Bell Work: FRIDAY 2/1/13 Go to page 79 in your science notebook:

Write a journal about what we did in class yesterday. Discuss some of the traits you did or did not have.

On the same page make a “Know and Wanna Know” chart as it pertains to Heredity.

If you have not taken or completed the test from Wednesday, please see me.

If you have work to turn in, please put it in the drawer for your class.

Heredity

• Why don’t you look like a rhinoceros? • The answer to this question seems simple: Neither

of your parents is a rhinoceros. • But there is more to this answer than meets the

eye.• As it turns out, heredity, or the passing of traits

from parents to offspring, is more complicated than you might think.

• For example, you may have curly hair, while both of your parents have straight hair. You might have blue eyes while both of your parents have brown eyes.

• How does this happen?

Who was Gregor Mendel?• Read pg. 100

– “Who Was Gregor Mendel?– “Unraveling the Mystery”

• Gregor Mendel discovered the principles of heredity while studying the characteristics and traits of pea plants.

• A characteristic is a feature that has different forms in a population.– For example, hair color is a characteristic of humans.

• The different forms, such as brown or red hair is called a trait.

Review Self Pollination and Cross Pollination

Self pollinating flowers have both male and female reproductive parts. (pistil and stamen). During pollination the sperm (pollen from the anther) attaches to the stigma (sticky opening of the pistil). self pollination creates a true breeding plant.

Pea plants can also cross-pollinate. In cross-pollination, pollen from one plant fertilizes the ovule of a flower on a different plant. There are several ways that this can happen. Pollen may be carried by insects to a flower on a different plant. Pollen can also be carried by the wind from one flower to another.

• Mendel studied one characteristic at a time as he worked with these pea plants.

• These are some of the plant characteristics that he worked with.

He was very careful to use only plants that had true breeding for each of the traits he was studying. That way he would know what to expect if they were to self pollinate.

He then decided to try cross pollinating with these flowers. He would pull the anther off of one plant and pollinate another plant with it. That way he knew the one flower could NOT self pollinate. He crossed a plant with wrinkled seeds with another plant with round seeds.

Mendel’s First Experiments

• One trait was always present in the first generation, and the other trait seemed to disappear.

• Mendel chose to call the trait that appeared the dominant trait.

• Because the other trait seemed to fade into the background, Mendel called it the recessive trait.

• The recessive trait for the white flower reappeared in the second generation.

In human terms

• Grandma has blue eyes.

• Grandpa has brown eyes.

• 1st generation:

Mom has brown eyes and so do all of her siblings.

• 2nd generation: Three out of four of mom’s children have brown eyes.

• The other one has blue eyes.

Review: Talk with your group…1. What is heredity?

• The passing of genetic traits from parent to offspring

2. Who was Gregor Mendel?• Discovered the principles, or ideas, of heredity

3. Which trait is present in the first generation?

• Dominant trait

4. Which trait is present in the second generation?

• Recessive trait

Review• How did Mendel make sure that the plant

didn’t self pollinate?

• How many plants out of the first generation were purple?

• How many plants out of the second generation were purple?

• How many out of the 3rd generation do you think would be purple? http://www.indiana.edu/~p1013447/dictionary/mendel.htm

He removed the anther from one plant and then cross pollinated it with another plant.

Bell work Tuesday, February 5Dominant Pistil

Recessive Stamen

Trait Pollination

Charactertics Fertilization

Heredity Self pollinate

True breeding Cross pollinate

FIND A DEFINITION FOR EACH WORD.

Here’s the problem…you can use a maximum of 5 words to define each term. In other words, put it in YOUR own terms. (hint: look at yesterday’s notes. )

Let’s pick the best definitions for each word.

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Traits and Inheritance• When Mendel calculated the ratio of

dominant traits to recessive traits, he found there was a 3:1 ratio. :

• Mendel knew from his experiment with pea plants that there must be twotwo sets of instructions for each characteristic.

• The first -generation plants carried the instructions for both the dominant and recessive traits.

• These instructions for an inherited trait are called genes.

• Each parent gives one set of genes to the offspring.

The offspring then has two forms of the same gene for every characteristic- one one from each parent. (pouty lips/thin lips)from each parent. (pouty lips/thin lips)

The two forms (often dominant and recessive) of a gene are known as alleles.

The genes we inherit are the same for all humans. However, how these manifest (show) themselves is actually determined by alleles!

DOMINANT alleles are shown with a capital letter . (P for dominant purple flowers).

recessive alleles are shown with a lowercase letter . (p for recessive white flowers).

Dominant and Recessive Alleles

Phenotype & Genotype Genes affect the traits of an offspring. An organism’s appearance (the way they look) is

known as its phenotype. In pea plants, possible phenotypes for the

characteristic of flower color would be purple flowers or white flowers or it could be a yellow or green seed.

Phenotypes for humans are much more complicated than those of peas.The boy has inherited a trait called albinism which prevents hair, skin, and eyes from having normal coloring.

The genotype of an organism is the entire genetic makeup of an organism; the combination of genes for a specific trait.

An organism with two dominant or two recessive alleles is homozygous (same size letters).

RRSS = round and green rrss = wrinkled and yellow (remind me next lesson to discuss what it is called when there are no dominant alleles.

An organism with one of each (Pp) is heterozygous.RrSs= round and greenrRsS= also round and green

R= round S=greenr= wrinkled s= yellow

1. What is an allele?

2. What is the difference in a gene and an allele?

3. What is the difference in a phenotype and a genotype?

4. What is the difference in a heterozygous and a homozygous allele?

Classwork or Homework- you choose

Label the concept map and paste it in your science notebook.

Review

Bell Work Tuesday, Feb 12, 2013JUSTIFY YOUR ANSWER!

Review Genes and Alleles• The first -generation plants carried the

instructions for both the dominant and recessive traits.

• These instructions for an inherited trait are called genes.

• Every person has two genes for each trait. One is from the mother and the other is from the father. This is called an allele.

• Some of the traits that we have are based on simple inheritance where one version of a gene (dominant allele) masks the expression of the other version of that gene (recessive allele).

Review Homozygous and HeterozygousWhen an organism has a pair of identical alleles for a character, they are said to be homozygous for that characteristic (PP, pp)

When an organism has two different alleles for a gene (Pp) they are said to be heterozygous for that characteristic dominance. For that characteristic, an organism will have one of two phenotypes.

ReviewGenotype and Phenotype

When an organism has the recessive phenotype, this means that both recessive alleles must be present (bb). With recessive traits, we clearly know what the genotype is if the phenotype is recessive.

An organism showing the dominant phenotype can be homozygous or heterozygous for dominant allele (PP, Pp). It is more difficult to know genotype when dominant allele is involved.

Let’s Put It In Human Terms

• For a simple trait like tongue rolling (curling) you have to have 2 allele. We will label the allele that allows rolling “R” and if it is an absent allele we will label that as “r”.

• What happens if you have RR? • Imagine you have rr. What does this mean? • What do you think will happen if you have Rr?• Think of recessive as laid back. If R is dominant and r is

laid back, what does this mean for a person who has Rr?• Does the order of the alleles matter? Talk with your

elbow partner about this.

•Mom’s genotype: Rr, Ss, Cc, ll, bb, gg, ee•Dad’s genotype: rr, ss, cc, Ll, Bb, Gg, Ee•Which parent has more dominant genes? •Describe how each parent will look. (Write the phenotypes.)•Get with your elbow partner and work these out!

DOMINANTGenotypes and Phenotype

recessiveGenotype and Phenotype

RR or Rr – red antennae rr – green antennae

SS or Ss – three body segments ss – two body segments

CC or Cc – curly tail cc- straight tail

LL or Ll – three pairs of legs ll – two pairs of legs

BB or Bb – blue nose bb – green nose

GG or Gg – green feet gg – black feet

EE or Ee – two eyes ee - three eyes

Mom Dad

___________________ _________________

___________________ _________________

___________________ _________________

___________________ _________________

___________________ _________________

___________________ _________________

___________________ _________________

So, in review…a genotype is the make up of your genes.

A phenotype is how that make up makes you look (green eyes), be able to do (roll

tongue), or other abilities.

Punnett Square• A Punnett square is used to

organize all possible combinations of offspring from particular parents.

• Genotype PP is a purebred. (true breeding)

• What is the genotype for the offspring to the right?

• The dominant allele P ensures that the offspring will have purple flowers.

• The recessive allele p may get passed to the next generation.

• Why?

Quick Labpg. 107

• Work with your group to complete the Punnett square.

• What would be the phenotypes for these offspring?– RR= round seeds– Rr= round seeds– rr= wrinkled seeds

RR(genotype- two

dominant alleles)

Rr(genotype- one

dominant allele,one

recessive allele)

Rr(genotype- one

dominant allele,one

recessive allele)

rr(genotype- two

recessive alleles)

R r

R

r

Probability

• The mathematical chance that something will happen is known as probability.

• Genotype probability:– Pp x Pp cross has a 50% chance of receiving

either allele from either parent.– The probability of inheriting two p alleles is

½x½, which equals ¼, or 25%.

R= round seedsr = wrinkled seeds

Rr x rr

Rr x rr

r r

R

r

RrYy x rryy

RY Ry rY ry

ry

ry

ry

ry

R= round seedsr= wrinkled seedsY= yellow seedsy= green seeds