Inheritance Flashcards
Inheritance refers to
how genetic information is passed from parents to their offspring.
What determines inherited characteristics?
Sections of your DNA called genes is what determines inherited characteristics.
Define alleles?
Different forms in genes are called alleles, which are in pairs.
Gregor Mendel pea plant experiment
Define Mendel’s explanation
- 2 ‘factors’ must be responsible for height
- these factors are called alleles (a gene that is responsible for the characteristic)
- Some alleles are stronger than others
- The stronger alleles are called dominant and the weaker are called recessive.
Mendel’s findings
- 2 alleles control characteristics, these can be different or identical.
- One allele is dominant and the other is recessive.
- One allele is inherited from each parent.
- If two purely different individuals reproduce, all offspring will show the dominant characteristics.
- If two the first generation reproduce then 3 offspring will show the dominant characteristics and 1 will show the recessive characteristics.
Does Mendel is findings apply to Humans?
In humans most characteristics (phenotypic features) are controlled by and therefore a result of multiple genes. For example there are over 400 genes in humans that control height. In addition several genes control eye colour and also hair colour in humans.
Gene
the physical unit of heredity
Allele
Different forms of the same gene
Dominant
a gene always expressed when present
Recessive
a gene only expressed in a homozygous pair
Phenotype
the characteristics of an organism
Genotype
the alleles contained in an organism
Homozygous
alleles are the same e.g. HH or hh
Heterozygous
alleles are different e.g. Hh
F1
First generation in a genetic cross
F2
second generation
