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AQA A level Biology > 4.1 DNA genes and chromosomes > Flashcards

4.1 DNA genes and chromosomes Flashcards

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1
Q

What is a gene

A

A base sequence of DNA that codes for a specific polypeptide or functional RNA

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2
Q

What is the name given to the position of a particular gene on a chromosome

A

Locus

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3
Q

What is an allele

A

Different form of a gene
e.g. eye colour

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4
Q

How many alleles form one gene

A

2, one from father and one from mother

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5
Q

List 3 differences between prokaryotic and eukaryotic DNA

A
  • Prokaryotic DNA is circular whereas eukaryotic DNA is linear
  • Eukaryotic DNA is associated with histone proteins whereas prokaryotic DNA isn’t
  • Prokaryotic DNA is shorter than eukaryotic DNA
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6
Q

How many chromosomes are in a human cell

A

46

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7
Q

How are chromosomes formed

A

The DNA wraps around histone proteins, continuous coiling results in a supercoil and further folding results in a chromosome

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8
Q

What does karyotype mean

A

The number and the type of chromosomes in a cell

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9
Q

What are homologous chromosomes

A

2 chromosomes with the same genes in the same loci

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10
Q

Can haploids have homologous chromosomes

A

No

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11
Q

What is the genetic code

A

The sequence of bases in DNA

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12
Q

If one base=one amino acid, what is the possible number of amino acids

A

4

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13
Q

If 2 bases= one amino acid, what is the possible number of amino acids

A

16

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14
Q

If 3 bases= one amino acid, what is the possible number of amino acids, and what does this show

A

64, there are only 20 naturally occurring amino acids therefore showing that some amino acids have multiple codes

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15
Q

What are the 3 features of the genetic code

A
  • Universal
  • Degenerate
  • Non-overlapping
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16
Q

How is the genetic code universal

A

The triplet that codes for one amino acid in one organism will code for the same amino acid in all organisms

17
Q

How is the genetic code degenerate

A

Each triplet codes for a specific amino acid, many amino acids have more than one code

18
Q

How is the genetic code non-overlapping

A

Each base is only read once

19
Q

What are introns

A

Non-coding regions of DNA

20
Q

What are exons

A

Coding regions of DNA

21
Q

What type of DNA, eukaryotic or prokaryotic, contains introns

A

Eukaryotic

22
Q

In what process are the introns in DNA cut out

A

Protein synthesis

23
Q

What is a genome

A

The entire genetic code of an organism

24
Q

What is a proteome

A

The entire set of proteins that can be produced by the genome

25
Q

What does mRNA carry

A

The code for one gene

26
Q

Why can mRNA fit out of the nuclear pores but DNA cannot

A

Because mRNA only carries the code for one gene and is single stranded whereas DNA carries the genetic code for all genes and is double stranded so too large to fit through the pores

27
Q

What are the series of 3 consecutive bases called in DNA

A

A triplet

28
Q

What are the series of 3 consecutive bases called in mRNA

A

A codon

29
Q

What are the series of 3 consecutive bases called in tRNA

A

An anticodon

30
Q

What shape is the polynucleotide of mRNA

A

Helical

31
Q

What is the name of the process when mRNA copied from DNA

A

Transcription

32
Q

As mRNA is copied from DNA, what is complementary to what

A

mRNA’s codons are complementary to DNA’s triplets

33
Q

What is the shape of a tRNA molecule

A

Cloverleaf shape

34
Q

Is tRNA single or double stranded

A

Single

35
Q

How is the cloverleaf shape of a tRNA molecule held in place

A

By hydrogen bonds between the bases

36
Q

What is the function of tRNA

A

To transfer amino acids

37
Q

In a tRNA molecule what is the name of the 3 exposed bases at the top

A

The amino acid attachment site

38
Q

What is the function of rRNA

A

It combines with proteins to make ribosomes

AQA A level Biology (33 decks)

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