Human Inheritance-text pp 106-110

i) Dominance and recessive-ii) Co dominance – Human Blood groupsOther Types of inheritance iii) Single Gene-Multiple alleles (Human Eye Colour)iv) Using Pedigreesv) Gender determinationvi) Sex Linkage – X Linked

i) Recessive trait

Dwarfism - dominant

• Dominant does not mean you will see lots of examples automatically in populations of individuals. It might be that it is a rare dominant form of a gene (allele) eg; dwarfism.

• The gene is said to have a low frequency in the human population

• Similarly recessive traits can be quite common in populations where the trait has a high frequency eg blue eyes in northern European populations eg; Danish, Swedish etc.

Dominant

Curved little finger - dominant

Observable Genetic TraitsCharacteristic dominant trait recessive trait

Earlobes Free ear lobes Attached ear lobes

Forelock White forelock No white forelock

Curve of thumb Straight thumb Curved thumb

Dimples Dimples No dimples

Pinky Bent pinky Straight pinky

Mid-digit hair Mid-digit hair No mid-digit hair

Tongue rolling Able to roll Not able to roll

Writing Hand right left

Crossing legs Left Leg up Right leg up

Second toe Length longer shorter

ii)Co dominance – Human Blood groups

ii)Co dominance – Human Blood groupsBoth Alleles are expressed in the phenotype

iii)Single Gene Inheritance-Multiple Alleles e.g Human Eye Colour

Discontinuous(one gene) VS Continuous(many genes)

Characteristics

iv)Using Pedigrees

Create Your own Pedigree for ear lobe attachment

v)Gender Determination

vi)Sex Linked Diseases eg Colour Blindness(can you see the number)

http://www.mediacollege.com/lighting/colour/colourblind.html

Comparison of X and Y chromosomes

X and Y chromosome Comparison

Colour Blindness(sex linked)Parents=Carrier female x Normal sited male

X X X XY

Now do

• Everyone read pp 106-110• If finding work hard complete Q 1-7• If finding easy -Completed • Q13,14,15,16,17,24