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MCAT bio > gene expression > Flashcards

gene expression Flashcards

1
Q

gene expression

A

all cells in body have same dna but very different morphology

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2
Q

cell differentiation

A

specialization of cells where they commit to specific morphology

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3
Q

what kinds of cells do stem cells differentiate into

A

ectoderm, mesoderm, endoderm

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4
Q

hematopoetic stem cells

A

stem cells of blood cells

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5
Q

totipotent

A

can differentiate into any type of cell
- applies only to zygote through stage of morula

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6
Q

pleuripotent

A

differentiate into any germ layer (ecto,endo,meso) obtained from blastocyst

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7
Q

multipotent

A

describes adult stem cells, can differentiate into several types of a specific cell

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8
Q

olgiopotent

A

can only differentiate into a few types

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9
Q

apopstosis importance to development

A

helps establish boundries between organs and structures

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10
Q

operon

A

gene expression in prokaryotes
- can be under positive or negative control

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11
Q

negative control operon

A

repressor prevents transcription by binding to an operator

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12
Q

operator

A

sequence upstream of the first protein coding region

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13
Q

positive control

A

activator stimulates trascription

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14
Q

lac operon

A

negative control and inducible
gives ecoli the ability to metabolize lactose
when lactose is present and glucose is active, lactose is metabolized

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15
Q

promoter region

A

upstream of operator

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16
Q

what happens to lac operon when lactose is NOT present

A

the represor is bound to the operator and prevents transcription of lactose metabolizing enzymes

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17
Q

when lactose is present what molecule binds to the repressor?

A

allolactose , which frees the oeprator and transcription may begin

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18
Q

why is the lac operon typically turned off?

A

because metabolizing lactose when glucose is available is energetically unfavorable

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19
Q

CAP binding sequence

A

bound by high levels of cAMP
positive control, when bound lactose metabolism is enhanced

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20
Q

what is the function of cap binding proteins

A

they promote protein synthesis

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21
Q

what is derived from endoderm

A

internal lining of respiratory tract, digestive tract
liver, pancreas, lungs, epithelial linings

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22
Q

what is derived from ectoderm

A

epidermis, brain, spinal cord,

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23
Q

what is derived from mesoderm

A

dermis, heart, bone, bonemarrow, muscle, urogenital system

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24
Q

what is the outcome when no lactose is present and glucose is present?

A

the repressor is bound to the lac operon and lactose is not metabolized

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25
Q

what happens when lactose is present and glucose is not

A

cap binds to cap binding sequence, and repressor is bound to allolactose so lactose can be metabolized

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26
Q

trp operon

A

contains genes that synthesize tryp, is turned off when trp is part of the diet
- trp binds to repressor which binds to the operator and prevents tryptophan synthesis

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27
Q

which operon is an example of repressible negative

A

trp, turned off in the presence of tryptophan which is the envirnmental change and is naturally on

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28
Q

promoters

A

upstream regions of dna that initiate transcription
bind to proteins that help recruit RNA polymerase to initiate transcription

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29
Q

example of common eukaryotic promoter

A

TATA box and CAAT

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30
Q

TATA binding protein

A

binds to tata box and contributes to the binding of RNA polymerase

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31
Q

transcription factors

A

proteins that regulate expression by binding to a specific sequence of DNA that recruit proteins that play a role in acetylation and methylation

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32
Q

enhancers

A

allow increased gene expression , not necessarily close upstream of coding region , bring transcription factors closer to gene

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33
Q

silencers

A

opposite of enhancers, where repressors bind

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34
Q

histones

A

positively charged proteins bound to dna

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35
Q

heterochromatin

A

tight structure of histones and dna

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36
Q

euchromatin

A

lose binding of dna and histones (beads on a string)
- associated with higher levels of transcription

37
Q

histone acetyltransferases

A

modify histone structure by transfering an acetyl group to histones and making them less positive to loosen binding to dna via LYSINE residues

38
Q

what amino acid residue of histones are acetylated

A

lysine

39
Q

histone deacetylases

A

remove acetyl groups from histones, making them more positively charged and repressing transcription

40
Q

dna methylation

A

methyl group is added to the dna via cystine or adenine and decreases transcription
- related to epigenetic changes

41
Q

non-coding rna

A

rna that is not translated into protein like trna or introns
- can be involved in gene expression

42
Q

major non coding rna

A

small interfering rna and mircorna

43
Q

siRNA structure

A

short double stranded rna

44
Q

microRNA

A

single stranded and long basic hairpin loop

45
Q

importance of miRNA and siRNA

A

they can silence genes by interrupting expression between transcription and translation

46
Q

cancer

A

abnormal gene expression

47
Q

tumor

A

proliferation of cells

48
Q

benign tumor

A

localize

49
Q

maligant tumor

A

metastasizes

50
Q

tumor initiation

A

changes that allow a single cell to proliferate abnormally
- develop ability to bypass cellular checkpoints

51
Q

tumor progression

A

cell devlops ability to proliferate more aggressivley and malignant cells mutate

52
Q

tumor promoters

A

induce the growth and proliferation of cells for growth and division

53
Q

oncogenes

A

promote abnormal growth

54
Q

tumor viruses

A

usually contain retroviral oncogenes that stimulate cell proliferation
(HPV)

55
Q

protooncogenes

A

genes that act as oncogenes after a mutation

56
Q

tumor supressor genes

A

inhibit oncogenesis (p53)

57
Q

restriction endonulceases

A

cleave dna at recognition sites that are palindromic that leave sticky ends after cleaving

58
Q

palidrome

A

has symmetry and can be cut down the middle
the 5’ to 3’ are the same on each half

59
Q

recombination

A

use an endonuclease to cleave dna and combine two different genomes that are sealed with dna ligase

60
Q

vectors

A

dna molecules that carry info into a cell that can replicate it
types are plasmids and bacteriophages

61
Q

types of vectors

A

plasmids (bacteria) bacteriophages (virus)

62
Q

plasmids

A

short circular dna molecules that replicate INDEPENDENTLY from bacterial genome and can confer resistance. also can be recombinant

63
Q

antibiotic resistnace genes

A

typically added to plasmids so researchers know which bacteria took plasmid

64
Q

reporter gene

A

codes for a product leading to an obvious phenotypic change that contains recognition sites for restriction enzymes
- so only bacteria that are not recombinant will posess reporter gene, and bacteria that is recombinant will not

65
Q

restriction site

A

recognition site for a restriction enzyme to cleave dna

66
Q

antibiotic resistance gene

A

allows selection of bacteria that have taken up plasmid

67
Q

reporter gene function

A

distinguishes bacteria with recombinant plasmid from those with nonrecombinant plasmids

68
Q

disadvantage of using plasmids for cloning dna sequences

A

only 2-4 kB of dna

69
Q

bacteriophage as vectors

A

sequence genomes as large as 15 kB

70
Q

major difference between bacteriophage vectors and plasmids

A

bacteriophages strip non-essential genes to carry recombinant sequences

71
Q

cDNA

A

complimentary dna, cloning rna
first synthesize a dna copy of the rna using reverse transcriptase which is cdna and is then ligated to dna vector

72
Q

major difference between cnda and dna

A

dna has coding and noncoding regions, cdna is from an oringial mrna trascript and has coding information only

73
Q

transgenic

A

genome modified

74
Q

gene therapy

A

splice in a functional copy of gene

75
Q

stem cell therapy

A

embryonic stem cells used to regenerate tissue

76
Q

gel electrophoresis

A

analyze nucleic acids by SIZE
- suspend charged molecules in agorose and apply electric field with positive and negative ends
- will move toward positive end and speed depends on size

77
Q

DTT

A

agent that degrades disulifde bridges on agarose

78
Q

hybridization

A

ability of single stranded dna to form base pairs with complimentary sequences
- dna annealed at high temps
- used in PCR

79
Q

hybridization probe

A

identify target sequences by using specific dna or rna sequence that is radioactive and anneal the radioactive strand to complimentary sequence

80
Q

blotting technique mnuemonic

A

SNOW
DROP

81
Q

blotting technique

A

molecule of interest undergoes gel electrophoresis to seperate by SIZE

82
Q

what macromolecule is examined with western blot

A

antibodies

83
Q

DNA microarrays

A

large scale version of southern blot
- global analysis of dna or rna
glass slide with cdna and more than 10000 dna sequences can be shown

84
Q

sanger method of dna sequencing

A

premature termination of dna synthesis resulting from inclusion of chain terminating dideoxynucleotides with no 3’ OH group
- dideoxynucleotides radioactively labeled and ran through gel electrophoresis to seperate

85
Q

PCR

A

amplification of a dna sequence in vitro
- dna doubles each round

86
Q

pcr primer

A

initate dna synthesis at desired point
- synthesized oligonucleotides
- 2 primers in opposite directions

87
Q

annealing of pcr

A

template dna is heated above 95C to seperate dna then themp os lowered to allow primers to pair with compliment dna , then dna ploymerase uses the primers to make new strands

88
Q

dna polymerase in pcr is

A

a heat-stable enzyme that can operate above 75C
- taq polymerase

89
Q

can cdna be used for pcr

A

yes, just need reverse transcrptase step prior to pcr to make the cdna

MCAT bio (12 decks)

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