Mendelian Genetics Review

Your test on meiosis and Mendelian genetics will be Tuesday, February

18th!!!

Who was Gregor Mendel?Gregor Mendel was an Austrian monk who studied the ____________ of the pea plants in his garden. He is often considered “The Father of Genetics.” His work was very important to the understanding of _________________.

What determines traits?

______________ are different forms of the same gene.

The presence of different _________ determines _______________.

What is the difference between homozygous and heterozygous?

An organism that is homozygous for a trait has two copies of the ___________ allele. If two recessive alleles are present, the organism is homozygous ______________. If two dominant alleles are present, the organism is homozygous ________________.An organism that is _____________________ for a trait has two different alleles, and only the _____________________ allele is expressed in the phenotype.

What are sex-linked traits?

Alleles for sex-linked traits can be located on either the ___ or ___ chromosome.Most genes for sex-linked traits are located on the ______chromosome (_____-linked)

What are Punnett squares used for?

Punnett squares are used to calculate the ratios of ___________ of the possible ____________ of two parents.Once we know the genotypes, we can figure out the ________________.

Is it possible for more than two alleles for a trait to exist?

Of course it _________!

Blood type is one example. There are three ___________: A, B, and O.

A and B are co__________, while O is ____________.

BUT – you can still only have ___________ alleles for one trait because chromosomes come in sets of _________.

What is codominance?

________________ alleles share dominance over a trait.

When alleles are codominant, both traits appear in the _______________.

What is incomplete dominance?

When alleles show incomplete dominance, the traits ______________.

Black chicken BB + white chicken WW = speckled chicken.

Red flower RR + white flower WW = ___________ flower RW

What are Mendel’s laws?

The law of _____________ states that allele pair separate during meiosis, or each gamete only gets ______ copy of each allele.The law of ____________ _________________ states that the combination of chromosomes that end up in gametes is completely _______________. In other words, traits do not affect each other.

What if a trait is controlled by more than one gene?

When a trait is controlled by more than one gene, it is called a _________________ trait. An example of this is feather color in parakeets. To determine the possible genotypes of the offspring, we can make a 4x4 Punnett square called a _______________ cross.

What else can we use a dihybrid cross for?

We can use a dihybrid cross to calculate the probability of the genotypes of offspring when looking at two _________________ traits.This cross is looking at seed color and seed shape in pea plants.

Activity: Human Single-Gene Traits

1. When Mrs. Campbell tells you to, get into groups. You may have 2, 3, or 4 people in your group.

2. Once you are in your groups, examine yourself to see which traits you have. You can have your group members help if you can’t see.

3. After all group members have discovered their traits, make a tally (total) of the number of people in your group who have each trait

4. Then, send ONE representative from your group to all of the other groups to collect data. Find out how many people in each group have each trait.

5. After you know how many people in the class have each trait, share the data with your group. Each person in your group needs to calculate the percent of people in the class with each trait (number of people with the trait divided by the total number of people in class today)

6. Make a bar graph of the data showing the number of people in class with each dominant trait and the number of people in class with the recessive trait. Mrs. Campbell will give you an example.