Understanding Genetics Unit 2

Of your family members who do you feel you act like, look like, etc.? Bell Ringer October 19th , 2011 Of your family members who do you feel you act like, look like, etc.?

Heredity The biological process by which certain traits are transmitted from parents to their children Genetics The study of how traits are passed from parents to child through heredity

It all starts with…. Chromosomes Long, threadlike structures in the nucleus or central portion, of each human cell

CYTOPLASM: Substance of a cell outside of the nucleus CELL: Basic unit of all living matter (Adult = over 10 trillion cells) CYTOPLASM: Substance of a cell outside of the nucleus NUCLEUS: Central point of cell / contains genetic coding for maintaining life systems and issuing commands for growth & reproduction CHROMOSOMES: 46 in each Nucleus (23 pairs) GENES: bands on chromosomes (thousands of genes) DNA on genes (billions of DNA)

GENES On each chromosome there are hundreds or thousands of genes Hereditary unit that determines a particular trait

T 2. _______ Genes carry inherited traits that are passed on from generations to generations. Hundreds of thousands of genes, which make up the traits of human beings, are carried on every chromosome.

Dominant and Recessive traits What happens when one parent carries the trait for blue eyes and one carries the trait for brown eyes? Dominant Stronger trait Recessive Weaker trait

Heterozygous (hybrid): having dissimilar pairs of alleles for any hereditary characteristic Rr Homozygous (purebred) : having identical pairs of alleles for any given pair of heredity characteristics RR, rr

T 4. _______ Dominant genes are stronger genes and recessive genes are weaker.

T DOMINANT RECESSIVE Brown hair Other Color hair Brown eyes Straight hair line Free Earlobes Roll Tongue Second finger shorter then the 4th Hitchhiker’s thumb T 5. _______ In the formation of a new individual where the genes are both recessive and dominant, the dominant will overpower. RECESSIVE Blonde hair Red hair Blue Eyes Widows peak Attached earlobes Can’t roll tongue Interlock hands and right thumb on top No hitchhiker’s thumb

Dominant vs. Recessive widow’s peak Unattached earlobe Short fingers Continuous hairline Unattached earlobe Attached earlobe Short fingers Long fingers Freckles Lack of freckles

Punnett Square

T BB Bb bB bb Wife B Wife b Husband B Husband b Determine the chances of passing on a genetic trait in the following situation: The wife is blue-eyed and carries genes for blue eyes on both of the chromosome pairs. The husband is brown eyed and carries a gene for brown eyes on one of the pairs and a gene for blue eyes on he other one of the pairs. Complete the following grid to determine the chances for each of their children to be born with blue or brown eyes. B = dominant brown gene b = recessive blue gene There is a _____________________ in four chance that the child will have brown eyes and carry a gene for blue eyes. There is a _____________________ in four chance that the child will have blue eyes and carry genes for only blue eyes. 6. _______ It is probable that a dominant brown-eyed mother and a recessive blue-eyed father will have a brown-eyed child. Wife B Wife b Husband B Husband b BB Bb bB bb

Red Hair and blue –green eyes T 7. _______ It is probable that a child can have recessive light colored hair even though both of his parents have dominant dark colored hair. Red Hair and blue –green eyes

Recessive (weaker) genes will not produce the characteristic unless transmitted by both parents.

Gender Determination Females:XX Males: XY Gender is determined by the male

Multiple Births Fraternal Twins: The ovary releases two separate eggs and each is fertilized by a different sperm cell. Can be boy and girl Do not look exactly alike Identical twins A single egg is fertilized and then splits into two Both boys or girls Look very much alike

MULTIPLE BIRTHS

F like siblings. identical 12. _______ Fraternal non-identical multiple births that come from two different eggs will look . like siblings. identical

F 13. _______ Identical multiple births that come from one fertilized egg can be different sexes. will be the same sex.

F 14. _______ are when the ovum splits apart but the separation is not complete. Double jointed twins Conjoined twins

CONJOINED TWINS Conjoined twins result when a fertilized ovum begins to split into two parts, but does not fully complete the process. The babies are joined at whatever location does not complete the splitting process.

Genetic Disorders Medical conditions caused by errors in genes or chromosomes Down syndrome Cystic fibrosis Muscular dystrophy Sickle cell disease Tay- sachs disease PKU

Activity Genetic Gamble

Genetic Counseling Genetic counselors help provide families with the information they need to understand genetic disorders.

Activity: Gene O Gram