Revision Generation Game Compiled by Dr Rat ￗ

gene allele phenotype genotype Section of DNA that codes for a particular trait or characteristic. A different form of a gene that codes for a different version of a characteristic. A description of the pair of alleles present for a characteristic. The physical expression of the alleles. What do these genetic terms mean?

homozygous heterozygous recessive dominant Pair of alleles that produce a characteristic that are the same, e.g. HH. Pair of alleles that produce a characteristic that are different, e.g. Hh. An allele that will only be expressed when both alleles are of this type, represented by a lower case letter. An allele that will always be expressed even when there is only one of these alleles present, represented by a capital letter.

Female Reproductive System A B C D E F A B C D E F A = oviduct B = ovary C = uterus D = cervix E = vagina F = thigh

A = sperm duct B = urethra (to bladder) C = penis D = testicle E = scrotum F = gland A B C D E F F B E C A D The male Reproductive System

NGA WAHANGA O TE PUTIPUTI kakau heki putiputi kohanga heki riunga hae tohere hapiapia Wahanga wahine o te putiputi rau arai puapua miro karure hae Wahanga tane Anther Filament Petal Stamen Ovule Sepal Stem Ovary Stigma Pistil Start here, go clockwise

x phenotype: genotype: RRrr Homozygous means that both alleles of a gene are the same. Red is the dominant allele for these flowers, so the alleles for petal colour are: red = R, yellow = r. RR x rr – crossing homozygous parents What are the possible offspring of a cross between a homozygous red flower and a homozygous yellow flower?

RRx rr RRrr parental genotype: gametes: rr R R Rr F1 offspring genotype: RR x rr – F1 offspring What are the phenotypes of the F1 offspring? ?

F1 genotypes: RR x rr – F1 phenotypes Rr F1 phenotypes: (Click twice on the buds to reveal the flowers; click again to close them.) The possible offspring of a cross between two homozygous parents are always heterozygous and so the dominant characteristic is always expressed in this generation. RRx rr parental genotype:

The offspring (Rr) from the first cross (RR x rr) are called the F1 generation. What happens in a cross between these offspring? Both parent plants are now heterozygous, so the alleles in each plant are different. F1 generation genotype: phenotype: X Rr Rr x Rr – crossing heterozygous parents

Rr x Rr – F2 offspring Rr R r RRRr rr What are the phenotypes of the F2 offspring? ? parental genotype: Rrx Rr RrRr gametes: F2 offspring genotype:

Rr x Rr – F2 phenotypes F2 genotypes: RRRr rr F2 phenotypes: (Click twice on the buds to reveal the flowers; click again to close them.) In the F2 generation, 3 of the 4 possible offspring are red. Only one offspring shows the recessive phenotype. When two heterozygous parents are crossed, the possible offspring will always show a 3:1 ratio in favour of the dominant phenotype. parental genotype: Rrx Rr