What is sex linkage?Males have the genotype XY

whereas females are XX.

Create a genetic diagram to show the possible genotypes

produced.

What are the phenotype ratios.

Objectives Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.

7: Evaluate the role of the X and Y chromosomes in the

inheritance of named examples of inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Sex linkageOutcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

Sex linkageOutcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

TaskComplete the questions on sex linked

conditions

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Sex-linked genetic crosses• Red-green colourblindness:Let XB = chromosome with the allele for normal visionLet Xb = chromosome with the allele for colour blindness Y = chromosome with no gene for visionParents phenotype Normal mother x Colour blind father

genotype XB XB Xb YGametes

♀\♂ Xb Y

XB XBXb XB Y

XB XBXb XB Y

Offspring genotypes: XBXb XBY

Offspring phenotypes: Female carrier Male normal

• HaemophiliaLet XH = chromosome with the allele for normal blood clottingLet Xh = chromosome with the allele for haemophilia Y = chromosome with no gene for blood clottingParents phenotype Carrier mother x Normal father

genotype XH Xh XH YGametes

♀\♂ XH Y

XH XHXH XH Y

Xh XHXh Xh Y

Offspring genotypes: XHXH XHXh XHY XhY

Offspring phenotypes: Female Female Male Male

normal carrier normal haemophilia

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?

Outcomes3: Describe sex linkage and some associated conditions

5: Explain fully how sex linked conditions can be inherited.7: Evaluate

the role of the X and Y

chromosomes in the transfer

of named examples of

inherited conditions.

Key terms: sex linkage, haemophilia, colour blindness, inheritances.

What is sex linkage?