Unit 3 Lesson 4 - Beyond Mendel

U3 Lesson 4 - Beyond Mendel

Notes

Vocabulary

• codominance – two alleles in a pair are equal, but instead of one dominating the other, both alleles show up at once

• incomplete dominance – instead of one allele dominating the other in a gene, the alleles combine or blend to produce a trait that is a combination of the two

• multiple gene inheritance – several genes in a chromosome work together to give an individual a certain trait

Greg Mendel

• Gregor Mendel's work with pea plants has been a tremendous contribution to the study of genetics.

• One exception to Mendel’s theories can be seen in the crossbreeding of red and white snapdragons.

• Some of the flowers resulting from this cross are pink, rather than completely red or white.

Multiple Choice

One exception to Mendel's theories can be seen in the crossbreeding of red and white snapdragons which produced _______ flowers rather than red or white.

• pink

• white

• red

• silver

• stripes

• •trait—a quality that is displayed in a living thing, such as hair color, height, or skin color

  •inheritance – the process in which traits are passed from parent to child through heredity; takes place in the genes.

  •allele – a form of a genetic trait; can be dominant or recessive

  •dominance – the allele that has the most influence in a pair of donated alleles, causing a certain trait to show up every time (Example: tall height in pea plants)

Multiple Choice

The allele that has the most influence in a pair of donated alleles, causing a certain trait to show up every time

• dominate

• allele

• trait

• inheritance

Multiple Choice

A quality that is displayed in a living thing, such as hair color, height, or skin color

• dominate

• allele

• trait

• inheritance

Incomplete dominance

• Sometimes, instead of one allele in a gene dominating the other, the alleles combine or blend together to produce a trait that is a combination of the two. 

• Example: flowers were a blend of the two colors ( red mixed with white) and pink flowers resulted

Multiple Choice

Incomplete dominance occurs when ______________.

• both alleles show equally

• the dominant trait takes over

• the alleles combine or blend together to produce a trait that is a combination of the two

• the recessive trait takes over

• neither allele is displayed, they are masked by a third allele

Codominance

• Sometimes, two alleles are equal, but instead of one dominating the other, both alleles show up at once.

• Example : Blood types in humans sometimes have codominance (AB blood Type) 🩸

• Example: & when a red cow breeds with a white cow. The calf that is born might have a roan color

Multiple Choice

Which is an example of codominance?

• red hair color

• a cow with roan color

• a pink flower resulting from a white flower and a red flower

• a person with blue eyes whose mother has blue eyes

• a medium size pea plant

Multiple Choice

Blood types in humans sometimes have _______ as in the blood type AB.

• incomplete dominance

• multiple allele inheritance

• recessive dominance

• codominance

• simple dominance

Multiple Gene Inheritance

• When alleles are the same then the organism is homozygous for that trait. (for example, if they are both alleles for brown eye color)

• When alleles are different then the organism is heterozygous for that trait, and the dominant trait will be expressed. [Example: one allele is dominant (brown eye color)-- and the other is recessive (blue eye color)]

• multiple gene inheritance - things such as hair color, skin color, and height, among many other traits, are also controlled by multiple genes, and therefore, multiple alleles. This occurrence explains why there are so many variations among individuals. 

Multiple Choice

The occurrence _____________ explains why so many variations exist among hair colors, skin colors, height, and other physical characteristics.

• Multiple Gene Inheritance

• incomplete dominance

• codominance

• total dominance

• recessive dominance