/199-genetics.html

1. /199-genetics.html GENETICS

2. Genetics the Study of Heredity • Heredity - the passing of traits from one generation to another through sex cells (egg or sperm) of the parent organism (plants or animals) • Heredity is passed through our cells, which is where chrmosomes are located • Humans have 46 chromosomes, 23 chromosomes from each parent, which means we inherit ½ of our genes from each parent.

3. Chromosomes Chromosomes occur in pairs Chromosomes are long pieces of DNA that are made up of genes

4. Genes A gene is a piece of DNA on a chromosome that determine a specific trait. (Example: eye color gene) Genes are located on chromosomes Genes contain the code or directions for our bodies Genes are the unit of heredity that control the cell

5. Chromosomes Occur in Pairs One copy of a chromosome comes from the male parent and one copy of a chromosome from the female parent In reproduction the male donates an x or y chromosome determining the sex of the offspring, the female only donates an x chromosome This pair of chromosomes is called a “homologous pair” because they represent the same genes (eye color genes, hair color genes…) eye color gene Female Male Chromosomes

6. Is it possible for two parents with blue eyes to have a brown eyed child? • Is it possible for two parents with brown eyes have a blue eyed child? • Let’s find out……

7. A feature or characteristic of an organism determined by genes. We receive inherited traits from our parents…. eye color, hair color, right or left handedness, widows peak, cleft chin There are dominant and recessivetraits Inherited Traits

8. Dominant and Recessive Traits • Dominant Trait (D) -a trait that can over ride • another trait. It is the trait that is visible • Examples: • Brown eye color • Unattached ear lobes • Brown hair • Straight thumb • Recessive Trait (d) – a trait that is only visible • if two of the recessive genes are there. (dd) • Examples: • Blue eye color • Attached ear lobes • Blond hair • Hitchhikers thumb

9. Dominant Traits ~ Recessive Traits unattached earlobe attached earlobe ability to roll tongue hitchhikers thumb

10. Genotype and Phenotype • Genotype – are the particular alleles that an individual carries. It is your genetic make-up • (DD, Dd, dd) • Phenotype – this is the trait you can see the physical expression of the genes • DD – you will see the dominant trait • Dd – you will see the dominant trait • dd – you will see the recessive trait

11. Genotype and Phenotype b b

12. Remember our Question? • Is it possible for two parents with blue eyes to have a brown eyed child? • Is it possible for two parents with brown eyes have a blue eyed child?

13. The combination of alleles determines the observed characteristics • Results Brown Gene Brown Gene Blue Gene Blue Gene Chromosome combination Brown Gene Blue Gene Genotype - Alleles on Gene Brown, blue (Bb) Blue, blue (bb) Brown, Brown (BB) Phenotype - Observed Characteristic Brown Eyes Brown Eyes Blue Eyes

14. What's in Your Genes?

15. Pipe Cleaner Babies The “dad” places one set of the homologous pairs (ex: that longer white set) behind his back, with a chromosome in each hand. The “mom” picks the hand she wants for the child. Lay this chromosome on the table in front of you and set the other aside. Repeat this procedure for the other homologous pair (ex: shorter set) Repeat for the sex chromosomes. It should be noted that if the blue chromosome gets chosen from the sex chromosomes, the child in this cross is going to be a boy. Now the “mom” places one set of the homologous pairs behind her back and the male chooses. The chromosomes chosen and set on the table in front of you are the genes your first child received.

16. Pipe Cleaner Babies Go to the last page and see the data table, the first group is you and your partner. You are going to have 4 children. Repeat the procedure you used to make you first child to make 3 others. Fill out their traits on the table.

17. Pipe Cleaner Babies Convert your data to percentages.  To get the percents, divide the number you have by the total number and x 100. Girls                         ______% Boys                       ______% Brown eyes           ______% Blue eyes               ______% Dark hair                ______% Blonde hair              ______% Compile Data Total number of babies?_______ Number of girls? _____ Number of boys?  _____ Number of children with brown eyes _______ Number of children with blue eyes _______ Number of children with dark hair ________ Number of children with blonde hair  ______ How many times was the dominant gene inherited instead of the recessive gene? Can you explain why offspring have different traits? Can we choose what type of traits our offspring will inheriat?

18. References http://www.valdosta.edu/~dkcullen/topic.html http://www.clipartguide.com/_pages/1386-0904-3008-1128.html http://teampub.wordpress.com/ http://www.uic.edu/classes/osci/osci590/5_3SimpleHumanNon-MetricTraits.html http://www.riversideonline.com/health_reference/Tools/DS00549.cfm?RenderForPrint=1 http://www.jewishgenetics.org/?q=content/spread-word http://jeanapettus.webs.com/