1.5. Nucleic acids and their functions Flashcards

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1
Q

What is the structure of a nucleotide?

A

Individual nucleotides are made up of 3 components.

1: a pentose sugar (so called because it has 5 carbon atoms)
2. a phosphate group
3. a nitrogen-containing organic base.

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2
Q

Why is chemical energy important in biological processes?

A

Because all processes in the body require the release of chemical energy - ATP being converted to ADP.

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3
Q

What is ATP?

A

The energy currency of the body.

COnversion to ADP liberates chemical energy for cell processes

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4
Q

Describe the structure of ATP.

A

ATP has 3 parts:

  1. Adenine
  2. Ribose
  3. A chain of 3 phosphate groups
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5
Q

What is Adenine?

A

A nitrogen containing organic base

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6
Q

What is Ribose?

A

A pentose sugar

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7
Q

How many phosphate groups on a molecule of ATP?

A

3

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8
Q

Describe the structure of DNA

A

Despite its complex structure, DNA is made up of nucleotides

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9
Q

Individual nucleotides are made up of 3 components, a pentose sugar (so called because it has 5 carbon atoms), a phosphate group and a nitrogen-containing organic base.
What are these nitrogen-containing organic bases?

A

These nitrogen-containing organic bases are:

  1. A - Adenine
  2. C - Cytosine
  3. G - Guanine
  4. T - Thymine
  5. U - Uracil
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10
Q

The pentose sugar, phosphate group and organic base are joined, as a result of condensation reactions, to form a single nucleotide (mononucleotide).
2 mononucleotides may, in turn, be joined as a result of a condensation reaction between the deoxyribose sugar of one mononucleotide and the phosphate group of another.
What is the bond formed between them called?

A

The bond formed between them is called a phosphodiester bond

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11
Q

What is a phosphodiester bond

A

In DNA mononucleotides are joined as a result of a condensation reaction between the deoxyribose sugar of one mononucleotide and the phosphate group of another.

This is a phosphodiester bond.

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12
Q

When two mono-nucleotides are joined this new structure is called?

A

Di-nucleotide.

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13
Q

Continuously linking mono-nucleotides is called a …

A

Poly-nucleotide

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14
Q

‘Thymine’ is a base in DNA, but what is ‘thiamine’?

A

‘Thymine’ is a base in DNA, but ‘thiamine’ is vitamin B1

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15
Q

Don’t get confused between DNA and proteins.

DNA is a sequence of bases, but proteins are a sequence of what?

A
  1. DNA is a sequence of bases
    ,but
  2. Proteins are a sequence of amino acids
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16
Q

What join to form a polynucleotide and what join to form a polypeptide?

A
  1. Nucleotides join to form a polynucleotide

2. Amino acids join to form a polypeptide

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17
Q
Ribonucleic acid (RNA) structure:
Ribonucleic acid is a polymer made up of what?
A

Ribonucleic acid is a polymer made up of nucleotides

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18
Q

Ribonucleic acid is a polymer made up of nucleotides.

RNA is a what chain?

A
RNA is a:
1. Single 
2. Relatively short 
3. Polynucleotide 
chain
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19
Q

RNA is a single, relatively short, polynucleotide chain in which the pentose sugar is always what?

A

Polynucleotide

chain in which the pentose sugar is always ribose

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20
Q

RNA is a single, relatively short, polynucleotide chain in which the pentose sugar is always ribose and what are the organic bases?

A

RNA is a single, relatively short, polynucleotide chain in which the:

  1. Pentose sugar is always ribose
  2. Organic bases are A, U, C and G
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21
Q

DNA structure:

In what year, who worked out the structure of DNA?

A

In 1953:
1. James Watson
2. Francis Crick
worked out the structure of DNA

**actually they totally piggy backed on the work of a female scientist, Rosalind Franklin and took all the credit. **

22
Q

DNA structure:

In DNA, what is the pentose sugar?

A

In DNA, the pentose sugar is deoxyribose

23
Q

In DNA, the pentose sugar is deoxyribose and what are the organic bases?

A

In DNA, the:

  1. Pentose sugar is deoxyribose
  2. Organic bases are A, T, C and G
24
Q

In DNA, the pentose sugar is deoxyribose and the organic bases are A, T, C and G.
What is DNA made up of?

A

DNA is made up of 2 strands of nucleotides (polynucleotides)

25
Q

The bases on the 2 strands of DNA attach to each other by what bonds?

A

The bases on the 2 strands of DNA attach to each other by hydrogen bonds

26
Q

Base pairing:
The bases on the 2 strands of DNA attach to each other by hydrogen bonds.
It is these hydrogen bonds that hold the 2 strands together.
The base pairing is specific.
What are the base pairs?

A

The base pairs are:

  1. A and T
  2. G and C
27
Q

A always pairs with T and G always pairs with C.

As a result of these pairings, A is said to be what and G is said to be what?

A

As a result of these pairings:

  1. A is said to be complementary to T
  2. G is said to be complementary to C
28
Q

What are the functions of DNA?

A

Replication and protein synthesis

29
Q

Exons are?

A

Regions of DNA that contain the code for proteins and that between
the exons are regions of non-coding DNA called introns

30
Q

Introns are?

A

between

the exons are regions of non-coding DNA called introns

31
Q

In DNA, the sugar is what, whereas in RNA, what is the sugar?

A

In:
1. DNA, the sugar is deoxyribose
,whereas
2. RNA, the sugar is ribose

32
Q

DNA and RNA have the same what, but a different pentose sugar and different what?

A
DNA and RNA have:
1. The same phosphate group 
,but: 
2. A different pentose sugar 
3. Different base pairs
33
Q

Apart from U in place of T, RNA is different to DNA in how many other ways?

A

Apart from U in place of T, RNA is different to DNA in 2 other ways - The:

  1. Sugar is ribose, not deoxyribose
  2. Nucleotide strand is a single strand, not double
34
Q

There are 5 bases (A, T, C, G and U), split into what?

A

There are 5 bases (A, T, C, G and U), split into 2 types:

  1. Purine bases
  2. Pyrimidine bases
35
Q

What are the purine bases?

A

The purine bases are:

  1. A
  2. G
36
Q

What are the pyrimidine bases?

A

The pyrimidine bases are:

  1. T
  2. C
  3. U
37
Q

What are the 2 antiparallel strands in DNA held together by?

A

The 2 antiparallel strands in DNA are held together by hydrogen bonds

38
Q

Why does DNA need to replicate?

What are reasons for DNA replication?

A

Reasons for DNA replication are:

  1. Cell division - New cells need new DNA for growth and tissue repair
  2. Reproduction - Gametes require DNA to pass on genetic information
39
Q

Enzymes in DNA replication:

What does DNA helicase do?

A

DNA helicase:

  1. Breaks hydrogen bonds
  2. Unwinds the molecule
40
Q

Enzymes in DNA replication:

What does DNA polymerase do?

A

DNA polymerase forms the phosphodiester bonds between nucleotides

41
Q

Before a nucleus divides, what must happen?

A

Before a nucleus divides, its DNA must be replicated (copied)

42
Q

Before a nucleus divides, its DNA must be replicated (copied).
This is to ensure what?

A

This is to ensure that all the daughter cells have the genetic information to produce the:
1. Enzymes
2. Other proteins
that they need

43
Q

For semi-conservative replication to take place, there are how many requirements?

A

For semi-conservative replication to take place, there are 4 requirements:

  1. The 4 types of nucleotide, each with their bases of A, T, C or G, must be present
  2. Both strands of the DNA molecule act as a template for the attachment of these nucleotides
  3. The enzyme DNA polymerase
  4. A source of chemical energy is required to drive the process
44
Q

What enzyme breaks the hydrogen bonds linking the base pairs of DNA?

A

The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA

45
Q

The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, what happens?

A

As a result, the double helix:

  1. Separates into its 2 strands
  2. Unwinds
46
Q

The process of semi-conservative replication:
The enzyme DNA helicase breaks the hydrogen bonds linking the base pairs of DNA.
As a result, the double helix separates into its 2 strands and unwinds.
Each exposed polynucleotide strand then acts as a template to which what?

A

Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing

47
Q

Why is it called semi-conservative replication?

A

Each of the new DNA molecules contains one of the original DNA strands.
This means that half of the original DNA has been saved and built into each of the new DNA molecules.

48
Q

What does the phrase ‘the strands of DNA are complementary’ mean?

A

The phrase ‘the strands of DNA are complementary’ means that:

  1. Wherever there’s a T in one strand, there will be an A in the opposite strand
  2. Wherever there’s a C in one strand, there will be a G in the opposite strand
49
Q

Which enzyme is involved in adding bases to a DNA template strand?

A

DNA polymerase is involved in adding bases to a DNA template strand

50
Q

Which enzyme seals up the strands of DNA?

A

DNA ligase seals up the strands of DNA

51
Q

Explain the the ‘one gene - one polypeptide’ hypothesis

A

The theory that each gene is responsible for the synthesis of a single polypeptide.

The one gene–one enzyme hypothesis is the idea that genes act through the production of enzymes, with each gene responsible for producing a single enzyme that in turn affects a single step in a metabolic pathway