Ch11 - Mendelian Genetics

Hybrid

Hybrid

Genetic makeup of an individual, having one capital allele and one lower case allele

Incomplete Dominance

Blending of two traits, such as a red flower and a white flower, producing a pink flower

Independent Assortment

Genes from separate traits can segregate separately from each other

Monohybrid Cross

Testing one hybrid trait such as Tt x Tt

F1

First generation

F2

Second generation

Genotype

Genetic makeup of an organism, indicated by letters, such as Yy, YY, or yy

Example of Heterozygous Alleles

Tt

Example of Homozygous Alleles

TT, tt

Mutiple Alleles

Genes having more than 2 alleles, such as rabbit fur

P

Parent generation

Rec 3:1

Ratio in a monohybrid cross

9:3:3:1

Ratio in a dihybrid cross

Alleles

Different forms of genes (Such as looking at a tall or short gene)

Co-dominance

Both alleles are expressed equally, such as checkered chicken feathers (Black hen, white rooster, making a black and white feathered chick)

Dihybrid Cross

Testing two hybrid traits such as TtRr x TtRr

Dominance

Some traits are dominant over others, indicated by a capital letter

Recessive

Trait masked by dominant gene

Phenotype

Physical characteristics of an organism, what it looks like

Polygenic Traits

Traits controlled by two or more genes, such as skin color

Probability

Likelihood that a trait will show up

If roan cows RW and roan bulls RW are bred, according to the principle of codominance, what percentage of the offspring are expected to be roan (Part red and part white)?

50%

Coat color in rabbits is determined by a single that has _____

Mutiple alleles

Gregor Mendel used pea plants to study _____

The inheritance of traits

Offspring that result from crosses between true-breeding parents with different traits…

Are called hybrids

The chemical factors that determine traits are called _____

Genes

Gregor Mendel concluded that traits are _____

Inherited through the passing of factors from parents to offspring

When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited…

An allele for tallness from the tall parent and an allele for shortness from the short parent

The principle of dominance states that…

Some alleles are dominant and others are recessive

When Gregor Mendel crossed the true-breeding tall plants with true-breeding short plants, all the offspring are tall because…

The allele for tall plants is dominant

If a pea plant has the recessive allele which is green peas, it will produce…

Green peas if it does not also have a dominant allele for yellow peas

A tall plant is crossed with a short plant. If the tall F1 pea plants are allowed to self-pollinate…

Some of the offspring will be tall and some will be short

In the P generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 generation because…

The allele for shortness and the allele for tallness segregated when the F1 produced gametes

In the P generation, a tall plant was crossed with a short plant. If the alleles did not segregate during gamete formation…

All of the F2 plants would be tall

When you flip a coin, what is the probability that it will come up tails?

1/2

The principles of probability can be used to…

Predict the traits of the offspring produced by genetic crosses

In the P generation, a homozygous tall plant is crossed with a homozygous short plant. This mating created in the F1 generation. The F1 generation self pollinated and produced the F2. Determine what the probability is that an F2 plant will be tall.

75%

Organisms that have two identical alleles for a particular trait are said to be…

Homozygous

If the Punnett square shown in Figure 11-1, which of the following is true about the offspring resulting from the cross?

All are expected to be tall

In the Punnett square shown in 11-1, the genotypes of the offspring are…

TT and Tt

A Punnett squares shows all of the following except…

The actual results of a genetic cross

If you made a Punnett square showing Gregor Mendel’s cross between true-breeding tall plants and true-breeding short plants, the square would show that the offspring had…

A genotype that was different from that of both parents

What principle states that during gamete formation genes for different traits separate without influencing each other’s inheritance?

Principle of independent assortment

The Punnett square in Figure 11-2 shows that the gene for pea shape and the gene for pea color…

Assorted independently

What is the phenotype ratio or percentage of the offspring in the Punnett square shown in Figure 11-2?

9 round and yellow, 3 round and green, 3 wrinkled and yellow, 1 wrinkled and green

How many different allele combinations of R, r, and Y would be found in the gametes produced by a pea plant whose genotype was RrYY? Look for all combinations of each of these letters.

2

If a pea plant that is a heterozygous for round, yellow peas (RrYy) is crossed with a pea plant

2

A situation in which one allele for a gene is not completely dominant over another allele for that gene are called…

Incomplete dominance

A cross of a red cow (RR) with a white bull (WW) produces all roan offspring (RRWW). This type of inheritance is known as…

Codominance

Variation in human skin color is a result of…

Polygenic traits

Gregor Mendel’s principles of genetics apply to…

All organisms

Which of the following assort independently?

Chromosomes

Linked genes…

Are on the same chromosome

If two genes are on the same chromosome and rarely assort independently…

The genes are probably located close to each other

The farther apart two genes are located on a chromosome, the…

Less likely they are to be inherited together

In corn, purple is dominant to yellow. If an ear of corn had 75 kernels that were purple and 72 kernels that were yellow, what is the genotype of both parents from this ear?

Pp x pp

In corn, purple is dominant. If a corn ear has 100% purple kernels, you may not be sure if it is a pure breed or hybrid. What should you do?

Breed it with homozygous recessive and see if all the offspring are purple

In chickens, when a black rooster is crossed with a white hen, or a black hen is crossed with a white rooster, all offspring have checkered feathers. Half of the feathers are black and half are white. Of what is this an example?

Codominant

In radish seeds, tall is dominant to short and purple is dominant to green. P1 was a heterozygous tall and homozygous green. List the genotype of parent 1.

Ttpp

In radish seeds, tall is dominant to short and purple is dominant to green. P1 was a heterozygous tall and homozygous green and parent two was a heterozygous tall and heterozygous purple. List the genotype of parent two.

TtPp

In radish seeds, tall is dominant to short and purple is dominant to green. What would the offspring look like if P1 was a heterozygous tall and homozygous green and parent two was heterozygous tall and heterozygous purple? What will the offspring look like? (Make a Punnett square on scratch paper)

6 tall purple, 6 tall green, 2 short green, and 2 short purple

In radish seeds, tall is dominant to short and purple is dominant to green. What would the offspring look like if P1 was heterozygous tall and homozygous purple (TtPP) and parent two were homozygous tall and heterozygous purple (TTPp)? What will the offspring look like? (Make a Punnett square on scratch paper)

All will be tall and purple

When two heterozygous tall pea plants are crossed, the expected genotype ratio of the offspring is _____. Use a Punnett to help answer.

3:1 three tall one short

If pea plants that are homozygous for round, yellow seeds (RRYY) were crossed with pea plants that are heterozygous for round, yellow seeds (RrYy), the expected phenotype(s) of the offsrping would be _____.

All will be round and yellow

Crossing a pink-flowered (RW) four o’ clock with a white-flowered (WW) four o' clock will produce what phenotypical offspring?

Pink and white

How many recessive alleles for a trait must an organism inherit in order to show that trait?

2

A cross between two organisms heterozygous for two different genes (AaBb) results in 9:3:3:1 phenotype ratio among the offspring. What can be said about the genotypes?

You cannot always determine genotype from phenotype. It could be AABB or AaBb and look exactly the same

Using tables and graphs, identify the phenotype of the offspring that would be represented in the square labeled x in figure 11-4.

bbRR

Using tables and graphs, identify the phenotype of the offspring represented in the square labeled X in figure 11-4.

White rough hair

Analyzing data, in figure 11-4, what are the genotypes of the offspring that have black, rough hair?

BBRR, BBRr, BbRR, and BbRr

Calculating, what fraction of the offspring in figure 11-4 would be expected to have white, smooth hair?

1/16

Interpreting graphs, in figure 11-5, what is the genotype of the pink-flowered snapdragons?

RI

Inferring, which do the alleles in figure 11-5 show?

Incomplete dominance

Inferring, according to figure 11-5, if red-flowered snapdragon and ivory-flowered snapdragons are crossed, what percentage of their offspring would be expected to be pink-flowered?

100%

Inferring, according to figure 11-5, if two pink-flowered snapdragons are crossed, what percentage of their offspring would be expected to be pink-flowered?

50%