Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology SL > 2.7 DNA-> Proteins > Flashcards

2.7 DNA-> Proteins Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

what kind of process is DNA replication? (3)

A

semi-conservative process (when a new double-stranded DNA molecule is formed)
- one strand will be from the original template molecule
- one strand will be newly synthesised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why is DNA replication a semi-conservative process?

A

because each nitrogenous base can only pair with its complementary partner
- A T
- C G

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what enzymes are involved when DNA is replicated?

A

helicase and DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what characteristic does the formed DNA strand have? (2)

A
  • each new strand formed will be identical to the original strand separated from the template
  • 2 semi-conservative molecules formed will have an identical base sequence to the original molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

who confirmed that DNA replication was semi-conservative?

A

Meselson-Stahl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

before the Meselson-Stahl experiment what three hypotheses had been proposed?

A
  • conservative model- an entirely new molecule is synthesised from a DNA template
  • semi-conservative - each new molecule consists of one newly synthesised strand and one template strand
  • dispersive model - new molecules are made of segments pf new and old DNA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how did Meselson and Stahl experiment the validity of the three models? (3)

A

using radioactive isotopes of nitrogen (N is a key component of DNA)
- DNA molecules were prepared using heavier 15H and includes to replicate in presence of lighter 14N
- the samples were then separated to determine the composition of DNA in the replicated molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what were the results of the experiment? (3)

A
  • after one division, DNA molecules were found to contain a mix of 15N and 14N disproving the conservative model
  • after two divisions, some molecules of DNA were found to consist solely of 14N disproving the dispersive model
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the role of helicase? (3)

A
  • unwinds the double helix and separates the 2 polynucleotide strands
  • by breaking the H bonds that exist between complementary base pairs
  • 2 separated polynucleotide strands will act as templates for the synthesis of new complementary strands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the role of DNA polymerase? (3)

A
  • synthesises new strands from 2 parental template strands
  • free deoxynucleoside triphosphates (nucleotide w/ 3 phosphate groups) align opposite their complementary base partner
  • DNA polymerase cleaves the 2 excess phosphates and uses the energy released to link the nucleotide to the new strand
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is PCR (polymerase chain reaction)?

A

artificial method of replicating DNA under laboratory conditions
- PCR is used to amplify large quantities of a specific sequence of DNA from an initial minute sample
- each reaction doubles the amount of DNA (30 cycles creates over 1 billion copies)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the process of PCR?

A

reaction occurs in a thermal cycler and uses variation in temperature to control the replication process:
1. denaturation - DNA sample is heated (-90) to separate the 2 strands
2. annealing - sample is cooled (-55) to allow primer to anneal (primers designate sequence to be copied)
3. elongation - sample is heated to the optimal temp for a heat-tolerant polymers (Taq) to function (-75)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is Taq polymerase and its function?(3)

A
  • an enzyme isolated from a thermophilic bacterium
  • as this enzyme’s optimal temp is -75 it is able to function at the high temps used in PCR without denaturing
  • Taq polymerase extends the nucleotide chain from the primers therefore, primers are used to select the sequence to be copied
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is transcription?

A

the process by which an RNA sequence is produced from a DNA template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the process of transcription? (4)

A
  1. RNA polymerase separated the DNA strands and synthesised a complementary RNA copy from one of the DNA strands
  2. when the DNA strands are separated, ribonucleoside triphosphate align opposite their exposed complementary base partner
  3. RNA polymerase removed the additional phosphate groups and uses the energy from the cleavage to covalently join the nucleotide to the growing sequence
  4. once the RNA sequence has been synthesised, RNA polymerase detached from the DNA molecules and the double helix reforms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is a gene?

A

the sequence of DNA that is transcribed into RNA

17
Q

what is the strand that is transcribed called? (2)

A

antisense strand
is complementary to the RNA sequence

18
Q

what is the strand that is not transcribed called? (2)

A

sense strand
identical to the RNA sequence (with T instead of U)

19
Q

where does transcription of genes occur?

A

in the nucleus (where DNA is)
before the RNA moves to the cytoplasm (fro translation)

20
Q

what are codons and their function? (4)

A
  • the base sequence of an mRNA molecule encodes the production of a polypeptide
  • the mRNA sequence is read by the ribosome in triplets of bases (codons)
  • each codon codes for 1 amino acid with a polypeptide chain
  • the order of the codons in an mRNA sequence determines the order of amino acids in a polypeptide chain
21
Q

what is the genetic code (4)?

A
  • genetic code = set of rules by which information encoded within the mRNA sequences is converted into amino acid sequences (polypeptides) by living cells
  • genetic code identified the corresponding amino acid for each codon combination
22
Q

how many codon possibilities are there and why? (2)

A

64 (4^3)
- 4 possible bases in a nucleotide sequence and 3 bases per codon

23
Q

how does an mRNA sequence start and end?

A

begins with a START codon (AUG)
terminates with a STOP codon

24
Q

what is translation?

A

the process of protein synthesis in which the genetic info encoded in mRNA is translated into a sequence of amino acids on a polypeptide chain

25
Q

what is the process of translation? (6)

A
  1. ribosomes bind to mRNA in the cytoplasm and move along the molecules in a 5’ -> 3’ direction until it reaches a start codon (AUG)
  2. anticodons on tRNA molecule align opposite appropriate codons according to complementary base pairings
  3. each tRNA molecule carries a specific amino acid (according to the genetic reactions)
  4. ribosomes catalyse the formation of peptide bonds between adjacent amino acids (via condensation reactions)
  5. the ribosome moves along the mRNA molecules synthesising a polypeptide chain until it reaches a stop codon
  6. at this point translation ceases and the polypeptide chain is released
26
Q

why do the same codons code for the same amino acids in all living things and what does this mean? (2)

A
  • as genetic code is universal (almost every living organism uses the same code)
  • genetic information is transferrable between species
27
Q

how is insulin produced through the ability to transfer genes between species? (4)

A
  • the gene responsible for insulin production is extracted from human cell
  • it is spliced into a plasmid vector (for autonomous replication and expression) before being inserted into bacterial cell
  • the transgenic bacteria (eg. E.coli) are then selected and cultured in a fermentation tank (to increase bacterial No.)
  • the bacteria now produce human insulin, which is harvested, purified and packaged for human use
28
Q

what is mRNA?

A

a complementary copy of DNA segments (gene) and can be used to deduce the gene sequence

29
Q

what are the rules of complementary base pairing for converting a sequence from mRNA?

A
  • C replaced by G (visa versa)
    U replaced by A
    A replaced by T

Biology SL (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions