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BIOL 241 > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

4 characteristics of genetic material

A

1) replicate
2) store information
3) express information
4) allow variation by mutation

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2
Q

what is Chargaff’s rule?

A

all DNA should have 1:1 ratio (base pair rule) of pyrimidine and purine bases

A = T
G = C

A+T does not necessarily equal C+G

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3
Q

What did Avery, Macleod, and McCarty’s transformation experiment entail?

A

demonstrated that DNA was the genetic material because Type R cells + Type S DNA extract + DNase resulted in no DNA being formed

Type R + Type S DNA extract + DNase ==> not transformed ==> no bacteria appeared on petri dishes

Type R + Type S DNA extract ==> transformed ==> bacteria appeared on petri dishes

Type R + Type S DNA extract + RNase ==> transformed ==> bacteria appeared on petri dishes

Type R + Type S DNA extract + protease ==> transformed ==> bacteria appeared on petri dishes

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4
Q

What did Hershey and Chase experiment show?

A

DNA, not protein, enters the bacterial cell during bacteriophage infection and directs viral reproduction

used T2 phage to infect E.coli

T2 phage protein is labeled with 35 Sulfur. DNA is labeled with 32 Phosphorus.

32P was detected in E.coli cells –> indicates that DNA is genetic material

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5
Q

what are the purines?

A

adenine

guanosine

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6
Q

what are the pyrimidines?

A

cytosine

thymine

uracil

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7
Q

what do nucleotides consist of?

A

nitrogenous base

pentose sugar

phosphate group

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8
Q

what is DNA nucleotide structure?

A

deoxyribose pentose sugar

nitrogenous base

phosphate group

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9
Q

what is RNA nucleotide structure?

A

ribose pentose sugar

nitrogenous base

phosphate group

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10
Q

what is difference between nucleoside and nucleotide?

A

nucleoside = nitrogenous base + pentose sugar

nucleotide = nitrogenous base + pentose sugar + phosphate group

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11
Q

DNA is a ___-handed double helix

A

right

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12
Q

the 2 DNA strands are ___

A

antiparallel

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13
Q

there are ___ base pairs per helix turn

A

10

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14
Q

what is hyper chromic shift?

A

absorbance of UV light by nucleic acids

ring (bases) can absorb UV light

ss nucleic acid absorbs more UV light than ds

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15
Q

what is hyper chromic shift used for?

A

determine melting temp of DNA strand

melting temp is method for estimating base composition of DNA

A-T rich DNA has lower melting temp (because only bound by 2 H-bonds while C-G has 3 H-bonds)

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16
Q

what is thickness of naked DNA fibers?

A

2 nm

17
Q

what is thickness of DNA + histone (==> chromatin) fibers?

A

11 nm

18
Q

what is thickness of solenoid fibers?

A

30 nm

19
Q

which type of reciprocal translocation causes viable offspring? Which one causes non-viable offspring?

A

alternative segregation –> viable

adjacent segregation –> non-viable

20
Q

describe hybrid dysgenesis

A

male w/ P element X female w/o P element ==> sterile progeny (hybrid dysgenesis)

male without P element X female w/ P element ==> fertile progeny

21
Q

describe rho-independent termination

A

prokaryotic transcription termination

doesn’t depend on rho protein

RNA Pol will eventually transcribe a hairpin loop that slows down the RNA Pol –> as RNA Pol travels downstream, it encounters a uracil-rich region to which the RNA Pol is weakly bound –> this allows RNA Pol to dissociate and end transcription

22
Q

describe rho-dependent termination

A

prokaryotic transcription termination

does depend on rho protein

RNA Pol transcribes rho recognition site (rut) in mRNA transcript –> rho protein comes and binds to rut –> RNA Pol will also transcribe a hairpin loop that slows it down –> this allows rho protein to come in contact with RNA Pol –> separates DNA and RNA –> terminates transcription

23
Q

what is a lariat?

A

a branched intron formed during the mRNA splicing

24
Q

what is a positive gene regulation?

A

when regulatory molecule is mutated, gene is not expressed

25
Q

what is a negative gene regulation?

A

even when regulatory molecule is mutated, gene is expressed

26
Q

what is inducible regulation?

A

when an agonist is present, it causes gene to be expressed

27
Q

what is repressible regulation?

A

when an agonist is present, it causes gene to not be expressed

28
Q

describe positive inducible regulation

A

when inducer is present, it binds to activator –> activator encourages gene expression –> gene is expressed

when inducer is absent –> activator does not bind to operator –> gene is not expressed

29
Q

describe negative inducible regulation

A

when inducer is absent, repressor binds to operator –> gene is not expressed

when inducer is present, repressor does not bind to operator –> gene is expressed

30
Q

describe positive repressible regulation

A

when coactivator is present –> gene is not expressed

31
Q

is shine-dalgarno sequence in eukaryotes?

A

no; only in prokaryotes

BIOL 241 (3 decks)

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