Mutations 2 Flashcards
What is evolution?
The change in characteristics of a species over time
What definition of genotype?
The genetic make up of an organism
what definition of phenotypes ?
The observed traits
what definition of population?
a group of organisms of the same species living together in a particular place
what definition of gene pool?
The sum of all the alleles in a given population
what definition of allele frequency ?
how common an allele is in a given population
what definition of mutation ?
change in the DNA sequence of an organism
what definition of gene mutation ?
change in a single gene so that the trait normally produced by that gene is changed or destroyed
what definition of chromosomal mutation ?
All or part of a chromosome is affected
what is the cause of a mutation?
Mutagens such as mustard gas, radioactive waste
what are the types of mutations?
Induced mutations - mustard gas
Spontaneous mutation - random errors
what categories can mutations be separated into?
- induced/spontaneous
- whether they are hereditary
- their effects on proteins
-extent of mutation
what are heritable mutation ?
- Mutation that occur in somatic cell cannot be passed on eg. Cancer
- Germline mutation that occur in gametes can be passed on eg. PKU
what is the extent of the mutation?
- The amount of DNA affected
- whether it is a gene or chromosomal mutation
what is the effect of mutations?
changes in nucleotide may cause point or frameshift mutation
what are point mutation?
- Missense
- Nonsense
- Neutral
- Silent
- Substitution
what is a missense mutation?
causes a change in amino acid
what is a nonsense mutation?
change in the base sequence to code for a stop codon
what is a neutral mutation?
causes a change in the amino acid but the structure of the protein ins’t changed enough to alter function
what is a silent mutation?
- do not cause any change in the amino acid or the protein
what is a substitution mutation?
an existing nucleotide is replaced with another one
what are frameshift mutation?
-inserted
-deletion
what is an insertion mutation?
- a new nucleotide is added
what is a deletion mutation?
- a nucleotide is removed from the DNA strand
what are chromosomal mutations?
- a mutation involving long segments of DNA or chromosome
-can increase or decrease number of chromosomes or chromosomes sets
what are the causes of chromosomal mutations ?
-error in mitosis, meiosis, fertilisation
-mutagens
what are some examples chromosomal mutations?
- Duplication
- Deletion
- Inversion
- Translocation
- Non-disjunction
what is duplication ?
a section of chromosome occurs twice
what is deletion ?
a section of DNA is removed
what is inversion?
a break in a chromosome occurs and then is reattached the wrong way
what is translocation?
part of a chromosome breaks off and reattaches to the wrong chromosome
what is non-disjunction?
occurs during meiosis
chromosomes don’t seperate properly during anaphase resulting in daughter cells with the incorrect number of chromosome called aneuploidy
how is variation caused?
-Random assortment
-Crossing over
-Non-disjunction
-Random fertilisation
-Mutation
what is random genetic drift?
a non-directional variation in allele frequency that occurs in a small population
what is the bottleneck effect?
when a population is sharply reduced
what is the founder effect?
when a small group moves away from its homeland
how is gene flow created?
the movement of alleles from one population to another through migration
what do barriers do?
-prevent inbreeding
-creates different selection pressure
-development of different gene pools
what are the types of barriers?
- Geographical barriers
- Sociocultural barriers
what is the population frequency of Tay – Sachs disease?
Jewish decent from Eastern Europe
Sociocultural barrier
Protection from TB
what is the population frequency of Thalassaemia?
Mediterranean coast and South East Asia
Sociocultural barrier
Protection from malaria
what is the population frequency of Sickle – cell anaemia?
Black Africans
- Protection from malaria
what is the process of natural selection ?
- there is variation within a species
- there are more offspring produced than can survive to adulthood
- there is a struggle for existence
- individuals with favourable characteristics survive and reproduce
- favourable characteristics are passed on to offspring
- proportion of favourable alleles gradually increase
what is Darwin’s theory of natural selection based on?
-variation
-birth rate
-natures balance
