Bio1 Mon 11/9 Lecture: Inheritance, Genes, and Chromosomes

Describe Mendel’s Particulate Theory

discrete particles that exist within an organism in pairs and separate during gamete formation are responsible for inheritance

Describe the Law of Segregation

During production of gametes, only copy of each gene passes to the gamete.

When fertilization occurs, the zygote gets one unit from each parent, restoring the pair.

Describe the Law of Independent Assortment

Alleles of different genes (e.g., Ss and Yy) assort into gametes independently of each other.

What is a Pedigree?

a family tree used to show phenotype segregation through several generations of related individuals

Explain Wild Type vs Mutant

The wild type refers to the usual phenotype.

The mutant refers to the unusual phenotype.

What is a Carrier?

an individual who has the trait but is not affected by it (they might have only one copy of the trait)

Describe other types of dominance (other than simple dominance)?

In incomplete dominance, the heterozygote has a unique phenotype.

• A snapdragon with homozygous dominant RR appears red, but a snapdragon with heterozygous Rr appears pink (the pigment isn’t as strong).

In codominance, there are multiple dominant alleles.

• Blood types can be A, B, AB, or O. The I^A and I^B allele are both dominant alleles and the i allele is recessive. The genotype I^AI^B with both dominant alleles will result in AB blood which expresses both alleles.

Most traits are a result of…

multiple genes and/or interactions with the environment

When might the Law of Independent Assortment be broken?

Linkage occurs when 2 genes are close together on the same chromosome. The 2 genes are linked genes.

Sex Linkage occurs when a gene is on the X or Y chromosome. The gene is a sex-linked gene.

What does Hemizygous mean?

a diploid cell/organism only has one copy or a gene (there is no corresponding gene on the partner chromosome)

DNA outside the nucleus is inherited through __

Include examples.

DNA outside the nucleus is inherited through the mother.

For example, DNA in mitochondria and chloroplasts