Patterns of Inheritance- Genetics

Question 1

Character?

Answer 1

A heritable feature (flower colour)

Question 2

Trait?

Answer 2

A variant of each character (purple or white)

Question 3

Gene?

Answer 3

The instructional area of DNA on a chromosome that codes for a certain inheritable trait. Ex. Gene for eye colour, hair colour, and height.

Question 4

Allele?

Answer 4

Two or more alternate forms of a gene, symbolized by letters. Each allele is located on the same position (Gene) on one of the pair of homologous chromosomes. Ex. Alleles for colour are blue or brown.

Question 5

Dominant?

Answer 5

Allele that masks the other allele

Question 6

Recessive?

Answer 6

Allele that is covered up

Question 7

Homozygous?

Answer 7

Having two of the same allele (AA or aa); true-breeding.

Question 8

Heterozygous?

Answer 8

Having two different alleles (Aa).

Question 9

Genotype?

Answer 9

All of the organisms alleles (genetic information)’ both expressed and hidden. Represented by letters. Ex. Bb, BB, bb

Question 10

Phenotype?

Answer 10

The visible, physical trait of the organism? Ex. Brown eyes.

Question 11

Cross pollination?

Answer 11

One plant fertilizes a different plant.

Question 12

Self pollination?

Answer 12

A plant fertilizes itself.

Question 13

True-Breeding (pure bred)?

Answer 13

Synonymous with homozygous; plants that over several generations only produce plants like themselves. Ex. AA or aa

Question 14

Hybrid?

Answer 14

Synonymous with heterozygous; carries two different alleles of the same gene. Ex. Aa

Question 15

Parent Generation?

Answer 15

First organisms to breed; represented by the letters P1.

Question 16

FIlial Generation?

Answer 16

The offspring resulting from the parent (P1) generation; represented by the letters F1 (first filial). The offspring that result from the F1 generation (first filial) are represented as the F2 generation (second filial).

Question 17

What are the two influences that determine what an organisms will be like?

Answer 17

Hereditary and Environment

Question 18

What is genetics?

Answer 18

The science of heredity

Question 19

Gregor Mendel did some of the earliest work studying hereditary. He chose to use pea plants for his work because:

Answer 19

1) Pea plants have contrasting pairs of the same trait (homologous genes).
2) Peas can easily be cross pollinated.

Question 20

Although peas usually___, Mendel was able to see Rudy how traits were inherited by using a process called___.

Answer 20

Self pollination

Cross pollination

Question 21

In the process of cross pollination that Mendel used,___grains from the___of one plant would be transferred to the___of another. (Pollen grains form the___nuclei, egg cells are found at the base of the___of the pea flower).

Answer 21

Pollen, stamen, egg cells, sperm, pistil

Question 22

What did Mendel observe?

Answer 22

That peas allowed to self-pollinate would consistently produce offspring identical to the parent plant. He then experimented with cross pollination to see what the offspring of parents plants that varied on only one trait would look like.

Question 23

When Mendel experimented with cross pollination to see what the offspring of parent plants that varied on only one trait would look like what did he find?

Answer 23

Tall plants X short plants yielded tall;
Yellow seeds X green seeds yielded yellow;
Round seeds X wrinkled seeds yielded round

Question 24

After Mendel’s experimented with cross pollination and parents that varied in only one trait what he did he wonder?

Answer 24

What happened to the characteristic lost when plants with different traits were cross-pollinated.

Question 25

What was Mendel’s next experiment? What did he find in the F2 generation?

Answer 25

He allowed this first generation of cross bread plants (F1) to self pollinate. In the F2 generation, he found that 3/4 of the offspring exhibited the traits of the F1 generation, byt also that 1/4 of the offspring exhibited the “lost” trait of the original parent generation. He realized this meant the F1 generation must have still carried information needed for the lost trait but, for some reason, just did not show the trait. This thinking led him to propose three hypothesis.

Question 26

What was Mendel’s first hypothesis?

Answer 26

Inherited Characteristics; The factors that Mendel referred to are now called genes.

Question 27

What was Mendel’s second hypothesis?

What is the principle of dominance and recessiveness? What does this hypothesis explain What is a hybrid?

Answer 27

The Principle of Dominance and Recessiveness is one factor in a pair may mask the other.
This hypothesis explained why all the plants of the F1 generation were identical (the dominant trait masked the recessive trait).
A hybrid is an offspring of parents that differ in one or more traits. Hybrids express the dominant trait.

Question 28

What was Mendel’s third hypothesis? What is the law of segregation? Why do we now know that this does occur? What does the first meitic division in a hybrid produce? What does the second meitic division in a hybrid produce?

Answer 28

The Law of Segregation is pairs of genees are separated.
We know know that this occurs as homologous chromosome are divided in the process of meiosis.
The first meitic division in a hybrid produces two different cells (one carries the dominant genes, the other the recessive).
The second meitic division in a hybrid produces four gametes with two arraign the dominant gene and two carrying the recessive gene?

Question 29

What is the fourth hypothesis?
What did Mendel believe?
What has modern knowledge of chromosomes made it possible to present this hypothesis as?
What does this hypothesis mean?

Answer 29

The Law of Independent Assortment.
Mendel believed that genes separated and were distributed in a way independent of the other gene pairs.
Modern knowledge of chromosomes has made it possible to present this hypothesis as the Law of Independent Assortment. It means that many inherited traits are independent of other traits.

Question 30

Genotype is the____.

Phenotype is____.

Answer 30

• actual gene

- how it works

Question 31

If both genes for a trait are the same, the organisms is said to be____.

Answer 31

Homozygous

Question 32

If the genes are not identical it is said to be____.

Answer 32

Heterozygous

Question 33

Alleles are?

Answer 33

Genes that have contrasting effects on a trait. For example, T is an allele of t, and t is an allele of T.

Question 34

What two things do punnet squares show?

Answer 34

1. Probability of each resulting genotype

2. Results of each crosses phenotype

Question 35

What is a monohybrid cross?

Answer 35

One pair of contrasting traits

Question 36

What is a dihybrid cross?

Answer 36

One pair of contrasting traits.

Question 37

What happens if heterozygous hybrid organisms are crossed in a monohybrid cross?

Answer 37

3/4 of the offspring will exhibit the dominant trait, and 1/4 offspring will exhibit the recessive.

Question 38

What happened if heterozygous organisms are cross in a dihybrid cross?

Answer 38

There will be 9 possible genotypes.