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Foundations of Medicine > Genetics- Cormier > Flashcards

Genetics- Cormier Flashcards

1
Q

What parts make up a nucleotide?

A

nitrogenous base, 5 carbon sugar, and a phosphate

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2
Q

Which NTs are purines?

A

Pure As Gold (2 rings)

-adenine and guanine

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3
Q

Which NTs are pyrimidines?

A

CUT the Py

-cytosine, thymine (DNA), uracil (RNA)

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4
Q

What is the difference between heterochromatin and euchromatin?

A

heterochromatin is wound tightly and not easily transcribed

euchromatin is easily and actively transcribed

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5
Q

How many pairs of chromosomes do humans have?

A

23 (homologous pair of 22 chromosomes and 1 pair of sex chromosomes)

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6
Q

What is ataxia?

A

disease, progressive deterioration of motor skills (1 normal and 1 aberrant chromosome 12 with extra piece from chromosome 4)

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7
Q

Do exons or introns become proteins?

A

exons, and only code about 1% of DNA

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8
Q

How is eukaryotic DNA organized?

A

histones (with lots of arginine and lysine) wrab DNA to make nucleosome which includes about 200 NT pairs of DNA

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9
Q

What are the names of histones involved in DNA organization?

A

2 H2A, 2 H2B, H3 and H4 are the histone core

-H1 is linker that joins DNA cores

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10
Q

What do HAT (histone acetyltransferase) enzymes do?

A

adds acetyl groups to histone tails, added charge loosens DNA to promote transcription

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11
Q

What do HDAC (histone de-acetyltransferase) enzymes do?

A

take acetyl groups off histone tails, silences DNA transcription and DNA compacts

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12
Q

How is eukaryotic DNA processed before leaving the nucleus?

A

5’ 7 methyl guanosine cap added, 3’ poly A tail, and introns spliced out

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13
Q

What subunits make up eukaryotic and prokaryotic ribosomes?

A

eukaryotic- 60S and 40S

prokaryotic- 50S and 30S

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14
Q

What size pieces of rRNA make up prokaryotic and eukaryotic ribosomes?

A

Prokaryotic (3 types): 5S, 23S, 16S

Eukaryotic (4 types): 5S, 5.8S, 18S, 28S

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15
Q

What are the distinguishing features of tRNA?

A
  • attaches AA at 3’ end
  • has 3’ to 5’ anti-codon
  • cloverleaf structure
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16
Q

How does DNA replication work for prokaryotes?

A

DnaA binds at OriC (single point of origin)
-bidirectional replication (2 replication forks)
DnaB = helicase
DnaG = primase
DNA gyrase = like topoisomerase

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17
Q

In what direction is all DNA and RNA made?

A

always made in 5’ to 3’ direction (so template strand is read 3’ to 5’)

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18
Q

What are the main functions of Pol 1, Pol 2, and Pol 3? (prokaryotes)

A

Pol 1 = fill lagging strand gaps, remove RNA primer
Pol 2 = DNA repair
Pol 3 = DNA replication

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19
Q

Which parts of the cell cycle are part of interphase?

A

G1, S1, and G2 (M phase = mitosis, cell division)

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20
Q

What is the difference between topo1 and topo2?

A 
topo1 = single strand breaks
topo2 = double stranded break, target for cancer drugs
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21
Q

How does telomerase help the dividing cell?

A

adds back DNA at end of telomere where it’s lost during replication
-reverse transcriptase, adds 5 nucleotide repeating sequence

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22
Q

During transcription, what type of bond is formed between incoming nucleotides and complementary NTs on DNA template strand?

A

ester bonds

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23
Q

How do cis and trans regulatory sequences differ?

A

cis- same side of DNA strand

trans- act from afar

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24
Q

In bacteria, what binds to the promoter (TATA box) to associate the polymerase enzyme?

A

Sigma factor. It dissociates soon after transcription begins

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25
Q

In eukaryotes, what do pol 1, pol 2, and pol 3 usually transcribe?

A

Pol 1 = rRNA
Pol 2 = mRNA, miRNA, lincRNA
Pol 3 = small RNAs (tRNAs and 5S RNA)

26
Q

How is transcription initiated in eukaryotes?

A

Pol 2 is main transcription factor

  • TF2D binds TATA box and binds TF2A and TF2B
  • other TFs and RNA pol assemble at promoter
  • TF2H uses ATP to open double helix
27
Q

What sequence is at each end of the intron for splicing?

A

5’ GU AG 3’ of intron gets spliced out

28
Q

What structure forms as an intermediate in splicing?

A

lariat structure

29
Q

What is the start codon, and what does it code?

A

methionine, AUG

30
Q

What is “wobble”?

A

the 3rd BP on mRNA or 5’ side on tRNA can vary and still code same amino acid

31
Q

Which end of the protein is made first and which end last?

A

Translation is from N-terminus to C- terminus (corresponds with 5’ to 3’)

32
Q

What is the order of ribosome assembly on mRNA for eukaryotes?

A

initiator tRNA first loads on small ribosomal subunit with euk initiation factors

  • small subunit scans mRNA for AUG
  • IFs dissociate and large subunit binds
33
Q

What are the 3 ribosomal sites?

A

E (exit)
P (where growing peptide chain attaches)
A (where tRNA binds codon)

34
Q

How does translation initiate in prokaryotes?

A

at Shine Dalgarno sequence, small ribosomal subunit binds

35
Q

What does the antibiotic tetracycline do?

A

blocks binding of amino-acyl tRNA to A site of ribosome

targets bacteria

36
Q

What does the antibiotic streptomycin do?

A

prevents transition from translation initiation to chain elongation
targets bacteria

37
Q

What does the antibiotic chloramphenicol do?

A

blocks peptidyl transferase reaction on ribosome

-targets bacteria

38
Q

What does the antibiotic erythromycin do?

A

binds in exit channel of ribosome and inhibits elongation of peptide chain
-targets bacteria

39
Q

What does the antibiotic rifamycin do?

A

prevents RNA synthesis by binding RNA polymerase

-targets bacteria

40
Q

What does the release of glucocorticoids signal to the body?

A

released during starvation

signal liver to produce glucose from AAs

41
Q

How is gene expression regulated?

A

transcriptional control, RNA processing, RNA transport and localization, translational control, mRNA degradation, protein activity control

42
Q

What are homeodomain proteins?

A

key regulators of animal development, subclass of helix turn helix motif

43
Q

What are the 2 regulatory parts in the lac operon?

A

to be on, lactose is broken into allolactose which binds to remove repressor

  • when no glucose, cAMP binds CAP to remove
  • lac operon is OFF if glucose is present
44
Q

What is epigenetics?

A

heritable (meiosis, mitosis), reversible changes in genome that regulate gene expression

45
Q

In mammal females, how is one X chromosome turned “off”?

A

inactivated by XIC (X inactivation center) and XIST (X inactivation specific transcript)
-association of XIST RNA with X chromosome is correlated with condensation

46
Q

What addition signals imprinting? What does it do?

A

add methyl group to cytosine in CG sequence on 5th carbon which causes chromatin condensation
-methylation is inherited in progeny DNA

47
Q

If it is a maternally imprinted gene, will either of the mom’s gametes be functional?

A

No, will imprint both genes so all children will have a maternally imprinted gene.
-if son gets maternally imprinted gene, will NOT pass along imprinted gene to children

48
Q

What HIV protein transports unspliced HIV mRNA from nucleus to cytoplasm?

A

Rev

49
Q

In low iron conditions, how does body respond?

A

Shut off ferritin product by inhibiting translation from IRE-BP in 5’UTR
-express transferrin receptor to uptake iron into cell

50
Q

What is Werner Syndrome?

A

premature aging, caused by genome instability (affects accessory DNA helicase for replication)

51
Q

Where is benzo[a]prene found?

A

the carcinogen produced by cigarette smoke

-only becomes carcinogenic when oxidized in cells

52
Q

What does cytosine de-aminate to ?

A

uracil

53
Q

What does 5-methyl Cytosine deaminate to?

A

thymine (usually missed by proofreading)

54
Q

How are thymine dimers created?

A

from UV light, binding of adjacent pyrimidine bases

55
Q

What is the process in strand directed mis-match repair?

A

in euk and prok: MutS binds to mismatched BP, MutL scans nearby DNA for nick (new strand) then MutL triggers degradation
Bacteria: no nicks so MutH nicks unmethylated DNA

56
Q

What is the process in base excision repair (BER)?

A

endonuclease and phosphodiesterase remove sugar base, DNA pol adds new nucleotides, ligase seals nick

57
Q

What is the process for nucleotide excision repair (NER)?

A

bigger problem: DNA helicase unwinds DNA, DNA pol adds NTs, DNA ligase seals back up

58
Q

What are the 2 solutions for double stranded breaks?

A

1) nonhomologous end joining- chop off jagged, ligate ends together, lose NTs, Ku protein
2) homologous end joining- more effective and difficult, use homologous chromosomes and recombination mechanisms

59
Q

What genes are involved in recombination in prok and eukaryotes?

A

Euk: Rad 51 and proteins ATM, Brca1, Brca2
Prok: RecA

60
Q

Where is p53 protein important?

A

at G1 checkpoint before cell division

Foundations of Medicine (7 decks)

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