Dear teacher this was adapted from a presentation by: Nancy Dow Jill Hansen Tammy Stundon

Who teach in Bay County The missing words have been noted for

each slide in the “Click to add notes” space at the bottom of each slide.

BENCHMARK

• SC.912.L.16.1* Use Mendel's laws of segregation and independent assortment to analyze patterns of inheritance. (HIGH)

• SC.912.L.16.2* Discuss observed inheritance patterns caused by

various modes of inheritance, including dominant & recessive

which are simple inheritance & codominant, sex-linked, polygenic,

and multiple alleles (complex inheritance). (HIGH)

For Humans: 23 homologous pairs; one chromosome form mom and the other from dad

Karyotype-display of pairs of chromosomes

Autosomes are chromosomes 1-22

Chromosome pair 23 is your sex chromosomes

Gene - a section of DNA that codes for a ________

Allele – Any form of a specific gene. You get ____ from each parent. Dominant Allele - ______case letter Recessive Allele - ______case letter

Karyotype - the display of the pair of chromosomes with highlighted alleles

Phenotype - the physical _________ of the alleles

Genotype - allele __________ for a gene of an individual Bb, BB, or bb (B is the dominant allele, b is the recessive allele)

Trait - term for distinguishing phenotypic features or ______________

INHERITANCE OF GENES

Maternal chromosome

pair

Paternal chromosome

pair

Gene

Paternal gamete: sperm

Maternal gamete: egg

Gametes unite during fertilization.

Child inherits one set of chromosomes from each parent and, thus, two copies of each gene.

Humans have 23 pairs of chromosomes (46 individual chromosomes) and, thus, two copies of each gene.Each human gamete has just one copy of each chromosome and, thus, one copy of each gene.

ALLELES

What traits will be expressed?

For simple inheritance, you only need _____Dominant allele for the Dominant trait to be expressed.

Naturally, the only way for a Recessive trait to be expressed is if the person has ______Recessive alleles.

Exceptions

Heterozygous - a __________ and a _________ allele (Bb) (also called hybrid)

Homozygous dominant - ____ dominant alleles (BB) (also called Purebred)

Homozygous recessive - ____ recessive alleles (bb) (also called Purebred)

Only one dominant allele need to be present to be expressed

The Punnett square is a grid system for predicting all __________ genotypes resulting from a cross. The axes represent

the possible _________of each parent.

The boxes show thepossible _________of the offspring.

• The Punnett square yields the ratio of possible ___________and ____________.

__________ crosses examine the inheritance of only ____specific trait. homozygous dominant X homozygous

recessive Genotype: all heterozygous (100%) Phenotype: all dominant (100%)

PUNNETT SQUARE: ALBINISMA Punnett square is a useful tool for

determining the possible outcomes of a cross between two individuals.

GAMETES

GAMETES

A

A

Aa Aa

Aa Aa

a a

OFFSPRING Genotype

Phenotype

All heterozygous Aa

All pigmented

FATHERpigmentedhomozygous

AA

MOTHERalbino

homozygousaa

Cross 1 (F 1)

– If you cross a heterozygous with a heterozygous (Ff X Ff) – What is the genotypic ratio of the offspring? – 1:2:1 homozygous dominant: heterozygous: homozygous

recessive; (25%:50%:25%)– What is the phenotypic ratio of the offspring? – 3:1 dominant: recessive (75%:25%)

GAMETES

GAMETES

A

a

AA Aa

Aa aa

A a

OFFSPRING Genotype

Phenotype

FATHERpigmentedheterozygou

sAa

MOTHERpigmentedheterozygou

sAa

Cross 2 (F2)

1/4 homozygous dominant AA2/4 heterozygous Aa

1/4 homozygous recessive aa

3/4 pigmented

1/4 albino

3:1RATIO

Your genotype and phenotype results are presented separately

• If you cross a heterozygous with homozygous recessive

(Ff X ff) • What is the genotypic ratio? • 1:1 heterozygous: homozygous recessive• What is the phenotypic ratio? • 1:1 dominant: recessive

• A ___________is a cross between an organism with an unknown genotype and an organism with the recessive phenotype

Why use the recessive phenotype to test an unknown?

____________is the likelihood that something will happen.

Probability predicts an average number of

occurrences, not an exact number of occurrences.• Probability =number of ways a specific event can occur

number of total possible outcomes

• Probability applies to _________ events such as meiosis and fertilization.

GENETICS AND PROBABILITY

IF…The mother is albino, andthe father is heterozygousTHEN…There is a 100% chance that the mother’s egg will carry the recessive a allele and a 50% chance that a sperm will carry the recessive a allele

aa Aa100% 50%

a a A a

1.0 0.5AND…0.5 or 50%chance theoffspring willbe albino.

Multiply the two components togetherto determine the overall probability.

=

aa

×

Goat g

enetic

s

Mendel’s dihybrid crosses with heterozygous plants yielded a 9:3:3:1 phenotypic ratio.

• Mendel’s dihybrid crosses led to his second law,the _____________________________________.

• The law of independent assortment states that allele pairs separate independently of each other during meiosis.

Dihybrid Cross:a cross that shows the possible

offspring for two traitsFur Color:

B: Black

b: White

Coat Texture:

R: Rough

r: Smooth

In this example, we will cross a heterozygous individual with

another heterozygous individual. Their genotypes will be:

BbRr x BbRr

Fur Color:B: Black b: White

Coat Texture:R: Roughr:

Smooth

BbRr x BbRr BR

bR

br

bR

Br

BR

br

Br

Then, find the possible genotypes of the offspring

Fur Color:B: Black b: White

Coat Texture:R: Roughr:

Smooth

BbRr x BbRr BR

bR

br

bR

Br

BR

br

Br

BBRR BbRR BbRr

BBRr BBrr BbRr Bbrr

BbRR BbRr bbRR bbRr

BbRr Bbrr bbRr bbrr

BBRr

BR bR

br

bR

Br

BR

br

Br

BBRR

BbRR

BbRr

BBRr BBrr BbRr Bbrr

BbRR

BbRr bbRR bbRr

BbRr Bbrr bbRr bbrr

BBRr

How many of the offspring would have a black, rough coat?

How many of the offspring would have a black, smooth coat?

How many of the offspring would have a white, rough coat?

How many of the offspring would have a white, smooth coat?

Fur Color:B: Black b: White

Coat Texture:R: Roughr:

Smooth

Nancy Dow Jill Hansen Tammy Stundon