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biology unit 1 > 1.5 Nucleotides > Flashcards

1.5 Nucleotides Flashcards

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1
Q

What is a mutation?

A

A mutation is a random, spontaneous change in the amount, arrangement or structure of the DNA of an organism.

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2
Q

What can a mutation affect?

A

A single gene or a whole chromosome, or even all the chromosomes of an individual.

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3
Q

Why are mutations important?

A

They increase variation in a population.

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4
Q

Are most mutations recessive?

A

Yes. They can only be expressed in the phenotype if there are two copies of the allele in the genotype.

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5
Q

In what situation would a mutation be beneficial?

A

When they give a competitive advantage to an individual when affected by natural selection pressures.

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6
Q

How can the rate of mutations be increased?

A

Ionising radiation and mutagenic chemicals.

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7
Q

Most mutations occur in what?

A

Somatic cells.

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8
Q

Mutations may cause what?

A

Cancer.

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9
Q

Only mutations occurring in the what can be inherited?

A

The formation of gametes (germ cell mutations.)

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10
Q

What is a oncogene?

A

A gene that, when mutated or expressed at high levels, can turn a normal cell
into a tumour cell.

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11
Q

What is apoptosis?

A

A programmed form of death.

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12
Q

Activated oncogene cause what?

A

Can cause cells meant to undergo apoptosis to survive and increase in number instead.

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13
Q

Most oncogenes require what to be activated?

A

An additional step, such as a mutation or environmental factors like a viral infection.

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14
Q

What are proto-oncogenes?

A

Genes that if they mutate can become oncogenes.

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15
Q

What are tumour suppressor genes?

A

They are protective genes that control cell growth by suppressing cell division.

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16
Q

When do gene mutations occur?

A

During DNA replication before cell division.

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17
Q

How does a mutation happen?

A

During DNA replication mistakes are made in the copying process so that there is a change to the sequence of bases.

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18
Q

What are gene mutations?

A

Changes in the base pairs within the genes.

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19
Q

What can gene mutations take the form of?

A

Duplication, insertion, deletion, inversion or substitution of bases.

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20
Q

What does a nucleotide consist of?

A

A pentose sugar bonded to phosphate and a nitrogenous base.

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21
Q

What is adenosine composed of?

A

Ribose bonded to adenine.

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22
Q

Adenosine is a component of what?

A

ATP (adenosine triphosphate).

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23
Q

DNA is an abbreviation for what?

A

Deoxyribonucleic acid.

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24
Q

In DNA the sugar is deoxyribose, and the base is one of what four?

A

Adenine, thymine, guanine or
cytosine.

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25
RNA is an abbreviation for what?
Ribonucleic acid.
26
What is the sugar in DNA?
Deoxyribose.
27
What is the sugar in RNA?
Ribose.
28
What are the possible bases in RNA?
Adenine, uracil, guanine or cytosine.
29
ATP is an abbreviation for what?
Adenosine triphosphate.
30
What is the sugar in ATP?
Ribose.
31
What is the base in ATP?
Adenine and there are three phosphate groups.
32
What is ATP formed in?
An endergonic reaction.
33
How is ATP formed?
ADP and phosphate (Pi) are combined to form ATP.
34
Where does the energy to form the bond in ATP come from?
An exergonic (energy releasing reactions) reaction in cellular respiration.
35
The reaction for ATP is what?
A condensation reaction.
36
What is the enzyme that catalyses the reaction for ATP to be formed?
ATP synthetase.
37
ATP can be hydrolysed to..?
ADP and Pi.
38
How much energy is released when ATP is converted to ADP and Pi?
30.6 kJmol-1
39
Why is ATP called the universal energy currency?
It provides energy to all reactions in all cells in all species.
40
Why can ATP be easily transported in cells where it is required?
Because it's relatively small and soluble.
41
What are the two main categories of base in nucleic acids?
Purines and pyrimidines.
42
What are the purine bases?
Guanine and adenine.
43
Do purine bases have a double or single ring in their structure?
Double.
44
What are the pyrimidine bases?
Thymine, cytosine and uracil.
45
Do pyrimidine bases have a double or single ring in their structure?
Single.
46
Guanine (G) and cytosine (C) are linked by how many hydrogen bonds?
Three.
47
Adenine (A) and thymine (T) are linked by how many hydrogen bonds?
Two.
48
The base pairs are termed what base pairs?
Complimentary.
49
Why are the proportions of adenine and uracil/ guanine and cytosine in RNA not equal?
Because the molecules are single stranded.
50
Complementary base pairing takes place in some areas of what?
tRNA (transfer RNA)
51
Why does complimentary base pairing happen in tRNA?
To hold the 3D structures in place.
52
What pairs to what in RNA?
C pairs to G, and A pairs to uracil (U) in RNA.
53
What are the two functions of DNA in cells?
- as the base sequence codes for amino acid sequences in protein synthesis - replicating prior to cell division so that each daughter cell gets equal DNA.
54
A DNA molecule is composed of what?
Two complementary polynucleotide strands.
55
What is a polynucleotide?
A polynucleotide is a polymer of nucleotides.
56
Sugar-phosphate joined by condensation reactions make what?
A phosphodiester linkage.
57
The sugar-phosphate molecules form what?
The two sugar-phosphate ‘backbones’ of DNA.
58
The bases in DNA project into where?
The centre of the molecule.
59
The two strands of DNA are what to each other?
Antiparallel.
60
How do the strands run in DNA?
In opposite directions, from 3’ to 5’ or 5’ to 3’.
61
What do 3' and 5' refer to in DNA?
The numbers of the carbons in the pentose.
62
RNA is shorter than what?
DNA.
63
rRNA has a single strand of what? It is highly folded to make a what?
A single polynucleotide strand that is highly folded to make a globular structure.
64
Messenger RNA is single stranded and made where?
In the nucleus.
65
mRNA is manufactured using complimentary base pairs of what?
RNA nucleotides using a strand of DNA as the template.
66
The three bases are called what on mRNA?
Codons.
67
tRNA is a single stranded polynucleotide of RNA twisted into a what?
Clover-leaf shape.
68
What is the function of tRNA?
To carry amino acids to the ribosomes.
69
The type of amino acid carried by the tRNA is determined by what?
Anticodon, a sequence of three bases on the ‘middle leaf’ of the clover shape.
70
Nucleic acids are what?
Polymers made of monomers called nucleotides.
71
A molecule containing many nucleotides is called what?
A polynucleotide.
72
What are the advantages of ATP over glucose?
- The hydrolysis of ATP to ADP involves a single reaction that releases energy immediately whereas breaking down glucose takes longer and many intermediates for the energy to be released. - Only one enzyme is needed to release energy from ATP, but many are needed to release energy from glucose. - ATP releases energy in small amounts, when and where it is needed, but glucose contains large amounts of energy, which would be released all at once. - ATP provides a common source of energy for many different chemical reactions, increasing efficiency and control by the cell.
73
What are the roles of ATP?
It provides the energy for cellular activity: - metabolic processes- to build large complex molecules, such as DNA synthesis from nucleotides. - active transport- to change the shape of carrier proteins in membranes and allow ions to be moved against the concentration gradient. - movement-for muscle contraction - nerve transmission-sodium-potassium actively pumped across the axon membrane. - secretion-the packaging and transport of secretory products into vesicles in cells.

biology unit 1 (23 decks)

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