Download - Introductory Genetics
Introductory Genetics
RIFAT ALI KHESHGI Student atNWFP AGRICULTURAL UNIVERSITY PESHAWARCell # 03139556067
GeneticsGenetics
Is the science of heredity.Is the science of heredity.
Heredity is the transmission of genetic or Heredity is the transmission of genetic or physical traits from parent to offspring.physical traits from parent to offspring.
Gregor MendelGregor Mendel
Austrian MonkAustrian Monk
Considered the “Father of Heredity”Considered the “Father of Heredity”
He conducted plant breeding experiments He conducted plant breeding experiments in their monastery garden.in their monastery garden.
In 1865 he made his work public, units of In 1865 he made his work public, units of inheritance.inheritance.
What makes us unique?What makes us unique?Each of the 100 Trillion cells in our body Each of the 100 Trillion cells in our body except the red blood cells contains the except the red blood cells contains the entire human genome, in the nucleus of entire human genome, in the nucleus of every cell is the genetic information every cell is the genetic information “blueprint” to construct the individual.“blueprint” to construct the individual.It is the Deoxyribonucleic acid (DNA)It is the Deoxyribonucleic acid (DNA)Function of DNA Function of DNA Genetic code for almost every organism.Genetic code for almost every organism. Provide template for protein synthesis.Provide template for protein synthesis.
Composition of DNAComposition of DNA
The structure of DNA was discovered by The structure of DNA was discovered by Watson and Crick in 1953.Watson and Crick in 1953.
It is a twisted double helix molecule, It is a twisted double helix molecule, containing sugar, phosphates, and containing sugar, phosphates, and nitrogenous bases.nitrogenous bases.
The sugar is deoxyribose and the phosphoric The sugar is deoxyribose and the phosphoric acid molecules are always the same and acid molecules are always the same and provides for the structure (side of the ladder).provides for the structure (side of the ladder).
The only difference between us is the order The only difference between us is the order and arrangement of the four bases (rungs of and arrangement of the four bases (rungs of the ladder).the ladder).
Bases of DNABases of DNA
Adenine= AAdenine= A
Thymine= TThymine= T
Guanine= GGuanine= G
Cytosine= CCytosine= C
A always pairs with TA always pairs with T
C always pairs with GC always pairs with G
Bases of RNABases of RNA
Adenine= AAdenine= A
Uracil= UUracil= U
Guanine= GGuanine= G
Cytosine= CCytosine= C
G always pairs with CG always pairs with C
T from the DNA = A in the RNAT from the DNA = A in the RNA
A from the DNA = U in the RNAA from the DNA = U in the RNA
DNA ModelDNA Model
ChromosomesChromosomes
The DNA in every cell is located in rod like The DNA in every cell is located in rod like segments called chromosomessegments called chromosomes
Chromosomes occurs in pairs in every cell Chromosomes occurs in pairs in every cell of our body except in the sperm and ovum.of our body except in the sperm and ovum.
Chromosomes numbers are the same for Chromosomes numbers are the same for each specie.each specie.
Chromosome NumbersChromosome Numbers
SpecieSpecie Diploid #Diploid # Haploid #Haploid #
CattleCattle 6060 3030
SwineSwine 3838 1919
SheepSheep 5454 2727
HorseHorse 6464 3232
HumanHuman 4646 2323
ChickenChicken 7878 3939
GoatGoat 6060 3030
DonkeyDonkey 6262 3131
ChromosomesChromosomes
There are 2 sex chromosomes included There are 2 sex chromosomes included in the diploid number of the in the diploid number of the chromosomes.chromosomes.
All of the other chromosomes are All of the other chromosomes are referred to as autosomes. referred to as autosomes.
In mammals if the sex chromosomes In mammals if the sex chromosomes are alike, XX it results in a female.are alike, XX it results in a female.
If the sex chromosomes are different, If the sex chromosomes are different, XY it results in a male.XY it results in a male.
Sex DeterminationSex Determination
Female can contribute only a X chromosome Female can contribute only a X chromosome towards the sex of their offspring.towards the sex of their offspring.Male can contribute an X or a Y chromosome Male can contribute an X or a Y chromosome toward the sex of their offspring.toward the sex of their offspring.Absence of an Y chromosome results in a the Absence of an Y chromosome results in a the embryo developing into a female.embryo developing into a female.Presence of an Y chromosome results in the Presence of an Y chromosome results in the embryo developing into a male.embryo developing into a male.
Sex DeterminationSex Determination
Gametogenesis = Gametogenesis = Formation of gametes Formation of gametes through meiosis.through meiosis.
Male = 4 viable Male = 4 viable spermatidsspermatids
Female = 1 viable Female = 1 viable ovum, 3 polar bodies.ovum, 3 polar bodies.
Tell me what I am ?????Tell me what I am ?????
Tell me what I am ?????Tell me what I am ?????
Cell DivisionCell Division
MeiosisMeiosis Is the form of cell division which results reducing Is the form of cell division which results reducing
the chromosome number from the diploid # to the the chromosome number from the diploid # to the haploid #.haploid #.
Occurs only in the sex cells, sperm and ovum.Occurs only in the sex cells, sperm and ovum.
MitosisMitosis Is the form of cell division which results in the Is the form of cell division which results in the
formation of identical daughter cells, keeps the formation of identical daughter cells, keeps the chromosome number constant.chromosome number constant.
Tissue growth and repair.Tissue growth and repair. Occurs throughout the body except in the sex Occurs throughout the body except in the sex
cells. cells.
Genotype or GameteGenotype or Gamete
Genotype contains Genotype contains twotwo copies of the copies of the gene.gene. AaBBAaBB
Gamete (sex cells) contains only one Gamete (sex cells) contains only one copy of the gene.copy of the gene. ABAB
Determine the possible gametes of Determine the possible gametes of AaBBAaBB ABAB aBaB
Gamete or GenotypeGamete or Genotype
State if its a gamete or genotype.State if its a gamete or genotype.
AaAa
DD
DdEeFFggDdEeFFgg
sRtxyqsRtxyq
AaBBeeFFAaBBeeFF
adgEFTadgEFT
List all the possible gametes.List all the possible gametes.
From the genotype From the genotype AaBbAaBb
ABAB
AbAb
aBaB
abab
GenesGenes
Chromosomes contains several units of Chromosomes contains several units of inheritance “genes”.inheritance “genes”.
Genes usually occurs in pairs, one from Genes usually occurs in pairs, one from each parent.each parent.
Some traits are inherited directly from one Some traits are inherited directly from one set of genes. set of genes.
Some traits are inherited through several Some traits are inherited through several sets of genes.sets of genes.
GenesGenes
It was presumed that we were composed It was presumed that we were composed of about 100,000 genes to construct us.of about 100,000 genes to construct us.Today, research has proven that number Today, research has proven that number is a lot less than 100,000.is a lot less than 100,000.Extra credit for the student that can find an Extra credit for the student that can find an article about the current number of genes.article about the current number of genes.
Terms to knowTerms to know
HomoHomozygous- contains 2 identical genes for the zygous- contains 2 identical genes for the same trait, AA, BB, ccsame trait, AA, BB, ccHeterHeterozygous- contains 2 different genes for ozygous- contains 2 different genes for the same trait, Aa, bB, Ccthe same trait, Aa, bB, CcPhenotype- Outward appearance of a trait, Phenotype- Outward appearance of a trait, coat color, polled, horned.coat color, polled, horned.Genotype- Genetic classification of a gene, Genotype- Genetic classification of a gene, AA, Aa, aa.AA, Aa, aa.Allele- Location of a gene on the chromosome.Allele- Location of a gene on the chromosome.F-one = First cross mating.F-one = First cross mating.F-two = Second cross mating.F-two = Second cross mating.
What are dominant genes?What are dominant genes?
The gene that express itself, the powerful The gene that express itself, the powerful and dominant gene.and dominant gene.
It has the power to overshadow the recessive It has the power to overshadow the recessive gene when there is complete dominance.gene when there is complete dominance.
Some examples are:Some examples are: White faced in cattleWhite faced in cattle Droopy ears in swineDroopy ears in swine Polled in cattlePolled in cattle Black coat color in Angus cattleBlack coat color in Angus cattle
What are What are Recessive GenesRecessive Genes??
The gene that is overshadowed by a The gene that is overshadowed by a dominant genedominant geneRecessive genes can only express Recessive genes can only express themselves in the absence of the themselves in the absence of the dominant genedominant genePolled vs Horned (Pp) (pp)Polled vs Horned (Pp) (pp)Black wool vs white (Ww) (ww)Black wool vs white (Ww) (ww)Dwarfism vs normal size (dd)Dwarfism vs normal size (dd)AlbinoAlbino
Punnet SquarePunnet Square
Angus- Black coat color is dominant.Angus- Black coat color is dominant.
BB = Homozygous Dominant and BlackBB = Homozygous Dominant and Black
Bb = Heterozygous and is blackBb = Heterozygous and is black
bb = Homozygous recessive and redbb = Homozygous recessive and red
A heterozygous bull is mated to 50 A heterozygous bull is mated to 50 homozygous recessive cows.homozygous recessive cows.
How many calves are black?How many calves are black?
How many calves are red?How many calves are red?
What is the genotypic and phenotypic ratios?What is the genotypic and phenotypic ratios?
Punnet SquarePunnet Square
B b
b
b
Bb bb
Bb bb
ResultsResults
2 heterozygous = Bb2 heterozygous = Bb2 Homozygous 2 Homozygous Recessive bbRecessive bb25 Black, 25 Red25 Black, 25 RedGenotypic ratio = Genotypic ratio = 0:2:20:2:2Phenotypic ratio = Phenotypic ratio =
2 Black: 2 Red2 Black: 2 Red
What are What are Sex Linked GenesSex Linked Genes??
Some recessive genes are attached to Some recessive genes are attached to the X and Y chromosomesthe X and Y chromosomes
Humans: Colorblindness and Baldness Humans: Colorblindness and Baldness are on the X chromosomesare on the X chromosomes
In Men, traits expressed anytime presentIn Men, traits expressed anytime present
In Women, must have two recessives to In Women, must have two recessives to show traitshow trait
Children get baldness from mothersChildren get baldness from mothers
If Dad is bald, will you be If Dad is bald, will you be bald?bald?
X Y
X XX X Y
XX XYX
B
B
B
Baldness is carried by the Baldness is carried by the mothermother
X Y
X XX X Y
XX XYX
BB B
What if Mom is bald?What if Mom is bald?
X Y
X XX X Y
XX XYX
BB B
B B B
What is What is Incomplete Incomplete DominanceDominance??
If both genes express themselvesIf both genes express themselves
Shorthorn Cattle: Red male mated to a Shorthorn Cattle: Red male mated to a White female = Roan calfWhite female = Roan calf
RR crossed rr = RrRR crossed rr = Rr
Punnet SquarePunnet Square
Shorthorn CattleShorthorn Cattle
RR = RedRR = Red
rr = whiterr = white
Rr = roanRr = roan
If a red bull (RR) is mated to a white cow If a red bull (RR) is mated to a white cow (rr), what color will the calves be?(rr), what color will the calves be?
Shorthorn: Red X WhiteShorthorn: Red X White
R R
r
r
Rr Rr
Rr Rr
Punnet SquarePunnet Square
If a red bull (RR) is mated to a roan (Rr) If a red bull (RR) is mated to a roan (Rr) cow, what color will the calves be?cow, what color will the calves be?
Shorthorn: Red X RoanShorthorn: Red X Roan
R R
R
r
RR RR
Rr Rr
What if Both Parents are Roan?What if Both Parents are Roan?
R r
R
r
RR Rr
Rr rr
What is a What is a MutationMutation??
Dramatically different from what is Dramatically different from what is expected geneticallyexpected genetically
Horned calf from polled parentsHorned calf from polled parents
Loss of some or extra body partsLoss of some or extra body parts
Lethal MutationLethal Mutation: causes death at birth: causes death at birth
Sublethal MutationSublethal Mutation: limits animals : limits animals ability to grow to maturityability to grow to maturity
Beneficial Mutation: loss of tail in lambsBeneficial Mutation: loss of tail in lambs
What is Heritability?What is Heritability?
Chance that traits will be inheritedChance that traits will be inherited
Low: multiple births, fat coveringLow: multiple births, fat covering
Medium: birth wt, wean wt, milk, wool Medium: birth wt, wean wt, milk, wool grade, carcass wt, rate of gaingrade, carcass wt, rate of gain
High: Loin eye area, fleece length & High: Loin eye area, fleece length & qualityquality
Mating SystemsMating SystemsUpgrading: mating purebreds with grade animalsUpgrading: mating purebreds with grade animalsInbreeding: mating closely related animalsInbreeding: mating closely related animalsLinebreeding: mating distantly related animalsLinebreeding: mating distantly related animalsOutcrossing: mating unrelated animals in the Outcrossing: mating unrelated animals in the same breed.same breed.Crossbreeding: mating animals of same species Crossbreeding: mating animals of same species but different breeds.but different breeds.
What is What is Hybrid VigorHybrid Vigor? ? HeterosisHeterosis
Offspring will outperform either of the Offspring will outperform either of the parentsparents
Corn Breed A yields 100 bu/acreCorn Breed A yields 100 bu/acre
Corn Breed B yields 100 bu/acreCorn Breed B yields 100 bu/acre
Crossbreed A & B yields corn that yields Crossbreed A & B yields corn that yields 200 bu/acre200 bu/acre
Vigor only expressed in crossbreedingVigor only expressed in crossbreeding
The EndThe End
You can use your notes to do the next two You can use your notes to do the next two worksheets.worksheets.
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