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Biology > DNA and protein synthesis > Flashcards

DNA and protein synthesis Flashcards

1
Q

What is a gene?

A

A section of genetic material that codes for a protein or characteristic e.g. eye colour, tongue rolling

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2
Q

How many genes are we made up of?

A

Roughly 25,000

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3
Q

What is an allele?

A

Variation in a gene (gene - eye colour, allele - brown/blue)

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4
Q

What is a chromosome?

A

The structure on which genes are stored
There are 23 pairs in humans

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5
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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6
Q

What is DNA?

A

It’s the chemical from which genes are constructed

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7
Q

What is a chromatin?

A

DNA and associated proteins(histones) found in the nucleus

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8
Q

What is a genome?

A

All the genes that comprise us/an organism

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9
Q

What is a proteome?

A

All the proteins that can be made from the genome

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10
Q

What are nucleic acids?

A

These are macromolecules built of up nucleotides e.g. RNA and DNA

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11
Q

What is a DNA strand made up of?

A

It is a long strand (2m) comprised of nucleotides - this will form our double helix

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12
Q

What is a nucleotide made up of?

A

A phosphate, deoxy ribose, nitrogenous base

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13
Q

How many bases are used to make DNA?

A

There are a total of 5 bases - 4 are used to make DNA nucleotides

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14
Q

What are the 4/5 bases?

A

Adenine, Thymine
Guanine, Cytosine
(uracil)

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15
Q

How many different DNA nucleotides can we make?

A

4

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16
Q

How many hydrogen bonds do adenine and thymine form?

A

2

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17
Q

How many hydrogen bonds do guanine and cytosine form?

A

3

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18
Q

What are adenine and guanine known as?

A

The purines - they have a double carbon ring

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19
Q

What are thymine and cytosine known as?

A

The pyramidines - they have a single carbon ring

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20
Q

How do we form nucleotides?

A

There are 2 condensation reactions
- nitrogenous bases + pentose = nucleoside + H2O
- nucleoside + phosphoric acid = nucleotide + H2O

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21
Q

How do different nucleotides bond together?

A

The phosphate from one nucleotide bonds to carbon 3 on the other DNA nucleotide

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22
Q

What is the bond between 2 nucleotides?

A

A phosphodiester bond

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23
Q

What are 2 nucleotides bonded together called?

A

Dinucleotide

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24
Q

What is the enzyme that helps phosphodiester bonds form?

A

DNA polymerase

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25
Q

What is the top end of the polynucleotide chain called?

A

5 ‘ carbon end

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26
Q

What is the bottom end of the polynucleotide chain called?

A

3 ‘ carbon end

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27
Q

In what way do the 2 polynucleotide strands run together?

A

They run anti parallel to each other

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28
Q

What are the 2 polynucleotide strands known as?

A

The coding strand and the non-coding strand
Or the sense strand and the non-sense strand

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29
Q

What is the DNA strand known as?

A

Polynucleotide strand

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30
Q

How do you describe a DNA strand?

A

2 polynucleotide strands join together to form a double helix

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31
Q

What provides DNA with stability?

A

The phosphate deoxyribose backbone

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32
Q

Why is it important that DNA has stability?

A

So it is stable enough to last the cell’s whole life
So the order of the bases is not damaged

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33
Q

How do we ensure that DNA has stability?

A

The bases are on the inside of the molecule

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34
Q

Why is it better to have hydrogen bonds between strands rather than another type?

A

On mass, they provide strength and stability but individually they are weak so they can still be separated out during protein synthesis

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35
Q

Why is it important that DNA is a very large molecule?

A

It can hold a lot of genetic information

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36
Q

What is a RNA nucleotide made of?

A

Phosphate
Ribose sugar
Base (A, U, G, C) - Thymine is replaced with uracil

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37
Q

What are all RNA molecules?

A

Single stranded

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38
Q

How do we create a poly RNA nucleotide strand?

A

We have condensation reactions between carbon 3 and the phosphate
Phosphodiester bond formed

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39
Q

What is the enzyme that helps form poly RNA nucleotide strands?

A

RNA polymerase - once the complimentary copy of the coding strand has been created inside the original strand, this helps to join them together to from a poly nucleotide RNA strand

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40
Q

What are the 4 types of RNA?

A

Pre-messenger RNA
Messenger RNA
Transfer RNA
Ribosomal RNA

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41
Q

What are some of the characteristics of messenger RNA?

A

Long strand
Single helix - single stranded
Shorter than DNA (as it only contains the genes for a specific protein)
Contains the genetic code - sequence of mRNA nucleotide bases

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42
Q

What is a degenerate?

A

Both codons can hold the same amino acid
Most amino acids have more than one codon

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43
Q

Where is the mRNA code derived from?

A

The DNA code - a complimentary strand is formed

44
Q

How is mRNA read?

A

In codons (3 bases) = 1 amino acid

45
Q

What are stop codons?

A

There are 3 codons that tell the strand when to stop being formed

46
Q

Are codons overlapping?

A

No

47
Q

Are codons universal and what does this mean?

A

Yes - for all organisms, the same codon codes for the same amino acid

48
Q

What does every single mRNA strand start with?

A

AUG

49
Q

How is the mRNA formed?

A

Through transcription from DNA

50
Q

How does mRNA leave the nucleus?

A

Via nuclear pores

51
Q

What is mRNA associated with?

A

Ribosomes in cytoplasm

52
Q

What does mRNA form?

A

The template from which proteins are built

53
Q

Why is it important that mRNA is easily broken down?

A

It only exists when needed (we don’t store amino acids) and no energy is wasted

54
Q

What structure does tRNA have?

A

A clover leaf structure

55
Q

What does tRNA have at the top?

A

Amino acid attachment site

56
Q

What does tRNA have at the bottom?

A

3 bases known as the anti-codon

57
Q

How many tRNA are there?

A

64

58
Q

What does RNA stand for?

A

Ribonucleic acid

59
Q

What do we do for protein synthesis within the nucleus?

A

We make a complimentary copy of the coding strand using RNA nucleotides - not the whole strand but rather just the section that codes for the specific protein that we want

60
Q

What do we use to break the hydrogen bonds in between complimentary bases in the DNA strand?

A

DNA helicases

61
Q

What happens after the hydrogen bonds in the DNA strand are broken?

A

The RNA nucleotides come and form a complimentary copy of the coding strand using base pair theory inside the original strand

62
Q

What happens once the mRNA polynucleotide strand is formed?

A

It will move out from between the 2 DNA strands and an enzyme called DNA ligase will help hydrogen bonds reform between the 2 DNA strands

63
Q

What are ribosomes made up of?

A

Amino acids and RNA

64
Q

What does ribosomal RNA help do in ribosomes?

A

Helps make sites in ribosomes for assembling proteins from amino acids

65
Q

What is ribosomal RNA?

A

It is a polynucleotide that is folded and attached to proteins to make ribosomes

66
Q

What is there at the beginning of each gene?

A

A promoter region

67
Q

What is there at the end of each gene?

A

A terminator region

68
Q

What is the 1st step of protein synthesis?

A

We identify the gene in the DNA strand

69
Q

What happens after we identify the gene in the DNA strand in protein synthesis?

A

The DNA helicase enzyme unwinds this section of the DNA strand breaking the hydrogen bonds between the complimentary bases

70
Q

What happens after the DNA strand is unwound in protein synthesis?

A

The RNA nucleotides come between them and the RNA bases line up opposite the bases on coding strand in complimentary fashion

71
Q

What do the RNA nucleotides form with the bases on the coding strand and why?

A

Hydrogen bonds to help fix them into place

72
Q

How are the RNA nucleotides opposite the coding strand joined together?

A

RNA polymerase joins them forming phosphodiester bonds

73
Q

What is formed when the RNA nucleotides opposite the coding strand are joined together?

A

Single-stranded pre-messenger RNA molecule (single helix)

74
Q

What happens once the pre-messenger RNA molecule is formed?

A

It will move out from between the 2 DNA strands (hydrogen bonds between RNA and coding strand break)

75
Q

What happens to the DNA strands after the pre-messenger RNA molecule moves out?

A

It recoils - hydrogen bonds, with DNA ligase, reform between complementary bases

76
Q

What is the final thing to happen to pre-messenger RNA before it moves out of the nucleus?

A

Splicing

77
Q

What is splicing?

A

This is where we cut out sections/RNA nucleotides from mRNA

78
Q

What are the sections we cut out in splicing called?

A

Introns - these are non-coding sections within a gene

79
Q

What are the sections that remain in splicing?

A

Exons

80
Q

What happens after the introns are removed?

A

The exons join together to form a shorter mRNA strand
(this is now mRNA and not pre mRNA)

81
Q

What happens after splicing has occurred?

A

mRNA leaves nucleus via nuclear pores into cytoplasm where we have ribosomes and tRNA

82
Q

What does the mRNA attach to in the cytoplasm?

A

The ribosome - covers 6 bases (2 codons)

83
Q

What happens after the mRNA attaches to the ribosome?

A

The tRNA with the complimentary anti-codon to the first codon sits on the mRNA

84
Q

How is the anti-codon kept in place with the codon during translation?

A

The bases form hydrogen bonds

85
Q

What will the tRNA sitting on the codon have?

A

A specific amino acid attached to its amino acid attachment site

86
Q

What happens after the first tRNA attached to the mRNA strand?

A

tRNA with the complimentary anti-codon to the next codon is also attached (brings specific amino acid)

87
Q

What happens once there are 2 amino acids on the ribosome?

A

They will form a peptide bond in a condensation reaction

88
Q

What happens once the 1st peptide bond is formed during translation?

A

The amino acid dissociates from the tRNA

89
Q

What happens to the tRNA once it dissociates from the amino acid?

A

It leaves the mRNA and ribosome and goes into the cytoplasm to attach another specific amino acid

90
Q

How does the process of translation continue throughout?

A

The ribosome moves down the mRNA strand to cover the next codon and the process is repeated until we get to the end (ribosome leaves mRNA at a stop codon)

91
Q

Can many ribosomes travel along the mRNA at the same time and what is this known as?

A

Yes - polysome

92
Q

When might gene mutations arise?

A

During DNA replication - they occur spontaneously

93
Q

What is a mutation?

A

The deletion, addition or substitution of bases

94
Q

Why might not all mutations have an impact?

A

Due to the degenerate nature of the genetic code

95
Q

What is a substitution mutation?

A

A DNA nucleotide is substituted for another

96
Q

What kind of effect does a substitution mutation have?

A

A less damaging effect on the polypeptide, only changing one amino acid - but can sometimes cause quite a severe change

97
Q

What is an addition substitution?

A

An extra DNA nucleotide may be added

98
Q

How will an addition substitution affect the genetic code?

A

It will impact all the subsequent triplets - all the amino acids to the right of the addition (known as a frameshift to the right)

99
Q

What is a deletion mutation?

A

A DNA nucleotide is removed

100
Q

How will a deletion substitution affect the genetic code?

A

All subsequent triplets affected - frameshift to the left

101
Q

What will happen to the polypeptide chain because of a frameshift?

A

It will have a different primary structure due to a different order of amino acids

102
Q

What could frame shifts also change the position of?

A

The stop and start codons

103
Q

What are point mutations?

A

They involve the change of 1 DNA nucleotide

104
Q

How can the appearance of the mutations be increased?

A

By mutagens

105
Q

Give examples of mutagens?

A

X-rays
High energy radiation
Chemicals in cigarette smoke
Chemicals in caffeine
UV light

Biology (15 decks)

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