L15 GENETICS I

Question 1

What is a gene?

Answer 1

Sequence of nucleotides contianing information needed to make a specific protein.

Question 2

Fill in the blanks.

Answer 2

Question 3

How many locuses/loci exist for each gene?

Answer 3

2: One for each chromosome copy.

Question 4

What are these?

Answer 4

Question 5

What are these?

Answer 5

Question 6

Who came up with the rules and theories we know about genetics today?

Answer 6

Mendel.

Question 7

What were Mendel’s three discoveries?

Answer 7

1. The dominance&receciveness of alleles
2. The law of segregation of alleles
3. The law of independent assortment.

Question 8

Briefly describe Mendel’s first experiment.

Answer 8

He experimented with crossing purple and white flowers, and observing the resulting colour.

Question 9

What were the two conclusions mendel came to after his experiment?

Answer 9

1. That characteristics of an organism depend on inherited genes
2. That each individual contains a pair of alleles for any particular gene.

Question 10

What does the law of segregation state?

Answer 10

The two alleles for a gene will always end up in different gametes after meiosis.

Question 11

Fill in the blanks.

Answer 11

Question 12

When is the Multiplication Rule used?

Answer 12

The multiplication rule is used to determine the probability that 2+ independent events will occur together.
In essence, their individual probabilities are multiplied.

Punnett Square is simple, visual way of carrying out multiplication rule.

Question 13

When would you use the addition rule?

Answer 13

When you want to find out the probability of an outcome when there are 2+ ways to get there.

Question 14

What is the genotype for this flower?

Answer 14

It could be Homozygous (PP) or Heterozygous Dominant (Pp)

Question 15

When is a test cross used? What do you need?

Answer 15

A test cross uses a recessive individual to find out if an organism with a dominant phenotype is homozygous or heterozygous..

Question 16

What is the difference between a monohybrid and dihybrid cross?

Answer 16

A monohybrid cross focuses onone character, a dihybrid focuses on two.

Question 17

What does the law of independent assortment state?

Answer 17

LAW OF INDEPENDENT ASSORTMENT states that chromosomes will separate independent of one another when
sex cells are formed.

Question 18

What will the resulting genotype for the 4 daughter cells be?

Answer 18

Ry, rY, ry, RY

Question 19

How many gamete combinations will an individual with the following genotype produce?
AaBBccDdEE

Answer 19

We need to keep in mind the number of heterozygous genes, since the homozygous genes will 100% be passed down.
2 gamete combos to the power of the number of heterozygous genes.
Therefore, 2^2 = 4.
The 4 possible combinations are ABcDE, ABcdE, aBcDE, aBcdE.

Question 20

Fill in the blanks.

Answer 20

Question 21

Solve the following.

George has PKU (a recessive trait) and is myopic (a recessive trait). Marilyn is a carrier for both genes.
What is the probability that George and Marilyn will have a son who is myopic but does not have PKU?

What type of cross is this? What law is applicable?

Answer 21

1ST STEP: assign genotype to phenotype.
nonPKU: P
PKU: p
nonMyopic: M
myopic: m
2ND STEP: assign parents genotype.
George: ppmm Marilyn: PpMm.
3RD STEP: set up Punnett square.
4TH STEP: calculate probability.
ANSWER: 12.5%.