Chapter 11,13 & 14Chapter 11,13 & 14GeneticsGenetics

(Or why you really shouldn’t date your cousin, and especially your

sister)

The Beginnings…..The Beginnings…..

Heredity: biological inheritance, the passing of genetic traits from one generation to the next

Genetics: the biological study of inheritance

Background...Background...Blending Inheritance: the blending of

traits in the offspring: Tall + short = medium offspring

Disproved by Gregor Mendel, a really boring monk

Came up with 5 laws of Inheritance, well sort of

Mendel’s Genetics:Mendel’s Genetics:

Used math to prove inheritanceStudied pea plants using self-

pollination of purebred pea plantsFollowed traits for 3 generations to see

how traits appear and disappear P (parents), F1 (first generation), and

F2 (second generation, from F1 cross)

Mendel’s Genetics:Mendel’s Genetics:

Mendel’s Laws of InheritanceMendel’s Laws of Inheritance

1. Unit Characters: individual factors control traits, these factors are called genes

Trait: CharacteristicAllele: different forms of a gene,

Tall or short, same gene, T or t

2. Dominance2. Dominance

Some factors are dominant over others, some are recessive. If the dominant is present, it will always show!

Example is Brown eyes over blue

3. Segregation3. Segregation

Individual alleles separate during meiosis (one allele from each parent)

Phenotype: the physical characteristic

Genotype: the genetic make-up of a characteristic

The Genotype is described by two terms

Homozygous: two identical alleles, also called purebred TT or tt, BB or bb

Heterozygous: two different alleles, called hybrid Tt, Bb

4. Independent AssortmentIndependent Assortment

Individual traits sort independently.

Example is that height does not depend on eye

Allows for a two factor cross

5. Incomplete Dominance5. Incomplete Dominance

If genes are not dominant or recessive, they mix.

Example is 4o’clock flowersRed flower crossed with a white

flower = a pink flower RR x rr = Rr

A few side notes……A few side notes……

Codominance: a condition in which both alleles of a gene are expressed. (Hair color in cows)

Polygenic Inheritance: A single trait controlled by more than one gene (hair color, eye color)

In order for all this to work…….In order for all this to work…….Organisms can only inherit a

single copy of a gene from each parent

Will replication and mitosis do the trick?

No…..We need…..

MeiosisMeiosisMeiosis is the process of reduction division

in which the number of chromosomes per cell is cut in half and homologous chromosomes that exist in a diploid cell are separated.

Basically, it is mitosis that happens two times to make 4 daughter cells with a haploid chromosome number.

Meiosis animation 1, 2, 3, 4, 5, 6

Applying Mendel’s GeneticsApplying Mendel’s Genetics

Probability: the likelihood that a particular event will occur.

It is figured by number of times something occurs, by the total number of opportunities

Figure by using Punnett Square

Tt x Tt Cross

Tt X Tt Cross

Gene linkageGene linkageSome genes do not undergo

independent assortment, these genes are said to be linked.

Genes that are inherited together.Early studies by Morgan with the

fruit flyBasic Types:

Sex LinkageSex Linkage

Genes that are linked and inherited according to your sex

On 23rd chromosomeSecondary sex characteristics,

verbal and spatial tendencies

Linkage GroupsLinkage Groups

Packages of genes that are always inherited together

Located on chromosomes other than the sex chromosomes.

Crossing OverCrossing OverExplain recombinants (individuals

with new combinations of genes )If two homologous chromosomes

were positioned side by side, sections of the two chromosomes might cross, break, and reattach.

Occurs during first meiotic division

Sex DeterminationSex Determination

From the process of Meiosis23rd chromosomeGenes on sex chromosome are said

to be linked

MutationsMutations

Mistakes in the transmission of the genetic information

1 in 1,000,000 genes are mutatedtypes:

Chromosomal Gene

ChromosomalChromosomal

Involve segments, whole, and entire sets of chromosomes, it is a change in the number and structure of chromosomes

Basic types:

Deletion: the loss of a part of a chromosome

Duplication: the addition of a part of a chromosome

Inversion: a reverse of a part of a chromosome

Translocation: Crossing over of two chromosomes

NonDisjunction: whole chromosome mutations, it is a failure to separate during meiosis

Too many chromosomes: called polyploidy Trisomy: (2n+1)Downs Syndrome

Too Few Chromosomes: from the left over gametes Turner’s Syndrome: (2n-1)

Gene MutationsGene Mutations

Mutations that result from a change involving many nucleotides within a gene, some may involve only one nucleotide

Point mutations: smallest change, effect single nucleotide

Frameshift mutation: when a point mutation single base is inserted or deleted, shifting the entire codon, this changes every codon following the mutation.

Beneficial MutationsBeneficial Mutations

Mutations that benefit an organism for fitness

Short sheep in IrelandSkin on a bulldog

Human HeredityHuman Heredity

Heredity vs. Environment: Which has a greater effect on the expression of traits

Himalayan rabbitSize

DisordersDisorders

Nondisjuction disorders Downs syndrome-moon child Kleinfelters Syndrome-sterile male,

XXY Turners syndrome- appear female, X

Sex Linked Genetic disordersSex Linked Genetic disorders

From genes on X & Y chromosome

Why do most show in males?You need homozygous recessive

to show in females, due to size difference.

Colorblindness: on X chromosome, 1% of women, 8 % of men, most common type is red- green. Color vision is on x chromosome

Hemophilia: Bleeders, recessive on X, missing clotting agent

1 in 10,000 males, 1 in 100,000,000 females

Muscular Dystrophy: the wasting away of skeletal muscle, is carried on X chromosome

Autosomal Genetic DisordersAutosomal Genetic Disorders

Huntington’s Chorea: Dominant disorder, deterioration of body from interior to exterior

Multiple Sclerosis: recessiveSickle Cell Anemia: recessiveAllergies: recessive

Diagnosis of Genetic DisordersDiagnosis of Genetic DisordersPre-Natal:

Amniocentesis: removal of a small amount of fluid from around the embryo, some disorders from biochemical abnormalities (Tay sachs), others from a karyotype (Downs Syndrome)

Ultrasound: can see kidney, heart, bone disorders, spina bifida

Diagnosis of Genetic DisordersDiagnosis of Genetic DisordersPre-Natal:

Chorionic villus sampling (CVS): suction off a portion of the fetal tissue from the placenta. Because these cells are reproducing so quickly, enough cells in mitosis to do a quick karyotye, results in 24 hours

Diagnosis of Genetic DisordersDiagnosis of Genetic DisordersNewborn Screening

Some genetic disorders can be detected at birth by a simple test for chemicals or reflexes.

PKU, Fragile X, Mental Retardation

Genetic EngineeringGenetic EngineeringModifying the living world in an attempt to

make it betterAccomplished by breeding and engineeringBreeding is done by selecting the most

productive plants or animals to produce the next generation, you can increase productivity

Genetic Engineering

The manipulation of genes to directly change an organism DNA, in humans this technique is use to find cures and diagnose childhood disease. In plants, it us used to manufacture produce that is bigger and better

BreedingBreeding

Selective: choose the best, multiply

Inbreeding: crossing individuals with similar characteristics, problems are massive recessive traits and mutations

Hybridization: Also called outbreeding, crossing two individuals with dissimilar characteristics. The offspring tend to be stronger than parents (Hybrid-Vigor). The offspring is generally sterile, the example is the mule

Genetic Engineering TechniquesGenetic Engineering Techniques

Restriction Enzymes: proteins that cut DNA at specific sequences

DNA Recombination: The use of a vector to incorporate DNA into another cell, sometimes done with plasmids

Genetic Engineering TechniquesGenetic Engineering Techniques

DNA Insertion: cloning, inserting copies of DNA into cells, then growing cells with new code. Use needle to inject, or a bacteria cell that will conjugate with another cell

Genetic Engineering TechniquesGenetic Engineering Techniques

PCR: Polymerase Chain Rection, a quick amplification of DNA, used in crime scenes along with DNA fingerprinting to gather genetic evidence

Human Genetics…..Human Genetics…..

The Human Genome Project

Mapping the human genome…. Why analyze the human

genome?

Applications of Genome Data

Genetic Counseling for prospective parents Show possible traits by figuring

probability after studying possible recombinants

Carrier Recognition- of Parents

Applications of Genome Data

Replace or Supplement defective genes with functional

Normal genes introduced into Somatic cells But…..can we control protein

production? Does new harm other cells?

Applications of Genome Data

Pharmaceutical applications Human Insulin Growth Hormone Engineer protein blocks to mimic

or block surface receptors (HIV) Vaccines

Applications of Genome Data

Forensics…is all about CSI… DNA Fingerprinting- marker

testing PCR to amplify small samples But…….what do we do with the

DNA data gathered?????? How reliable?

Genetic Engineering……..How far should we go?Should Genome Factor for jobs?Who gets to examine your genes?Costs? Insurance gets the bill?Are vectors safe?Who approves new products?