Non-Mendelian Genetics
Define the term 'Sex-Linkage'.
Characteristics and traits that are influenced by recessive genes carried on the sex chromosomes (XX, XY)
List 3 conditions caused by sex-linkage:
Red/Green colour blindness
Haemophilia
Muscular Dystrophy
Define the term 'Sex-limitage".
Traits visible within only one sex.
What is a pedigree used for?
Used to diagram the inheritance of a trait or condition through multiple generations.
Explain 'multiple alleles'.
Having three or more variants for the same gene.
Elaborate on Incomplete/partial dominance:
Causes multiple genotypes to be expressed simultaneously - contradicting Mendelian Genetics.
Define 'Lethality' and provide 2 examples.
Alleles that can cause death or lethal conditions when present in even a single copy, such as cystic fibrosis or sickle-cell anaemia.
Define 'Pleiotropy'.
One gene that affects multiple characteristics.
What is a Polygenic Trait?
A trait that can be influenced by multiple genes and environment.
What is a Monogenic Trait?
A trait influenced by a single gene with two alleles.
Define a 'Mutation'.
A change in the DNA sequence of an organism.
What can cause mutations? (3)
Errors in DNA replication
Exposure to mutagens
Exposure to a viral infection
What are the 4 types of mutation?
Germline
Somatic
Chromosomal
Gene or Point
What mutation occurs in gametes and is passed onto offspring?
Germline mutations
What mutation occurs in body cells after fertilization are not passed on genetically?
Somatic mutation
Name some features of Chromosomal mutation.
Chromosome deletion, duplication, inversion or translation caused by a separation failure during meiosis. It affects many genes, causing conditions like Down's Syndrome, and Turner's Syndrome.
Elaborate on Gene/Point mutation.
Most common kind of mutation caused by the change of a single nucleotide in the DNA sequence through addition, deletion or alteration.