Unit 6.2- Patterns of Inheritance Flashcards
Types of chromosome mutations:
- Deletion
- Inversion
- Translocation
- Duplication
- Non-disjunction
Translocation chromosomal mutation definition:
A piece of a chromosome breaks off and then becomes attached to another chromosome
Duplication chromosomal mutation definition:
Part of a chromosome may be duplicated
Non-disjunction chromosomal mutation definition:
One pair of chromosomes or chromatids fails to separate, leaving one gamete with an extra chromosome. When fertilised with a normal haploid gamete, the resulting zygote has one extra chromosome
Aneuplody defintion:
The chromosome number is not an exact multiple of the haploid number for that organism. Sometimes chromosomes or chromatids fail to separate during meiosis
Polyploidy definition:
If a diploid gamete is fertilised by a haploid gamete, resulting in a zygote that will be triploid
When does genetic variation occur in meiosis?
- Allele shuffling/ crossing over in prophase 1
- Independent assortment in anaphase 1 and 2
Heterozygous definition:
Not true-breeding; having different alleles at a particular gene locus on a pair of homologous chromosomes
Homozygrous definition:
True-breeding; having identical alleles at a particular gene locus on a pair of homologous chromosomes
Monogenic definition:
Determined by a single gene
Dyhybrid definition:
Involving two gene loci
Codominance definition:
Where both alleles present in the genotype of a heterozygous individual contribute to the individual’s phenotype
Sex-linked definition:
Gene present on one of the sex chromosomes
Autosomal linkage definition:
Gene loci present on the same autosome (non- sex chromosome) that are often inherited together
What genes form as a result of crossing over of autosomal genes?
Recombiant genes
Epistasis definition:
Interaction of non-linked gene loci where one masks the expression of the other
Recessive epistasis:
The homozygous presence of a recessive allele at the first locus prevents the expression of another allele at a second locus. The alleles at the first locus are epistatic to those at the second locus, which are hypostatic to those at the first
Dominant epistasis:
The presence of one epistatic allele prevents the other being shown
How can genes work in a complementary fashion (epistasis)?
They code for two enzymes that work in succession, catalysing sequential steps of a metabolic pathway
Directional selection definition:
A type of natural selection that occurs when an environmental change favours a new phenotype and so results in a change in the population mean
Founder effect definition:
When a small sample of an original population establishes in a new area; its gene poo; is not as diverse as that of the parent population
Genetic bottleneck definition:
A sharp reduction in population size due to environmental catastrophes or human activities, which reduces genetic diversity. As the population expands, it is less diverse than it was before
Stabilising selection definition:
Natural selection leading a constancy within a population. Intermediate phenotypes are favoured and extreme phenotypes selected against. Alleles for extreme phenotypes may be removed from the population. This reduces genetic diversity
What are the two equations for the Hardy-Weinberg principle?
p+q=1
p^2 +2pq +q^2 =1
Speciation definition:
The splitting of a genetically similar population into two or more populations that undergo genetic differentiation and eventually reproductive isolation, leading to the evolution of two or more new species
Allopatric speciation:
Formation of two different species from one original species, due to geographical isolation
Sympatric speciation definition:
Formation of two different species from one original species due to reproductive isolation, while the populations inhabit the same geographical location
Examples of gene banks:
- Rare breed farms
- Wild populations of organisms
- Botanic gardens and zoos
- Seed banks
- Sperm banks
- Frozen embryos
Ethical considerations of artificial selection:
- Domesticated animals may retain juvenile characteristics, making them less able to defend themselves
- Some inbred dogs have susceptibility to disease
- Some coat colours would fail to camouflage animals
