Lecture 9

Question 1

What did people think before Mendel?

Answer 1

Inheritance is a blend of parent phenotypes and there is no recessive or dominant alleles

Question 2

Why did Mendel choose peas?

Answer 2

They had distinct phenotypes, they were easy to grow, it was easy to set up crosses

Question 3

What is the n number of peas?

Answer 3

2n=14 so it is diploid

Question 4

What is the life cycle of the pea?

Answer 4

One year

Question 5

What is the female part of the pea plant?

Answer 5

The stigma and ovule

Question 6

What is the male part of the pea plant?

Answer 6

The filament and anther. This is within the stamen

Question 7

How did Mendel do Cross pollination?

Answer 7

He took pollen from the anther of one plant and brushed it onto the sigma of the other plant and cut off the anthers

Question 8

How many pea characters did Mendel begin with?

Answer 8

7

Question 9

How many true breeding lines to Mendel have?

Answer 9

14

Question 10

What are True breeding strains?

Answer 10

Population of organisms that produce offspring with specific parental traits that remain constant from generation to generation

Question 11

Why was Mendel successful when other weren’t?

Answer 11

Because he made pure-breeding strains for genetic crosses
He also used discontinuous traits
He also noticed repeatable ratios

Question 12

What is a Genetic Cross?

Answer 12

An experiment in which males and females of a model organism are mated to produce offspring

Question 13

What is Hybridization?

Answer 13

A cross between two true-breeding individuals from distinct populations

Question 14

What are the offspring of a hybridization cross known as?

Answer 14

Hybrids (monohybrids for one character, dihybrids for two characters)

Question 15

What is a Monohybrid Cross?

Answer 15

A Genetic cross between two individuals that are identically heterozygous for a given gene e.g. A/a

Question 16

What is a Reciprocal cross?

Answer 16

The same as a monohybrid cross except the phenotypes of the male and female are reversed

Question 17

What are Monohybrids?

Answer 17

The offspring that are the result of a cross between two true breeding opposite homozygous alleles

Question 18

What is Mendel’s first law?

Answer 18

Heredity is controlled by discrete factors (genes)

Question 19

What is Mendel’s second law?

Answer 19

Alternative versions of genes explain the variation with respect to characters/traits (alleles)

Question 20

What is Mendel’s third law?

Answer 20

An individual inherits one allele from each parent and therefore each gene exists as pair

Question 21

What is Mendel’s fourth law?

Answer 21

Alleles in an individual may differ so that one allele is dominant and determines the phenotype

Question 22

What is the Law of Segregation or Mendel’s first law created by Mendel?

Answer 22

The two alleles in a diploid organism separate during gamete formation, ensuring that an egg or sperm cell only receives one of the alleles

Question 23

What is Random Fertilization?

Answer 23

Any male gamete can join with any female gamete

Question 24

What a Test Cross used to test?

Answer 24

To test if an individual expressing a dominant trait is homozygous or heterozygous

Question 25

What causes a wrinkled pea?

Answer 25

A mutation in a gene that makes an enzyme that converts starch to branched starch. Wrinkles peas don’t have this

Question 26

How did Mendel tell if genes were linked?

Answer 26

He crossed true-breeding lines for a single trait and crossed them to create dihybrids

Question 27

What are Dihybrids?

Answer 27

Plants that were heterozygous for 2 traits that were created by crossing two pure breeding parents YyRr

Question 28

What is the Law of independent assortment?

Answer 28

The idea that genes could be inherited independently of each other

Question 29

What would the ratio be if the cross was dependant?

Answer 29

The ratio would be 3:1 phenotypically

Question 30

What would the ratio be if the cross was Independent?

Answer 30

9:3:3:1 phenotypically

Question 31

What is the nomenclature for genes on different chromosomes?

Answer 31

A/a; B/b

Question 32

What is the nomenclature for genes on the same chromosome?

Answer 32

AB/ab

Question 33

What is a test cross for a Dihybrid cross?

Answer 33

Crossing an unknown with the dominant phenotypes with homozygous recessive genotype to determine the unknown genotype

Question 34

What does Mendel’s Second law state?

Answer 34

Two different genes assort their alleles independently in gamete formation if they are found on different chromosomes

Question 35

What is probability?

Answer 35

The chance that an event will occur

Question 36

How can you calculate probability?

Answer 36

Number of times an event occurs/ total number of events

Question 37

What is Synteny?

Answer 37

Two or more genes are located on the same chromosome and are physically linked

Question 38

What is genetic linkage?

Answer 38

When genes are located near each other on the same chromosome tend to be transmitted as a unit

Question 39

What are syntenic blocks?

Answer 39

Evolutionary conserved regions of chromosomes that display the same order of genes in different species

Question 40

What is a Map unit?

Answer 40

A measurement that correlates amount of recombination seen with the distance between genes

Question 41

What does it mean if genes are less than 50 mu apart?

Answer 41

They do not assort independently

Question 42

What does it mean if genes are more than 50 map units apart?

Answer 42

They assort independently even though they reside on the same chromosome

Question 43

What does a recombination frequency of 50% indicate?

Answer 43

The 2 gene are on the same chromosome 50 mu apart
The 2 gene loci are on the same chromosome more than 50 mu apart
The 2 gene loci are on separate chromosomes

Question 44

If genes are unlinked what will the ratio of parents to recombinants in a dihybrid test cross?

Answer 44

1:1:1:1