NA. 6.2 Patterns of Inheritance Flashcards
Define Phenotype
The expression of an organism’s genetic constitution combined with its interaction with the environment
Define Genotype
the Genetic material of an organism
How can Meiosis bring about Genetic Variation?
- Random arrangement of chromosomes during lining up.
* Crossing over of chromatids before the first division.
How does random fertilisation bring about Genetic Variation?
Gametes are haploid cells, meaning they only contain half of a person’s DNA. As this is determined by meiosis, every gamete contains different DNA. Therefore the same two individuals can produce genetically different offspring.
What is a Mutagen?
certain physical or chemical agents that can cause a mutations
When in the cell cycle is Gene/ DNA Mutation most likely to occur?
the S phase, when DNA is synthesized and replicated
When in the cell cycle is Chromosome Mutation most likely to occur?
during meiosis stages of Metaphase or Anaphase
crossing over and separation
What are the Chromosome Mutations?
- deletion, part of chromosome deleted
- inversion, section breaks off inverts then reattaches
- translocation,section attaches to another chromosome
- duplication, piece of chromosome duplicated
What’s Discontinuous Variation?
variation that can be assigned a particular category
e.g blood type
What’s Continuous Variation?
variation where differences in phenotypic features are quantitative
e.g height, weight
What’s an Allele?
the different versions of a gene
Homozygous?
having different alleles at a certain locus on a pair of homologous chromosomes
Heterozygous?
having the same alleles at a certain locus on a pair of homologous chromosomes
What is Monogenic Inheritance?
when a characteristic(phenotype) is determined by One gene
Define Dihybrid Inheritance.
Where two phenotypic characteristics are determined by two different genes present on two different chromosomes at the same time.
What is meant by multiple Alleles?
characteristics for which there are more than two alleles in the populations gene pool
What is meant by Codominant Alleles?
Two dominant alleles that both contribute to the phenotype, either by showing a blend of both characteristics, or the characteristics appearing together.
What is meant by Sex-linkage?
Where an allele is located on one of the sex chromosomes, meaning its expression depends on the sex of the individual.
What is an Autosome?
the 22 pairs of fully homologous chromosomes
How many Chromosomes do humans have?
23 total pairs of chromosomes where;
22 pairs are Autosomes
1 pair are the sex chromosomes
What is meant by Autosomal linkage?
Gene loci presents on the same autosomes that are usually inherited together