Cellular control-gene mutations

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  • Created by: Anca.a
  • Created on: 01-04-18 18:17
What is a mutation?
random change to genetic material.
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What is a gene mutation?
change to rearrangement of bases or small sequences of bases on a chromosomes NOT entire chromosomes. Due to mutagenic chemicals-changes the bases, replication errors, high energy ionising radiation.
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What can happen to the structure of chromosomes during a mutation?
structure/# of chromosomes can change due to the incorrect segregation of chromosomes in mitosis/meiosis.Or bits of chromosomes can become detached & attach to other chromosomes making a shorter and elongated chromosome- called translocation.
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What are mutations that effect mitotic division called?
somatic mutation-not inherited, associated with cancerous tumours.
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How do mutations exert their effects?
they can affect protein function and production eg. affects primary structure of the protein which can change the tertiary structure. Can also affect other metabolic processes.
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What is the difference between a structural gene and a regulatory gene?
a structural gene codes for a protein and a regulatory gene controls whether or not a structural gene is expressed.
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What is a degenerate code?
it's when more than one codon codes for the same amino acid. This can lessen the effect of mutations.
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What is a point mutation?
base substitutions
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Silent effect of a point mutation eg. ATG TTA:
degenerate, same amino acid eg. ATG TTG
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Missense effect of a point mutation eg. ATG TTA:
codes for something else, due to change in primary protein structure as the amino acid has changed. 18 amino acids are coded for by more than one triplet.
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Nonsense effect of a point mutation eg. ATG TTA:
it's when there is a premature STOP codon which means only part of the polypeptide is is made. It is likely to degrade in the cell.
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What are indel (insertion/deletion) mutations?
involves the addition of an extra base pair or the loss of a base pair in the DNA sequence.
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What are the effects of indel mutations?
-causes a frameshift in the reading of the genetic code-since bases are read in triplets-the loss or addition of a base changes all triplets after the mutation.
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What is expanding triple nucleotide repeats?
It is an effect of indel mutations, where an extra amino acid is added and a triplet is repeated during meiosis and again in each subsequent generation. Frameshifts can happen with nucleotide repeats that are more than 3 bases.
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What are inversions?
for some reason, a codon in the gene detaches and when it reattaches, the sequence of the codon is reversed eg. TTG to GGT - this is a substitution rather than insertion.
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Card 2

Front

What is a gene mutation?

Back

change to rearrangement of bases or small sequences of bases on a chromosomes NOT entire chromosomes. Due to mutagenic chemicals-changes the bases, replication errors, high energy ionising radiation.

Card 3

Front

What can happen to the structure of chromosomes during a mutation?

Back

Preview of the front of card 3

Card 4

Front

What are mutations that effect mitotic division called?

Back

Preview of the front of card 4

Card 5

Front

How do mutations exert their effects?

Back

Preview of the front of card 5
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