Intro to Agriculture AAEC Paradise Valley Spring 2015
Animal Genetics Intro to Agriculture AAEC Paradise Valley Spring
2015 Genetics: the science of heredity.
Heredity is thetransmission of geneticor physical traits fromparent
to offspring. Gregor Mendel Austrian Monk Considered the Father of
Heredity
He conducted plant breedingexperiments in their monasterygarden. In
1865 he made his workpublic, units of inheritance. What makes us
unique? Each of the 100 Trillion cells in our body exceptthe red
blood cells contains the entire humangenome, in the nucleus of
every cell is the geneticinformation blueprint to construct
theindividual. It is the Deoxyribonucleic acid (DNA) Function of
DNA Genetic code for almost every organism. Provide template for
protein synthesis. DNA in Pop Culture Chromosomes The DNA in every
cell is located in rod likesegments called chromosomes Chromosomes
occurs in pairs in every cell ofour body except in the sperm and
ovum. Chromosomes numbers are the same for eachspecies. Chromosome
Numbers Species Diploid # Haploid # Cattle Swine Sheep Horse Human
Chicken Goat Donkey 62 31 Sex Determination Females contribute an X
chromosome towards thesex of their offspring. Males can contribute
an X or a Y chromosometoward the sex of their offspring. Absence of
an Y chromosome results in a theembryo developing into a female.
Presence of an Y chromosome results in theembryo developing into a
male. Tell me what I am ????? Genes Chromosomes contains several
units of inheritance genes.
Genes usually occurs in pairs, one from eachparent. Some traits are
inherited directly from oneset of genes. Some traits are inherited
through several setsof genes. Terms to know (you need all
this)
Homozygous contains 2 identical genes for thesame trait (ie. AA,
BB, cc) Heterozygous contains 2 different genes for thesame trait
(ie. Aa, bB, Cc) Phenotype Outward appearance of a trait,
coatcolor, polled, horned. Genotype Genetic classification of a
gene,AA,Aa, aa. Allele- Location of a gene on the chromosome.
Genotype or Gamete Genotype contains two copies of the gene.
AaBB Gamete (sex cells) contains only one copy ofthe gene. AB
Determine the possible gametes of AaBB ABaB Gamete or Genotype
State if its a gamete or genotype. Aa D Genotype
DdEeFFgg sRtxyq AaBBeeFF adgEFT Genotype Gamete Genotype Gamete
Genotype Gamete List all the possible gametes.
From the genotype AaBb AB Ab aB ab What are dominant genes?
Write all this What are dominant genes? The gene that express
itself, the powerful anddominant gene. It has the power to
overshadow the recessive genewhen there is complete dominance. Some
examples are: White faced in cattle Droopy ears in swine Polled in
cattle Black coat color in Angus cattle What are Recessive
Genes?
Write all this What are Recessive Genes? The gene that is
overshadowed by a dominant gene Recessive genes can only express
themselves in theabsence of the dominant gene Polled vs Horned (Pp)
(pp) Black wool vs white (Ww) (ww) Dwarfism vs normal size (dd)
Albino Punnet Square Angus - Black coat color is dominant.
BB = Homozygous Dominant and Black Bb = Heterozygous and is black
bb= Homozygous recessive and red A heterozygous bull is mated to 50
homozygous recessivecows. How many calves are black? How many
calves are red? What is the genotypic and phenotypic ratios? Punnet
Square Results 2 Heterozygous = Bb 2 Homozygous Recessive =
bb
25 Black, 25 Red Genotypic ratio = 0:2:2 Phenotypic ratio = 2
Black: 2 Red Practice Problem #1 Let's say that in seals, the gene
for the length of the whiskershas two alleles. The dominant allele
(W) codes long whiskers& the recessive allele (w) codes for
short whiskers. What percentage of offspring would be expected to
haveshort whiskers from the cross of two long-whiskeredseals, one
that is homozygous dominant and one that isheterozygous? If one
parent seal is pure long-whiskered and the other isshort-whiskered,
what percent of offspring would haveshort whiskers? Practice
Problem #1 Practice Problem #2 In purple people eaters, one-horn is
dominant and no hornsis recessive. Draw a Punnet Square showing the
cross of apurple people eater that is hybrid for horns with a
purplepeople eater that does not have horns. Summarize thegenotypes
& phenotypes of the possible offspring. Practice Problem #2
Practice Problem #3 Mendel found that crossing wrinkle-seeded
plants with pureround-seeded plants produced only
round-seededplants. What genotypic & phenotypic ratios can
beexpected from a cross of a wrinkle-seeded plant & a
plantheterozygous for this trait (seed appearance)? Practice
Problem #3 Your Turn!!! What are Sex Linked Genes?
Some recessive genes are attached to the X and Ychromosomes Humans:
Colorblindness and Baldness are on the Xchromosomes In Men, traits
expressed anytime present In Women, must have two recessives to
show trait Children get baldness from mothers If Dad is bald, will
you be bald? Baldness is carried by the mother What if Mom is bald?
What is Incomplete Dominance?
If both genes express themselves Shorthorn Cattle: Red male mated
to a White female = Roan calf RR crossed rr = Rr Punnet Square
Shorthorn Cattle
RR = Red rr = white Rr = roan If a red bull (RR) is mated to a
white cow(rr), what color will the calves be? Shorthorn: Red X
White Punnet Square If a red bull (RR) is mated to a roan(Rr) cow,
what color will the calves be? Shorthorn: Red X Roan What if Both
Parents are Roan? What is a Mutation? Dramatically different from
what isexpected genetically Horned calf from polled parents Loss of
some or extra body parts Lethal Mutation: causes death at birth
Sublethal Mutation: limits animalsability to grow to maturity
Beneficial Mutation: loss of tail inlambs What is Heritability?
Chance that traits will be inherited
Low: multiple births, fat covering Medium: birth weight wean
weight, milk, wool grade, carcass weight, rate of gain High: Loin
eye area, fleece length & quality Mating Systems Upgrading:
mating purebreds with grade animals
Inbreeding: mating closely relatedanimals Linebreeding: mating
distantlyrelated animals Outcrossing: mating unrelatedanimals in
the same breed. Crossbreeding: mating animals ofsame species but
different breeds. What is Hybrid Vigor? Offspring will outperform
either of the parents
Example: Corn Breed A yields 100 bu/acre Corn Breed B yields 100
bu/acre Crossbreed A & B yields corn that yields bu/acre Vigor
only expressed in crossbreeding
Top Related