Download presentation

Presentation is loading. Please wait.

Published byBrett Wing Modified over 2 years ago

1
Dihybrid Crosses Biology 30 Mrs. S. Pipke-Painchaud

2
Dihybrid Crosses the natural progression for Mendel was to study 2 characteristics at the same time. thus, the study of 2 pairs of contrasting traits at the same time = a dihybrid cross ex.. round yellow seeds X wrinkled green seeds

3
Mendel’s Fourth Law The Law of Independent Assortment During gamete formation, segregating pairs of unit factors assort independently of each other. the two traits are inherited totally independently of each other. i.e. color is inherited independently of seed shape. Example: Homozygous round green X wrinkled homozygous yellow

4
Solving Dihybrid Crosses Follow the steps If you were to cross a Homozygous round green X wrinkled homozygous yellow plant, what would your phenotypic and genotypic ratios be?

5
Step 1: Make a Key…. G= yellow g = green W = round w = wrinkled

6
Step 2: Give the genotypes of the parents... Step 2: Give the genotypes of the parents... Homozygous round green X wrinkled homozygous yellow plant P1 = WWgg X wwGG

7
Step 3: Determine the Gametes... WWgg X wwGG WWgg = Wg, Wg, Wg, Wg wwGG = wG, wG, wG, wG HINT: Foil to get the gametes

8
Step 4: Fill in the Punnett square... WgWgWgWg wGWwGgWwGgWwGgWwGg wGWwGgWwGgWwGgWwGg wGWwGgWwGgWwGgWwGg wGWwGgWwGgWwGgWwGg

9
Step 5: Answer any questions... Genotypic ratio = all WwGg Phenotypic ratio = all round yellow G= yellow g = green W = round w = wrinkled

10
F1 X F1 = WwGg X WwGg Remember to determine the gametes for your punnett square.

11
Fill in the Punnett Square WGWgwGwgWGWWGGWWGgWwGGWwGg WgWWGgWWggWwGgWwgg wGWwGGWwGgwwGGwwGg wgWwGgWwggwwGgwwgg

12
The PATTERN... WGWgwGwg WG WWGG WWGg WwGG WwGg Wg WWGg WWgg WwGg Wwgg wG WwGG WwGg wwGG wwGg Wg WwGg Wwgg wwGg wwgg

13
What are the ratios? Genotypic Ratio: 1 WWGG 2 WWGg 1 WWgg 2 WwGG 4 WwGg 2 Wwgg 1 wwGG 2 wwGg 1 wwgg WGWgwGwg WGWWGGWWGgWwGGWwGg WgWWGgWWggWwGgWwgg wGWwGGWwGgwwGGwwGg WgWwGgWwggwwGgwwgg

14
Phenotypic Ratio: Phenotypic Ratio: 9 Yellow Round Dominant Dominant 3 Yellow Wrinkled Dominant Recessive 3 Green Round Recessive Dominant 1 Green Wrinkled Recessive Recessive Genotypic Ratio: 1 WWGG 2 WWGg 1 WWgg 2 WwGG 4 WwGg 2 Wwgg 1 wwGG 2 wwGg 1 wwgg G= yellow g = green W = round w = wrinkled ** Explain the patterns

15
The Short Cut: can only be used if you have (Big little Big little X Big little Big little) BbTt x BbTt Do these fit? BBTt X BbTt BbTt x Bb tt

16
Try this: C= Inflated Podc = constricted pod D = Talld = dwarf The cross: a plant heterozygous for inflated pod and heterozygous tall is crossed with a another heterozygous inflated pod and heterozygous tall plant. What are the genotypic and phenotypic ratios? The parents are: CcDd x CcDd

17
Example: Does this fit the short cut? Yes C= Inflated Pod c = constricted pod D = Tall d = dwarf Genotypic Ratio: 1 2 1 2 4 2 1 2 1 Genotypic Ratio: 1 CCDD 2 CCDd 1 CCdd 2 CcDD 4 CcDd 2 Ccdd 1 ccDD 2 ccDd 1 ccdd Phenotypic Ratio: (D) (D) 9 (D) ® 3 ® (D) 3 ® ® 1 Phenotypic Ratio: (D) (D) 9 Inflated Tall (D) ® 3 Inflated Dwarf ® (D) 3 Constricted Tall ® ® 1 Constricted Dwarf

18
Now try... Refer to the assigned questions in your duotang.

Similar presentations

OK

Exploring Mendelian Genetics. Independent Assortment Does the segregation of one pair of alleles affect the segregation of another pair of alleles? –Mendel.

Exploring Mendelian Genetics. Independent Assortment Does the segregation of one pair of alleles affect the segregation of another pair of alleles? –Mendel.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on soft skills development Download ppt on search engines Ppt on tcp/ip protocol suite tutorial Ppt on history of olympics video Ppt on hlookup in excel Ppt on prevention of needlestick injury Ppt on javascript events tutorials Ppt on anticancer therapy Ppt on foreign exchange market mechanism View my ppt online