Presentation is loading. Please wait.

Presentation is loading. Please wait.

Studying the inheritance of two characters simultaneously

Published byTyler Thornton Modified over 5 years ago

Similar presentations

Presentation on theme: "Studying the inheritance of two characters simultaneously"— Presentation transcript:

1 Studying the inheritance of two characters simultaneously
THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously

2 Mendel’s peas Character Trait Allele Seed shape Round R Wrinkled r
Cotyledon colour Yellow Y Green y

3 Combinations Genotype Phenotype RRYY Round Yellow RRYy RrYY RrYy RRyy
Round Green Rryy rrYY Wrinkled Yellow rrYy rryy Wrinkled Green

4 Is the inheritance of one character affected by the inheritance of another?
P Phenotypes Round Yellow x Wrinkled Green (Pure Bred) F1 Phenotypes All Round Yellow (Selfed) F2 Phenotypes Seed colour Yellow Green TOTAL RATIO Round 315 108 423 shape Wrinkled 101 32 133 416 140 556

5 Is the inheritance of one character affected by the inheritance of another?
P Phenotypes Round Yellow x Wrinkled Green (Pure Bred) F1 Phenotypes All Round Yellow (Selfed) F2 Phenotypes Seed colour Yellow Green TOTAL RATIO Round 315 108 423 3.18 shape Wrinkled 101 32 133 1 416 140 556 2.97

6 A dihybrid cross can be treated as two separate monohybrid crosses
The expected probability of each type of seed can be calculated: Probability of an F2 seed being round = 75% or ¾ Probability of an F2 seed being wrinkled = Probability of an F2 seed being yellow = Probability of an F2 seed being green =

7 The expected probability of each type of seed can be calculated:
A dihybrid cross can be treated as two separate monohybrid crosses The expected probability of each type of seed can be calculated: Probability of an F2 seed being round = 75% or ¾ Probability of an F2 seed being wrinkled = 25% or ¼ Probability of an F2 seed being yellow = 75% or ¾ Probability of an F2 seed being green = 25% or ¼

8 Therefore Probability of an F2 seed being round and yellow = ¾ x ¾ = 9/16 = % Probability of an F2 seed being round and green = Probability of an F2 seed being wrinkled and yellow = Probability of an F2 seed being wrinkled and green =

9 Therefore Probability of an F2 seed being round and yellow = ¾ x ¾ = 9/16 = % Probability of an F2 seed being round and green = ¾ x ¼ = 3/16 = % Probability of an F2 seed being wrinkled and yellow = ¼ x ¾ = 3/16 = % Probability of an F2 seed being wrinkled and green = ¼ x ¼ = 1/16 = %

10 We could expect What Mendel observed 556 x 9/16 round yellow 313 315
Predicting how many seeds we could expect to get in a sample We could expect What Mendel observed 556 x 9/16 round yellow 313 315 556 x 3/16 round green 108 556 x 3/16 wrinkled yellow 101 556 x 1/16 wrinkled green 32

11 Predicting how many seeds we could expect to get in a sample
What Mendel observed 556 x 9/16 round yellow 313 315 556 x 3/16 round green 104 108 556 x 3/16 wrinkled yellow 101 556 x 1/16 wrinkled green 35 32

12 THE LAW OF INDEPENDENT ASSORTMENT
It appears that the inheritance of seed shape has no influence over the inheritance of seed colour The two characters are inherited INDEPENDENTLY The pairs of alleles that control these two characters assort themselves independently

13 Mendel & Meiosis The pairs of chromosomes could orientate in different ways at Anaphase 1

14 Dihybrid cross genetic diagram
P Phenotypes Round Yellow seed X Wrinkled Green seed (Pure bred) Genotypes RRYY rryy meiosis Gametes RY ry fertilisation F1 RrYy (Selfed) Round Yellow Proportions 100%

15 Dihybrid cross genetic diagram
F1 Phenotypes RrYy (Selfed) Genotypes Round Yellow Proportions 100% meiosis Gametes Y y R RY Ry r rY ry

16 Dihybrid cross genetic diagram
Gametes Y y R RY Ry r rY ry fertilisation F2 Genotypes RRYY RRYy RrYY RrYy RRyy Rryy rrYY rrYy rryy

17 Dihybrid cross proportions
Phenotypes Proportions Round Yellow 9/16 or 56.25% Round Green Wrinkled Yellow Wrinkled Green

18 Dihybrid cross proportions
Phenotypes Proportions Round Yellow 9/16 or 56.25% Round Green 3/16 or 18.75% Wrinkled Yellow Wrinkled Green 1/16 or 6.25%

19 Dihybrid test cross In monohybrid crosses, to know if a dominant trait is homozygous (RR) or heterozygous (Rr) it is necessary to carry out a test cross This is done with a homozygous recessive (rr) individual The same is true for a dihybrid cross where the test cross is made with an individual which is homozygous recessive for both characters (rryy) © 2007 Paul Billiet ODWS

20 Dihybrid test cross Phenotypes Round Yellow X Wrinkled Green Genotypes
RrYy rryy Gametes RY, Ry, rY, ry ry Genotypes RY Ry rY ry RrYy Rryy rrYy rryy Phenotypes Round Yellow Round Green Wrinkled Yellow Wrinkled Green Proportions 1/4 or 25%

21 SsYy 1. SY 2. Sy 3. sY 4. sy 9/16 Smooth/yellow 3 / 16 Smooth/green
Possible Gamete Combinations 1. SY 2. Sy 3. sY 4. sy 9/16 Smooth/yellow 3 / 16 Smooth/green 3 / 16 Wrinkled/yellow 1 Wrinkled /green

Download ppt "Studying the inheritance of two characters simultaneously"

Similar presentations

Chapter 10: Mendel and Meiosis September 28 2010.

Chapter 10: Mendel and Meiosis September
THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously © 2007 Paul Billiet ODWSODWS.

THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously © 2007 Paul Billiet ODWSODWS.
THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously © 2007 Paul Billiet ODWSODWS.

THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously © 2007 Paul Billiet ODWSODWS.
THE DIHYBRID CROSS Studying the inheritance of two traits simultaneously © 2007 Paul Billiet ODWSODWS.

THE DIHYBRID CROSS Studying the inheritance of two traits simultaneously © 2007 Paul Billiet ODWSODWS.
THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously BY- DR (Mrs.) T.S.KHAN (PGT BIOLOGY)

THE DIHYBRID CROSS Studying the inheritance of two characters simultaneously BY- DR (Mrs.) T.S.KHAN (PGT BIOLOGY)
Mendel and Genetic Crosses. Mendel Gregor Mendel – botanist Studied inheritance through pea plants 1850’s Pea plants – sexual reproduction Usually self-fertilize.

Mendel and Genetic Crosses. Mendel Gregor Mendel – botanist Studied inheritance through pea plants 1850’s Pea plants – sexual reproduction Usually self-fertilize.
Basic Genetics *. View video at: https://www.youtube.com/watch?v=YxKFdQo10rE.

Basic Genetics *. View video at:
Genetics Ms. Tetrev.

Genetics Ms. Tetrev.
Mendel’s Second Experiment Inheritance of Two Traits Dihybrid Cross.

Mendel’s Second Experiment Inheritance of Two Traits Dihybrid Cross.
Dihybrid Crosses. Let’s review So far, we have looked only at different types of monohybrid crosses –the inheritance of only ONE trait at a time –Ex:

Dihybrid Crosses. Let’s review So far, we have looked only at different types of monohybrid crosses –the inheritance of only ONE trait at a time –Ex:
Test Cross Tall (dominant phenotype) plants of the F1 generation will have one of the following genotypes: DD or Dd.

Test Cross Tall (dominant phenotype) plants of the F1 generation will have one of the following genotypes: DD or Dd.
DIHYBRID CROSSES ( 2 traits)

DIHYBRID CROSSES ( 2 traits)
Genetic Crosses Section 9.2. Genotype  The genetic makeup of an organism  Consists of the alleles that the organism inherits from its parents  Example:

Genetic Crosses Section 9.2. Genotype  The genetic makeup of an organism  Consists of the alleles that the organism inherits from its parents  Example:
Dihybrid Crosses Inheritance of two characteristics at the same time Objective: E3 - Predict possible outcomes of various genetic combinations such as…dihybrid.

Dihybrid Crosses Inheritance of two characteristics at the same time Objective: E3 - Predict possible outcomes of various genetic combinations such as…dihybrid.
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.
Genetics Take 2 Dihybrid Crosses. Monohybrid vs. Dihybrid Monohybrid crosses are crosses that examine the inheritance of only one specific trait. Dihybrid.

Genetics Take 2 Dihybrid Crosses. Monohybrid vs. Dihybrid Monohybrid crosses are crosses that examine the inheritance of only one specific trait. Dihybrid.
Mendelian Genetics. Let’s Review How are traits coded? Where are genes located? Chromosomes are composed of what macromolecule?

Mendelian Genetics. Let’s Review How are traits coded? Where are genes located? Chromosomes are composed of what macromolecule?
Definition Crosses looking at two traits simultaneously Mendels law of segregation states that Mendels law of independent assortment states that.

Definition Crosses looking at two traits simultaneously Mendels law of segregation states that Mendels law of independent assortment states that.
Jumpstart 11/27 Create a Venn Diagram comparing monohybrid and dihybrid crosses. Your venn should have at least 5 differences and 3 similarities.

Jumpstart 11/27 Create a Venn Diagram comparing monohybrid and dihybrid crosses. Your venn should have at least 5 differences and 3 similarities.
KMarsh. Vocabulary dominant gene: dominant gene: F 1 generation: F 1 generation: F 2 generation: F 2 generation: gene: gene: genetic trait: genetic trait:

KMarsh. Vocabulary dominant gene: dominant gene: F 1 generation: F 1 generation: F 2 generation: F 2 generation: gene: gene: genetic trait: genetic trait:

Similar presentations

Ads by Google