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Aqa A-level Biology > Chromosomes And Protiens > Flashcards

Chromosomes And Protiens Flashcards

1
Q

In what type of cells does splicing occur to pre-mRNA

A

Eukaryotic cells

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2
Q

What is the role of DNA helicase in transcription

A

Break hydrogen bonds in DNA molecule

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3
Q

what joins to the DNA template strand during transcription

A

Free RNA nucleotides in the nucleus join there complementary base pair on the template strand and form hydrogen bonds

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4
Q

What enzymes catalyses the formation of phophodiester bonds between the RNA nucleotides in transcription

A

RNA polymerase

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5
Q

When does transcription stop

A

When a stop codon is reached

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6
Q

What does pre-mRNA do with the template strand in transcription?and why ?

A

Dissociâtes from the DNA template strand because of the instability.
Therefore the hydrogen bonds are broken

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7
Q

What is splicing?

A

The removal of introns from pre-mRNA

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8
Q

What is a pre-mRNA strand made up of

A

Introns and exons

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9
Q

What is an intron

A

A non coding section of a pre-mRNA strand

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10
Q

What is a codon

A

A coding section of a pre-mRNA strand

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11
Q

Name a disease caused by incorrect splicing

A

Cistic fibrosis

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12
Q

What organelle is involved in the process of translation during protein synthesis

A

Ribosomes

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13
Q

What is free floating in the cytoplasm that attaches to the ribosome with complementary bases in translation

A

tRNA

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14
Q

What on the tRNA molecule is complementary to the mRNA

A

The anticodon

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15
Q

What does a tRNA molecule carry

A

A specific amino acid

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16
Q

What is used to hydrolyse the bonds between two amino acids in translation

A

ATP
An enzyme

17
Q

What bond forms between amino acids

A

Peptide bonds

18
Q

When does the ribosome stop doing translation

A

When a stop codon is reached

19
Q

What is formed during translation

A

A polypeptide chain of amino acids
The primary structure of a protein

20
Q

Define mutation

A

A change within the DNA usually the sequence or quantity of the nitrogenous bases

21
Q

What causes mutations

A
  1. Natural copying errors
  2. Exposure to mutagens
22
Q

What is a mutagen

A

A chemical or physical agent that is capable of inducing change in DNA known as mutations

23
Q

What is a substitution mutation

A

When one nucleotide is replaced by another nucleotide which will change the base within the triplet that codes for an amino acid 

24
Q

What is a silent mutation

A

When a change in base has no impact on the sequence of amino acids in the polypeptide chain 

25
Q

Why do silent mutations occur?

A

 the DNA code is degenerate

26
Q

What is a missense mutation?

A

When a change in the base causes a change in the amino acid that the triplet codon codes for which could change the overall 3D tertiary structure of the protein altering its function

27
Q

What is a nonsense, mutation

A

When a change in the nucleotide changes, the nitrogenous base, so therefore causes the amino acid to change. In this case it is a stop code on and makes the protein completely non-functional.

28
Q

What is a deletion mutation?

A

When one nitrogenous base is completely removed, which completely changes the triplet codon

29
Q

What is the name given to what happens when a deletion mutation occurs?

A

Frame shift

30
Q

What is a nondisjunction mutation?

A

When the chromosomes fail to separate during meiosis, which causes the gametes to have one more or one less chromosome
E.g. down syndrome

31
Q

What are the benefits of mutations?

A

It produces genetic diversity
It helps with natural selection
It has helped with evolution

32
Q

What are the disadvantages of mutation?

A

Most mutations produced organisms that are less suited to the environment 

33
Q

Give some features of prokaryotic DNA

A

Found in the cytoplasm of bacteria
The DNA is circular and non linear
It is not associated with proteins / histones
It does not contain introns (non coding sections)
Shorter than eukaryotic DNA

Aqa A-level Biology (9 decks)

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