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Biology 2/2 > Unit 3 - Molecular Genetics > Flashcards

Unit 3 - Molecular Genetics Flashcards

1
Q

What does the DNA helicase do?

A

Breaks hydrogen bonds between complementary bases

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2
Q

Where does the replication fork end?

A

Where the hydrogen bonds are left unbroken

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3
Q

What does the single strand binding protein do?

A

They anneal to the strand to prevent them from reannealing

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4
Q

What does it mean to anneal?

A

To bond

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5
Q

What does the enzyme primase do?

A

Lays down RNA primers

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6
Q

What does DNA polymerase III do?

A

Creates strands using the template as a guide

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7
Q

Where direction is the leading strand built in?

A

5’ to 3’ (according to the new one)

Towards the replication fork

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8
Q

Which direction is the lagging strand built in?

A

3’ to 5’

Away from replication fork

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9
Q

The lagging strand is built in fragments, what are they called?

A

Okazaki fragments

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10
Q

What does DNA ligase do?

A

Joins Okazaki fragments with phosphodiester bonds

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11
Q

What do polymerase I and III do at the end?

A

Proofread for wrongly paired nucleotides then remove and replace them

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12
Q

What does DNA gyrase do?

A

Relieves tension from the unwinding of double helix

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13
Q

What bond keeps together DNAs backbone?

A

Phosphodiester bond

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14
Q

When does DNA replication occur?

A

During s phase

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15
Q

Why do we need to replicate DNA?

A

To keep DNA fresh and use it to make proteins

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16
Q

What are the three DNA replication models?

A

Conservative
Dispersive
Semi conservative

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17
Q

How does conservative DNA replication work?

A

Leaves original DNA strand intact and copies it

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18
Q

How does dispersive DNA replication work?

A

Produces two DNA molecules with sections of both old and new DNA in ever strand

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19
Q

How does semiconstructive DNA replication work?

A

Produces two DNA molecules with both an old strand and a new strand

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20
Q

What does re-annealing mean?

A

Coming back together

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21
Q

What happens to DNA when hydrogen bonds are formed?

A

It twists into a double helix

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22
Q

What is transcription?

A

The information in DNA is the transcribed into a complementary mRNA message

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23
Q

What is translation?

A

The ribosomes read the information in RNA and translate it to synthesize a protein

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24
Q

What does mRNA stand for?

A

Messenger RNA

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25
What does tRNA stand for?
Transfer RNA
26
What does rRNA stand for?
Ribosomal RNA
27
What does mRNA do?
Copies DNA code and carries genetic information to the ribosomes
28
What does rRNA do?
Makes up the ribosomes (along with proteins)
29
What does tRNA do?
Transfers amino acids to the ribosomes where proteins are synthesized
30
Where are mRNA and rRNA made?
In the nucleus
31
What is a codon?
Sequences of three bases
32
What are eukaryotes start codon?
AUG (methionine)
33
What are prokaryotes start codon?
Formyl methionine
34
What does a codon designate?
An amino acid
35
How many amino acids are there?
20
36
How many codons are there?
64
37
What shape is tRNA?
A clover-leaf
38
What is the basic structure of tRNA?
It's single stranded with an attachment site at one end
39
What is the attachment site used for?
Carrying an amino acid
40
What makes up the attachment site and why?
3 nucleotides that make up an anticodon to hold the complementary base pairs amino acid
41
What does transcription create?
mRNA
42
What does translation create?
Proteins or a polypeptide
43
What are the names of the two DNA strands used in transcription?
Template strand | Coding strand
44
Which DNA strand will be identical to mRNA (except for T -> U)?
Coding strand
45
What are the four steps of transcription?
1) initiation 2) elongation 3) termination 4) post-transcriptional modification
46
What enzyme is involved in transcription initiation?
RNA polymerase
47
What is a promoter region?
Location which is high in A-T base pairs (called tata box)
48
Why is a promoter needed to initiate transcription?
The promoters bases only have two hydrogen bonds between them so they're easier to break
49
What happens in transcription initiation?
RNA polymerase binds to a promoter region and unzips the double strand to expose the bases
50
Where are promoters located on DNA?
Upstream of the gene
51
What happens during transcription elongation?
RNA polymerase builds an mRNA strand off the template strand
52
RNA polymerase catalyzes what in transcription elongation?
Formation of phosphodiester bonds
53
What direction does transcription occur?
5' --> 3'
54
What happens in transcription termination?
RNA polymerase recognizes the termination and then releases the mRNA strand
55
What happens during post-transcription modifications of mRNA?
1) spliced 2) adds 5' cap 3) adds poly-A tail
56
What is splicing?
The removal of introns using spliceosomes and ligation of exams
57
What is an intron?
Non-coding region
58
What is an exon?
Coding region
59
What direction do ribosomes read mRNA?
5' --> 3'
60
What are the three steps of translation?
1) initiation 2) elongation 3) termination
61
Why must mRNA be modified before leaving the nucleus?
To protect it in the cytoplasm where there are dangerous enzymes and such
62
What happens during translation initiation?
Ribosomes recognize the 5' cap and bind to mRNA | Start translation at the start codon
63
What is the start codon used to ensure?
That the correct reading frame is used
64
What are the two ribosomal sites that bind to tRNA
A (acceptor) site | P (peptide) site
65
What is the a site?
Where tRNA brings a new amino acid
66
What is the p site?
Where peptide bonds for, between amino acids in the growing polypeptide
67
What happens during translation elongation?
tRNAs are released from the p site and then recycled
68
What happens during translation termination?
The ribosomes reaches the stop codon and translation ends
69
Where are operons located?
In prokaryotes
70
What are two examples of operons?
Lac and trp
71
What do operons accomplish?
Regulation of enzyme production
72
Lac operon is what kind of operon regulation ? Trp?
Enzyme induction, enzyme repression
73
What are the basics of operons?
Enzyme induction creates enzymes when the levels of effector are high (lactose for lac) Enzyme repression stops making enzymes when effector levels are high (tryptophan for trp)
74
What are the two classes of mutations?
Nucleotide mutations, and | Transposition mutations
75
What are 3 examples of nucleotide mutation (point mutation)
1) silent mutation 2) missense mutation 3) nonsense mutation
76
What are two examples of transposition mutation?
1) translocation | 2) inversion
77
What is silent mutation?
The change of a base that doesn't change the amino acid
78
What is missense mutation?
A substitution of a base that makes a different amino acid
79
What is a nonsense mutation?
A subsection of a base in a codon that causes a stop codon to replace a codon that was once an amino acid
80
What are frame shift mutations?
Changes in the reading frame caused by insertion or deletion of a base
81
What is not considered a frame shift mutation?
The deleting or inserting of 3 bases
82
What is translocation mutation?
Transfer of a fragment of DNA from one site in the genome to another location
83
What is inversion mutation?
The reversal of a segment of DNA within a chromosome
84
What is spontaneous mutation caused by?
Errors in DNA replication
85
What can induced mutation be caused by?
Radiation, chemicals, etc

Biology 2/2 (2 decks)

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