Mendelian Genetics Flashcards
What is the definition of genetics
A branch of biology that deals with heredity and genetic variation
Define genetic variation and heredity
Genetic variation- differences that make organisms different from their parents
Heredity- passing of traits from one organism to the next e.g. eye colour
What are genes
Units of heredity that carry genetic information
Define allele
Different forms of a gene
Differ in nucleotide sequence
Gregor Mendel
He crossed male and female pea plants
Mendel called genes as factors, some factors are always expressed some factors are always suppressed. These factors are what we refer to as genes or alleles
Homozygous
Same set of alleles/ genes
Both dominant/ recessive
Heterozygous
Different set of genes/ alleles
One dominant and the other recessive
Monohybrid cross
Cross involving single character/ trait at a time
Monohybrid ratio
Phenotypic ratio 3:1
Genotypic ration 1:2:1
Dihybrid cross
Cross involving two characters at a time
Dihybrid ratio
Phenotypic ratio 9:3:3:1
Phenotype
Features that can be seen/ observed externally
Physical expression of the genes giving rise to particular observable traits
Genotype
Genetic make up that cannot be observed
Set of genes that give rise to a particular trait
Dominance
One allele masks the affects of the other
Codominace
Both the dominant alleles are equally strong and expressed in the offspring simultaneously
1:2:1 ratio
Incomplete dominance
Dominant allele does not completely suppress the recessive allele
