Turn in your genetics assignment to Turn in your genetics assignment to the traythe tray

Other Inheritance Other Inheritance PatternsPatterns

Unlinked Autosomal GenesUnlinked Autosomal Genes

R r

Y y

Linked GenesLinked Genes

R r

Y y

RYRY ryry

RYRY RRYYRRYY RrYyRrYy

ryry RrYyRrYy rryyrryy

3 round, yellow : 1 wrinkled, green

Crossing over can Crossing over can create create

recombinantsrecombinants

Hypothetical Linked Gene DataHypothetical Linked Gene Data

Round, Yellow – 93Round, Yellow – 93 Round, Green – 7 (recombinants)Round, Green – 7 (recombinants) Wrinkled, Yellow – 7 (recombinants)Wrinkled, Yellow – 7 (recombinants) Wrinkled, Green – 93Wrinkled, Green – 93 Recombination Frequency = Recombination Frequency =

recombinant total / total offspringrecombinant total / total offspring 14/200 = 7%14/200 = 7%

Gene mappingGene mapping

Each % pt of recombinants = 1 map Each % pt of recombinants = 1 map unit on the chromosomeunit on the chromosome

R is 7 map units away from YR is 7 map units away from Y

R Y

7 map units

EpistasisEpistasis

When 2 or more genes control 1 When 2 or more genes control 1 phenotype (gene-gene interactions)phenotype (gene-gene interactions)

Remember – normal dihybrid cross of Remember – normal dihybrid cross of 2 heterozygotes give you a 9:3:3:1 2 heterozygotes give you a 9:3:3:1 phenotypic ratiophenotypic ratio

If 2 genes show epistasis, this ratio If 2 genes show epistasis, this ratio can changecan change

ExamplesExamples

Kernel Color in Kernel Color in wheatwheat

If 1 allele of gene A If 1 allele of gene A or gene B is or gene B is dominant, the dominant, the wheat is coloredwheat is colored

The only individual The only individual that is white is that is white is aabbaabb

Ratio 15:1Ratio 15:1

Flower color in sweet peaFlower color in sweet pea

Both genes need a Both genes need a dominant dominant (functional) allele (functional) allele to create to create anthocyanin (color)anthocyanin (color)

Ratio is 9:7Ratio is 9:7

Albinism in miceAlbinism in mice

B gene – determines if mice pigment B gene – determines if mice pigment color is brown or blackcolor is brown or black

C gene – determines if any pigment C gene – determines if any pigment is present at allis present at all

PleiotropyPleiotropy When 1 gene has multiple phenotypic When 1 gene has multiple phenotypic

effectseffects ExamplesExamples

– Vestigial wing gene also causes changes in the Vestigial wing gene also causes changes in the balancers, the direction of bristles, and the balancers, the direction of bristles, and the number of eggs in the ovariesnumber of eggs in the ovaries

– GAPDH – 1GAPDH – 1stst known for the metabolism of known for the metabolism of glucose, also known for the regulation of glucose, also known for the regulation of protein translation, aiding in the transport of protein translation, aiding in the transport of RNA to cytoplasm, aiding in DNA repair and RNA to cytoplasm, aiding in DNA repair and DNA replicationDNA replication

Polygenic (quantitative) TraitsPolygenic (quantitative) Traits

When multiple genes aid in the When multiple genes aid in the expression of a single traitexpression of a single trait

Examples – height, coloration (skin Examples – height, coloration (skin color, eye color)color, eye color)

AssumptionsAssumptions– Effects of each gene is additiveEffects of each gene is additive– No dominance (incomplete dominance)No dominance (incomplete dominance)– No linkageNo linkage

Plant Height in Tobacco PlantsPlant Height in Tobacco Plants

7 classes of height – 0 to 6 7 classes of height – 0 to 6 (depending on number of dominant (depending on number of dominant alleles the plant has at 3 separate alleles the plant has at 3 separate genes (A, B, and C)genes (A, B, and C)

AABBCC (6) x aabbcc (0) yields all AABBCC (6) x aabbcc (0) yields all intermediate (3) heterozygotes intermediate (3) heterozygotes AaBbCcAaBbCc

Let’s look at the F1 crossLet’s look at the F1 cross– AaBbCc x AaBbCcAaBbCc x AaBbCc

ABCABC ABcABc AbCAbC aBCaBC AbcAbc abCabC aBcaBc abcabc

ABCABC AABBCCAABBCC AABBCcAABBCc AABbCCAABbCC AaBBCCAaBBCC AABbCcAABbCc AaBbCCAaBbCC AaBBCcAaBBCc AaBbCcAaBbCc

ABcABc AABBCcAABBCc AABBccAABBcc AABbCcAABbCc AaBBCcAaBBCc AABbccAABbcc AaBbCcAaBbCc AaBBccAaBBcc AaBbccAaBbcc

AbCAbC AABbCCAABbCC AABbCcAABbCc AAbbCCAAbbCC AaBbCCAaBbCC AAbbCcAAbbCc AabbCCAabbCC AaBbCcAaBbCc AabbCcAabbCc

aBCaBC AaBBCCAaBBCC AaBBCcAaBBCc AaBbCCAaBbCC aaBBCCaaBBCC AaBbCcAaBbCc aaBbCCaaBbCC aaBBCcaaBBCc aaBbCcaaBbCc

AbcAbc AABbCcAABbCc AABbccAABbcc AAbbCcAAbbCc AaBbCcAaBbCc AAbbccAAbbcc AabbCcAabbCc AaBbccAaBbcc AabbccAabbcc

abCabC AaBbCcAaBbCc AaBbCcAaBbCc AabbCCAabbCC aaBbCCaaBbCC AabbCcAabbCc aabbCCaabbCC aaBbCcaaBbCc aabbCcaabbCc

aBcaBc AaBBCcAaBBCc AaBBccAaBBcc AaBbCcAaBbCc aaBBCcaaBBCc AaBbccAaBbcc aaBbCcaaBbCc aaBBccaaBBcc aaBbccaaBbcc

abcabc AaBbCcAaBbCc AaBbccAaBbcc AabbCcAabbCc aaBbCcaaBbCc AabbccAabbcc aabbCcaabbCc aaBbccaaBbcc aabbccaabbcc

Polygenic Polygenic Inheritance Inheritance

GraphGraph

When Bad Things Happen When Bad Things Happen to Good Chromosomesto Good Chromosomes

Research - DisordersResearch - Disorders