chapter 13.4 probability and genetics. computer karyotypes(new) now we know enough about chromosomes...
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Chapter 13.4Chapter 13.4
Probability and GeneticsProbability and Genetics
Computer Karyotypes(new)Computer Karyotypes(new)Now we know Now we know enough about enough about chromosomeschromosomesDyes specific to Dyes specific to certain certain chromosomeschromosomes– Bind to specBind to spec
Different colorsDifferent colorsComputers can sort Computers can sort them into them into karyotypekaryotype
Example of chromosomal disorderExample of chromosomal disorder
Down’s SyndromeDown’s Syndrome– Extra chromosome Extra chromosome
# 21# 21– Learning difficultiesLearning difficulties
Diploid OrganimsDiploid OrganimsTwo of every chromosomeTwo of every chromosome
One from mom, one from dadOne from mom, one from dad
Both have same gene(ex. Eye color)Both have same gene(ex. Eye color)
Both may have different forms(alleles)Both may have different forms(alleles)
ProbabilityProbabilityMathematicsMathematics
The chance that a certain event will The chance that a certain event will happenhappen– 33% chance of rain33% chance of rain– 50% chance of having a baby boy50% chance of having a baby boy– Flipping a coin, how many outcomes?Flipping a coin, how many outcomes?
How many outcomes?How many outcomes?2 outcomes:2 outcomes:
What is the chance of flipping tails?What is the chance of flipping tails?
1/21/2Probability expressed as fractionProbability expressed as fraction
(number of desired trait)/(all possible (number of desired trait)/(all possible outcomes)outcomes)
If you toss a coin ten times, how many tails do you think you will get?
Prediction: 5 TailsPrediction: 5 Tails# of Trials# of Trials x x probability probability = prediction = prediction
Ex. Ex. 1010 x x ½ ½ = = 5 Tails 5 Tails
Genetics use ProbabilityGenetics use Probability
GenderGender
How many outcomes?How many outcomes?
Chance of having a boy?Chance of having a boy?
If you have four children, how many If you have four children, how many boys do you predict?boys do you predict?
Two Laws Affecting ProbabilityTwo Laws Affecting Probability
Previous events don’t affect one Previous events don’t affect one eventevent– If you have five girls already, you still If you have five girls already, you still
have the ½ chance of having a girlhave the ½ chance of having a girl
You can predict the possibility of You can predict the possibility of having three girls or three head having three girls or three head tosses in a row.tosses in a row.– (1/2) x (1/2) x (1/2)= 1/8(1/2) x (1/2) x (1/2)= 1/8
Probability works bestProbability works best
Constant environmentConstant environment– No varying factorsNo varying factors
Large sample sizeLarge sample size
One outcome does not have One outcome does not have advantage than any other outcomeadvantage than any other outcome
Monohybrid CrossMonohybrid CrossMendel studied plants Mendel studied plants
Monohybrid=refers to only differing in Monohybrid=refers to only differing in one traitone trait
Cross=mate, reproduceCross=mate, reproduce
PgenPgen= parental generation= parental generation– Plants involved in initial crossPlants involved in initial cross
F1 generation: First Filial F1 generation: First Filial generationgeneration
F1: all green podsF1: all green pods
F2:Second Filial GenerationF2:Second Filial GenerationRoughly a 3 green:1 yellow ratioRoughly a 3 green:1 yellow ratio
Alleles(different forms of gene)Alleles(different forms of gene)Gene: pod colorGene: pod color– Allele: green vs yellowAllele: green vs yellow
Dominant alleleDominant alleleRecessive alleleRecessive allele– Is hidden when dominant is presentIs hidden when dominant is present
We use letters to represent a gene We use letters to represent a gene and capitals to represent the and capitals to represent the dominant formdominant form– G= green pods g= yellow podsG= green pods g= yellow pods
You are diploid You are diploid
Two pairs of chromosomes=two Two pairs of chromosomes=two alleles for each genealleles for each gene
HomozygouHomozygous:s:– Have two same alleles,GG or ggHave two same alleles,GG or gg– True-breeding organismsTrue-breeding organisms
Heterozygous:Heterozygous:– Different alleles for a gene, GgDifferent alleles for a gene, Gg– Dominant gene is seen over recessiveDominant gene is seen over recessive
Genotype:Genotype:– Genetic makeupGenetic makeup– What two alleles you haveWhat two alleles you have– Ex. GG is a genotypeEx. GG is a genotype
Phenotype:Phenotype:– Physical traitPhysical trait– What can be seenWhat can be seen– Ex. Green pods are the phenotype Ex. Green pods are the phenotype
Mendel’s PrinciplesMendel’s Principles
Principle of SegregationPrinciple of Segregation
Principle of Independent AssortmentPrinciple of Independent Assortment
Principle of SegregationPrinciple of SegregationYou have two You have two allelesallelesMeiosis takes one Meiosis takes one cell and divides into cell and divides into four gametesfour gametes– A plant cell with A plant cell with – Cell cycle replicates Cell cycle replicates
chromosomeschromosomes– Meiosis separates Meiosis separates
into four gametesinto four gametes
Gg
GGgg
g
G
G
g
Any one of those gametes can mate with the Any one of those gametes can mate with the gametes of another organismgametes of another organism
g
G
G
g
g
G
G
g
Genotype: Gg
Phenotype: green pods
Punnett SquaresPunnett SquaresUsed to predict Used to predict offspring of 2 offspring of 2 organismsorganisms
Step 1: Draw a Step 1: Draw a punnett squarepunnett square– One box divided One box divided
into four into four quandrantsquandrants
Punnett SquaresPunnett SquaresStep 2: Determine the possible genotypes Step 2: Determine the possible genotypes of both parentsof both parents– If there is more than one possibility, do more If there is more than one possibility, do more
one punnet square for eachone punnet square for each– Ex. Tall plant(Tt) with short plant(tt)Ex. Tall plant(Tt) with short plant(tt)
Step 3: Take one parentStep 3: Take one parent
and split genotype up onand split genotype up on
left sideleft side
Punnett SquaresPunnett SquaresStep 4: Take genotype of other parents and Step 4: Take genotype of other parents and split it up over top of squaresplit it up over top of square
Punnett SquaresPunnett Squares
Step 5: Write down all possible Step 5: Write down all possible genotypes genotypes in ratio form in ratio form
Ex. 1 2 Tt: 2 ttEx. 1 2 Tt: 2 tt
simplify ratio 1 Tt: 1 ttsimplify ratio 1 Tt: 1 tt
Step 6: Write down all possible Step 6: Write down all possible phenotypes in ratio formphenotypes in ratio form
Ex. 1 1 Tall plant: 1 Short plantEx. 1 1 Tall plant: 1 Short plant