription

A

Activators

38
Q

Example of activator binding to enhancer

A

Estrogen binding its nuclear estrogen receptor, which then binds enhancers, known as estrogen response elements, to enhance transcription of specific genes

39
Q

Sequences that when bound by repressor, repress the expression of specific genes

A

Silencers

40
Q

In the nucleus, DNA is wound around ________ and then condensed further into densely-packed _____________ or relatively looser ___________

A

Histones; heterochromatin; euchromatin

41
Q

Certain enzymes can modify histones by adding or removing

A

Acetyl groups- referred to as acetylation or deacetylation

*affect how tightly DNA is packaged

42
Q

What enzymes add acetyl groups to histones and what is the effect of this?

A

Histone acetyltransferases

They reduce histone-DNA interactions which makes DNA more accessible for transcription

43
Q

What enzymes remove acetyl groups and what is the effect of this

A

Histone deacetylases

Promote Histone-DNA interactions, making it less accessible for transcription

44
Q

The addition of methyl groups directly to cytosine or adenine nucleotides in DNA

A

Methylation

45
Q

Methylation effect

A

Generally deactivates or silences gene sequences, preventing their expression
*plays an important role in epigenetics

46
Q

Refers to heritable changes that affect gene expression without directly changing the genetic sequence itself

A

Epigenetics

  • some epigenetic changes can be transmitted through multiple generations
  • can affect metabolism, aging, cancer, and other disease processes
47
Q

Certain types of non coding RNA can literally interfere with gene expression by degrading mRNA prior to translation. Pretty much intercepting the pass between DNA and protein

A

RNA interference

48
Q

Two non coding RNAs that could interfere

A

Small interfering RNA (siRNA)and microRNA- similar function but differs a bit in structure

49
Q

Differing structures of siRNA and microRNA

A

microRNA- single stranded

siRNA- double stranded

50
Q

How siRNA and microRNA interfere with mRNA

A

RNA-induced silencing complex -> cleavage of target mRNA -> death of target mRNA

Biology (16 decks)

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