3.4.4 MUTATIONS + MEIOSIS Flashcards
Gene mutations involve…
a change in the base sequence of chromosomes
Gene mutations can arise..
Spontaneously
Gene mutations occur during…
DNA replication and can involve deletion and substitution
Due to the ………. nature of the genetic code, not all base ………… cause a change in the sequence of amino acids:
- degenerate
- substitutions
What increase the rate of a gene mutation?
Mutagenic agents
How do mutations in the number of chromosomes occur?
- spontaneously
- by chromosome non- disjunction
- during meiosis
Materials which may increase the risk of a mutation:
- ultraviolet/ ionising radiation
- chemicals
- viruses
What happens in substitution?
One base is replaced by another
What happens in deletion?
One base is removed from the sequence
What happens in insertion?
One base is added into the sequence
Will substitution result in a change to the amino acid sequence of a protein?
Not always- may still code for the same amino acid
Will deletion result in a change to the amino acid sequence?
Yes, they are more likely to change the amino acid sequence because they cause a frame shift- this changes all the triplets after the deletion and so also changes the amino acid sequence
Will insertion cause a change to the amino acid sequence?
More likely to because they cause a frame shift
What is a polyploidy chromosome mutation?
When organisms have more than two sets of chromosomes- mostly seen in plants
How many daughter cells does meiosis produce?
4
Are the daughter cells from meiosis genetically different of the same as one another?
Different
Are the daughter cells produced in meiosis haploid or diploid?
Haploid
How many divisions occur in meiosis?
2
What are genetically different daughter cells a result of in meiosis?
Independent segregation of homogolous chromosomes
Crossing over of homologous chromosomes results in…
Further genetic variation among daughter cells