Genetics

Genetics VocabularyGenetics Vocabulary

Genetics- The branch of biology that studies biological inheritance.

Genetics VocabularyGenetics Vocabulary

Gametes = reproductive cells

SPERM EGGS

Genetics VocabularyGenetics VocabularySelf-Pollination- When pollen from a plant fertilizes an egg from the same plant (this is how pea plants normally

reproduce.)

Genetics VocabularyGenetics VocabularyCross-pollination- produces seeds that

are the offspring of two different plants. Pollen from one plant is dusted

onto the ovules of another.This allow scientists to

manipulate which plants reproduce

together.

Genetics VocabularyGenetics VocabularyTrue-breeding- if allowed to self-pollination purebred peas would produce offspring identical to

themselves.Tall pea plants only reproduce with tall

for many generations

Genetics VocabularyGenetics Vocabulary

Traits –

characteristics

Genetics VocabularyGenetics Vocabulary

Hybrids – organisms produced by crossing parents with different

characteristics

Example- crossing a tall pea plant with a short pea plant.

PugglesPuggles

Labradoodles Labradoodles

Jackapoos Jackapoos

Chiweenies Chiweenies

Genetics VocabularyGenetics Vocabulary

Genes – The factors that control traits.

Today we know these genes are

located on specific sections of DNA.

Genetics VocabularyGenetics Vocabulary

Alleles- Different forms of a gene

2 different alleles for a gene in a pea plant

•Tall or short

•Yellow or green

Genetics VocabularyGenetics Vocabulary

Dominant – the alleles that are “stronger” than others

In Pea Plants

Tall is Dominant to short.

Genetics VocabularyGenetics Vocabulary

Recessive – the weaker form of a gene

In Pea Plants

Only shows up if two are present.

Short + short = short.

Genetics VocabularyGenetics VocabularyPunnett Square – a diagram used to determine the PROBABILITY of offspring from a particular cross.

T = Tall

t = short

Genetics VocabularyGenetics Vocabulary

Phenotype – the physical characteristics of an organism

TALL

YELLOW

BLUE EYES

RED HAIR

PINK PETALS

Genetics VocabularyGenetics Vocabulary

Genotype – what an organism genetic makeup looks like

TT GGTt

gg

YY

Genetics VocabularyGenetics Vocabulary

Homozygous – has two of the same alleles.

TT GGtt

gg

YY

Genetics VocabularyGenetics Vocabulary

Heterozygous – 2 different genes

Tt GgYy

Mendel’s ConclusionsMendel’s Conclusions

The factors that control heredity are individual units known as genes. In organisms that reproduce sexually, genes are inherited from each parent.

In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and the other may be recessive.

The two form of each gene are segregated during the formation of reproductive cells.

Te genes for different traits may assort independently of one another.

Gregor MendelGregor Mendel

Gregor Mendel, a monk in the Czech Republic, is considered the "Father of Genetics", based upon experiments he conducted using garden peas. He helped lay down the principles of modern genetics.

Mendel’s ExperimentsMendel’s ExperimentsMendel was

given a garden of pure bred pea plants.

He studied various traits in pea plants

The First Generation Cross (fThe First Generation Cross (f11))

Mendel Crossed a purebred tall with a purebred

short plant and

got all tall

plants!

Step one = Define the Parents Genotype and Phenotype

XTall ShortPhenotype =

Genotype = TT X tt

The First Generation Cross (fThe First Generation Cross (f11))

ShortXTallPhenotype

Genotype TT X tt

Step two = Set up the punnett square

T T

t

t

Mendel Crossed a purebred tall with a purebred

short plant and

got all tall

plants!

Tttall

Tttall

Tttall

Tttall

Phenotype =

100 % Tall

Genotype =

100 % Tt

The Second Generation Cross (fThe Second Generation Cross (f22))

Mendel Crossed a

two heterozygous Tall

pea plants

Step one = Define the Parents Genotype and Phenotype

XTall TallPhenotype =

Genotype = Tt X Tt

The Second Generation Cross (fThe Second Generation Cross (f22))

TallXTallPhenotype

Genotype Tt X Tt

Step two = Set up the punnett square

T t

T

t

Mendel Crossed a purebred tall with a purebred

short plant and

got all tall

plants!

TTtall

Tttall

ttshort

Tttall

Phenotype =

75 % Tall: 25% short

Genotype =

25% TT; 50%Tt;

25% tt

Review Mendel’s ConclusionsReview Mendel’s Conclusions

The factors that control heredity are individual units known as genes. In organisms that reproduce sexually, genes are inherited from each parent.

In cases in which two or more forms of the gene for a single trait exist, some forms of the gene may be dominant and the other may be recessive.

The two form of each gene are segregated during the formation of reproductive cells.

Te genes for different traits may assort independently of one another.

Sample Problem #1Sample Problem #1

A yellow pod plant is crossed with a heterozygous pod plant. What is the genotype and phenotype of the offspring?

Sample Problem #2Sample Problem #2

A white flower pea plant is crossed with a homozygous recessive flower plant. What are the genotype and phenotypes of the offspring?

Sample Problems Sample Problems

A heterozygous tall plant is crossed with a homozygous tall plant. What is the genotype and phenotypes of the offspring.

Two Trait CrossTwo Trait Cross

Mendel determined that alleles assort independently from each other, even when multiple traits are studied.

Phenotype= 9:3:3:1

Genotype = 1:2:1:2:4:2:1:2:1

Common Traits Name_________________

Objective: To observe some patterns of human heredity in our classroom.

Trait

Dominant Recessive

Number of Students

Demonstrat- ing Dominant Phenotype

Number of Students

Demonstrat- ing

Recessive Phenotype

Percentage

Demonstrat- ing

Dominant Phenotype

Percentage

Demonstrat- ing

Recessive Phenotype

Tongue Roller ( R )

Nonroller ( r )

Widow’s Peak ( W )

Straight Hairline ( w )

Free Earlobes ( E )

Attached Earlobes ( e )

Dimples ( D )

No Dimples ( d )

Freckles ( F )

No Freckles ( f )

Selected Traits in Cats

Trait Dominant Allele Recessive Allele

Coat Length Short Hair (H) Long Hair (h)

Tabby Stripes Tabby (T) Stripeless (t)

Color point (markings on nose, ears, paws, and

tail)

Normal Color point

Sample Problem #1A color point cat is crossed with a heterozygous normal cat. What are the expected genotypes and phenotypes of their offspring?

The British Royal FamilyThe British Royal Family

Human traits are difficult to study for several reasons. Unlike some organisms, which produce slowly and only a few offspring at one time. Thus human traits must be studied through population sampling and pedigree analysis. A pedigree is a diagram that shows the phenotype of different generations.

Royal family tree

Pedigree for ColorBlindness – a sex linked trait