Mendelian Genetics

Question 1

What was used before Mendel?

Answer 1

• Practical Genetics: Farming
• Blending: scientists believed offspring traits should be a perfect blend of parent traits

Question 2

Why did Mendel’s experiments work with peas?

Answer 2

• They can either be self fertilized or cross fertilized
• They have many distinguishing traits
• Short life cycle = fast generations

Question 3

T or F: Genetic factors can be present but not expressed

Answer 3

True. The expressed trait is dominant and the unexpressed trait is recessive.

Question 4

What were some of Mendel’s conclusions?

Answer 4

• Traits weren’t blended when passed down to the next generation
• Each plant carries 2 genetic factors for each trait
• Despite identical appearance, P1 and F1 smooth plants are genetically different

Question 5

what is phenotype?

Answer 5

observable properties of an organism

Question 6

What is genotype?

Answer 6

The specific genetic constitution of an organism

Question 7

what is an allele?

Answer 7

one possible alternative form of a gene, usually distinguished by its phenotypic effects

Question 8

Homozygous vs Heterozygous

Answer 8

• Homozygous has identical alleles (ex. SS or ss)
• Heterozygous has two different alleles (ex. Ss)

Question 9

T or F: Individuals carry 2 alleles for each trait and pass both allele onto their offspring

Answer 9

False. Individuals carry 2 alleles for each trait and only pass one allele onto their offspring

Question 10

Principle of Segregation

Answer 10

The alleles of a gene pair separate during gamete formation & one allele on each homologous chromosome

Question 11

How does albinism occur?

Answer 11

People with albinism carry 2 copies of a mutant, recessive allele. Therefore, they cannot make melanin.

Question 12

A pure breeding red rose (RR) is crossed with a pure breeding white rose (rr). Their offspring plants produced pink roses. This is an example of:

Answer 12

Incomplete dominance. Has a distinctive phenotype in heterozygotes.

Question 13

A pure breeding blue rose is crossed with a pure breeding white rose. The offspring plants produced have both white and blue splotches. This is an example of:

Answer 13

Codominance. Both alleles are expressed equally and shown in the trait.

Question 14

Blood type A is crossed with blood type B. The offspring has blood type AB. This is an example of:

Answer 14

Codominance. the IA and IB alleles are codominant.

Question 15

The inheritance of the ABO blood type is humans is controlled by the dominant IA and IB alleles and the recessive i allele. This is an example of:

Answer 15

Multiple alleles. Traits are controlled by genes that have more than two possible alleles (IA, IB, and i)