Week 1 - Gene basics Flashcards
Phenotype
The organism’s observable traits
Genotype
Traits that can be passed on to children through genetic material
Mendel’s four ideas:
- Two kinds of inherited factors for each dichotomous trait (i.e., genes)
- Each organism possesses two genes for each of its dichotomous traits
- One of the genes in a heterozygous pair dominates the other in expression of the trait
- For each trait, a child randomly inherits one of the father’s two genes and one of the mother’s two genes
Genes are
Two kinds of inherited factors for each dichotomous trait
Alleles
is the variant form of a given gene
Homozygous
Alternative forms of a given gene are called alleles, and they can be dominant or recessive. When an individual has two of the same allele, whether dominant or recessive, they are homozygous.
Heterozygous
A diploid organism is heterozygous at a gene locus when its cells contain two different alleles of a gene. The cell or organism is called a heterozygote specifically for the allele in question, and therefore, heterozygosity refers to a specific genotype.
Where are genes located?
On the chromosomes in the nucleus of cells
Are chromosomes singular entities?
No, they occur in matched paris
How many chromosomes do humans have?
46 arranged in 23 pairs
How many pairs of sex chromosomes?
One pair
If they aren’t sex chromosomes, what are they?
autosomes
Let’s try that again, what are autosomes?
The 22 pairs which are not sex chromosomes
Where would you find the two genes (alleles) that control a trait?
At the same locus, one on each chromosome of a particular pair
How many genes?
20,000
