Brainscape's Knowledge GenomeTM

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


See full index

OCR Biology > ✨Module 2: Nucleic acids > Flashcards

✨Module 2: Nucleic acids Flashcards

1
Q

Basic unit of the polymer nucleic acids?

A

Nucleotides (DNA and RNA). Nucleotides are monomers of nucleic acids.

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

Nucleotides are composed of a …

A

Pentose sugar, phosphate group and nitrogenous base.

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

What is the phosphate group?

A

Inorganic molecule that is acidic and negatively charged.

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

Sugar component in DNA nucleotides?
Sugar component in RNA nucleotides?

A

Deoxyribose
Ribose.

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

DNA is a …
RNA is a …

A

Double stranded molecule.
Single stranded polymer of nucleotide monomers/single helix.

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

Nitrogenous bases in DNA?
Nitrogenous bases in RNA?

A

ATCG
AUCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How do nucleotides link together?

A

Condensation reaction to form a polynucleotide. The phosphate group at the 5’ (carbon 5) end of one nucleotide and the OH group on the 3’ end of another nucleotide form phosphodiester bonds (type of covalent bond).

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

What is it meant by 3’ and 5’ end?

A

These numbers relate to which carbon on the pentose sugar could be bonded with another nucleotide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are the phosphodiester bonds between adjacent nucleotides broken?

A

By hydrolysis, releasing individual nucleotides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the function of DNA in cells?

A

Stores genetic information.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain the structure of DNA.

A

Double helix with 2 polynucleotide chains bonded together by hydrogen bonds between the bases. Two chains are antiparallel to each other. All DNA nucleotides have the pentose sugar deoxyribose, same phosphate group but the nitrogenous base can be different.

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

What is the function of RNA in cells?

A

Transcription and translation of genetic information. It is used to make proteins from the instructions in DNA.

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

Pyramidines have …
Purine have …

A

1 nitrogen containing ring.
2 nitrogen containing rings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

3 examples of pyramidines?
2 examples of purines?

A

CUT
AG

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

Describe the structure of DNA.

A

-> Made up of 2 strands of polynucleotides that are antiparallel.

-> These 2 strands coil into the double helix, and there are hydrogen bonds between complementary base pairs in the two strands.

-> This double strand makes DNA stable.

-> Each strand has a phosphate group at one end (5’) and a hydroxyl group at the other (3’).

-> The pairing of bases allows DNA to be copied and transcribed.

-> Polymer so has a lots of information.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Adenine and thymine form …
Cytosine and guanine form …

A

2 hydrogen bonds.
3 hydrogen bonds.

This means that a small pyramidine base always binds to a larger purine base.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

DNA replication.

A

->DNA helicase binds to the DNA molecule and breaks the hydrogen bonds between comp. base pairs to form 2 single DNA strands.

->Each strand acts as a template and activated free nucleotides (have 3 phosphate groups and 2 break off to release energy for this reaction) form hydrogen bonds with the exposed bases in the single-stranded DNA.

->DNA polymerase then binds to the DNA molecule and catalyses the formation of phosphodiester bonds between adjacent nucleotides in a condensation reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is a phosphodiester bond?

A

Bonds formed between a phosphate group and a sugar group (OH) of another nucleotide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is DNA ligase?

A

Enzyme that facilitates the joining of Okazaki fragments by catalysing the formation of phosphodiester bonds.
It seals the ‘nicks’ between the fragments, converting them to a continuous strand of DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why is DNA replication called semi-conservative?

A

Each new DNA molecule contains one original and new strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Codons are non-overlapping which means …

A

Successive triplets are read in order and each nucleotide is part of 1 codon. Each base is only read once.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is a mutation?

A

Change in DNA base sequence. They can alter the sequence of amino acids in a protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the genetic code?

A

Three bases that is equivalent to one codon. One codon codes for one amino acid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why is the genetic code universal?

A

All known organisms use the same 4 nucleotide bases. Organisms differ according to the arrangement of nucleotide bases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is a gene?

A

Section of DNA that contains the complete sequence of bases (codons) that code for an entire protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is ATP called the universal energy currency?

A

It is present in all cells, it is present in all organisms, it releases energy in small quantities.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

ATP is made up of …

A

Nucleotides bonded together. Contains the base adenine, pentose sugar ribose and 3 inorganic phosphate groups.
Actually adenine + ribose = adenosine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

ATP and ADP are described as …

A

Phosphorylated nucleotides - several nucleotides can be added by condensation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does ATP release energy? Give the equation for this.

A

The removal of phosphate group by hydrolysis releases LOTS of energy required by cells for chemical reactions.
ATP + H2O = ADP + Pi + energy

30
Q

Why is ATP needed for cellular processes?

A

ATP supplies energy for muscle contraction, cell division, transmission of nerve impulses.

31
Q

How is ATP produced? Give the equation for this.

A

Energy SUPPLIED from respiration is used to:
ADP + Pi + energy = ATP + H2O.
This is a phosphorylation/condensation reaction.

32
Q

What are some properties of ATP that help its function?

A

Small so can be moved easily.
Water soluble due to charged phosphate groups attract water and the hydroxyl groups on ribose can form hydrogen bonds with water molecules.
Contains unstable bonds between phosphates so lots of energy is released when broken.

33
Q

Why is ATP a good IMMEDIATE energy store but not long term energy store?

A

Not good for long term due to the instability of the phosphate bonds in ATP. ATP is easily broken down.

34
Q

What does ATP hydrolase do?

A

Catalyses the breakdown of ATP into ADP and inorganic phosphate group (Pi) through hydrolysis.
This releases LOTS of energy needed by cells due to breakdown of phosphate group.

35
Q

What can happen to this Pi molecule?

A

It can be added to other molecules to increase their reactivity.

36
Q

What does ATP synthase do?

A

Phosphorylation (adding a phosphate increases the molecule’s reactivity). ATP is regenerated by combining ADP and Pi.

37
Q

When does phosphorylation happen?

A

Photosynthesis and respiration.

38
Q

What are the 3 types of RNA involved in protein synthesis?
(Remember all of this has U instead of T)

A

tRNA, mRNA, rRNA (inside ribosome).

39
Q

What is mRNA?

A

Single polynucleotide chain that is made in the nucleus during translation. Group of 3 adjacent bases in mRNA are called codons.

40
Q

What is the link between DNA and mRNA?

A

mRNA has the complementary base sequence to DNA.

41
Q

What is rRNA?

A

It transfers genetic information from DNA to the proteins. Forms 2 subunits in the ribosome. The ribosome moves along the mRNA strand during protein synthesis. rRNA in the ribosome catalyses the formation of peptide bonds between amino acids.

42
Q

During transcription that happens in the nucleus …

A

DNA is transcribed to mRNA. mRNA leaves the nucleopores to reach the ribosomes for translation.

43
Q

During translation at the ribosome, mRNA is used to create ________.

A

Proteins

44
Q

What is tRNA?

A

1 polynucleotide strand that is folded into a clover shape. Hydrogen bonds between specific base pairs hold the molecule in this shape.

45
Q

Amino acids is bound to tRNA by …

A

Ester bonds.

46
Q

What is the anti-codon (on one end of tRNA)?
What is on the other end of tRNA?

A

Region of complementary base pairs to bind to potential codons.
Where the amino acid is. Bound to 3’ end of tRNA.

47
Q

Ribosomes are made up of …

A

Proteins and rRNA. It is only involved in translation to convert mRNA to polypeptide chains.

48
Q

If there are 4 bases, how many possible amino acids could be coded for?

A

4x4x4 = 64 as 3 bases code for 1 amino acid and each base there are 4 possibilities.

49
Q

Why are codons degenerate?

A

Multiple codons can code for the same amino acid in protein synthesis.
6 codons for Leucine, 4 codons for glycene.

50
Q

What is the genetic code? (also is degenerate)

A

Sequence of codons on the DNA or mRNA, which codes for particular amino acids.
There are 20 amino acids but 64 possible codons.

51
Q
A

j

52
Q

How do nucleic acids play a crucial role in protein synthesis?

A

The sequence of bases in DNA provides coded instructions to make proteins.

53
Q

What happens in cellular respiration?

A

Glucose is broken down into ATP, allowing us to use the energy stored in ATP for metabolic processes.

54
Q

Explain what happens in transcription in protein synthesis.

A

-> DNA helicase breaks the hydrogen bonds between the two DNA strands, exposing the bases on each strand. One of the strands, the antisense strand, act as a template.

-> RNA polymerase binds in a region just before the start codon of the gene and transcribes DNA to mRNA. It reads the nucleotides on the unwound template strand from 3’ to 5’. The growing mRNA strand forms in 5’ to 3’. RNA polymerase lines up free RNA nucleotides along the template/antisense strand. Complementary base pairing where T is replaced by U. RNA polymerase stops transcribing mRNA once it reaches the stop codon.

->RNA polymerase catalyses the formation of phosphodiester bonds between RNA nucleotides.

-> Hydrogen bonds between uncoiled strands of DNA reform after RNA polymerase has read it. It coils back to double helix.

-> mRNA leaves nucleus and moves out of nuclear pore to the ribosome in cytoplasm.

55
Q

Where does transcription happen?

A

In the nucleus.

56
Q

Why is DNA transcribed to mRNA?

A

DNA is too large to leave the nucleopores to the ribosome.

57
Q

The ribosome is made up of …

A

2 subunits which contain rRNA and proteins.

58
Q

Explain what happens in translation in protein synthesis.

A

-> mRNA attaches to ribosome and tRNA carries amino acids to the ribosome. tRNA with the complementary anticodon to the start of mRNA, attaches to mRNA by complementary base pairing and so do the other tRNA.

-> rRNA catalyses the formation of peptide bonds between amino acids. First tRNA moves away, leaving the amino acid behind in the correct sequence. This keeps happening until there is a stop codon on mRNA. This forms the primary structure of the protein coded for by the mRNA.

-> Polypeptide chain (protein) moves away from ribosome.

59
Q

Where does translation happen?

A

In the ribosome in cytoplasm.

60
Q

What is gene expression?

A

When a protein that a gene codes for is made.

61
Q

Codon is a group of … bases on mRNA or DNA that codes for specific amino acids. Template strand read from … but synthesised from …
Sugar-phosphate backbone is …
ATP has …
ADP has …

ATP + H20 =
The 2 enzymes involved in this?
64 different codons but only … amino acids.
So it is degenerative - what does this mean?

A

3.
3’ to 5’, 5’ to 3’.
Antiparallel.
3 phosphates, 1 ribose, 1 adenine.
2 phosphates, 1 ribose, adenine.

ADP + Pi (inorganic phosphate) + free energy. This is dephosphorylation.
ATP hydrolase and ATP synthase.
20.
More than 1 codon can code for amino acid.

62
Q

The body cannot directly get its energy from …
Instead, the body uses the … from breaking down glucose, to drive …
This makes … which is an immediate energy source that cells can use quickly.

A

Glucose.
Energy released.
Phosphorylation of ADP.
ATP.

63
Q

tRNA is …
At one end of tRNA, there is an attachment site for …
At the opposite end of tRNA, there is an attachment site for …
tRNA carries …

A

Single-stranded with the bases A, U, G, C.
Amino acids.
Anti-codons.
Amino acids to ribosomes.

64
Q

PAG: Purification/extraction of DNA by precipitation.

A
  1. Grind the sample in a pestle and mortar to break down the cell wall. Add detergent and mix gently.
  2. Add salt.
  3. Put beaker in water bath at 60 degrees C for 15 minutes.
  4. Cool mixture by putting in ice bath for 5 mins.
  5. Blend mixture for 5 secs to degrade the cell walls/membranes further, so DNA is released.
  6. Filter the mixture and ensure no contamination of foam in filtrate.
  7. Add 2-3 drops of protease to the filtrate in a boiling tube and mix.
  8. Pour ice cold ethanol down the side to form a layer.
65
Q

What is the purpose of detergent?

A

It degrades the membrane/phospholipids, releasing the DNA and cell contents.

66
Q

What is the purpose of salt?

A

Salt breaks the hydrogen ones between the negatively charged phosphate group in the DNA and the water molecules.

67
Q

Why should the temperature throughout this experiment stay low?

A

It reduces the activity of enzymes so reduces the breakdown of DNA. Slows the breakdown of DNA which would occur is a high temp was maintained.

68
Q

Why add the protease enzyme?

A

Protease denatures the histones associated with DNA. This allows it to hydrolyse the peptide bonds.

69
Q

Why do we add ethanol to the top of the sample?

A

Alcohol causes the DNA to precipitate out of the solution.

70
Q

DNA replication concerning why Okazaki fragments.

A

DNA polymerase moves through the leading strand from 3’ to 5’. But as helicase unwinds, the dna polymerase moves from 3’ to 5’ end from the lagging strand in the opposite direction. As helicase unwinds, dna polymerase keeps moving back towards the intersection and causes Okazaki fragments on the lagging strand. The DNA ligase forms the nicks between the Okazaki fragment.

OCR Biology (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions