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30 Biology > 3C - Cell Division, Genetics, and Molecular Biology > Flashcards

3C - Cell Division, Genetics, and Molecular Biology Flashcards

molecular biology (109 cards)

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1
Q

Chargaffs rule

A

The amount of adenine is equal to the amount of thymine.

The amount of guanine is equal to the amount of thymine.

Two strands of DNA are held together by complementary base pairs

Pivotal in understanding the double helix structure of DNA

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2
Q

Rosalind Franklin (THE GOAT)

A

Used x-rat diffraction to capture the famous “Photo 51” which revealed the helical structure of DNA

DNA is a double helix with two strands twisting around eachother

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3
Q

Watson and Crick (assholes)

A

Proposed thr DNA double helix model.

DNA structure slows dor STORAGE and transmission of genetic info

Two complementary strands with base pairs forming rungs of the thr helix

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4
Q

Where is thymine found

A

DNA

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5
Q

Where’s uracil found

A

RNA

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6
Q

Purine bases

A

pure AG
adenine guanine
double carbon ring

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7
Q

Pyrimidine bases

A

Thymine and cytosine

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8
Q

How to read dna strand

A

5’ to 3’

Recognize start? Fuh-Ive stante with fuh-sphate

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9
Q

Covalent vs hydrogen bonding strength

A

Covalent wins

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10
Q

A _____ is the building block of the DNA molecule. it contains a ______, a nitrogen-containing molecule called a “_____” and a sugar molecule/deoxy Ribose.

A

Nucleotide

phosphate group

base

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11
Q

how many hydrogen bonds do A&T and G&C

A

A&T = 2

G&C = 3

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12
Q

when DNA unravels, its typically the ____ unravelling

A

NUCLEOTIDE bases

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13
Q

which bonds win in a fight? A&T or G&C?

A

G&C, having 3 hydrogen bonds

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14
Q

what bond holds ribose/sugar molecule and phosphate group?

A

covalent bone = strong!

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15
Q

how does DNA run?

A

it has directionality, runs anti-parralel

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16
Q

summarize what each scientist did

A

| Erwin Chargaff | Found A=T and C=G (Chargaff’s Rule) |

| Rosalind Franklin | Took X-ray photos showing DNA is a helix |

| Watson & Crick | Built the 3D double helix model |

Phoebus Levene | Discovered DNA is made of nucleotides |

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17
Q

What are single-stranded binding proteins (SSBs) and what is their role in DNA replication?

A

SSBs are proteins that bind to separated DNA strands during replication. They keep the strands apart, prevent them from rejoining or forming tangles, and help enzymes copy the DNA accurately.

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18
Q

Why is DNA always built in a 5′ to 3′ direction?

A

Because DNA polymerase can only add new nucleotides to the 3′ end of the strand. It uses the energy from the incoming nucleotide’s phosphate group to do this, and that only works in the 5′ to 3′ direction.

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19
Q

what is the strand that is continously being added to?

A

leading strand

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20
Q

whats the choppy strand

A

lagging strand

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21
Q

What is primase and what does it do during DNA replication?

A

Primase is an enzyme that builds a short RNA primer on the DNA strand. This primer gives DNA polymerase a starting point to begin DNA synthesis, since it can’t start on its own.

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22
Q

What is DNA polymerase and what does it do during DNA replication?

A

DNA polymerase is the enzyme that builds new DNA strands by adding nucleotides to a primer in the 5′ to 3′ direction. It reads the template strand, matches bases correctly, and even proofreads for errors.

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23
Q

What are Okazaki fragments and why do they form?

A

Okazaki fragments are short DNA pieces made on the lagging strand during replication. They form because DNA polymerase can only build in the 5′ to 3′ direction, so the lagging strand is copied in sections, not all at once.

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24
Q

What is an exonuclease and what does it do during DNA replication?

A

An exonuclease is an enzyme that removes nucleotides from the ends of DNA or RNA strands. It helps with proofreading errors and removing RNA primers during replication.

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25
What is RNA polymerase and what does it do?
RNA polymerase is the enzyme that builds RNA during transcription. It reads a DNA template and makes a strand of RNA without needing a primer. It uses uracil (U) instead of thymine (T).
26
Proteins (polypeptides) are made up of
Amino acids
27
What is transcription and what are its main steps?
Transcription is the process of copying a gene from DNA into RNA. Steps: Initiation – RNA polymerase binds to the promoter. Elongation – It builds the RNA strand by matching RNA bases to the DNA template. Termination – It stops at a termination signal, and the RNA is released.
28
What is mRNA and what is its role in the cell?
mRNA (messenger RNA) is a single-stranded copy of a gene made during transcription. It carries instructions from DNA to ribosomes so proteins can be built during translation.
29
What is translation and what are its steps?
Translation is the process of making a protein from mRNA at the ribosome. Steps: Initiation – Ribosome binds to mRNA at AUG. Elongation – tRNAs bring amino acids; the chain grows. Termination – A stop codon ends translation, and the protein is released.
30
What is the role of DNA helicase?
Unwinds the DNA double helix at the replication fork.
31
What are single-stranded binding proteins (SSBs)?
Proteins that keep the DNA strands apart after they are separated by helicase.
32
Why is DNA built in the 5' to 3' direction?
DNA polymerase can only add nucleotides to the 3' end of the growing strand.
33
What is primase?
An enzyme that creates RNA primers so DNA polymerase can begin replication.
34
What is DNA polymerase?
An enzyme that adds new DNA nucleotides to a growing DNA strand during replication.
35
What are Okazaki fragments?
Short DNA segments synthesized on the lagging strand.
36
What is the function of exonuclease in DNA replication?
Removes RNA primers and helps proofread and fix errors.
37
What is the role of DNA ligase?
Seals gaps between DNA fragments, especially on the lagging strand.
38
What is RNA polymerase?
An enzyme that builds RNA from a DNA template during transcription.
39
What is transcription?
The process of copying a gene from DNA into RNA.
40
What are the steps of transcription?
Initiation, elongation, and termination.
41
What happens during transcription initiation?
RNA polymerase binds to a promoter and unwinds the DNA.
42
What happens during transcription elongation?
RNA polymerase adds RNA nucleotides complementary to the DNA template.
43
What happens during transcription termination?
RNA polymerase reaches a termination signal and releases the RNA strand.
44
What is mRNA?
Messenger RNA that carries instructions from DNA to the ribosome.
45
What is AUG?
The start codon in mRNA, which codes for methionine.
46
What is translation?
The process where ribosomes build proteins using mRNA instructions.
47
What are the steps of translation?
Initiation, elongation, and termination.
48
What happens during translation initiation?
Ribosome binds to mRNA at the start codon (AUG).
49
What happens during translation elongation?
tRNAs bring amino acids, which are joined to form a protein.
50
What happens during translation termination?
Ribosome reaches a stop codon and releases the finished protein.
51
What is tRNA?
Transfer RNA that brings amino acids to the ribosome and matches codons with anticodons.
52
What is a codon?
A sequence of three mRNA bases that codes for a specific amino acid.
53
What is an anticodon?
A sequence of three bases on tRNA that pairs with a codon on mRNA.
54
What is the replication fork?
The Y-shaped region where the DNA is split into two strands for copying.
55
Why is replication called 'semi-conservative'?
Each new DNA molecule has one original strand and one new strand.
56
What is the difference between the leading and lagging strand?
The leading strand is synthesized continuously; the lagging strand is synthesized in Okazaki fragments.
57
Why does the lagging strand need multiple primers?
Because it's made in short segments that each need a starting point.
58
What happens if DNA polymerase makes a mistake?
Exonuclease activity can remove the incorrect base and replace it.
59
Which enzyme replaces RNA primers with DNA?
DNA polymerase I (in prokaryotes) replaces RNA primers with DNA.
60
Which strand of DNA is used as the template in transcription?
The antisense strand (or template strand) is used to build mRNA.
61
What is the promoter?
A DNA sequence that signals RNA polymerase where to start transcription.
62
What is the TATA box?
A common promoter sequence where transcription factors and RNA polymerase bind.
63
What are introns and exons?
Introns are non-coding regions removed from RNA; exons are coding regions that remain.
64
Where does transcription occur in eukaryotic cells?
In the nucleus.
65
Why is RNA processing important?
It protects mRNA and ensures only coding regions are translated.
66
What is the ribosome made of?
rRNA and proteins.
67
What are the A, P, and E sites of the ribosome?
Sites for tRNA binding and movement during translation: Aminoacyl, Peptidyl, Exit.
68
What is the function of rRNA?
Forms the core of the ribosome and catalyzes peptide bond formation.
69
What is the genetic code?
The set of rules that determine how codons correspond to amino acids.
70
What is a stop codon?
A codon that signals the end of translation: UAA, UAG, UGA.
71
Why is the genetic code called 'redundant'?
Multiple codons can code for the same amino acid.
72
What determines the sequence of amino acids in a protein?
The sequence of codons in the mRNA.
73
What happens to a protein after translation?
It folds into its functional shape and may undergo further modification.
74
germ/gamete cell mutations
inheritable
75
somatic cell mutations
NOT inherited
76
77
mWhat is a point mutation?
🧬 A point mutation is a change in one single base (letter) of the DNA sequence. It can be a substitution, insertion, or deletion of one nucleotide. This may affect how proteins are made!
78
What is a point germline mutation?
🧬 A point germline mutation is a change in one DNA base in a sperm or egg cell. If passed on, it affects every cell in the baby and can be inherited by future generations.
79
What is a silent mutation?
🤫 A silent mutation is a point mutation where the DNA changes, but the amino acid stays the same, so the protein is not affected.
80
What is a missense mutation?
💥 A missense mutation is a point mutation where one base changes, causing a different amino acid to be made. This can change how the protein works and may lead to disease.
81
What is a nonsense mutation?
🛑 A nonsense mutation is a point mutation that changes a codon into a STOP codon, causing the protein to be cut short and usually nonfunctional.
82
What is a conservative missense mutation?
😌 A conservative missense mutation changes one amino acid to a similar one, so the protein usually keeps its normal function.
83
What is a non-conservative missense mutation?
(╥﹏╥) A non-conservative missense mutation changes one amino acid to a very different one, which can disrupt the protein’s structure and function, often leading to problems.
84
What is a plasmid?
A small, circular piece of DNA found in bacteria that can be used to carry new genes.
85
Why do scientists use restriction enzymes in genetic engineering?
To cut open the plasmid at specific spots, making room to insert a new gene (like insulin).
86
What is inserted into the plasmid after cutting it with restriction enzymes?
The human insulin gene and a marker gene like GFP (green fluorescent protein).
87
What is the purpose of adding a marker gene like GFP?
It lets scientists see which bacteria have successfully taken up the engineered plasmid (they glow!).
88
What is bacterial transformation?
A process where bacteria absorb and incorporate foreign DNA (like a plasmid with the insulin gene).
89
What happens after the plasmid is inserted into the bacterium?
The bacterium uses the new gene to make human insulin and then divides, passing the gene to new bacteria.
90
Why do scientists use bacteria to make insulin?
Bacteria grow and divide quickly, making lots of insulin cheaply and efficiently.
91
What is bacterial conjugation and how does it help?
It's when bacteria share plasmids with each other using pili — it helps spread the insulin gene to more bacteria.
92
What is recombinant DNA?
DNA that’s been combined from different sources (like human + bacterial DNA) in a lab.
93
Why is this process important for medicine?
It allows mass production of human insulin for people with diabetes, saving millions of lives.
94
What is gel electrophoresis used for?
To separate molecules like DNA or proteins based on size and charge.
95
Why does DNA move in gel electrophoresis?
Because it's negatively charged and is pulled toward the positive electrode (cathode).
96
What part of the DNA makes it negatively charged?
The phosphate groups on its backbone.
97
What is agarose gel?
A jelly-like substance with tiny pores that DNA moves through.
98
What does a buffer solution do in gel electrophoresis?
It conducts electricity and keeps the DNA stable.
99
Which electrode is positive in gel electrophoresis?
The cathode is positive.
100
Do smaller or larger DNA fragments travel faster?
Smaller fragments travel faster because they fit through the gel pores more easily.
101
How are DNA fragments created before gel electrophoresis?
Using restriction enzymes (REs).
102
What is a DNA ladder?
A set of DNA fragments of known sizes used as a reference to measure unknown fragments.
103
Why should the same restriction enzyme be used on all samples?
To make sure the DNA is cut in the same way, making comparisons fair.
104
Why is it important to use the same restriction enzyme on all DNA samples in gel electrophoresis?
Because restriction enzymes cut DNA at specific sequences, using the same enzyme ensures all DNA is cut the same way so differences in fragment sizes reflect real DNA differences, not differences in cutting
105
What do restriction endonucleases do? ✂️
They are enzymes that cut DNA at specific sequences called restriction sites. 🧬
106
What are sticky ends? 🧲
Uneven cuts by restriction enzymes that leave single-stranded overhangs which can stick to matching DNA sequences. 🔗
107
Why is it important to use the same restriction enzyme on different DNA pieces?
So the sticky ends match perfectly and can join together like puzzle pieces! 🧩
108
What enzyme “glues” DNA strands together after they join? 🧰
DNA ligase seals the sugar-phosphate backbone to create stable recombinant DNA. 🔥
109
What is recombinant DNA? 🤖
DNA made by joining pieces from different sources using restriction enzymes and ligase. 🌟

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