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AQA Biology > 1.5 Nucleic Acids: Structure & DNA Replication > Flashcards

1.5 Nucleic Acids: Structure & DNA Replication Flashcards

1
Q

What is a gene?

A

A section of DNA that codes for a protein/characteristic

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2
Q

Who discovered the double helix structure of DNA?

A

Watson and Crick

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3
Q

What did Rosalind Franklin do?

A

A X ray crystallography technique that led to the discovery of the double helix structure of DNA

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4
Q

What is an allele?

A

Versions of a gene located at the same loci on homologous chromosomes

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5
Q

What are the monomers of DNA?

A

Nucleotides

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6
Q

What are nucleotides made of?

A

Pentose Sugar
Phosphate
Base

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7
Q

What are DNA nucleotides made of?

A

Deoxyribose
Phosphate
Base

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8
Q

What are the four DNA bases

A

A C G T

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9
Q

How does the base sequence relate to the function of DNA?

A

Allows information to be stored

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10
Q

How does being helical relate to the function of DNA?

A

Compact

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11
Q

How does being a large molecule relate to the function of DNA?

A

Can store lots of information

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12
Q

How does being double stranded relate to the function of DNA?

A

To allow replication to occur semi-conservatively

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13
Q

How do weak hydrogen bonds between strands relate to the function of DNA?

A

Easy to separate strands for replication

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14
Q

How does a sugar phosphate backbone relate to the function of DNA?

A

Protects the bases

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15
Q

What is an intron?

A

Section of non coding DNA within a gene

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16
Q

What is an exon?

A

Section of DNA coding for a protein

17
Q

What is the purpose of introns?

A

Thought to help regulate transcription (turning genes on and off)

18
Q

What is the first step of DNA replication?

A

DNA helicase breaks H bonds between strands
Each strand can act as a template

19
Q

What is the second step of DNA replication?

A

Free DNA nucleotides join and form H bonds with exposed strands
According to complementary base pairing rule

20
Q

What enzyme seals free DNA nucleotides into the exposed strand?

A

DNA polymerase

21
Q

What bonds form between free nucleotides?

A

Phosphodiester

22
Q

What was grown to test the semi-conservative replication model?

A

Ecoli

23
Q

What two incorrect theories are there for the model of DNA replication?

A

Conservative
Disruptive

24
Q

What is the conservative replication model?

A

An entirely new strand is synthesised each time - none of the old one is incorporated

25
Q

What is the disruptive replication model?

A

Sections of old and new strands are incorporated each time

26
Q

Describe Meshelson and Stahl’s experiment.

A

1Ecoli grown on N15 agar
When isolated and weighed, all the DNA will contain N15 and will form single band at that weight
The ecoli are transferred to new agar containing N14
After a single round of DNA replication, 1 new strand of DNA is made in each ecoli
A band is seen between N15 and N14 as the DNA is 1 strand of each
After another replication, both an N14 and mid band will be seen as the strands separate to 1 N15 and 1 N14 and an N14 strand will form from free nucleotides and join

27
Q

Why was the nitrogen isotope relevant to Meshelson and Stahl’s experiment?

A

The ecoli use nitrogen to make their DNA bases so the nitrogen can be tracked

28
Q

Why was extracted DNA in Meshelson and Stahl’s experiment spun in a centrifuge?

A

To separate the DNA by mass

29
Q

What are the bases of RNA?

A

A C G U

30
Q

What are RNA nucleotides made of?

A

Ribose
Phosphate
Base

31
Q

What bonds join RNA?

A

Phosphodiester

32
Q

What is the role of mRNA?

A

Complementary to specific gene so can carry code to cytoplasm

33
Q

What is the role of tRNA?

A

Takes specific amino acid groups to DNA

34
Q

What is the role of rRNA?

A

Forms a ribosome with proteins

AQA Biology (35 decks)

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