Beyond Mendelian Genetics

Question 1

T/F All Mandelian monohybrid crosses are simple.

Answer 1

FALSE!

Question 2

What are 5 possible complicators of crosses?

CLIMP

Answer 2

Incomplete Dominance
Co-Dominance
Multiple Alleles
Polygenic Traits
Lethal Dominant Traits

Question 3

This situation features a recessive allele which is not completely hidden.

Answer 3

Incomplete Dominance

Question 4

If there is no dominant allele we have:

Answer 4

Incomplete Dominance

Question 5

Phenotypic ratio in F2 generation with incomplete dominance?

Answer 5

1:2:1

Question 6

This situation entails 2 possible alleles for a different gene.

Answer 6

Multiple Alleles

Question 7

A good example of Multiple Alleles is:

Answer 7

ABO Blood Types!

Question 8

Blood types are determined by presence of:

Answer 8

CHO on RBC surface.

Question 9

The multiple alleles in blood types are:

Answer 9

IA & IB (Codominant), both dominant to i

Question 10

In co-dominance we have…

Answer 10

No dominant allele, No intermediate phenotypes

Question 11

A prime example of co-dominance =

Answer 11

Sickle Cell Anemia!

Question 12

Always in co-dominance we have…

Answer 12

Half of one phenotype, half of the other

Question 13

In this situation we have multiple genes affecting a single trait:

Answer 13

Polygenic Traits

Question 14

In polygenic traits there are more than _ alleles that are contributing to each gene.

Answer 14

2

Question 15

Example of polygenic traits?

Answer 15

Human skin pigmentation, 3 Melanin genes

Question 16

T/F In polygenic traits we have less dominant alleles.

Answer 16

FALSE - More dominant alleles

Question 17

Most genetic disorders come from..

Answer 17

Homozygous Recessive Genes (Some co-dominant)

Question 18

In the case of a dominant allele which causes disease we have a…

Answer 18

Lethal Dominant Gene

Question 19

In a Lethal Dominant Gene:

Answer 19

One mutant allele can lead to disease. 2 will be fatal.

Question 20

If heterozygous dominant?

Answer 20

Lethal = fetus will die in utero

Question 21

If the homozygous dominant is fatal?

Answer 21

Partial lethal dominance

Question 22

Therefore, heterozygous with one dominant and one recessive can:

Answer 22

Survive!

Question 23

Example of Partial Lethal Dominance?

Answer 23

Achondroplastic Dwarfism

Question 24

In achondroplastic dwarfism AA= Aa= aa=

Answer 24

Aa= Dwarf
aa= Average Height
AA = lethal!

Question 25

Phenotypic & genotypic ratio in partial lethal dominance?

Answer 25

Phenotypic
2:1
Genotypic
1:2:1 (Count fatal as possible outcome!)

Question 26

In Complete Lethal Dominance, Homozygous Dominant:

Answer 26

Die in utero

Question 27

Heterozygous?

Answer 27

Die in utero

Question 28

Example of complete lethal dominance?

Answer 28

Huntingtons Disease

Question 29

T/F There are several completely lethal dominant diseases.

Answer 29

FALSE

Question 30

What makes Huntington’s common?

Answer 30

Most have offspring before they know, as later onset (35-45)