Free Powerpoint Presentations

Genetic Crosses
Page
1

DOWNLOAD

PREVIEW

WATCH ALL SLIDES

Slide 1

Genetic Crosses

Genetic Crosses

Show possible outcomes of genes the new generation will have

We use:

Gene diagrams

Punnett Squares

Slide 2

Terminology

Terminology

Genotype Phenotype Parent Gamete Offspring

dominant recessive allele

Slide 3

Gene control of characteristics

Gene control of characteristics

All characteristics are controlled by a minimum of 2 genes.

These genes give the characteristic a different of presenting itself.

Different genes that control the same feature are called ALLELES

Slide 4

Eye Colour

Eye Colour

Possible alleles blue , brown, green, hazel etc (each colour needs its own gene)

It is possible to have pairs of different alleles, alleles are usually given a letter

Slide 5

Genotype and phenotype

Genotype and phenotype

Genotype is the letter or term used to describe the allele of an individual gene or pair of genes

Phenotype is how the gene (or pair) shows itself, how it appears.

Slide 6

Dominance and recessiveness

Dominance and recessiveness

Some alleles for a feature are able to mask the influence of other (weaker) gene when they are paired

Stronger gene is DOMINANT and is represented by a capital letter e.g. H

The masked gene is RESSESIVE shown as lower case of the same letter e.g. h

Slide 7

Gene diagram  Flower colour

Gene diagram Flower colour

Genotype of alleles- R = red flower r = yellow flower

All genes occur in pairs so 2 alleles affect a characteristic possible combinations are;

genotype RR Rr rr

Phenotype RED RED YELLOW

Slide 8

Gene diagram  Flower colour

Gene diagram Flower colour

Male female

RR

rr

parent

gamete

R R r r

Offspring genotype

Rr

Rr

Rr

Rr

Phenotype

All red

Slide 9

Gene diagram  Flower colour

Gene diagram Flower colour

Male female

Rr

Rr

parent

gamete

R r R r

Offspring genotype

RR

Rr

Rr

rr

Phenotype

Red yellow red red

3 red : 1 yellow

Slide 10

Gene diagram  Flower colour

Gene diagram Flower colour

Male female

Rr

rr

parent

gamete

R r r r

Offspring genotype

Rr

Rr

rr

rr

Phenotype

Red yellow yellow red

Go to page:
 1  2 

Contents

Last added presentations

2010-2018 powerpoint presentations