Heredity

Genetics

• _____ is the scientific stufy of heredity.
• ______ is largely the study of genetic material and how this material affects the characteristics of life forms.

Science

Philosophy

Natural Philosophy

Philosophy of science

Science can only consider those ideas that meet two criteria:

1. The idea must be about the physical universe.
2. The idea must be falsifiable.

Falsifiable

Gene

• The definition of this concept is currently under review.
• A nucleic acid segment, DNA or RNA that can ultimately direct the production of RNA (and therefore protein) that affects the phenotype.
• It includes at least one region of nucleotides that promote accurate transcription.

Locus

(plural: Loci)

Allele

(plural: Alleles)

Zygote

Genotype

The list of alleles found at the locus or loci under consideration.

ex. AaBbCc

Phenotype

1. The genotype
2. The environment
3. Developmental noise

The Principle of Allocation

Each individual in a species can only collect a finite amount of resources. If those resources are spent to build a good phenotype for one habitat then they can not be spent to build the best phenotype in another habitat.

Ex. Organisms that are selected to develop well in one environment, typically are not selected to develop well in a contrasting environment.

Norm of Reaction

Developmental Noise

Biotin

Develpomental Cananlization

Catalyst

• Of almost all of the chemical reactions in a life form, none of them would take place at the termperatures, pressures, and pH of living matter, without the prescence of some _______.
• _______ are enzymes either composed of protein or RNA.

Gregor Mendel

• (1822-1884)
• Born in what was the Austro-Hungarian Empire.
• Flunked out of a university in Vienna.
• Later called the founder of the science of genetics.

The Theory of Blending Inheritance

• It was the predominant theory at the time Mendel began his work.
• States that the phenotype of the offspring will be intermediate between the phenotypes of the two parents.

Mendel's #1 contribution

Genus

The 1st part of the species' name.

Ex. Achillea Millefolium

Specific Epithet

The 2nd part of the species' name.

Ex. Drosophila Melanogaster

Hypothesizes that inheritance is produced by discrete particles. Alternative forms of these particles account for the genetic variations in inheritable characteristics. Each particle controls one characteristic. These particles exsist in the cell and are not physically connected. Therefore they are not on structures like chromosomes. The particles assort into the gametes according to two principles we call: Mendel's Laws.

Equal Segregation

• Means that if there are two or more different particles in a cell, they are placed into gametes in equal numbers.
• Ex. Aa (50% A / 50% a)
• Falsified by Meiotic Drive Theory

Independent Assortment

• Means that the particles that code for one trait are placed in gametes without regard to the placement of particles coding for another trait.
• Falsified by Linkage Theory

Probability

3 Systems of sex determination

1. XY
2. WZ
3. Environmentally determined

Product Rule

Sum Rule

Test Cross

XY System

1. XY=Male (Heterogametic sex)
2. XX=Female(Homogametic sex)
3. In humans, the presence of the Y chromosome makes the inividual male. The loci that codes for "maleness" is located on the Y chromosome.
4. XO=Turner's Syndrome (female)
5. XXY=Kleinfelter's Syndrome (Male)
6. In fruit flys the abscence of the Y chromosomes determines maleness.
7. XO is a sterile female.

Sex-linked

WZ System

(Birds & Lepidoptera)

1. WZ=Female (Heterogametic sex)
2. WW=Male (Homogametic sex)
3. Most genes are on the W, no the Z

Environmentally Determined Sex

Autosomes

3 Parts to Biodiversity

1. Species diversity
2. Genetic diversity
3. Habitat diversity

Species Diversity

1. Species richness: The number of different species in the area in question.
2. Species eveness: How evenly the individuals are distributed across the different species.

Genetic Diveristy

Habitat Diveristy

The total number of diferent habitats in an area.

Note: Important because the habitat gives rise to new species and maintains existing ones.

Disease

Pseudo-autosomal regions

The differential regions

The 5 modes of inheritance

1. Autosomal dominant
2. Autosomal recessive
3. X-linked dominant
4. X-linked recessive
5. Cytoplasmic inheritance

Cytoplasmic inheritance results from:

Plastid

Endosymbiotic Theory

Who contributes more cytoplasm to the zygote?

Maternal Inheritance

Dosage Compensation

Barr body

Why shouldn't we release genetically modified food?

Y linked inherited gene. Also called test determining factor. 

Complete Dominance

Incomplete Dominance

When the heterzygote has a phenotype that is intermediate between the two alleles.

Ex: Four-o' Clock plants (Homozygouse dominant x homozygous recessive F1= All pink, F1 selfed= 1/4 red, 1/4 white, and 1/2 pink) 

Co-dominance

When each allele produces its full phenotype in the heterozygote.

Ex. ABO blood groups

Genotype            Bloodtype

                  IA/IA, IA/i                 A 

                  IB/IB, IB/i                 B

                  IA/IB                       AB

                       i/i                       O

Polymorphism in the loosest sense

Polymorphism in the most qualified sense

Multiple Allelism

The existence of ore than two alleles at once.

(Note: Of course multiple allelism means you have a strict polymorphism, but that's not neccesarily the cases) 

 What is the goal of genetic analysis

Complementation Test

The dihybrid ratio

Normal: 9:3:3:1

 Modified Ratios (suspect lethality):

12:3:1

9:6:1

9:3:4

9:7

How do you get a modified 9:3:3:1?

Epistasis

A downstream locus

 Regulatory Protein

A suppressor

An allele that reverse the effect of a mutation att another locus, resulting in the normal phenotype.

(Note: Most commonly associated with a mutated mRNA that codes for the wrong protein, but a mutated tRNA (this would be the suppressor), brings the correct amino acid.)

Penetrance

Expressivity

Measures the extent to which a given genotype is expressed at the phenotypic legel:

-Variable expressivity

-Non variable expressivity 

(Note: could be done with 1 individual) 

Multiple Alleles

Sickle Cell Anemia

Two main alleles: Hb^A and Hb^S

 Hb^S is dominant to Hb^B in amenia at all:

Hb^A/Hb^A: No amenia

Hb^S/Hb^S: Amenia.

Hb^A/Hb^S: Amenia

 for severe amenia:

Hb^A/Hb^A: No sever amenia

Hb^A/Hb^S: No sever amenia

Hb^S/Hb^S: Sever amenia 

Hb^A exhibits incomplete dominance to Hb^S for RBC shape.

Hb^A/Hb^A: Normal RBC

Hb^A/Hb^S: RBC only under low [O_2]

Hb^S/Hb^S: Sever sickle shape

Lethal Alleles

1. There's a missing portion of the ratio.

2. We can never produce a pure breeding organism for this trait.

(Note: Lethality can range from 0-100%, depending on the property of the allele itself, the environment, and the rest of the genome.)

Ex. Yellow coats in mice (lethal) x homozygous wild type. 

Multiple Alleles or An allelic series

Null Mutation