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DNA Flashcards

1
Q

What is DNA composed of?

A

Nucleotides: phosphate, sugar, base

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2
Q

What is Chargaffs rule?

A

Adenine always binds thymine with two hydrogen bonds. Guanine always binds to cytosine with three hydrogen bonds

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3
Q

What is DNA replication?

A

This process makes identical copies of DNA for body cells used for growth, reproduction and repair. Every new cell needs a copy of the DNA or instructions to know how to be a cell

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4
Q

What are the three phases of replication?

A

Initiation, elongation, termination

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5
Q

What is initiation in DNA replication?

A

Replication takes place at several places on the double helix at the same time. This causes the replication to bubble. DNA opens in both directions creating the replication fork

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6
Q

What is elongation in DNA replication?

A

A large team of enzymes coordinate assembly of the new DNA strands

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7
Q

What is termination in DNA replication?

A

Completed process. Products are one new strand and one old strand of DNA

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8
Q

How many steps are there to DNA replication?

A

Seven

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9
Q

Describe each step in the enzyme used in DNA replication

A
  1. Unwind: DNA is unzipped by the hydrogen bonds breaking. This is done by helicase. Both sides of DNA act as templates to build the new strands.
  2. Maintain Separation:bases are prevented from re-bonding to their complementary bases (re-annealing) by attaching single-stranded binding proteins.
  3. Start Process: Primase add RNA primers to the strand to indicate the starting location of DNA replication. Topoisomerase relieves strain on parenting as it unwinds.
  4. Building It: DNA polymerase three locates the primer and begins adding free nucleotides to build the new DNA complementary strand.
  5. Finished: DNA polymerase one removes primers and as complementary bases.
  6. Review: DNA polymerase 1, 2, 3proofread the new strand to correct errors.
  7. Stick: Ligase forms phosphodiester bonds by dehydration synthesis to link Okasaki fragments together.
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10
Q

What are the three models of DNA replication and which is proved to be correct?

A

Conservative, semi conservative, dispersive. Semiconservative is proved to be correct

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11
Q

What does the semi conservative model of DNA replication entail?

A

Each new cell contains one original and one new strand.

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12
Q

What are three types of RNA?

A

Messenger, transfer, ribosomal

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13
Q

Describe the RNA structure

A

Single-stranded, uracil base, ribose sugar, shorter lengths

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14
Q

What is transcription?

A

A gene is copied into a complementary strand called messenger RNA. This occurs because DNA cannot leave the nucleus and it will be broken down by enzymes

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15
Q

Describe the initiation step of transcription

A

Starting the messenger RNA. RNA polymerase enzyme untwists/unzips a gene. Recognizes and binds upstream of the gene at the promoter site known as the TATA box indicating the start of transcription

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16
Q

Describe the elongation step of transcription

A

Building the messenger RNA. Only one strand of DNA serves as a template this is called the coding or sense strand. The unused strand hangs out and is called the non-coding/antisense strand. RNAP pairs free RNA nucleotides to the exposed bases of the DNA strand following chargaffs rule, but uracil replaces thymine. Messenger RNA is built five prime to three prime

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17
Q

Describe the termination stage of transcription

A

Completing the messenger RNA. RNAP recognizes a stop sequence along DNA and falls off. The newly synthesized messenger RNA separates from template DNA, and DNA zips back up.

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18
Q

What are three post transcriptional modifications?

A

Capping, tailing, splicing

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19
Q

What is capping?

A

A five prime cap added to protect messenger RNA from digestion as it exits the nucleus

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20
Q

What is tailing?

A

A three prime tail made of approximately 200 adenine bases is added by poly-a polymerase for protection.

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21
Q

What is splicing?

A

Spliceosome enzymes cut out undesirable intervening coding regions of messenger RNA called Intron’s. This leaves exons which are the protein building instructions that are expressed.

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22
Q

What is the final product of transcription?

A

A final messenger RNA strand that has instructions for building a protein. This will leave the nucleus and go to the cytoplasm

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23
Q

What is translation?

A

Messenger RNA is translated into a chain of amino acids to build a protein

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24
Q

What is the initiation stage of translation?

A

Starting the polypeptide. Ribosomes are the workers that read messenger RNA’s instructions and use it to build a polypeptide. A functional ribosome is made went to ribosomal subunits are put together. The ribosome recognizes and binds to the five prime cap of messenger RNA. The ribosome reads along the messenger RNA until it finds a specific sequence of bases AUG which represents the start codon. This establishes the reading frame which is the start of the polypeptide chain. From here, the ribosome continues to read three bases at a time called a codon

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25
Describe the elongation stage of translation
Building the polypeptide. As the ribosome moves three bases at a time, a tRNA molecule brings the correct amino acid. The tRNA must have the correct anti-codon for the amino acid to be added to the polypeptide. TRNA continues lining up amino acids according to codons
26
Describe the termination stage of translation
Completing the polypeptide. The ribosome reaches a stop codon and no tRNA is brought in. A release factor causes the rapids them to fall off the mRNA. The polypeptide chain is released.
27
What are post translation modifications?
The four levels of protein organization
28
What is the final product of translation?
A functional protein
29
What is protein synthesis?
Makes proteins for the functioning of the body cells. The process consists of transcription and translation. This is also referred to as the central dogma
30
What are mutations?
A change in the DNA from its original form. It may because spontaneously by an error in DNA replication or could be caused by mutagenic agents such as chemicals, viruses and UV lights. Mutations can have three different effects
31
What three effects can a mutation have?
Positive, negative, neutral
32
What are the two types of single gene mutations?
Point or frameshift
33
What is a point mutation?
Affects the single base pair substitution, insertion or deletion. There are four types including silent, non-silent, missense,non-sense
34
What is a silent mutation?
There's no change in the amino acid that is brought in
35
What is a non-silent mutation?
Affect the operation of the cell. Arises from the substitution of one base pair
36
What is a missense mutation?
Mutation that results in the single substitution of one amino acid
37
What is the nonsense mutation?
Converts a codon for an amino acid into a termination codon prematurely. Usually produces a nonfunctional protein as the protein does not finish building
38
What is the frameshift mutation?
A mutation caused by the addition or deletion of a nucleotide that results in a change in the reading frame
39
What are the five types of chromosome mutation's?
Deletion, insertion, inversion, translocation, duplication
40
What are the three types of gene expression?
Constitutive, inducible, repressible
41
What is constitutive gene expression?
Genes are always on. Unregulated
42
What is inducible gene expression?
Genes are only turned on as needed
43
What is repressible gene expression?
Genes are only turned off as needed
44
What is gene regulation?
The ability to control whether a structural gene is actively being expressed or not. The regulation of structural genes can occur at the same level of the chromosome, transcription, translation.
45
What are the parts of an operon?
Promoter, operator, genes, terminator
46
What is a promoter?
A binding site of RNA polymerase
47
What is an operator?
Control site of gene transcription
48
What is an epigenome?
Regulates which genes are transcribed and controls the rate of transcription
49
Who discovered DNA and when?
James Watson and Francis Crick in 1953
50
What is translational control of gene expression?
Controls how often and how rapidly mRNA is translated. Controls the rate at which a protein becomes active and the time it remains functional.
51
What is biotechnology?
The use of living organisms and systems to develop or make products
52
What is recombinant DNA?
DNA molecules formed by laboratory methods of genetic recombination to bring together genetic material from multiple sources
53
What are the four steps of DNA isolation?
Collecting cells from the organism, burst cells open using a detergent and warm water to release DNA, separate DNA from proteins and debris by spinning the solution, isolate the concentrated DNA using isopropyl alcohol
54
What is the polymerase chain reaction?
Increases the amount of DNA, amplifies DNA, creates millions of copies of a specific DNA sequence synthetically, DNA replication in a tube. The process occurs in three steps
55
What are the three steps of the polymerase chain reaction?
Denaturation: where DNA is heated to break the week hydrogen bonds allowing the strands to separate, primer annealing: the mixtures cooled allowing primers to buy into the complementary sequences, synthesis: the reaction is then heated to optimal temperature for DNA deliveries to act
56
What is transformation?
Alternation of bacterial cells genotype by the uptake of foreign DNA. The recipient cell takes up donor DNA. Recombination occurs between donor DNA and recipient DNA
57
What are restriction enzymes?
Biological scissors that can cut DNA. Originate from bacteria. Break phosphodiester bonds in nucleotides. Also called endonucleases
58
What are restriction fragments?
Pieces of DNA created by restriction enzymes
59
What are sticky ends?
A single-stranded end of the restriction fragment
60
What are blunt ends?
Straight ends without any single-stranded fragments
61
What is gel electrophoresis?
A gene is separated from the remaining unwanted fragments using an electric current. DNA has an overall negative charge from the phosphate group. Molecules are separated on the basis of size by sorting through a gel meshwork
62
How can gel electrophoresis separate DNA fragments?
Short DNA moves through the gel easily and travels further, long DNA moves through The gel slower due to the long pieces getting caught and therefore it does not move as far
63
What are variable number tandem repeats?
The number of times that genetic sequence is repeated
64
What is DNA fingerprinting?
A method that the identifies an individual based on the patterns formed from variations in the genetic code and terrible number tandem repeats. It is used in forensics, paternity test and other applications
65
What genetic techniques are used in DNA fingerprinting?
Restriction enzymes cut DNA into short tandem repeats, polymerase chain reaction primers amplify fragments of interest, gel electrophoresis separates fragments by size to create a banding pattern known as the genetic fingerprint
66
What are the seven steps of gene therapy?
Cells harvested from patient, in the lab virus altered so it cannot reproduce, gene is inserted into the virus, altered virus is mixed with patient cells, cells to come genetically altered, altered cells injected into patient, altered cells can produce desired protein
67
What is a GMO?
genetically modified organisms

Biology 12 (5 decks)

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