Topic: GeneticsAim: Why do offspring look similar to their parents?Do Now:1.) List the similarities you notice amongst the family members

2.) State why they may have the same features

What is Genetics?

The study of how variations of traits are inherited (or passed down) through living organisms Key Words gene

Alleles Parent & offspring

DNAChromosomes

Heredity

How are organisms genetically structured?

Living organisms contain ___________________ inside of their nucleus which are made up of strands of ___________. This carries the hereditary information for the organism. Sections of the ____ code for a particular ________ that makes a specific trait.

chromosomes

DNA

DNA

gene

Who was the Father of Genetics?

Gregor Mendel1822-1884

•He was a monk and gardener who studied Math and Science•He was the 1st to study heredity in pea plants •He was 1st to trace one trait passed down through several generations

How did Mendel study pea plants?

•He pollinated two parent pea plants and observed and recorded the traits of the new plant He referred to the

traits as: Dominant- Seen often (Common) or Recessive- Not seen often(Uncommon)

Why Pea plants to study traits?

•Pea plants have fewer traits

•Can grow in a large amount (quantity)•He could control the plants he desired to mate in his experiment

Topic: GeneticsAim: How can we examine the inherited traits found in offspring?

How do scientist today tracetraits?

•One or more genes found at the same point on the chromosomes represents a trait•Each person has a pair of genes for each trait

•One Allele from MOM•One Allele from DAD

Alleles

•Each trait is represented by two versions called alleles

•One person may have two of the same version or one of each version•The dominant allele is represented by a CAPITAL letter and the recessive is represented by a lower case letter

EXAMPLE:

ALLELES

TRAITDimples

Dimples no dimples

Dominant

Recessive

Principles of Genetics• Traits are passed on from one generation to the

next.• Traits are controlled by genes.• Organisms inherit genes in pairs (2 alleles for

every trait, 1 on each strand).• Some genes are dominant, some are recessive.• Dominant genes hide recessive genes when both

are inherited by an organism.• Some genes are neither dominant nor recessive

(incomplete dominance)

What do scientists study in understanding a trait?

PhenotypeIs the physical appearance (___________) expressed (__________)by the organism because of their genotype

featureshown

Genotype It is the combination of alleles (genes) in the chromosomes that determine a specific characteristic (trait)

There are many types of Alleles for a traitAlleles can be _____________ or_____________

Dominant

Recessive

1 mom & 1 dad

When the dominant allele is present the recessive trait is

not seen in the phenotype

BrownEyes

BrownEyes

Blue Eyes

How many ways can alleles be represented?

Heterozygous

Two different alleles present in the organism

Homozygous

Two of the same alleles present in the organism

Homozygous Dominant

Homozygous Recessive

How do the genotype help determine the phenotype in human organisms?

It is based upon the variations of alleles found on the __________________that each parent gives the offspring during the process of _______________________.

chromosomes

Fertilization

TOPIC: GeneticsAIM: What are Punnett Squares?

DO NOW:Explain the difference

between genotype and phenotype

PunnettSquares

• Special chart

• Shows probability of possible gene combinations of offspring between 2

organisms

What isprobability

?

The possibility that an event may or may not happen

• ¼ = 25%• 2/4 = 50%• 3/4 = 75%• 4/4 = 100%

Steps to using a Steps to using a Punnett SquarePunnett Square

Step # 1 – Draw Step # 1 – Draw Punnett squarePunnett square

Step # 2 – Apply maternal and paternal genotypesStep # 3 – Move alleles into appropriate boxes

Steps to Steps to reading a reading a Punnett Punnett SquareSquareStep #1- Classify Genotypes

Step # 2- Tally genotypes and phenotypes

Step # 3-Calulate ratios and percentages Homozygous

Dominant Heterozygous

Heterozygous HomozygousRecessive

Genotypes Phenotype

1 BB2 Bb1 bb

Trait – Hair colorAllele – Purple (Dom), Yellow (Rec)

3 Purple1 Yellow

Heterozygous X Heterozygous

 

Heterozygous X Homozygous recessive

Heterozygous X Homozygous recessive

 

Homozygous Dominant X Homozygous Recessive

Is the range of differences between a male and female

Biologically, male and females differ in ___________which are determined by____________________

sex traits

genes

Whether you are a male or female depends on the presence or absence of certain chromosomes.

FEMALE

MALE

The sex chromosomes are the X chromosome and the Y chromosome. Chromosomes determine gender.

Human cells contain 23 pairs of chromosomes for a total of 46.

MOM

DAD

A technique that involves a photograph of the chromosomes from a nucleus that are paired and arranged in size order.

The first 22 pairs are called autosomes and the last pair are sex chromosomes.

When the chromosomes are different they are an X and a Y therefore it is a male