Lecture 2.14 Introduction to Genetics¬

Question 1

What is the difference between constitutive and regulated gene expression?

Answer 1

Constitutive is the constantly expressed genes (housekeeping) and regulated is the genes that are more tightly controlled for expression

Question 2

What are the types of inheritance and their features?

Answer 2

• Dominant: a phenotype is dominant if the trait can be seen in individuals who are heterozygous for an allele (i.e. only need one copy) – Huntington’s, polydactyly
• Recessive: a phenotype is recessive if the trait is seen only in individuals homozygous for the allele (i.e. need both copies), sickle cell, albinism, in X-linked recessive mothers are carriers and pass on to all of their sons
• Co-dominant: a phenotype is co-dominant when the effects of both alleles are seen in the heterozygote, i.e. a heterozygote’s phenotype is distinct from and not intermediate between those of two homozygotes, e.g. ABO blood groups

Question 3

What is penetrance?

Answer 3

Reduced penetrance is when someone with a genotype doesn’t have the associated phenotype (BRCA1)

Question 4

What is incomplete dominance?

Answer 4

Heterozygous phenotype is an intermediate between homozygotes (homozygous form is lethal - achondroplasia)

Question 5

What is genetic heterogeneity?

Answer 5

Different genotypes associated with the same phenotype (hearing impairment)

Question 6

What is mitochondrial inheritance?

Answer 6

Only get mitochondrial genes from mother (none in sperm) so mother passes on to son