Genetics EOC Remediation

Some definitions to know Gregor Mendel - the Father of Genetics Trait - a characteristic that can be passed to offspring Genotype – the pair of genes that make up a trait (one from mom, one from dad) Aa, AA, aa Phenotype – What the trait looks like Black or brown fur color

Independent assortment means that genes are separated during meiosis, and each egg and sperm is unique.

Punnett squares are used to predict the genotype and phenotype of the offspring

Punnet Squares and Ratios

A test cross is used to determine the genotype of an unknown parent

Types of Dominance Complete One allele is dominant and one is recessive B allele for black fur b allele for brown fur If the genotype is Bb, the fur would be black, because black is dominant

Practice crosses Flower Red is dominant White is recessive Cross a homozygous dominant red flower with a heterozygous red flower. What are the genotypic and phenotypic ratios? Seeds Green is dominant Yellow is recessive Cross a homozygous recessive yellow seed with a homozygous dominant green seed. What are the genotypic and phenotypic ratios?

Types of Dominance Incomplete When neither allele is dominant and the phenotype is intermediate or a blend of the two alleles. R is the allele for red flowers R’ is the allele for white flowers The genotype RR’ would produce pink flowers

Incomplete Dominance Long water melon (LL) * Round watermelon (L’L’) Do the cross What is the genotypic ratio? What is the phenotypic ratio? Remember – The phenotype in this case has 3 possibilities, LL long : L’L’ round: LL’ oval

Types of Dominance Codominance When both alleles are dominant and each allele is expressed in the trait Type AB blood has both A and B antigens on it

Punnet Square For Blood Types IA IB i i

Multiple alleles vs. polygenic inheritance more than 2 forms of a gene Bloodtype alleles IA IB i Polygenic inheritance When two or more genes work together to give you one trait Ex. Hair and eye color

Sex linked genes are on the sex chromosomes (colorblindness and hemophilia) XX = normal female XhX = carrrier female XhXh = hemophiliac female A female who is a carrier does not have that trait! She is not sick at all. She won’t even know that she carries that gene. XY = normal male XhY = hemophiliac male Males only have I X chromosome. They cannot be carriers. This is why sex linked disorders are more common in men

Pedigrees show the inheritance of traits through families

Hemophilia – Offspring of Queen Victoria

Chromosome map shows all the genes on single chromosome

Karyotypes show the complete set of chromosomes that a human has

Biotechnology Gel electrophoresis Used in DNA fingerprinting to match DNA at a crime scene with a suspect.