HEREDITY Why do we look like we do?. Learning Targets Describe how evolution lead to the diversity of species on earth today. Explain the function.

HEREDITY

Why do we look like we do?

Learning Targets¨ Describe how evolution lead to the diversity of species on

earth today.¨ Explain the function of chromosomes, where they are

located and what information they carry. ¨ Explain the process of mitosis and why the offspring of

sexual reproduction have more diverse characteristics that asexual reproduction.

¨ Understand that genes are passed on independently of each other trait.

¨ Be able to predict the outcome of genetic crosses .¨ Explain why genetic variation is important to survival of a

species.

Read pgs. 110 – 117; Ch.6 Friday 4/23

Vocabulary Definitions of key terms pgs. 110

Questions pg. 115

Read pgs. 118-123

Questions pg. 123

Questions pg. 130

Read pg. 131-137 & 144 - 155

ActivitiesClass surveyPunnett SquaresCorn tossDragon activity

Opening Tasks

4/5/10

How do the nitrogen bases pair up to code for protein.4/6/10

What is your definition of genetics?4/7/10

Which scientist led us to understanding genetics?

Where are your genes located?4/8/10

What are dominant and recessive traits?

4/9/10

What are phenotype and genotypes?

April 6, 2010¨ ?? of the day¨ How do the nitrogen bases pair

up to code for protein?

¨ Go over DNA/Genes Worksheet¨ Read Pages 110-117¨ Vocabulary due Thursday, key

terms page 110¨ Pre – activity worksheet¨ Begin Notes

April 7, 2010

¨ ?? Of the day: ¨ Which scientist led us to

understanding genetics?

¨ Where are your genes located?¨ Go over Video Worksheet¨ Notes/Review on DNA¨ Start that genetics!!

DNA Replication¨ Ensures each daughter cell will have an exact copy of the

genetic material it needs to carry out its activities.¨ Reminder: DNA (and RNA) is made up of nucleic acids –

long organic molecules made of – C, O, H, N, and phosphorus

¨ Replication of DNA takes place during Interphase

DNA Replication (cont.)¨ DNA is made of a sugar molecule called deoxyribose, a

phosphate, and nitrogen bases in the shape of a ladder or spiral staircase.– Deoxyribose and phosphate make up the outside supports (or the

sides of the ladder)– Nitrogen bases make up the rungs of the ladder

• The same bases always pair, A-T and C-G and in a specific order determining protein formation.

• Adenine - Thymine• Guanine - Cytosine

The Structure of DNA

DNA Replication Process¨ Replication begins when the two sides unwind and

separate (like unzipping a zipper)¨ The DNA separate between the paired bases ¨ Nitrogen bases floating in the nucleus pair up with the

bases on each half of the DNA molecule to make two new identical strands.

DNA Replication

DNA Replication (in action)

www.geneticalpha.com/what%20we%20do/default.html

PRINCIPLES OF HEREDITY

¨ Mendel’s research led to our understanding of genetics.

• The genetic code DNA, determines all our traits inherited from our parents.

• These traits are passed on by genes which are located on the chromatids in the nucleus.

Mendel’s Experiment¨ P generation = grandparents¨ F1 generation are the offspring of the grandparents

(your parents)¨ F2 generation are the offspring of the F1

generation (you)¨ Trait is a characteristic passed on to the offspring

like height.¨ Traits are controlled by the alleles inherited from

the parents¨ Alleles are different forms of a gene, for example

the gene for height has 2 alleles – tall and short.

D om in an ttra its th a t a re s tron g es t

th ey sh ow u p & can h id e o th er tra its

R ecess ivetra its th a t a re w eak

th ey can b e h id d en b y d om in an t tra its

G en es

Inheritance Patterns Continued

¨ Genotypes show the combination of genes that are specific for all traits.

¨ Phenotypes show your physical characteristics like height, eye, hair color & skin color. Dominant traits are

symbolized by capital letters, TT. One letter from each parent.

Recessive traits are symbolized by lower case letters, tt.

In each pair of genes, one comes from the mother and the other comes from the father.

Punnett Squares¨ These can be used to show the probability of

specific traits showing up in the offspring. For Example, sex of the child

¨ X X¨ X

¨ Y¨ XX = mother; XY = father genotyoes, now bring

the letter over the box into the boxes under it.

Practice

¨ Write mom XX; dad XY

Now draw a square like the last slide and place mom’s traits over the top 2 boxes and dad’s traits next to the boxes on the side.

Start with mom and the first X, bring it down & write it into each box it’s over. Do the same for the second X.

repeat this for dad’s traits bringing each trait across into the boxes it’s next to.

Let’s do some others.

Cell division of the sex cells that form gametes.

Parent cell has 23 pairs of chromosomes

The chromosomes duplicate in the first stage

Chromosomes duplicate giving 46 pairs

Cell divides into 2 cells with half the number of the previous cell. Each has the original number. 23 pairs

After the final division 4 gamete cells are formed with ½ the number of chromosomes as the parent. Gametes are the egg cells in females and the sperm cells in males. Fertilization of the egg and sperm form a zygote.

The father determines the sex of the child because he passes on the Y chromosome.

Remember mom is XX

and dad is XY, therefore

Mom can only pass on the X.

These traits can be passed on by mom only. The reason for this is only the X chromosome carries traits.

Baldness, colorblindness & hemophilia are examples of these traits.