Mendel and the Gene Idea

Question 1

What were the advantages of using peas in Mendel’s experiment?

Answer 1

• Short generation time
• Large numbers of offspring
• Mating could be controlled

Question 2

How did Mendel start his scientific approach?

Answer 2

With true-breeding

Question 3

What is true-breeding?

Answer 3

Plants that produce offspring of the same variety when they self-pollinate

Question 4

What four related concepts make up the Mendel Model?

Answer 4

• Alt versions of genes account for variations in inherited characters
• For each character, an organism inherits two alleles, one from each parent
• If the two alleles at locus differ, then the dominant allele determines the appearance
• The law of segregation

Question 5

What is the law of segregation?

Answer 5

Two alleles for a heritable character separate during gamete formation and end up in different gametes

Question 6

What is an example of homozygous?

Answer 6

AA or aa

Question 7

What is an example of heterozygous?

Answer 7

Aa

Question 8

What is monohybrid?

Answer 8

heterozygous for one character

Question 9

What is a monohybrid cross?

Answer 9

A cross between heteroyzgotes

Question 10

What is dihybrid?

Answer 10

heterozygous for both characters

Question 12

How did Mendel develop the law of independent assortment?

Answer 12

Using a dihybrid cross

Question 13

What does the law of independent assortment state?

Answer 13

Each pair of alleles segregate independently of any other pair of alleles during gamete formation

Question 14

The law of independent only applies to what?

Answer 14

Genes on different, nonhomologous chromosomes or those far apart on the same chromosome

Question 15

What happens to genes locate near each other on the same chromosome?

Answer 15

They tend to be inherited together

Question 16

Inheritance of characters by a single gene may deviate from simple Mendelian patterns when?

Answer 16

• Alleles are not completely dominant or recessive (incomplete dominance)
• Gene has more than two alleles
• Gene produced multiple phenotypes

Question 17

What are the degrees of dominance?

Answer 17

• Complete dominance
• Incomplete dominance
• Co-dominance

Question 18

What is complete dominance?

Answer 18

When the dominant allele completely masks the recessive allele (Ex. brown eyes)

Question 19

What is incomplete dominance?

Answer 19

When neither allele is completely dominant over the other (Ex. white+black=grey)

Question 20

What is codominance

Answer 20

Two different versions are present in an organism (Ex. roan cows)

Question 21

What is pleiotropy?

Answer 21

Genetic condition where a single gene controls or influences multiple phenotypic traits

Question 22

Pleiotropic alleles are responsible for what?

Answer 22

Multiple symptoms of certain hereditary diseases such as cystic fibrosis and sickle-cell disease

Question 23

What happens during epistasis?

Answer 23

One gene affects the phenotype of another due to interaction of their gene products

Question 24

What happens during polygenic inheritance?

Answer 24

Multiple genes affect a single trait

Question 25

What are quantitative characters?

Answer 25

Those that vary in the population along a continuum

Question 26

Quantitative variation usually indicates ____ ____

Answer 26

Polygenic inheritance, an additive effect of two or more genes on a single phenotype

Question 27

What is an example of polygenic inheritance?

Answer 27

Height, over 180 genes affect height