Bio & Chem Grade 12 > Molecular genetics > Flashcards

Molecular genetics Flashcards

(89 cards)

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1
Q

Nucleoside

A

Bare-bones DNA part: sugar + nitrogenous base, no phosphate tail.

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2
Q

Nucleoside triphosphates

A

Full package: nucleoside + three phosphates. Energy-rich building blocks used by DNA polymerase.

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3
Q

Helicase

A

The “unzipper” enzyme — breaks H-bonds to separate DNA strands.

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4
Q

Gyrase

A

The “tangle manager” — relieves supercoiling ahead of the fork.

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5
Q

Single stranded binding (SSB) proteins

A

Keep DNA strands apart so they don’t re-anneal.

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6
Q

DNA primase

A

The starter enzyme — makes RNA primers.

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7
Q

RNA primer

A

Short RNA piece that provides the 3’ end for DNA polymerase to start.

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8
Q

5’ to 3’

A

Direction DNA is built; new nucleotides added to the 3’ end only.

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9
Q

ssDNA

A

A single DNA strand used as a template.

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10
Q

DNA Polymerase III

A

Main builder — adds DNA nucleotides in 5’→3’.

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11
Q

DNA polymerase I

A

Clean-up crew — removes RNA primers & replaces with DNA.

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12
Q

DNA Ligase

A

The gluer — seals gaps between Okazaki fragments.

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13
Q

Okazaki fragments

A

Short DNA pieces made on the lagging strand.

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14
Q

Replication Fork

A

Y-shaped area where DNA is unwound and replicated.

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15
Q

dNTP’s

A

Deoxynucleotide triphosphates (dATP, dCTP, dGTP, dTTP).

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16
Q

Leading strand

A

Built continuously toward the fork; needs one primer.

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17
Q

Lagging strand

A

Built in pieces away from the fork; needs many primers.

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18
Q

What is mRNA

A

Blueprint carrying instructions from DNA to ribosomes.

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19
Q

RNA Polymerase II

A

Enzyme that builds RNA from DNA during transcription.

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20
Q

Promoter region

A

“Start here” signal for transcription.

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21
Q

Transcription factors

A

Helper proteins that guide RNA polymerase to the promoter.

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22
Q

Anti-sense strand

A

The DNA strand used as a template for mRNA

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23
Q

Sense Strand

A

Matches mRNA sequence (except T→U) but is not read.

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24
Q

Pre-mRNA

A

First draft of mRNA — contains introns.

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25
Exons
Coding regions kept in final mRNA.
26
Introns
Non-coding sections removed during splicing
27
Spliceosome
Edits pre-mRNA by removing introns and joining exons.
28
Capping
Protective 5’ cap added to mRNA.
29
Polyadenylation
Poly-A tail added at 3’ end to protect mRNA.
30
Terminator region
Stop signal for transcription.
31
Rho-dependant termination
Rho protein chases RNA polymerase off DNA.
32
Termination via Hairpin Loop
RNA folds into a loop causing polymerase to fall off.
33
Termination via Termination Factors
Proteins signal polymerase to stop and release RNA.
34
3 groups of nucleotides
Phosphate group, pentose sugar, nitrogenous base
35
Purines
Guanine and adenine
36
Pyrimidines
Cytosine, thymine (DNA) , uracil (RNA)
37
Complementary base pairs
Uracil and adenine (apple in the tree). Cytosine and guanine (cars in the garage).
38
Bonds in the DNA
Phosphodiester bonds, glycosidic bond
39
Structure of RNA
Single helix
40
Pentose of RNA
Ribose
41
Base pairs
A=U & C ≡G
42
Location of RNA
Nucleus & cytoplasm
43
Function of RNA
Transmit information
44
Forms of RNA
1. Messenger (mRNA) 2. Transfer (tRNA) 3. Ribosomal (rRNA)
45
Structure of DNA
Double helix
46
Pentose of DNA
Deoxyrisbose
47
Directionality of DNA
Antiparallel
48
Base pairs of DNA
A=T & C≡G
49
Location of DNA
Nucleus
50
Function of DNA
Store information
51
Semiconservative replication
Each new DNA has one parent and one new strand.
52
First step of DNA replication
Helicase unzips DNA from origins of replication
53
Second step of DNA replication
DNA primase lays short RNA primers on exposed ssDNA strands
54
Third step of DNA replication
DNA polyemase 3 extends DNA from primers
55
Fourth step of DNA replication
DNA polymerase 1 replaces RNA primers with DNA
56
Fifth step of DNA replication
DNA ligase seals gaps between Okazaki fragments
57
First step of transcription
RNA Pol II binds promoter and unzips DNA (initiation).
58
Second step of transcription
Polymerase builds RNA copy (elongation).
59
Third step of transcription
Reaches terminator and releases pre-mRNA (termination).
60
What is translation
Ribosomes make protein from mRNA transcript
61
What is a codon
A sequence of 3 mRNA nucleotides
62
What is a anticodon
3-nucleotide sequence on tRNA.
63
Why is tRNA important
It carries specific amino acids matched by synthetases.
64
The first step of translation
Ribosome binds mRNA near 5’ end, finds AUG start codon (initiation)
65
Second step of translation
Ribosome moves codon to codon adding amino acids (elongation)
66
Third step of translation
Ribosome hits stop codon, finished protein detaches (termination)
67
What is an operon
A cluster of genes under the control of a promoter
68
When lactose is present in lac operon
Lactose removes repressor → operon ON.
69
When lactose is absent in lac operon
Repressor binds operator → operon OFF.
70
What is the promoter
Where transcription starts
71
What is an operator
On/off switch
72
What is an repressor
Turns gene off
73
What is the inducer
Removes repressor to turn gene on
74
What are histones
Proteins DNA wraps around; form nucleosomes.
75
What is the transcription regulation
Stronger TATA → more transcription.
76
What is post-trancriptional regulation
Alternative splicing — different mRNAs from 1 transcript.
77
What is point mutations
Substitution and frameshift.
78
What is a silent mutation
Substitution mutation. Has no effect on the cell.
79
What is a missense mutation
Substitution mutation. Changes a single amino acid.
80
What is a nonsense mutation
Substitution mutation. A stop codon replace an amino acid.
81
What is a deletion mutation
Frameshift mutation. Removes 1 or more nucleotides.
82
What is a insertion mutation
Frameshift mutation
83
How do you get mutations from your parents
Through sex cells DNA
84
What is Translational Regulation
Poly-A tail editing: addition/deletion of 3’ adenines
85
What is Post-translational Regulation
After a protein is made, the cell may need to fold it, cut it, or combine it with other pieces so it actually works.
86
What is Restriction Endonuclease
Enzymes that act like molecular scissors — they cut DNA at specific sequences.
87
What is Gel Electrophoresis
A method that separates pieces of DNA by size using an electric current — smaller pieces move farther through the gel.
88
When tryptophan is absent
The operon is turned ON
89
When tryptophan is present
the operon is turned OFF as the trp binds to the repressor
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