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Table of contents

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1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

3. Extensions to Mendelian Inheritance

Variations of Dominance

3. Extensions to Mendelian Inheritance

Variations of Dominance - Video Tutorials & Practice Problems

Previous Topic: Epistasis and Complementation

Next Topic: Penetrance and Expressivity

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1

concept

Variations on Dominance

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Hi in this video we're gonna be talking about variations on dominance. So there are many different types of dominance and the one that we've been referring to so far is called complete dominance. And that is any time a dominant allele is present, it's going to be expressed. So even it doesn't matter if it's Hamas I guess or if it's hetero, I guess you're gonna have the same phenotype. So Hamas I guess is not finna typically different than hetero I guess. So this is what the Planet Square normally looks like. You have a red flower. Here you go. It's homesickness dominant. You have a white flower, its home is like it's recessive. If you make them together, you get four offspring, they're all red, they look exactly like this parent because they have one dominant allele and then it looks the same as the two dominant alleles. This is what we're familiar with. This is what we've been talking about. This is called complete dominance. But genetics is very rarely like this, it's very rarely complete. So let's talk about some types of dominance that aren't complete. So the first one is incomplete dominance and this is when the number of dominant alleles affects the phenotype. So homos, I guess dominant is going to appear different than heterosexuals dominant. So this is if you do the same mating, so you have a red flower that's home as I guess dominant. And a white flower homicide is recessive when you make them together, you get four offspring each with one dominant allele and one recessive, but that doesn't look red instead, it looks pink. And that's because you're just getting one dose of the dominant allele. So what's the phenotype of the offspring from a red flower mating and a white flower mating under incomplete dominance? It's going to be pink. So it's gonna be pink. That question mark. It is pink. So that's incomplete dominance. A upper case does not look like a uppercase A lowercase. They're different types. Then the 3rd type is co dominant. And this is a really interesting example because there's usually two dominant alleles and both are expressed equally. So a good example of this is human blood types. We say it's the A. B. O. Blood type because some people have A some people have B. And some people have. So what this looks like is if you're actually looking at the genotype to get blood type A. You can have called I. A. And you can be homos I guess dominant for this gene or you can be heterocyclic dominant for A. And that will give you A. For B. It's the same except you replace the superscript A. With superscript B. And it can be home as I guess or hetero I guess. And you get B. Now the co dominance comes in here. Co dominance happens because what happens if you have one A dominant allele and one B. Well you get both proteins and that makes you type blood type A. B. And then if you're homicide is recessive meaning that you have neither dominant allele that you're classified as blood type O. So right here is the example of co dominance because there's two dominant alleles I. A. And I. B. And both are expressed giving you the A. B. Blood type. So if you were to mate a hetero zig asse blood type A. With a hetero ziggy's blood type B, you get one dominant allele and one recessive allele for each one. And so when you get four offspring you get this offspring, this offspring this offspring and this offspring. And so that produces four different types of blood. You can have Type A. B. Which is the co dominance because there's two dominant alleles you can have Type B. Because you have your blu l you can have type A. And you're a leo or you can have type O. Because there's no dominant allele present. So that's an example of co dominance. I feel people have hardest time understanding this one. Um But it's just that the fact that there's two dominant alleles and both are expressed equally. So with that let's now move on.

2

Problem

Problem

Which of the following is NOT a type of dominance?

A

Complete dominance

B

Incomplete dominance

C

Codominance

D

Leaky dominance

3

Problem

Problem

Which of the following parents could produce offspring with an AB blood type?

A

A x A

B

O x A

C

A x AB

D

AB x O

4

Problem

Problem

Blood types are an example of what type of dominance?

A

Complete dominance

B

Incomplete dominance

C

Codominance

D

Leaky dominance

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Previous Topic: Epistasis and Complementation

Next Topic: Penetrance and Expressivity

Additional resources for Variations of Dominance

PRACTICE PROBLEMS AND ACTIVITIES (26)

In this chapter, we focused on extensions and modifications of Mendelian principles and ratios. In the process...
In shorthorn cattle, coat color may be red, white, or roan. Roan is an intermediate phenotype expressed as a m...
In foxes, two alleles of a single gene, P and p, may result in lethality (PP), platinum coat (Pp), or silver c...
In mice, a short-tailed mutant was discovered. When it was crossed to a normal long-tailed mouse, 4 offspring ...
The ABO and MN blood groups are shown for four sets of parents (1 to 4) and four children (a to d). Recall tha...
List all possible genotypes for the A, B, AB, and O phenotypes. Is the mode of inheritance of the ABO blood ty...
The wild-type color of horned beetles is black, although other colors are known. A black horned beetle from a ...
With regard to the ABO blood types in humans, determine the genotype of the male parent and female parent show...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
Two genes interact to produce various phenotypic ratios among F₂ progeny of a dihybrid cross. Design a differe...
In a disputed parentage case, the child is blood type O, while the mother is blood type A. What blood type wou...
The A and B antigens in humans may be found in water-soluble form in secretions, including saliva, of some ind...
The A and B antigens in humans may be found in water-soluble form in secretions, including saliva, of some ind...
In rabbits, a series of multiple alleles controls coat color in the following way: C is dominant to all other ...
Flower color in snapdragons results from the amount of the pigment anthocyanin in the petals. Red flowers are ...
Horses can be cremello (a light cream color), chestnut (a brownish color), or palomino (a golden color with wh...
Horses can be cremello (a light cream color), chestnut (a brownish color), or palomino (a golden color with wh...
The coat color in mink is controlled by two codominant alleles at a single locus. Red coat color is produced b...
Five human matings (1–5), identified by both maternal and paternal phenotypes for ABO and MN blood-group antig...
A variety of pea plant called Blue Persian produces a tall plant with blue seeds. A second variety of pea plan...
You have four guinea pigs for a genetic study. One male and one female are from a strain that is pure-breeding...

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