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Biology > Unit 1.5 - Nucleic Acids and their functions > Flashcards

Unit 1.5 - Nucleic Acids and their functions Flashcards

1
Q

Give 3 examples of Nucleic acids

A

Deoxyribonucleic acid
Ribonucleic acid
ATP

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2
Q

What are Deoxyribonucleic acid, Ribonucleic acid and ATP all?

A

Nucleic acids

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3
Q

What are all nucleic acids formed from?

A

Nucleotides

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4
Q

What to nucleotides form?

A

Nucleic acids

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5
Q

What’s the basic unit of nucleic acids?

A

Nucleotides

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6
Q

What are all the different sections on a nucleotide?

A

Phosphate
Organic base/nitrogenous base
Pentose sugar

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7
Q

What do Phosphate, Organic base/nitrogenous base and Pentose sugar all make up?

A

Nucleotides

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8
Q

Name of the base on a nucleotide

A

Organic or nitrogenous

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9
Q

What does ATP stand for?

A

Adenosine triphosphate

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10
Q

What’s the organic/nitrogenous base on ATP?

A

Adenine

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11
Q

What’s the Pentose sugar on ATP?

A

Ribose

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12
Q

What’s the phosphate on ATP?

A

Triphosphate (3 phosphate groups)

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13
Q

What type of bonds are between the phosphate groups on ATP?

A

High energy bonds

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14
Q

What are high energy bonds in ATP?

A

The bonds between the phosphate groups

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15
Q

What is adenine in ATP?

A

Organic/nitrogenous base

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16
Q

What is ribose in ATP?

A

Pentose sugar

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17
Q

Does ATP form polymers? (+explanation)

A

No - it’s a single nucleotide

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18
Q

What’s the only part of a nucleotide that has nitrogen atoms?

A

The base

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19
Q

What can vary with a nucleotide?

A

The organic base

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20
Q

Which element does the organic base of a nucleotide contain that isn’t in any other part of it?

A

Nitrogen

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21
Q

Do nucleotides form polymers?

A

Yes - like DNA and RNA

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22
Q

Give examples of polymers formed by nucleotides

A

DNA and RNA

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23
Q

What is ATP known as?

A

The universal energy currency of the cell

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24
Q

What is known as the universal energy currency of the cell?

A

ATP

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25
Q

Which process is ATP used in?

A

All processes requiring energy in all reactions in all living organisms

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26
Q

What is used in all processes requiring energy in all reactions in all living organisms?

A

ATP

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27
Q

Is there a living organism that doesn’t use ATP as the main energy transport system in the cell and why?

A

No - a cell would quickly die without a constant supply

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28
Q

Give 4 examples of cellular activities which use ATP

A

Protein synthesis
Active transport
DNA replication
Cell division

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29
Q

What do the following processes all use?

Protein synthesis, Active transport, DNA replication, Cell division

A

ATP

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30
Q

How is energy released from ATP?

A

By hydrolysing the bond between the last two phosphate groups in the molecule

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31
Q

Which bond is hydrolysed in order to release energy from ATP?

A

The bond between the last two phosphate groups in the molecule

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32
Q

What does hydrolysing the bond between the last two phosphate groups in a molecule do?

A

Releases energy from ATP

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33
Q

Equation for hydrolysing ATP

A

ATP + H20 —> ADP + Pi + H+
<—

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34
Q

What’s the approximate energy released when bonds are broken in ATP?

A

-30.6 kjmol-1

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35
Q

What type of reaction is it when bonds are broken in ATP? Why?

A

Exergonic as energy is released

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36
Q

What IS the energy released when breaking bonds in ATP?

A

Energy available for processes

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37
Q

Which products do we receive from hydrolysing ATP?

A

Adenosine diphosphate (ADP)
Inorganic phosphate (Pi)

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38
Q

Inorganic phosphate formed from hydrolysing ATP symbol

A

Pi

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39
Q

Pi

A

Inorganic phosphate formed from hydrolysing ATP

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40
Q

When does ADP form?

A

From hydrolysing ATP

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41
Q

Describe the ATP cycle

A

—> ATP —> energy for cellular work —> ADP + P —> Energy from respiration —>…

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42
Q

Phosphorylation

A

Adding a phosphate group

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43
Q

Adding a phosphate group

A

Phosphorylation

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44
Q

Which process is ATP made through?

A

Phosphorylation

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45
Q

Energy from metabolism to make ATP in humans

A

Break down of glucose using respiration

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46
Q

Energy from metabolism to make ATP in plants

A

Photons of light exciting electrons during photosynthesis

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47
Q

What does respiration and photosynthesis do?

A

Gives energy to form ATP

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48
Q

How much ATP do we use per day?

A

40kg

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49
Q

How much ATP is there at one point within our cells?

A

5g

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50
Q

Do we store ATP?

A

Nope

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51
Q

Why is there no need for us to store ATP?

A

It’s cycled, so the ATP is constantly remade and reused

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52
Q

Due to the process of making and using ATP being cycles, what is there no need for us to do?

A

Store it

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53
Q

Advantages of ATP

A

-Hydrolysis of ATP to ADP involved a single reaction that releases immediate energy
-Soluble and easily transported
-Only one enzyme (ATPase) is needed to release energy from ATP
-ATP releases energy in small amounts when and where needed
-ATP provides a common source of energy for many different chemical reactions (increases efficiency and control by the cell, the universal intermediary molecule between energy-yielding and energy-requiring reactions in the cell)

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54
Q

Example of ATP being soluble and easily transported

A

From companion cell to sieve element in Phoelem

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55
Q

Wha’t’s the only enzyme needed to release energy from ATP?

A

ATPase

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56
Q

How is ATP better than glucose in terms of the amount of reactions required to release energy?

A

ATP = a single reaction that releases immediate energy
Glucose = breakdown involves a number of intermediates and it takes much longer for energy to be released

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57
Q

How is ATP better than glucose in terms of the amount of energy released?

A

ATP = releases energy in small amounts when and where needed
Glucose = contains large amount of energy that may not be needed immediately

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58
Q

How is ATP better than glucose in terms of the enzymes needed to release energy?

A

ATP = only one enzyme needed to release energy (ATPase)
Glucose = requires many enzymes

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59
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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60
Q

Made is the structure of DNA made up of?

A

Nulceotides, each including a Pentose deoxyribose sugar

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61
Q

What type of sugar do the nucleotides in DNA include?

A

Pentose deoxyribose sugar

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62
Q

What forms the backbone of DNA strands?

A

Nucleotides hooked together to make a sugar-phosphate backbone for each DNA strand

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63
Q

What do nucleotide units form in DNA?

A

Polymers known as the sugar-phosphate backbone

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64
Q

What happens for complementary base pairing in the DNA?

A

Adenine to Thymine
Cytosine to Guanine

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65
Q

What do Adenine, Thymine, Cytosine and Guanine all include?

A

Nitrogen

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66
Q

What is nitrogen included in all of?

A

The bases in DNA

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67
Q

What do the sequences of bases form in the DNA?

A

The genetic code

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68
Q

What forms the genetic code in the DNA?

A

The sequences of bases

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69
Q

Which type of bond is between Adenine and Thymine and how many?

A

2 hydrogen bonds

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70
Q

Which type of bond is between Cytosine and Guanine and how many?

A

3 hydrogen bonds

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71
Q

What two bases in the DNA have 1 hydrogen bonds between them?

A

Adenine and Thymine

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72
Q

Which two bases in the DNA have 3 hydrogen bonds between them?

A

Cytosine and guanine

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73
Q

Draw the structure of DNA

A

(Check notes)

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74
Q

What are different monomer units in the DNA joined by? What does this do?

A

A bond between the sugar and the phosphate of the next nucleotide, which forms the DNA molecule’s backbone

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75
Q

What maintains the DNA’s double helix shape?

A

Weak hydrogen bonds

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76
Q

What do weak hydrogen bonds maintain?

A

The double helix shape of the DNA

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77
Q

What are two strands of DNA linked together by?

A

Weak hydrogen bonds

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78
Q

How is the double helix shape of the DNA formed?

A

2 strands of DNA are linked together by weak hydrogen bonds and stacked like a ladder who’s sides spiral around each other into their double helix shape

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79
Q

Describe the polynucleotide chains/strands in DNA

A

Are anti-parallel to each other (running in opposite directions - 1 chain facing up, 1 chain facing down)

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80
Q

What are anti-parallel to each other in the DNA?

A

Polynucleotide chains/strands

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81
Q

How many nucleotide units does each polynucleotide chain in the DNA chain contain?

A

Many million (in pairs)

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82
Q

What do you call the chains of nucleotides joined together in the DNA?

A

Polynucleotide chains/strands

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83
Q

What can contain many million nucleotide units in pairs?

A

Each polynucleotide chain/strand

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84
Q

Name 4 scientists responsible for helping solve the structure of DNA

A

Erwin Chargaff
Rosalind Franklin
Watson & Crick

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85
Q

What were Erwin Chargaff, Rosalind Franklin and Watson & Crick all responsible for?

A

Helping solve the structure of DNA

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86
Q

What did Erwin Chargaff uncover?

A

% of Adenine = % of Thymine
% of Guanine = % of Cytosine
(Chargaff’s rule)

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87
Q

What is Chargaff’s rule?

A

% of Adenine = % of Thymine
% of Guanine = % of Cytosine

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88
Q

What did Rosalind Franklin do?

A

Shot X-ray beams at DNA samples and hypothesised a spiral structure

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89
Q

Who shot x-ray beams at DNA samples and hypothesised a spiral structure?

A

Rosalind Franklin

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90
Q

What do scientists do to uncover big things?

A

Use each other’s work

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91
Q

What did Watson and Crick do?

A

Used franklin’s x-ray pictures to build a model of DNA

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92
Q

Who used Franklin’s x-ray pictures to build a model of DNA?

A

Watson & Crick

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93
Q

What two things does Chargaff’s rule state?

A

% of Adenine = % of Thymine
% of Guanine = % of Cytosine

And

Ratio of purine to pyrimidine bases in DNA must always be 1:1

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94
Q

Describe purine bases

A

Double ring structure

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95
Q

Which bases have a double ring structure?

A

Purine bases

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96
Q

Describe pyramidine bases

A

Single ring stucture

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97
Q

Which bases have a single ring structure?

A

Pyrimidines

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98
Q

What connects adenine and thymine/ guanine and cytosine?

A

Hydrogen bonds

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99
Q

Name the purine bases

A

Adenine and guanine

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100
Q

Name the pyrimidine bases

A

Thymine and cytosine

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101
Q

What type of bases are adenine and guanine?

A

Purine

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102
Q

What type of bases are thymine and cytosine?

A

Pyrimidines

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103
Q

How do we remember which bases are Pyrimidines?

A

Thymine and cytosine have a “y” in them, like the word “pyrimidine”

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104
Q

What does adenine form a bond with?

A

Thymine OR uracil

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105
Q

What does uracil form bonds with?

A

Adenine

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106
Q

How many bonds are between adenine and thymine/uracil?

A

2 hydrogen bonds

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107
Q

How many bonds are between cytosine and guanine?

A

3 hydrogen bonds

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108
Q

Which bases form two hydrogen bonds?

A

Adenine with thymine/uracil

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109
Q

Which bases form 3 hydrogen bonds?

A

Cytosine with guanine

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110
Q

What does RNA stand for?

A

Ribonucleic acid

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111
Q

What is RNA?

A

A single stranded polynucleotide

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112
Q

Which type of nucleic acid is a single stranded polynucleotide?

A

RNA

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113
Q

Which Pentose sugar does RNA contain?

A

Ribose

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114
Q

Which nucleic acid containers the Pentose sugar ribose?

A

ATP and RNA

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115
Q

What type of bases are adenine, guanine, cytosine, thymine and uracil?

A

Organic bases

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116
Q

Which organic bases does RNA include?

A

Adenine, guanine, cytosine and uracil (no thymine)

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117
Q

Draw the difference between DNA and RNA

A

(Check notes)

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118
Q

What do the nucleotide units form in RNA?

A

A polymer

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119
Q

What forms a polymer in RNA?

A

Nucleotide units

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120
Q

Which is shortest - DNA or RNA?

A

RNA is much shorter than DNA

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121
Q

What are the three types of RNA?

A

mRNA - messenger
tRNA - transfer
rRNA - ribosomal

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122
Q

Compare DNA and RNA

A

(DNA first in the list each time, then RNA)

Deoxibose sugar v.s ribose sugar
Thymine v.s uracil
Double helix v.s single stranded
One type v.s 3 types (mRNA, tRNA and rRNA)
In the nucleus, mitochondria and chloroplasts v.s in the nucleus, cytoplasm and ribosomes

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123
Q

What’s the difference between the structure of DNA and RNA?

A

DNA lacks the OH- group at carbon no.2

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124
Q

Where is DNA found?

A

In the nucleus, mitochondria and chloroplasts

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125
Q

Where is RNA found?

A

In the nucleus, cytoplasm and ribosomes

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126
Q

What are both DNA and RNA?

A

Polynucleotide chains

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127
Q

What do mRNA, tRNA and mRNA all play a role in?

A

Protein synthesis

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128
Q

What is DNA’s role?

A

-Carries the code for protein synthesis
-structure of the protein is down to the DNA deciding the order the amino acids are in the polypeptide chain to form a code

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129
Q

How is the structure of a protein decided?

A

The DNA decided the order the amino acids are in the polypeptide chain to form a code

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130
Q

What must happen before cell division?

A

All of the DNA in the cell must be copied so that there’s a copy of each gene for both new cells (DNA replication)

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131
Q

DNA replication

A

Copying all of the DNA in a cell so that there’s a copy of each gene in both new cells after division

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132
Q

What’s the name for all of the DNA in a cell being copied so that there’s a copy of each gene in each new cell?

A

DNA replication

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133
Q

Why must DNA be copied in the cell before cell division?

A

So that there’s a copy of each gene for both new cells

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134
Q

How can we ensure that there’s a copy of each gene in both new cells following cell division?

A

DNA replication

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135
Q

The first step of cell division

A

The interphase - DNA is copied

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136
Q

What’s the interphase during cell division?

A

The first step, where DNA is copied

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137
Q

What’s the second step of cell division?

A

Mitosis, where the DNA is split equally into two daughter cells

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138
Q

Mitosis

A

Where DNA is split equally into 2 daughter cells

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139
Q

What’s the final step of cell division?

A

Cytokinesis, where the parent cell is cleaved in half

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140
Q

Cytokinesis

A

Where a parent cell is cleaved in half

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141
Q

What’s the name of the process where a parent cell is cleaved in half?

A

Cytokinesis

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142
Q

How is DNA stored in the cell?

A

Wrapped around histone protein molecules

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143
Q

Chromatin

A

Histone protein molecules packed together to form fibres, held in the nucleus

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144
Q

Histone protein molecules packed together to form fibres, held in the nucleus

A

Chromatin

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145
Q

How are chromosomes formed?

A

The thread-like structure of chromatin packs itself in tightly to form chromosomes when a cell starts to divide

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146
Q

What packs itself in tightly to form chromosomes?

A

Chromatin

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147
Q

What does chromatin packing itself in tightly form? When?

A

Chromosomes, when a cell starts to divide

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148
Q

Describe the structure of chromatin

A

Thread-like

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149
Q

Chromatid

A

A copy of the duplicated chromosome, which is generally joined to the other by a centromere

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150
Q

A copy of the duplicated chromosome, which is generally joined to the other by a centromere

A

Chromatid

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151
Q

What are chromatids joined together by and what does this form?

A

A centromere
A chromosome

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152
Q

Draw and label a chromosome

A

(Check notes)

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153
Q

What’s the reason for condensing DNA into chromosomes?

A

Prevents DNA tangling and damage during cell division

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154
Q

How is DNA tangling and damage prevented during cell division?

A

DNA is condensed into chromosomes

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155
Q

What’s the name of the process DNA uses for its replication?

A

Semi-conservative replication

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156
Q

Semi-conservative replication

A

The process DNA uses for its replication

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157
Q

Why is it called “semi-conservative replication”?

A

Half of the old molecule is kept

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158
Q

Describe semi-conservative replication in simple terms

A

1.Old molecule
2.Two polynucleotide strands unzip (hydrogen bonds break 1 by 1 down the strand) and new bases are added
3.Two new molecules are created, each containing 1/2 the original molecule

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159
Q

Describe the polynucleotide strands during DNA replication

A

Complementary

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160
Q

How do polynucleotide chains unzip during DNA replication?

A

Unzip, as hydrogen bonds break 1 by 1 down the strand

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161
Q

What do the hydrogen bonds breaking 1 by 1 occur during semi-conservative replication?

A

The polynucleotide chain to unzip

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162
Q

How many new molecules are created via semi-conservative replication?

A

2

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163
Q

What’s the name of the time where DNA replication happens before mitosis or meiosis?

A

Interphase

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164
Q

Interphase

A

The space of time when DNA replication occurs, before mitosis or meiosis

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165
Q

Where is 5’ labelled on the DNA structure?

A

Outside of the sugar’s structure

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166
Q

Where is 1’ labelled on a DNA’s structure?

A

First one clockwise from the oxygen (closest to the base)

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167
Q

Describe the strands of DNA

A

Anti-parallel - they run parallel to each other but in opposite directions

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168
Q

In which direction is DNA always synthesised?

A

5’-to3’ direction

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169
Q

What’s the 5’-to-3’ direction always required for?

A

Protein synthesis

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170
Q

Which end of the polynucleotide chain are nucleotides only ever added to?

A

The 3’ end of the growing strand

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171
Q

What binds to what in order to grow a polynucleotide strand?

A

5’ phosphate group of the new nucleotide binds to the 3’ OH group of the last nucleotide in the growing strand

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172
Q

What binds to the OH group on the last nucleotide in a polynucleotide chain and where?

A

5’ phosphate group at the 3’ OH group

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173
Q

What does the 5’ phosphate group bind to, where and to do what?

A

The 3’ OH group of the last nucleotide in the growing strand to form a polynucleotide

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174
Q

What’s the name of the original molecule that’s split into 2 other strands during DNA replication?

A

Parental DNA

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175
Q

Which two strands does the parental molecule split into during DNA replication?

A

Leading strand
Lagging strand

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176
Q

What’s the name of the shape formed during DNA replication?

A

Replication fork

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177
Q

Parental DNA

A

Original molecule for DNA replication

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178
Q

Replication fork

A

The shape produced during DNA replication

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179
Q

When does DNA replication occur?

A

During interphase - a phase in cell cycle between divisions

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180
Q

Interphase

A

A phase in cell cycle between divisions

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181
Q

What does helicase do?

A

Causes the parental DNA to unzip by breaking hydrogen bonds that expose the bases

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182
Q

Which enzyme is responsible for unzipping the parental DNA by breaking its hydrogen bonds?

A

Helicase

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183
Q

What type of bonds does helicase break when unzipping the parental DNA?

A

Hydrogen bonds

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184
Q

Where does helicase work?

A

In the replication fork

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185
Q

What does polymerase do?

A

Joins new, free nucleotides to their complementary bases to build a new DNA strand, by catalysing the formation of phosphodiester bonds between deoxyribose and phosphate groups

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186
Q

Which enzyme joins new, free nucleotides to their complementary bases?

A

Polymerase

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187
Q

How does polymerase join new, free nucleotides to their complementary bases?

A

Catalyses the formation of phosphodiester bonds between deoxyribose and phosphate groups

188
Q

Phosphodiester bonds

A

Form between deoxyribose and phosphate groups (when polymerase joins free nucleotides to their complementary bases)

189
Q

What type of bond forms between deoxyribose and phosphate groups (when joining complementary bases during DNA replication)?

A

Phosphodiester bonds

190
Q

How does polymerase make near no mistakes?

A

Proof reading abilities

191
Q

Which enzyme has proof-reading abilities and what does this help with?

A

Polymerase, which helps to make near no mistake when joining new, free nucleotides to their complementary bases

192
Q

In which direction to polymerase enzymes build the new DNA strand?

A

5’ to 3’ direction

193
Q

In which direction does polymerase move along the OLD DNA template?

A

In the 3’ to 5’ direction

194
Q

Which template is moved along in the 3’ to 5’ direction during DNA replication by polymerase and why?

A

The old DNA template, as they build the NEW strand in the 5’ to 3’ direction

195
Q

What do the original polynucleotide chains act as during DNA replication?

A

The template for the aligning of new nucleotides

196
Q

What acts as the template for the aligning of new nucleotides during DNA replication?

A

The original polynucleotide chains

197
Q

What’s the ONLY direction polymerase can work in, so what does it continue to do therefore?

A

5’ to 3’, so it keeps adding new bases to the 3’ end on the new strand

198
Q

Which end on the new strand does polymerase keep adding bases?

A

3’

199
Q

Which strand is worked on continuously by polymerase?

A

The leading strand

200
Q

How is the leading strand worked on by polymerase?

A

Continuously

201
Q

Why is the “lagging strand” called this?

A

It runs anti-parallel to the other strand, so polymerase has to keep moving back to add bases to the 3’ end

202
Q

In which strand does polymerase have to keep moving back to add bases and where is it adding these bases?

A

“Lagging” strand, to the 3’ end

203
Q

What does the fact that polymerase has to keep moving back to add bases to the 3’ end of the “lagging” strand do?

A

Creates disjoined fragments known as Okazaki fragments

204
Q

Okazaki fragments

A

Disjoined fragments on the lagging strand

205
Q

Why are Okazaki fragments present on the lagging strand?

A

As the strand runs anti-parallel to the other one, so the polymerase enzyme has to keep running back to add bases to the 3’ end

206
Q

What does ligase do?

A

Glues the Okazaki fragments together, ensuring there’s no gaps in the DNA chain

207
Q

Which enzyme glues Okazaki fragments together and what does this do?

A

Ligase, ensuring there’s no gaps in the DNA molecule

208
Q

Which fragments does the ligase enzyme glue together during DNA replication?

A

Okazaki fragments

209
Q

What happens when helicase has caused the entire DNA molecule to unravel?

A

Reactions occur to form covalent bonds between nucleotides

210
Q

What’s the final step of DNA replication and when does this happen?

A

Reactions occur to form covalent bonds between nucleotides after helicase has completely unravelled the DNA molecule

211
Q

What is our product at the end of DNA replication?

A

2 identical DNA molecules, each one made up of one newly synthesised chain and one from the original molecule

212
Q

What does each DNA molecule synthesised during DNA replication consist of?

A

One newly synthesised DNA chain, and one from the original molecule

213
Q

What’s the name of the experiment that decided that DNA replication occurs through the semi-conservative model?

A

Meselson and Stahl experiment

214
Q

What did the Meselson and Stahl experiment do?

A

Decided on the semi-conservative model of replication for DNA replication

215
Q

What was described as the most “beautiful experiment in Biology”?

A

The Meselson and Stahl experiment

216
Q

What was meselson and Stahl’s experiment described as?

A

The most beautiful experiment in Biology

217
Q

What were the 3 possible mechanisms for DNA replication at the time of the Meselson and Stahl experiment?

A
  1. Conservative replication
  2. Semi-conservative replication
  3. Dispersive replication
218
Q

Conservative replication

A

The DNA molecule would be copied from the original, leaving the original DNA molecule as it was and having a new copy

219
Q

What’s the name of the type of DNA replication where the DNA molecule would be copied from the original, leaving the original DNA molecule as it was and having a new copy?

A

Conservative replication

220
Q

Semi-conservative replication

A

The two polynucleotide chains would part, and new nucleotides attach to each of the chains, leading to each new molecule having both an original chain and a new one

221
Q

What’s the name of the type of DNA replication where the two polynucleotide chains would part, and new nucleotides attach to each of the chains, leading to each new molecule having both an original chain and a new one ?

A

Semi-conservative replication

222
Q

Dispersive replication

A

Sections of the DNA molecule would be copied and spliced together, making each new DNA molecule a mix of original and new DNA

223
Q

What’s the name of the DNA replication model where sections of the DNA molecule would be copied and spliced together, making each new DNA molecule a mix of original and new DNA?

A

Dispersive replication

224
Q

What was used as the DNA source in the Meselson and Stahl experiment?

A

E.coli bacteria

225
Q

What was E.coli bacteria used for in the Meselson and Stahl experiment?

A

The source of DNA

226
Q

Why was E.coli bacteria used as the source of DNA in the Meselson and Stahl experiment?

A

-easily grown in a flask of culture medium
-replicate their cells (and DNA) every 20 minutes under optimal conditions

227
Q

How often do E.coli bacteria replicate their cells (and DNA) and under which conditions?

A

Every 20 minutes under optimal conditions

228
Q

What do E.Coli bacteria cell do every 20 minutes under optimal conditions?

A

Replicate their cells (and DNA)

229
Q

How were ‘new’ and ‘old’ nucleotides distinguished in the Meselson and Stahl experiment?

A

By the isotope of Nitrogen in the nitrogenous bases

230
Q

What did the isotope of nitrogen in the nitrogenous bases help do in the Meselson and Stahl experiment?

A

Distinguish ‘new’ and ‘old’ nucleotides

231
Q

What were the 2 isotopes of nitrogen used in the Meselson and Stahl experiment?

A

15N and 14N

232
Q

What’s the normal nitrogen isotope of E.coli bacteria?

A

14N

233
Q

Which part of the nucleotide contained the nitrogen isotopes in the Meselson and Stahl experiment?

A

The nitrogenous bases

234
Q

Which nitrogen isotope was heaviest in the Meselson and Stahl experiment?

A

15N (heavier than 14N)

235
Q

How can the different isotopes of nitrogen be separated in the Meselson and Stahl experiment?

A

Separated by mass via centrifugation

236
Q

Why does centrifugation work to separate the nitrogen isotopes in the Meselson and Stahl experiment?

A

They have different masses, and centrifugation separates by mass

237
Q

What’s the first stage of the Meselson and Stahl experiment?

A

DNA was extracted from E.Coli in a growth medium containing the 14N isotope and put in the centrifuge

238
Q

How does a centrifuge work for the Meselson and Stahl experiment?

A

Turns the sample at high speeds which settles the DNA
It settles at about the same level due to it having the same density
Forms a band in the tube

239
Q

How does a DNA band form in the tubes from a centrifuge?

A

DNA settles at about the same level due to it having he same density

240
Q

What’s the name of the device used to turn the DNA samples at high speeds to form bands in the tube in the Meselson and Stahl experiment?

A

Centrifuge

241
Q

What does a centrifuge separate by?

A

Mass

242
Q

What would appear in the tube after centrifugation for the E.coli in a growing medium containing the 14N isotope?

A

A singular band in the light position

243
Q

What’s the second step of the Meselson and Stahl experiment?

A

Extract E.coli DNA from a sample in a growing medium containing the 15N isotope that’s been allowed to replicate over many generations and place this into a centrifuge

244
Q

What would appear in the tube after centrifugation of an E.coli sample that’s been in a growing medium containing the 15N isotope?

A

The band of DNA settles lower down in the tube than the DNA from the 14N growing medium

245
Q

Why does the DNA band lie lower down in the tube for the 15N growing medium compared to the 14N growing medium?

A

15N is heavier/more dense

246
Q

What does the fact that the 15N isotope is heavier than the 14N isotope cause in the Meselson and Stahl experiment?

A

The band of DNA from the sample in this growing medium settles lower down in the tube

247
Q

How do all of the bases in the extracted DNA sample form the 15N sample all contain 15N?

A

They’ve been allowed to replicate over many generations

248
Q

What does allowing E.coli to replicate over many generations in the 15N growing medium cause?

A

All of the nitrogenous bases to contain 15N

249
Q

What’s the third step of the Meselson and Stahl experiment?

A

The sample from the 15N growing medium is washed and placed back in the 14N medium to replicate for 1 generation before extracting the DNA and centrifuging it

250
Q

What must be done before placing the DNA sample from the 15N into the 14N growing medium?

A

It must be washed

251
Q

How many generations is the E.coli allowed to replicate for in the 14N medium following previously being in the 15N medium?

A

1 generation

252
Q

What was shown on the tube when the DNA sample was centrifuged following the E.coli being in both the 15N growing medium and the 14N growing medium for 1 generation?

A

DNA was found at the intermediate position between the 14N and 15N bands

253
Q

What’s the name of the position the DNA band lies between the 14N and 15N bands?

A

Intermediate position

254
Q

What do we label the DNA bands on the test tubes in the Meselson and Stahl experiment?

A

Light
Intermediate
Heavy

255
Q

What did the DNA sample found at intermediate between the 14N and 15N bands prove?

A

That replication is not conservative, as each new DNA molecule consists of half new 14N nucleotides and half 15N nucleotides, whereas the conservative model would show 2 separate bands

256
Q

What would the conservative model of DNA replication have shown as the DNA bands in the Meselson and Stahl experiment? How was this proved wrong?

A

2 seperate bands, however we received a band in intermediate position between 14N and 15N, showing that each DNA molecule consists of half new 14N nucleotides and half 15N nucleotides

257
Q

What did the line in the intermediate position between the light and heavy positions of DNA not rule out?

A

The dispersive model

258
Q

How was the dispersive model ruled out in the Meselson and Stahl experiment?

A

E.coli as allowed to replicate 2 more times in the same external medium, leading to generations 2 and 3

259
Q

How many times was the E.coli allowed to replicate and in which external medium for the final stage of the Meselson and Stahl experiment?

A

Twice in the same 14N external medium

260
Q

What did generation 2 when E.coli was left in the same 14N external medium reveal in the tube?

A

The bands appeared at the light and intermediate positions, showing that the replication was not dispersive

261
Q

How was it proved that DNA replication was not dispersive in the Meselson and Stahl experiment?

A

When left in the 14N growing medium to generation 2, the bands appeared at the light and intermediate positions

262
Q

What would the dispersive model have shown when E.coli was left to replicate in the 14N growing medium to generation 2 in the Meselson and Stahl experiment?

A

All the DNA molecules in generation 2 would have more 14N than N and the DNA would appear between the intermediate and light position

263
Q

What did the tube from generation 2 in the 14N growing medium prove in the Meselson and Stahl experiment?

A

The parental DNA molecules of one light and one heavy chain had parted and each had been used as a template for the new nucleotides to attach to

264
Q

What did the ‘heavy’ chain cause in the final DNA replication of the E.Coli in the 14N external medium?

A

The DNA molecule in the intermediate position, but getting thinner over the next generations

265
Q

What did the ‘light’ chain show in the final DNA replication stage in the 14N external medium of the E.coli?

A

New nucleotides attached from the light 14N medium, so the band in the light position got thicker

266
Q

How did the DNA band in the light position get thicker in the final E.coli DNA replication stage?

A

New nucleotides attached from the light external medium - there was more light DNA developing per generation

267
Q

Which DNA replication model was the only one left supported by the Meselson and Stahl experiment?

A

The semi-conservative replication model

268
Q

Where is the genetic code?

A

On the DNA

269
Q

What does the genetic code do?

A

Instruct the cell on which order to put the amino acids in a polypeptide chain

270
Q

What instruct the cell on which order to put the amino acids in a polypeptide chain?

A

Genetic code

271
Q

What’s the sequence of amino acids in a polypeptide chain responsible for?

A

The primary structure of a protein and how it works

272
Q

What is responsible for the primary structure of protein and how it works?

A

The sequence of amino acids in the genetic code

273
Q

Gene

A

Length of DNA that codes for a specific polypeptide

274
Q

Length of DNA that codes for a single polypeptide

A

Gene

275
Q

What does an intron code for?

A

Nothing

276
Q

Which part of a gene codes for nothing?

A

Introns

277
Q

What do exon’s do in a gene?

A

Code for part of the polypeptide

278
Q

What are repsonsible for coding for part of the polypeptide in a gene?

A

Exons

279
Q

What contains 100s and 1000s of genes coding for different polypeptides?

A

Chromosomes

280
Q

What do chromosomes contain?

A

100s and 1000s of genes coding for different polypeptides

281
Q

What carries the genetic information to build the primary structure of a single polypeptide?

A

The sequences of bases which make up a gene

282
Q

What do the sequences of bases which make up a gene do?

A

Carry the genetic information to build the primary structure of a single polypeptide

283
Q

What make up a gene?

A

Sequences of bases

284
Q

What do 3 bases code for?

A

1 amino acid

285
Q

What codes for 1 amino acid?

A

3 bases

286
Q

What are the three bases that code for 1 amino acid known as?

A

The triplet code/codon

287
Q

Codon

A

Three bases that code for 1 amino acid

288
Q

What does protein synthesis require (in short)?

A

-the transcription of a gene into a mRNA molecule, from the original DNA template
-the code within the mRNA molecule is translated into a polypeptide by a ribosome

289
Q

Which process requires the transcription of a gene into a mRNA molecule, from the original DNA template and the code within the mRNA molecule is being translated into a polypeptide by a ribosome?

A

Protein synthesis

290
Q

Write the steps of transcription

A

(Check notes)

291
Q

What causes DNA to unwind and unzip at a particular region to be copied?

A

Helicase enzyme

292
Q

What does helicase do?

A

Unwinds and unzips a particular region of the DNA to be copied

293
Q

How DOES helicase unzip DNA?

A

Breaks hydrogen bonds between complimentary bases

294
Q

How many coding strands are used in transcription and what happens to it?

A

Only 1, the enzyme polymerase attaches to the DNA at the beginning of the sequence to be copied

295
Q

What does the enzyme polymerase do to the DNA?

A

Attaches itself at the beginning of the sequence to be copied

296
Q

How does transcription itself actually occur?

A

Free RNA nucleotides align themselves opposite complimentary nucleotides on the coding DNA strand

297
Q

What align themselves opposite complimentary nucleotides on the coding DNA strand during transcription?

A

Free DNA nucleotides

298
Q

What do free RNA nucleotides do during transcription?

A

Align themselves opposite complimentary nucleotides on the coding DNA strand

299
Q

Which strand of DNA does RNA polymerase move along?

A

The coding strand (the bottoms strand)

300
Q

What does RNA polymerase do as it moves along the coding DNA strand?

A

Forms bonds that add nucleotides one at a time to the RNA (pre mRNA)

301
Q

What forms bonds that add nucleotides one at a time to RNA during transcription?

A

RNA polymerase moving along the coding DNA strand

302
Q

What’s left when nucleotides have all been added to the coding DNA strand by the RNA polymerase?

A

A molecule of mRNA alongside the unzipped portion of DNA

303
Q

What happens behind RNA polymerase during transcription?

A

DNA strands re-join to form their double helix

304
Q

Where does DNA rejoin to form a double helix during transcription?

A

Behind the RNA polymerase

305
Q

What’s the final step of transcription?

A

mRNA carries the DNA code out of the nucleus through a nuclear pore to the cytoplasm and attaches itself to a ribosome

306
Q

How does mRNA exit the nucleus?

A

Through the nuclear pore

307
Q

Where does mRNA carry the DNA code following transcription?

A

Out of the nucleus and into the cytoplasm to attach itself to a ribosome

308
Q

Where does transcription happen?

A

All in the nucleus

309
Q

Does the DNA ever leave the nucleus?

A

No

310
Q

What does DNA act as in transcription?

A

A template for the production of mRNA (messenger RNA)

311
Q

What’s the name for an mRNA molecule receiving the DNA’s genetic code?

A

Transcription

312
Q

What’s the name for an mRNA molecule being transferred into a polypeptide by a ribosome?

A

Translation

313
Q

How do we modify pre-mRNA before moving onto the translation stage of protein synthesis?

A

Edit out the introns

314
Q

What’s edited by removing mitrons?

A

Pre-mRNA

315
Q

What’s the name of the process of modifying pre-mRNA to mRNA before the translation stage of protein synthesis?

A

Post-transcriptional modification of pre mRNA to mRNA

316
Q

What’s the first stage of post-transcriptional modification of pre-mRNA?

A

Introns are removed (spliced out) aided by enzymes containing RNA that hydrolyse the bonds between nucleotides

317
Q

What’s the name for the removal of introns?

A

Splicing

318
Q

Splicing

A

Removing introns of unknown function from pre-mRNA

319
Q

How are introns spliced out from pre-mRNA?

A

By enzymes containing RNA, that hydrolyse the bonds between nucleotides

320
Q

What are introns for?

A

We don’t know, but they’ve been in DNA for millions of years through evolution, so they must have some sort of purpose

321
Q

What’s the final step of post-transcription modification of pre mRNA?

A

Exons are joined together to form mRNA

322
Q

Steps of post-transcriptional modification of pre mRNA

A
  1. Introns are removed (spliced out) by enzymes containing RNA
  2. Exons are joined together to form mRNA
323
Q

What happens in Eukaryotes during splicing?

A

Non-coding DNA/RNA of unknown function (introns) are removed, and exons which code for the protein are joined together

324
Q

Where does splicing occur?

A

Is thought to occur in the nucleus of the cytoplasm

325
Q

Does splicing occur in prokaryotes? Why?

A

No, as they have continuous genes that don’t contain introns

326
Q

What type of cells contain introns and which don’t?

A

Eukaryotes do
Prokaryotes don’t

327
Q

How is the base sequence on an mRNA molecule read by a ribosome?

A

In groups of 3 bases at a time, known as codons

328
Q

How many codons are available for each amino acid?

A

More than one

329
Q

What does each codon code for?

A

Only ONE specific amino acid

330
Q

Describe genetic code across all species and describe what this means

A

Universal - each codon codes for the same amino acid in ALL species

331
Q

What does the fact that each specific codon codes for the same amino acid in all species show?

A

That genetic code is universal

332
Q

What are codons used to make?

A

A polypeptide chain

333
Q

What are the mRNA codons for the following DNA template?
TAC

A

AUG
(Remember - in RNA, the complementary base pair of adenine is uracil, not thymine)

334
Q

Complementary base pair of adenine in RNA

A

Uracil

335
Q

What is uracil’s complementary base pair?

A

Adenine

336
Q

What is AUG?

A

The initiation codon

337
Q

Initiation codon code

A

AUG

338
Q

What is added with the initiation codon, AUG?

A

The amino acid methionine

339
Q

When is the amino acid methionine added to a polypeptide chain?

A

With the AUG initiation codon

340
Q

What does the AUG initiation codon do?

A

Tells the ribosome when to start making the polypeptide

341
Q

What tells the ribosome when to start making the polypeptide?

A

The initiation codon, AUG

342
Q

What happens to the AUG initiation codon if it has no role and when?

A

Can be removed during post-transactional modification in the Golgi body

343
Q

What could be removed during post-translational modification in the Golgi body and when?

A

The initiation codon (AUG) if it has no role

344
Q

Stop codons

A

UAA, UAG, UGA

345
Q

What are UAA, UAG, UGA all examples of?

A

Stop codons

346
Q

What do stop codons do?

A

Tell the ribosome when to stop making a polypeptide

347
Q

What tells a ribosome when to stop making a polypeptide?

A

A stop codon (UAA, UAG or UGA)

348
Q

Why is the code a triplet code?

A

Three bases in the code give enough combinations to code for all 20 amino acids, as we need at least 1 unique combination for each

349
Q

How many amino acids do we have and what do we require for each?

A

20, we need at least 1 unique base combination for each one

350
Q

How many different codes would 2 bases in a codon give us?

A

4^2 - 16 different codes (not enough)

351
Q

How many different codes does having 3 bases in a codon give us?

A

4^3 - 64 codes

352
Q

What’s the word to describe the fact that we have more than 1 codon per amino acid?

A

Our genetic code is degenerate

353
Q

What is “degenerate” for us and why?

A

Our genetic code, as we have more than 1 codon per amino acid

354
Q

Why is the fact that our genetic code is degenerate advantageous to our cells?

A

If there were to be a mutation in the codon, the mutation may change the codon to another codon which codes for the same amino acid, which prevents against the mutation affecting the functionality of the protein

355
Q

What prevents mutation affecting the functionality of our proteins?

A

The fact that our genetic code is degenerate

356
Q

What is prevented through a degenerate genetic code?

A

The affects of mutation

357
Q

What has to happen for the translation stage of protein synthesis to occur?

A

Transfer RNA (tRNA) has to be binded to an amino acid

358
Q

What does tRNA have to be binded to for translation to occur?

A

An amino acid and to mRNA

359
Q

Draw tRNA

A

(Check notes)

360
Q

How is the type of amino acid attached to tRNA determined?

A

The anticodon sequence of the tRNA

361
Q

What does the anticodon sequence of the tRNA determine?

A

The type of amino acid attached to the tRNA

362
Q

How many amino acids does each tRNA molecule bind to?

A

1 specific amino acid

363
Q

What is tRNA responsible for?

A

Transporting amino acid from the cytoplasm to the ribosome in order to create a polypeptide

364
Q

What’s responsible or transporting amino acids from the cytoplasm to the ribosome to form a polypeptide?

A

TRNA

365
Q

Where does tRNA transport amino acids to and from and for what?

A

From the cytoplasm to the ribosome to create a polypeptide

366
Q

What is transported from the cytoplasm to the ribosome to form a polypeptide by tRNA?

A

Amino acids

367
Q

What has to happen in order for tRNA to be re-used

A

It needs to be re-activated

368
Q

When does tRNA need to be reactivated?

A

When tRNA has left the ribosome and amino acid

369
Q

What has to be re-activated upon leaving the ribosome and amino acid?

A

TRNA

370
Q

What are the steps in tRNA activation?

A

-tRNA activating enzyme
-enzyme binds to ATP which provides energy and a specific amino acid
-amino acid-AMP complex is formed and a specific tRNA molecule is recruited
-the tRNA is bound to the amino acid and AMP is released
-“charged” tRNA is produced

371
Q

What does tRNA have to be in order to be re-used?

A

Charged

372
Q

Draw and label a ribosome during translation

A

(Check notes)

373
Q

How many attachment sites does each ribosome have for translation and what are they?

A

2 - P site and A site

374
Q

Which organelle has the P site and A sit for the translation stage of protein synthesis?

A

Ribosome

375
Q

How many tRNA molecules can occupy 2 sites on a ribosome at any given time?

A

2

376
Q

How is the mRNA code read by the ribosome?

A

In groups of 3

377
Q

What does the ribosome read in groups of 3?

A

The mRNA code

378
Q

Where does the ribosome detach from the mRNA molecule?

A

When it reaches a stop codon

379
Q

What happens when a ribosome reaches a stop codon?

A

Detaches from the mRNA molecule

380
Q

What must be complementary during translation?

A

The anticodon sequence of the tRNA’s to the codon on the attached mRNA molecule

381
Q

How does tRNA enter the attachment site of a ribosome during translation?

A

The anticodon sequence of the tRNA must be complementary to the codon n the attached mRNA molecule

382
Q

What happens when the anticodon sequence of tRNA is complementary to the codon on the attached mRNA molecule?

A

A codon-anticodon complex forms with hydrogen bonds forming between complementary bases of the codons

383
Q

How is a codon-anticodon complex formed?

A

With hydrogen bonds between complimentary bases of the codons

384
Q

What have HYDROGEN bonds during the translation stage of protein synthesis?

A

The complimentary bases of the codons

385
Q

What has a PEPTIDE bond during the translation stage of protein synthesis?

A

Between 2 amino acids carried by tRNA

386
Q

What occurs between 2 amino acids carried by tRNA during the translation stage of protein synthesis?

A

Peptide bonds

387
Q

What happens during the translation stage of protein synthesis once a peptide bod is formed between 2 amino acids carried by tRNA?

A

The ribosome moves along the mRNA to the next codon

388
Q

What happens when the ribosome moves along the mRNA to the next codon during translation?

A

The first tRNA leaves without its amino acid

389
Q

How does the tRNA molecule leave the attachment site of the ribosome during translation?

A

Without its amino acid

390
Q

When does tRNA leave the attachment site of a ribosome without its amino acid?

A

When the ribosome moves along to the next codon

391
Q

What happens when the first tRNA leaves the attachment site of a ribosome during translation?

A

A new tRNA with an anticodon complementary to the new codon in the second attachment moves in

392
Q

Which sites does tRNA move to and from and repeats this?

A

From the A site to the P site

393
Q

What happens as the process of translation continues?

A

A polypeptide molecule is built up, 1 amino acid at a time

394
Q

How is a polypeptide molecule built up?

A

1 amino acid at a time through translation

395
Q

What happens when the ribosome reaches a “stop” codon on the mRNA molecule during translation?

A

The ribosome dissociates and a newly formed polypeptide chain is released, which is the primary structure of protein

396
Q

When does a ribosome dissociates form an mRNA molecule and a newly formed polypeptide chain is released, which is the primary structure of protein?

A

Upon reaching the “stop” codon

397
Q

What IS the polypeptide chai released at the end of translation?

A

The primary structure of protein

398
Q

Where does the primary structure of protein move following translation? Why?

A

To the Golgi body for modification (e.g - folded to form the secondary protein structure)

399
Q

What is translated into what during the translation stage of protein synthesis?

A

The sequence of codons on the mRNA
To
The primary structure of a new proton molecule

400
Q

What does this entire unit come back to?

A

Francis Crick’s Central Dogma (of molecular Biology)

401
Q

What moves to the Golgi body?

A

The primary structure of protein

402
Q

Francis Crick’s Central Dogma (of molecular Biology)

A

An explanation of the flow of genetic information within a biological system

403
Q

What gives an explanation of the flow of genetic information within a biological system?

A

Francis Crick’s Central Dogma (of molecular Biology)

404
Q

What is Francis Crick’s central Dogma (of molecular Biology) summed up as?

A

DNA makes RNA makes protein

405
Q

Transcription summed up under Francis Crick’s Central Dogma (of molecular Biology)

A

The DNA is copied in the nucleus to form messenger RNA (mRNA)

406
Q

Translation summed up in Francis Crick’s Central Dogma (of molecular Biology)

A

The mRNA associated with a ribosome and transfer RNA (tRNA) brings amino acids to form a polypeptide

407
Q

What does Francis Crick’s Central Dogma (of molecular Biology) cover?

A

Transcription, translation and codons

408
Q

Codes on an mRNA molecule summed up in Francis Crick’s Central Dogma (of molecular Biology)

A

The code is arranged in codons (triplet of bases) which are matched by complementary anti-codons on tRNA

409
Q

2 processes of protein synthesis?

A

Transcription
Translation

410
Q

What type of reaction is ATP formed in and why?

A

Endergonic as it uses energy

411
Q

Endergonic - definition and example

A

Uses energy - forming ATP

412
Q

Give an example of an exergonic reaction and explain what this is

A

Hydrolysis of ATP
A reaction that releases energy

413
Q

What is the reaction condensing ADP and Pi to make ATP?

A

Reversible

414
Q

Draw and label ADP

A

(Check notes)

415
Q

Is uracil a purine or a pyrimidine?

A

A pyrimidine

416
Q

What does Chargaff’s rule not apply to and why?

A

RNA as the proportions of bases are not equal due to the molecules being single stranded

417
Q

What rule does not apply to RNA and why?

A

Chargaff’s rule, as the bases are not in equal proportions in RNA, as molecules are single stranded

418
Q

What does having single stranded molecules in RNA mean?

A

Chargaff’s rule doesn’t apply

419
Q

Why are the bases not in equal proportions in RNA?

A

As it’s single stranded

420
Q

What’s the product of transcription?

A

RNA

421
Q

Where does transcription occur?

A

Nucleus

422
Q

What’s the product of translation?

A

Polypeptide amino acid chain

423
Q

What’s the location of translation?

A

Cytoplasm and endoplasmic reticulum (ribosome)

424
Q

Give 2 differences between translation and transcription

A

Transcription -
Product = RNA
Location = Nucleus

Translation -
Product - polypeptide amino acid chain
Location - cytoplasm and endoplasmic reticulum (ribosome)

425
Q

Does transcription or translation occur in the nucleus?

A

Transcription

426
Q

Does transcription or translation occur in the cytoplasm and endoplasmic reticulum (ribosome)?

A

Translation

427
Q

What’s RNA the product of?

A

Transcription

428
Q

What’s a polypeptide amino acid chain the product of?

A

Translation

429
Q

Which variables should be controlled during the centrifugation in the Meselson and Stahl experiment?

A

-time
-rate of spin
-temperature
-volume of DNA sample
-concentration of tube contents

430
Q

Which parts of the molecule are in common to DNA, RNA and ATP nucleotides?

A

Pentose sugar
Phosphate groups
Nitrogenous bases

431
Q

What is meant by the term “universal energy currency’?

A

ATP is required in all energy requiring reactions in all living organisms

432
Q

Is hydrolysing ATP to ADP exergonic or Endergonic and why?

A

Exergonic as approximately 30.6kJmol is released

433
Q

How many nucleotides make up one amino acid?

A

3

434
Q

Are tRNA specific?

A

Yes, to each amino acid

435
Q

What’s specific to each amino acid?

A

tRNA

436
Q

Which organelle contains DNA?

A

Nucleus

437
Q

What part of a cell makes rRNA and assembles ribosomes?

A

Nucleolus

438
Q

What does a nucleolus do?

A

Makes rRNA and assembles ribosomes

439
Q

Name 3 ways in which the Golgi Body can process a polypeptide into a functional protein

A

-folding to give secondary/tertiary structure
-adding carbohydrate chains
-combining polypeptides

440
Q

Which organelles produce ATP?

A

Mitochondria and chloroplasts

441
Q

What do mitochondria and chloroplasts synthesise?

A

ATP

442
Q

What’s the difference between where transcription and translation take place?

A

Transcription - nucleus
Translation - ribosome

443
Q

Describe 3 differences between tRNA and mRNA

A

tRNA
Clover shape
Double stranded sections
Caries an amino acids to the growing polypeptide chain during translation

mRNA
Linear
Single stranded
Carries genetic information copied from DNA

444
Q

How many nucleotides are there per amino acid?

A

3

445
Q

How does a peptide bond form between 2 amino acid molecules?

A

Via a condensation reaction

446
Q

How happens of introns are included in the amino acid sequence?

A

A different protein structure would be produced

447
Q

What do exons code for?

A

The protein

448
Q

How many nucleotides make up an amino acid and why?

A

3 nucleotides, as there is one base on each nucleotide and 3 bases make up one amino acid

449
Q

What does DNA helicase do?

A

Breaks the hydrogen bonds between bases

450
Q

Where would the band in the centrifuge tube remain throughout for dispersive replication?

A

Intermediate positions (except generation 1)

451
Q

Which mechanism for DNA replication involves no intermediate DNA?

A

Conservative

452
Q

What is more ATP in muscles advantageous for?

A

Contraction

453
Q

What type of reaction is translation and why?

A

Endergonic
Uses ATP

454
Q

How does the peptide bond form between 2 amino acid molecules during translation?

A

Part of the ribosome acts as a catalyst

455
Q

Difference between DNA replication and transcription

A

DNA polymerase and DNA nucleotides
RNA polymerase and RNA nucleotides

456
Q

What does a gene code for?

A

One polypeptide

457
Q

Why can’t DNA be replicated outside of the nucleus of a cell?

A

Free DNA nucleotides are not outside of the nucleus

458
Q

Which codons code for amino acids?

A

mRNA codons

459
Q

Is DNA reactive? What does this allow us to do?

A

No, its very Unreactive
Bases in the core are protected by the sugar phosphate backbone
It means that it lasts millions of years under the right conditions

460
Q

What do we measure the length of DNA in?

A

Base pairs

461
Q

What does ligase do?

A

Joins fragments of DNA to an existing fragment

462
Q

What’s the name for the method used in Meselson and stahl’s experiment?

A

Ultracentrifugation

463
Q

What does DNA replication form?

A

The sugar phosphate backbone

464
Q

Which carbon is the base attached to in DNA?

A

C1

465
Q

Which carbon is the phosphate group attached to in DNA?

A

C

466
Q

What do the bonds between nucleotides to form DNA strands attach between? In which direction?

A

Phosphate and C3, in the 5’ to 3’ direction

Biology (26 decks)

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