5.3-6 Non-Mendelian Genetics

Question 1

Why do many traits not follow the ratios predicted by Mendel’s laws? (5)

Answer 1

1. Varying degrees of dominance
2. Many traits are produced through multiple genes acting together
3. some traits are determined by genes on the sex xmes
4. Some genes are adjacent or close to one another on the same xme and will segregate as a unit
5. Some traits are the result of non-nuclear inheritance (ex. Chloroplast and mitochondrial DNA)

Question 2

Alleles can show varying degrees of ____. In Mendel’s experiments, he worked with traits that showed complete dominance, meaning that?

Answer 2

• Dominance

- homozygous dominant and heterozygous individuals are phenotypically the same

Question 3

What is incomplete dominance? (2)

Answer 3

• neither allele is fully dominant
• F1 gen has a phenotype that is a mix of those of the parental gen
• ex. Red crossed with white flowers will produce pink offspring

Question 4

What is codominance?

Answer 4

• two alleles that affect phenotype are both expressed
  Ex. Human blood group
  — TYPE AB BLOOD: A and B are both expressed (not a blend girl)

Question 5

What are multiple alleles?

Answer 5

• genes that exist in forms with more than two alleles

- ex. Human blood group: Alleles I^A, I^B (Big I always dominant over little i)