Module 3 - Part 2

Question 1

Complete penetrance

Answer 1

• if you carry the allele, you will show the phenotype
• ex. HH45 - will manifest huntingtons

Question 2

Incomplete penetrance

Answer 2

• if you carry the allele you may show the phenotype
• ex. HH36 - may of may not have huntingtons

Question 3

Penetrance

Answer 3

how many individuals of a pop. w a particular genotype show the expected phenotype (incomplete vs. complete)

Question 4

Expressivity

Answer 4

degree of intensity w which a particular genotype is expressed at the phenotypic level (variable vs. invariable)

Question 5

Complete dominance

Answer 5

heterozygote phenotype is indistinguishable from that of the homozygous dominant parent

Question 6

Partial/incomplete dominance

Answer 6

heterozygote displays an intermediate phenotype between those of both homozygous parents

Question 7

Co-dominance

Answer 7

occurs when the phenotype of both homozygous parents are simultaneously expressed in the F1 hybrid
- ex. blood types
- co-dom between AA, AB, BB
- complete dom between A/O & B/O

Question 8

Polygenic traits (interchangeable with complex traits)

Answer 8

A trait controlled by more than one gene - often show con’t variation
- ex. hair colour, height

Question 9

Mendel’s Second Law

Answer 9

Law of independent assortment
- two or more alleles will sort into gametes independently of one another
- skin colour: 3 genes (more genes = more variation)
- height: >100 genes

Question 10

Pleiotrophy

Answer 10

A single gene can effect multiple traits/phenotypes
- ex. sickle cell: mutant sickle cell B-globin gene
- from HBBa - HBBs

Question 11

Recessive lethal alleles

Answer 11

lethality early in life
- homozygous recessive die/allele passed on by heterozygous (carriers)
delayed lethality
- homozygous can pass on lethal allele at reproductive age (eg. CF, SCA)

Question 12

Dominant lethal alleles

Answer 12

lethality early in life
- neither homo/hetero exist (appear as mutations)
delayed lethality
- homo/hetero individuals may pass allele if they reach reproductive age (ex. HD)

Question 13

Eugenics movement

Answer 13

aimed at improving the genetic comp of the human race through selective breeding for “positive traits”
or
the elimination of “negative traits” through sterilization programs
- forceful sterilization
- selective breeding

Question 14

Charles Davenport

Answer 14

• “disharmonious combo’s” would arise in the second gen of “wild race crosses”
• when to Jamaica & studied interracial marriages
• concluded: certain # of mixed race individuals were mentally inferior

Question 15

Racial hygiene in Nazi Germany

Answer 15

Aktion T4 euthanasia program
- effort to “cleanse” the aryan race of ethnically impure blood
- mentally/physically disabled considered inferior and were murdered
- gas chambers were used (than later used by Adolf Hitler)