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Molecular Bio, Developmental Bio, Immunology > Molecular Biology > Flashcards

Molecular Biology Flashcards

Exam 1 Material

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1
Q

TRUE/FALSE
Although DNA is the genetic material in most organisms, RNA can act as the genetic material in some viruses.

A

True. In the event RNA acts as the genetic material for viruses, when infecting a cell, either host or sometimes viral reverse transcriptase is used to perform reverse transcription on the RNA to convert it into DNA so that it may be properly used to the viruses advantage.

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2
Q

TRUE OR FALSE
Nucleic acids are polymers of nucleoside monophosphate which consists of a 6-carbon sugar backbone, a base, and a phosphate group.

A

FALSE on two counts.

  1. A nucleoside is a sugar + a base. What was described here is sugar + base + phosphate which is a nucleotide.
  2. The sugar backbone, be it deoxyribose or ribose have a 5 carbon backbone, not 6. Hence 5’ to 3’.
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3
Q

Which of the following conditions does not lead to DNA denaturation?

Make the solution more basic Mechanical force
Add more salt to the solution
Increase the temperature
All of the above

A

Adding more salt to the solution. Though some sources online debate this and claim the opposite.

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4
Q

Which nucleotide pairs with Cytosine (C)?

A

Guanine (G)

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5
Q

What is the complementary strand for the sequence 5’ ATCGTCA 3’

A

5’ TGACGAT3 3’

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6
Q

What is a nucleoside?

A

A nucleoside is a sugar backbone with a purine or pyrimidine base (such as guanine, adenine, thymine, cytosine, or, uracil)

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7
Q

What is a nucleotide?

A

A nucleotide is a sugar backbone with a purine or pyrimidine base attached (such as guanine, adenine, thymine, cytosine, or, uracil) and with a phosphate group attached.

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8
Q

TRUE or FALSE

The bases in a nucleotide stick out.

A

True.

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9
Q

Stronger hydrogen bonds exist between which pairs, A-T or C-G

A

C-G

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10
Q

What is the normal role of the HD protein in Cells and what goes wrong in cells with the Mutant protein?

A

HD mutation is both a “gain of function” Mutation and a “loss of function” mutation

HD protein is involved in vesicle
Traffic in neurons.
HD mutation alters transcription
In neurons.

Mutant HD protein reduces acetylation and increases methylation of histone proteins.
Drugs are being found that reverse this effect

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11
Q

DNA replication can be divided into three stages

A

Initiation:
Elongation:
Termination:

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12
Q

-some means what?

A

A collection of things

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13
Q

Where does DNA replication start?

A

C: From a special piece of DNA named ori.

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14
Q

In eukaryotes, which of the following nucleic acids is used as the primer to initiate DNA replication?

A

A: RNA

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15
Q

DNA replication starts where?

A

At the origin, or ORI, a specific origin of replication, but do not have an identifiable sequence.

In bacteria they have a defined feature.

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16
Q

Bacterial have a ________ (shape) chromosome.

A

Circular

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17
Q

Single origin =

A

Single replicon

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18
Q

oriC is around _____ bp

A

245bp

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19
Q

Ori is ___ rich.

A

A-T rich.

It contains 11 GATC sequences.

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20
Q

Ori has two motifs. One is ______ long and another that is ______ long.

A

13 and 9mers long (mer = polymer)

21
Q

The A of GATC in ori is subject to _________.

A

N^6 methylation

22
Q

What is a conditional mutation?

A

A mutation that exerts a phenotype under defined conditions.

i.e. Temperature sensitive mutants

E.coli ts mutations in the dna genes.

Conditional mutations are necessary for genetic studies of identifying critical/necessary genes.

23
Q

Mutants of replication =

A

lethality

24
Q

DnaA binding to oriC involves:

A

DnaA-ATP, then DnaA-ATP tetramer binds 9-mers. ATP is used as a form of supporting brute-force into opening oriC.

25
Q

DnaA unwinds the ______ (13mers or 9mers), using ________ as energy.

A

13mers
Using ATP as energy

26
Q

When DnaA-ATP binds 9mers, what happens?

A

The DNA bends.

27
Q

DnaA binds to motifs and forms a ________.

A

loop

28
Q

After DnaA performs its function, what does it recruit?

A

DnaB and DnaC.
DnaB is an ATP dependant helicase.
DnaC is a Chaperone and Suppressor of DnaB. It is ATP-bound.

29
Q

Phospholipids and single stranded DNA stimulate ______ activity for DnaA.

A

ATPase

30
Q

DnaA-ATP (______ form), DnaA-ADP (_______ form)

A

active, inactive

31
Q

After 13mer opens up, what happens to DnaA-ADP?

A

It dissociates.

32
Q

DnaG is what?

A

A Primase used to synthesis the primer.
It is an RNA polymerase that generates small RNA primers.

33
Q

After DnaG activation, the _________ complex is ready.

A

Initiation complex

Now proceeds to elongation.

34
Q

dnaG RNA polymerase priming starts with these two base pairs __.

A

AG

35
Q

Additional factors for initiation are three other proteins:

A

Hu: DNA binding protein
Gyrase: Type II topoisomerase
SSB: Single stranded binding protein

36
Q

Initiation of DNA replication in bacteria (E.coli) requires:

A
  1. New protein synthesis ->
    Block synthesis, either initiation,
    replication in progress proceeds, or 2nd
    round
  2. Transcription. 2 genes flanking oriC must
    be transcribed, provide torsional stress to
    open origin.
  3. Membrane/cell wall synthesis -> Block
    synthesis -> initiation
  4. Full methylation of both strands of oriC
37
Q

Both strands of DNA must be fully ______ before replication will begin.

A

methylated

38
Q

What is the term for one strand of DNA being methylated at the GTAC, but not the other, and what is the consequence?

A

Hemi-methylated
Initiation phase of replication is subsequently blocked.

39
Q

Checkpoints in the cell cycle do what?

A

Regulate all stages of the cell cycle, These are disrupted in cancer.

40
Q

Entry into what phase is TIGHTLY regulated?

A

S phase

41
Q

Only ____ percent of chromosomal origins are active at a time.

A

15%. The rest are queued and waiting.

42
Q

Prokaryotic DNA is replicated _____ while eukaryotic DNA is replicated _____.

A

Fast (50kb/min)
Slow (2kb/min)

43
Q

DNA synthesis requires a ______ factor. It is found in the nucleus. This is for EUKARYOTIC organisms and is similar to the purpose of dnaA.

A

DNA synthesis requires a LICENSING factor

44
Q

What is an ARS?

A

An autonomously replicating sequence

45
Q

What happens when you administer ARS to a plasmid?

A

It replicates. It acts as an ori, as an origin of replication. Synthesized from yeast.

46
Q

What is an ORC?

A

An origin of replication complex.

It associates throughout cell cycle, likely purpose to identify origin for replication of machinery.
ORC platform on which pre-replication machinery assemble.
Well conserved.

47
Q

Cdc6 is what?

A

A licensing factor, made in G1 phase and binds ORC, Helicase then binds.

48
Q
A

Molecular Bio, Developmental Bio, Immunology (9 decks)

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