A Closer Look at Conception Chapter 3 Section 2

The Genetic Package Nature– Genetics/ Heredity Physical build Skin color Hair texture/color Color/shape of eyes Shape/size of ears, hands, and feet Blood type

Moment of Conception _____ chromosomes Each contains genes 23 from ______ (father) 23 from mother (_____) Each contains genes Determine characteristics ____ genes for each characteristic One from mom, one from dad

Dominant Vs. Recessive When both genes ________, the child will receive that trait Ex: both parents pass the blue-eyed trait, child will have blue eyes When different, the _________ trait will win Ex: brown-eyed trait (D) vs blue-eyed trait (R): the child will have _______ eyes

Gene Pool How are the genes picked? Create an _________ individual Matter of _________ Create an _________ individual Siblings will look similar but ________________ __________________

How Does it Work??? What does this mean? 1 in 4 chance of blue eyes BB: 2 dominant= brown Bb: brown bb: Blue eye 1 in 4 chance of blue eyes

Sex Determination Gender is determined by 2 chromosomes ____________ The _____ contains ___ Sperm – __________ During fertilization XX= ______________ XY= ______________

Multiple Births Beginning of _____________the cell divides into 2 Continue until they divide into millions Sometimes the growing mass divides into 2 Grow into separate ______________ Produces _____________ twins

Identical Twins Dividing mass of cells Form 2 embryos Same ______ Very similar characteristics Due to the same _______ and same _________ If the split is not complete- ___________ twins occurs

Fraternal Twins Results when 2 eggs are released at the _________________ Each fertilized by different _________ Not always the same sex No more alike than ordinary ___________

Multiple Births In more than 2 births: Example: triplets Can be identical, fraternal, or both Example: triplets One ovum could divide into 3 parts (_________) 2 eggs are fertilized and one splits (2 identical & one fraternal) ______ eggs released at once (_____________)

Genetic Worksheet