Inq. 5 Flashcards
How can the genetic similarities and differences within and between species be compared?
What is Autosomal Inheritance?
A genetic trait or condition being passed down from parent to child. (Normal Punnett Square)
What are sex-linked traits?
Trait occurs on one or both of the sex chromosomes. If it occurs on the X chromosome, then females need two copies for it to be shown, whereas males only need one.
What is codominance?
Both alleles are expressed - creating a new phenotype.
What is incomplete dominance?
The alleles are blended - creating a hybrid phenotype.
What is ‘multiple alleles’ inheritance?
Many traits can be coded for by more than two alleles (e.g. blood type, skin colour)
Mutation definition
A change in the DNA sequence of an organism.
How can mutations affect polypeptide production?
The ribosomes will read the mRNA wrong, which will result in making different amino acids that join the polypeptide chain. It can also not make proteins that are required for the organism.
How can mutations affect phenotype?
Most mutations will have no effect on the phenotype. However, certain mutations will be passed on to offspring, and others will cause diseases/body deterioration over time.
What is crossing over?
Exchange of genes between homologous chromosomes, mixing the parental characteristics for offspring.
Process of fertilisation
Sperm and egg unite to form a zygote
Population genetics
the study of how the gene pool changes over time
Gene pool
The sum total of all the genes and their alleles ina population. It looks at how changes in allele frequencies can lead to short and long term changes.
Fixed vs highly variable genes
Fixed genes: an allele that is the only variation existent in a population
Highly variable genes: genes that have a large variability in expression across a population.
Allele Frequency
A measure of how common a specific allele is in a population.
How is allele frequency calculated?
Frequency of allele G =
no. of copies of allele G in population
DIVIDED BY
total no. of copies of the gene (G+g) in population
