Chapter 11: Mendel and the Gene Idea

Alleles are

One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Gene locus is

A specific, fixed position on a chromosome where a particular gene or genetic marker is located.

If the allele for brown hair is represented as "B," it would mean that:

brown hair is a dominant trait

Assuming that brown hair is a dominant trait, which of the following genotypes would show brown hair as a phenotype?

Bb and BB

While other scientists had tried to study heredity, none had been as successful as Mendel. His success is in big part due to the study organisms he selected. What was the advantage of studying pea plants?

- Can control who mates with who and do controlled crosses

- Can breed large numbers of organisms in a small space

- The traits are easy to see and quantify

Why do we have two alleles for each gene?

- Because we inherit one allele from mom and one from dad.

- Because we are diploid, we have homologous chromosomes that code for the same genes but have different alleles

Which of these statements are true about alleles?

- Alleles are located on the same area on the two homologous chromosomes

- Alleles code for the same gene but may have different traits

- Alleles are sections of DNA that have different nucleotide sequences.

Which of the following statements are related to the Law of Segregation?

- parents only pass on one of their two alleles to their offspring

- During meiosis, the resulting gametes are haploid (containing only one version of each chromosome)

Which one of Mendel's laws states that "the allele a gamete receives for one gene does not influence the allele received for another gene"?

Law of independent assortment

When we split the alleles from each parent into the Punnett square, which one of Mendel's laws are we applying?

Segregation

In a dihybrid cross, when we assign equal probabilities to each of the different combinations of alleles a gamete could have, which one of Mendel's laws are we applying?

Independent Assortment

In a dihybrid cross, when we place every allele combination into each box of the Punnett square, which one of Mendel's laws are we applying?

Both segregation and independent assortment

Which events in meiosis are responsible for the principle of segregation?

-Separation of homologous chromosomes in anaphase I

- Separation of chromatids in anaphase II

Which events in meiosis are responsible for the principle of independent assortment?

- Crossing over in prophase I

- Random orientation of homologous chromosomes in metaphase I

- Random orientation of recombinant chromatids in metaphase II

What is the genotype of individual III-4 (Individual #4 in the 3rd generation, where the cursor is pointing)?

Ff

Which of the following mutations are likely to result in a recessive allele?

- The mutation causes a stop codon to appear early on in the gene and the resulting protein is too short to function

- The promoter sequence is altered and the DNA doesn't get transcribed so the proteins isn't made.

Which of the following mutations are likely to result in a dominant allele?

- The mutation produces a proteins that is now toxic to the cell

- Their mutation produces a protein that has a new function and it's produces a new flower color

This color patter in cats is produced by a gene that codes for an enzyme that produces a color molecule only when the temperature is below 33ºC. This is an example of:

Environmental Effects

In a particular family, one parent has Type A blood, the other has Type B. They have four children. One has Type A, one has Type B, one has Type AB, and the last has Type O. What are the genotypes of the parents?The ABO blood type gene has three alleles. IA and IB are codominant; i (for Type O) is recessive to both.

IAi 7 IBi