Human GeneticsHeredity- the passing of characteristics from parents to offspring

The process begins in complex structures called chromosomes.

Chromosomes- structure within nuclei of cells that carry information about hereditary traits.

Genes- specific information coded in the chromosomes which consist of segments of DNA molecules.

Let’s break it down…What’s the deal with chromosomes and genes?

How many are we talking about here? Spiral staircase?No, it’s DNA!

How many chromosomes are in each sex cell (sperm/egg)?

Normal Karyotypeshttp://www.ornl.gov/sci/techresources/Human_Genome/posters/chromosome/chooser.shtml

What determines the sex of the baby?

Why?

Gene PairingWhy do we look like we do?

The genes can be in one of two forms:

Dominant- show up in offspring when present

*symbolized by capital letters, ex: C

*dark hair and eyes, curly hair, full lips

Recessive- only shows up in offspring if two copies are present

*symbolized by lower case, ex. c

*light hair and eyes, straight hair, thin lips

Every person inherits two genes for every trait, one from mom and one from dad.

Extra ChromosomesCan you find them?

*Language delay*Lack of body & facial hair*Not as physically strong*Slight breast enlargement*May be infertile

Missing or Deleted ChromosomesWhere are they supposed to be?

Monotone, weak, cat-like cry Small head (microcephally) High palate Round face Small receding chinWidely spaced eyesLow set ears Folds of skin over the upper eyelid

Short statureLack of ovarian developmentWebbed neckProne to cardiovascular, kidney, andthyroid problemsCan be infertile

Amniocentesis

*A test in which fluid is taken from the amniotic sac surrounding the fetus to determine sex and many abnormalities

*Can be done at 16-20 weeks after fertilization

Chorionic Villi Sampling (CVS)• A small piece of membrane is removed from the

chorion (a layer of tissue that develops into the placenta)

• Done around 8th week of fetal development

Ultrasound

Sound waves are directed at the female’s abdomen & reflected onto a screen to form an image of the fetus

Can determine position of fetus, # of fetuses, sex of fetus,& deformity