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Biology 1B > DNA > Flashcards

DNA Flashcards

git gud

1
Q

What did Morgan study?

A

gene inheritance in Drosophila

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2
Q

What did Miescher do?

A

Isolated the ‘nuclein’ (DNA)

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3
Q

What did Hershey and Chase do?

A

Proved that DNA is the genetic material of a cell. Used viruses that infected bacteria

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4
Q

Nitrogenous bases are hydrophobic/hydrophilic?

A

hydrophobic

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5
Q

DNA does dissolve in water due to highly..

A

charged phosphate backbone

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6
Q

Which bases are purines? And what is their structure?

A

Guanine and Adenine. 2 fused rings.

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7
Q

Which bases are pyrimidines? What is their structure?

A

Cytosine and Thymine. They have 1 ring

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8
Q

What side of the DNA strand can you add bases to?

A

3’ end. Running 5’ -> 3’ direction

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9
Q

What kind of replication does DNA go through?

A

Semi-consevative

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10
Q

Watson and Crick discovered..

A

The base pairings of DNA

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11
Q

How do replication bubbles work?

A

Small areas of separation along the DNA with replication forks and origins of replication, where processes can begin. Daughter strands fuse in-between parent strands.

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12
Q

What does DNA polymerase do?

A

elongates the strands

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13
Q

What are the sources of nucleotide units?

A

triphosphates (ATP, GTP etc.)
2 Pi are ejected (pyrophosphate)

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14
Q

What does single-stranded binding protein do?

A

Stops H bonds from reforming

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15
Q

What does topoisomerase do?

A

breaks DNA, stops it from coiling, and puts it back together

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16
Q

what does primase do?

A

runs in opposite direction, adding RNA primers

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17
Q

what does DNA Pol III do?

A

adds bases between primers (produces Okazaki fragments)

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18
Q

What does DNA Pol I do?

A

Recognises RNA stretches (such as primers) and changes them to DNA fragments

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19
Q

What does ligase do?

A

joins together fragments

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20
Q

What does helicase do?

A

unwinds the double strand at replication forks

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21
Q

How does RNA polymerase catalyse transcription?

A

unwinds the double helix and makes a complementary copy of one strand (the template strand) of the DNA

22
Q

RNA does not have _______ capabilities.

A

Proof-reading

23
Q

What are the 3 steps of transcription:

A

Initiation, Elongation and Termination

24
Q

Describe the Initiation of transcription

A

Starts at the promoter (TATA box) where transcription factors (RNA Pol) bind

25
Describe the elongation step of transcription:
Local unwinding of 1-2 turns of the DNA and addition of nucleotide units
26
Describe the termination step of transcription:
Signalled by the sequence of the RNA transcript itself. In eukaryotes: AAUAAA (polyadenylation signal). Proteins then bind the transcript and cut free from RNA Pol, which then detaches from DNA
27
What is the 5' cap made from?
GTP
28
What is the Poly-A tail?
50-200 nucleotides at the 3' end to be cut
29
What are spliceosomes made from?
snRNPs and other proteins
30
What are snRNPs?
Small Nuclear RiboNucleoProteins
31
What are codons?
3 base pairs that code for an amino acid
32
What loads tRNA with the correct amino acid? This action requires ATP
Aminoacyl-tRNA synthetase. This is an enzyme
33
There are 20 different aminoacyl-tRNA synthetases because..
There are 20 different amino acids. Needs to be individual
34
What holds tRNA together
H bonds
35
What are the main features of tRNA?
Amino acid attachment site (has a 3' and 5' end), Anti-codon.
36
Describe how an aminoacyl-tRNA synthetase works?
ATP is used..AMP binds to amino-acid in the specific cleft. The trna binds to the anticodon recognition site and ejects the AMP.
37
What are the 3 sites in a ribosome?
P, A and E
38
Describe P the site
binds the growing peptide chain
39
Describe the A site
binds the incoming aminoacyl-tRNA
40
Describe the E site
Exit site to allow discharged tRNA to leave the ribosome
41
What are the 3 stages of translation?
Initiation, elongation and termination
42
Describe the initiation stage of translation
5' cap binds to the mRNA binding site to orientate the transcription. The start codon is AUG which produces a Methionine amino acid.
43
What are the 2 components of the ribosome?
large ribosomal subunit and the small ribosomal subunit. GTP -> GDP energy required to bring in large subunit.
44
Describe the elongation stage of translation
Codon recognition requires energy, 2GTP -> 2GDP.. enters A site. Peptide bond formation takes place by chain being passed on from P tRNA to A tRNA. Catalysed by large rRNA. Translocation occurs where both tRNA shuffle left and the one in site E exits (requiring GTP -> GDP)
45
Describe the termination stage of translation
UAG, UAA, UGA don't code for an acid. Release Factor Protein recognises this and adds a water group the final carbon, to cap the protein. Protein released and subunits come apart
46
What are some post-translation modifications a protein could go through?
-Protein folding -Sugars or lipids added -Amino acids removed -Moved to the required location
47
What is SRP?
Signal-recognition particle
48
What is SRP used for?
binds to signal peptide on the synthesising protein and binds to the ER membrane translocation complex. SRP leaves while polypeptide grows through pore
49
What are the base-pair substitution mutations?
Missense: changes the amino acid Nonsense: makes a premature stop codon or it can have no effect (still produces the correct amino acid)
50
What are the base-pair insertion or deletion mutations
Frameshift causing nonsense Frameshift causing extensive missense Insertion or deletion of 3 nucleotides, no frameshift, but extra/missing amino acid
51
How many possibilities of codons are there?
64.. 3 of these are stop codons

Biology 1B (6 decks)

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