Where you can tell what type of molecule it is.

C2" Carbon - OH Group = RNA

C2" Carbon - no OH Group = DNA (Deoxy)

1. Allows to create homozygous recessive in other wise heterozygous organisms - Loss of Heterozygosity
2. Can cause cancer
3. VERY rare - DCO's do not occur
4. Occurs in somatic cells - can result in patches of cells with different genotypes: mosaicism

Curt Stern - noticed "twin spots" of yelow and singed regions of fruit flies that were heterozygous for both genes.

Because both sn and y are recessive the fly should have normal body color and bristles. How do the singed and yellow patches arise? Mitotic Recombination

What is Mendel's Law of Independent Assortment?

• During gamete formation alleles of different genes segregate independentaly of each other.
• Always true for genes on different chromosomes.
• True for genes on same chromosomes if they are far enough apart. 

Both alleles contribute equally to the phenotype of the heterozygote.  (i.e Spotted x Dotted = spotted & dotted)

It implies that the trait is a single gene expressed by two alleles that are neither dominant or recessive to each other.

Incomplete dominance is when the phenotype of the heterozygote is intermeditate between the homozygote. (i.e purebreeding red snap dragons x purebreeding white snapdragons = 100% pink snapdragons)

This implies that it's a single gene with two alleles.

The proportion of individuals of a given genotype that displays the phenotype associated with that genotype.

If a gene has incomplete penetrane; 50% penetrant, then it's expressed 50% of the time when present. It causes variations in expressivity.

Pleiotropy is when an allele affects more than one phenotype. 

(i.e the gene for yellow color in mice is dominant, but when homozygous, is recessive and causes death. When heterozygous, mice will be yellow.)

Homozygous = Dead

Heterozygous = Yellow

Expressivity is the degree of severity of a phenotype. 

(i.e Polydactyly: extra digits - you can have 1 extra finger on one or 1 extra finger on all hands and feet.)

The alleles of one gene can affect the alleles of a second gene.

(i.e to exhibit A or B bloodtype, a person must be homozygous HH or heterozygous Hh)

Epistasis refers to the relationship between two different genes. The type of epistasis can be determined by looking at the phenotypic ratio.

No Epistasis

9:3:3:1

Epistatic (other combos also possible)

9:7

9:3:4

15:1

9:6:1

• What is the Hardy-Weinberg Equilibrium Equation?
• Do allele frequencies change from one generation to the next?

p^2 * 2(pq) * q^2

Where p = dominant and q = recessive

Allele frequencies do not change from one generation to the next

1. Population size is infinite
2. Mating is assortative or random with respect to alleles
3. No new alleles are being introduced by new mutations
4. There is no migration by individuals either into or out of the population
5. There is no selective disadvantage

Anaphase of Mitosis 

Anaphase of Meiosis II

1. Meiosis I
2. Meiosis II 

2X:2A = 1 = Female

1X : 2A = .5 = Male

If X is equal ratio to autosomes then will be female

The proportion of phenotypic variation due to all genetic variation

A ratio of 2 variants - a property of populations

The proportion of phenotypic variation due to additive genetic variation only.

Predicts similarity etween parents and offspring; useful for selective breeding

R = h^2 * S

where S = selection differential  and h^2 = narrow sense heritability

Recessive mutant phenotypes are observed in diploids because of a deletion in one of the homologues.

Hemizygous parent chromosome makes recessive trait look dominant but really, the dominant allele is absent

Heterozygous deletions exhibit a phenotype because there is insufficient gene activity to produce a normal phenotype. 

i.e small deletion of chr 5 in humans caused "cri de chat" syndrome

Chromosome Abberation: Duplication

What is it? What are some benefits from it?

part of a chromosome present in more than one copy 

2 types: Direct Tandem A-B-C-B-C-D-E

Reverse Tandem: A-B-C-C-B-D-E

duplications allow for multigene families, can take on new functions, provides mechanism for generating high levesl of abundant proteins

• Can cause mutations if break points are in genes. 
• When homozygous go through meiosis normally.
• When heterozygous have problems and exhibit reduced fertility. 
• Associated with several cancers because the fusion of two previously unconnected sequences can give rise to inappropriate gene expression
• change linkage relationship between genes