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?
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