Bio Grade 12 > DNA test > Flashcards

DNA test Flashcards

(42 cards)

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1
Q

What are the 3 components of DNA?

A
  • deoxyribose sugar
  • phosphate group
  • nitrogenous base
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2
Q

What is a Nucleotide?

A

a molecule that consists of a 5-carbon sugar with a nitrogenous base attached to their 1’ carbon of the sugar and 1’ phosphate group that is attached to the 5’ carbon of the sugar.

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3
Q

What are the 4 nitrogenous bases?

A
  • adenine
  • thymine
  • guanine
  • cytosine
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4
Q

How do the nitrogenous bases bond?

A
  • A bonds with T (using 2 H-bonds)
  • G bonds with U (using 3 H-bonds)
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5
Q

What does DNA helicase do?

A

it unwinds the double helix by breaking the h-bonds that holds the bases together

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6
Q

What does DNA gyrase do?

A

When DNA unwinds tension is created so DNA gyrase relieves it by cutting the strands which allows the strands to swivel around and then rejoins the cut strands

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7
Q

What is the DNA replication Fork?

A
  • the area where DNA is about to be seperated
  • lots of them in eukaryotic cells (b/c they are large)
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8
Q

What is a replication bubble?

A

an area where the forks are close together

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9
Q

In what direction does DNA replicate?

A

5’ to 3’

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10
Q

What is a leading strand?

A

it is the strand that is built by primase

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11
Q

What are Okazaki Fragments?

A

When DNA opens primers are constantly added. These short segments are called Okazaki fragments

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12
Q

What does DNA ligase do?

A

it joins the Okazaki fragments together, attaching the DNA “backbone”, by creating phosphodiesterase bonds

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13
Q

What are the 3 major classes of RNA and what do they do?

A
  • mRNA (messenger) used as a template to make proteins
  • rRNA (ribosomel) gives ribosomes their structure
  • tRNA (transfer) matches amino acids to mRNA to help make protiens
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14
Q

What is a promoter?

A

it is the upstream area where the RNA polymerase binds on the DNA for the gene to be transcribe. It indicates where the RNA polymerase should start

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15
Q

What are the 3 stages of transcription?

A
  • initiation
  • elongation
  • termination
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16
Q

What is initiation?

A

it is when the enzyme RNA polymerase binds to a specific site on the DNA and unzips it. The promotor indicates where it should start. This spot is where there is a high amount of A and T bases. this indicates the beginning of the gene

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17
Q

What is elongation?

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A

the mRNA is built 5’ to 3’ direction without the need for a primer. The promoter sequence made in initiation isn’t transcribed. The strand that is used to code for the mRNA is called the template strand. and the other strand that isn’t transcribed is called the coding strand. Therefore the mRNA sequence is identical except that it contains U instead of T

18
Q

What is Termination?

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A

a termination sequence tells the RNA sequence to stop. when this sequence is reached the mRNA strand comes off and the RNA polymerase can transcribe another gene

19
Q

What are exons and introns?

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A
  • exons are coding regions that are only found in mRNA that is sent to the ribosome
    -introns are non coding regions that are found all throughout the cell
20
Q

What enzymes are involved in post-transcriptional modifications?

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A

Poly-A polymerase and spliceozons

21
Q

What happens in translation?

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A

the mRNA produced is decoded to make a protein that contains a specific amino acid.
- initiation: the ribosome gather around the mRNA and reads it to see what amino acid is needed
-Elongation: it recognizes the start codon and codes for methionine. it has 3 sites where tRNA can bond the A,P and E site. the tRNA takes the methionine to the P then carries the amino acid to A
- Termination: When the ribosome hits a stop codon. there isn’t a code so no corresponding tRNA exists. When hits a stop codon the 2 sub units separate

22
Q

What are the start and stop codons?

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A
  • Start codon (Aug): codes for a “met” which stands for the amino acids “methionine”
  • Stop Codon: when the ribosome comes in contact with this it stops protein synthesis stops. UGA, UAG, UAA
23
Q

What are the 4 levels of gene regulation that occur in eukaryotic cells?

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A

1) transcriptional: regulates which genes are transcribed or controls the rate
2) post-transcriptional: mRNA undergoes changes in the nucleus before translation, and involves removing introns and splicing together exons
3) translational: controls the length of time translation can take and the time it takes for “usual” mRNA to be broken down in cytoplasm
4) post-translational: the rate is controlled regarding how long it takes for a protein to become active and how long it can remain functioning, as well as adding various chemical groups to it

24
Q

What is a Operon?

Study These Flashcards
A

is a cluster of genes controlled by a promoter and an operator (in prokaryotes) and the structural genes that follow

25
How does the LAC operon operate when lactose levels are too low?
when too low, the regular form of the LACl protein can be found. its called a repressor protein b/c it has the ability to block transcription. It attaches to the operator and promoter which doesn't allow the RNA polymerase to start
26
How does the LAC operon operate when lactose levels are too High?
the increase acts as a signal molecule or an inducer. the increase naturally binds to the LACl protein which changes the shape, so it can no longer bind to the DNA to block the RNA polymerase
27
How does the TRP operon operate when tryptophan levels are too low?
the Operon is able to translate because there is no tryptophan which is needed to block it. So it is in its inactive form so it can't bind
28
How does the TRP operon operate when tryptophan levels are too high?
once the levels start to rise, it starts to bind increasingly to the TRP repressor protein. This allows it to bind to the operator and blocks the RNA polymerase
29
What is the difference between missense and nonsense mutations?
Missense: when a codon is altered but this time resulting in a different amino acid being included in the protein sequence Nonsense: when a change in the DNA sequence causes the stop codon to occur to early.These are harmful because a large part of the protein might not be made.`
30
What are point mutations?
silent missense and nonsense mutations. involve mutations at a specific base pair a long a Nucleotide sequence.
31
What are silence mutations?
they have no effect on the cells operation and usually occur in the non-coding regions of DNA and are very common. They may be cut out when the mRNA is prepared for translation in the cytoplasm
32
What is an inversion mutation?
if this segment reattaches to a correct homolog but in reverse order
33
What is an translocation mutation?
a segment of DNA attaches to the non homologous chromosome (a different chromosome not part of the "pair")
34
What is recombinant DNA?
a technology that allows DNA to be moved from one molecule to another. It enables the analysis of DNA and alteration of genes
35
What are restriction enzyme?
they come from bacteria and allow DNA to be cut at specific base pair sequence. There are many types that are able to recognize specific recognition sites
36
What is the difference between sticky and blunt ends?
sticky ends: a restriction enzyme leaves an overhang. This makes them easy to rejoin when they encounter the same sticky from another DNA cut site Blunt ends: the DNA strand separate, but there are no overhangs produced( it doesn't separate any h-bonds between base pairs) and don't really join together
37
What does gel electrophoresis do? And what is the gel made out of?
it separates DNA fragments and looks at the length of DNA strands. It is made up of agarose or polyacrylamide
38
What are plasmids? And how do they work?
They are small circulate double stranded DNA molecules that are found in bacteria. make multiple cloning sites and can cut out different restriction enzymes.
39
What does PCR do?
it makes copies of a specific DNA region. Is used to make gene fragments
40
What does RFLP stand for?
Restriction fragment length polymorphism
41
What do each of the 4 rxn tubes contain in DNA sequencing
datp, dgtp, dttp, dctp
42
How is the RFLP procedure accomplished step by step?
DNA is digested, put through gel, DNA is denatured and placed on nylon membrane, then compared to radioactive DNA strand (matching hybrodized-join) x-ray used to see strands
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