GENETICS AND YOU define heredity as the passage of genetic instructions from one generation to the next generation.[7.14A]

A long time ago… The first recorded ideas of offspring “inheriting” features from parents... Born: 384 BC Died: 322 BC Aristotle * observed common facial features of family members -basis for artistic styles, etc. * theories included the passing of scars and internal injuries from parent to children

Charles Darwin 1858 Charles Darwin *Announcement of the theory of natural selection members of a population who are better adapted to the environment will survive and pass on their traits. * (1859) Published The Origin of Species. famous text cataloging the many adaptations and variations among same/similar species fueled the (controversial) theory of evolution See Darwin’s Finches!-->

Darwin’s Finches

The science we call Genetics * is the study of heredity - passing of traits from parent to offspring - has more than one theory (“point of view”) --> most common/accepted is Mendelian Genetics Mendelian Genetics is based upon the research of Now credited as the “Father of Genetics”

Mendel is most famous for his experiments with the pea plants ( Pisum sativum ).. Plus, they reproduce quickly AND have a fast LIFE CYCLE Flowering plants can be either selfcross self or cross-pollinated

So What does it all mean to me? First you need to realize you are ½ of your mom and ½ of your dad. One gamete (reproductive cell) is 23 chromosomes for humans ALL other cells in your body have 46 chromosomes It all starts with your conception and the passing of their genes to you.

Female egg cell …with half of “mom” DNA Male sperm cell..with half of “dad” DNA + First you need FERTILIZATION They become one …fertilized cell with a complete Set of DNA

FERTILIZATION, Continued The cell then begins to divide Your first two months!

Chromosomes!!!..at this point all present and accounted for Humans should have 46 chromosomes The fertilized egg cell is now a ZYGOTE

tiny threadlike structures in nucleus of cell * contain sections of DNA = GENES *humans---> ,000 genes

How does it all fit together? Nucleus Chromosomes DNA Genes Cell

4. Some genes are dominant, while others are recessive. “Stronger” traits are called dominant. “Weaker” traits are called recessive. Geneticists use symbols (letters) to represent the different forms of a gene.

Dominant traits are represented by a capital letter. Yellow seeds are dominant…….. Y

Recessive genes (for the same trait) are represented by THE SAME lower case letter. Green seeds are recessive… lower case y. Dominant (yellow) = Y Recessive (green) = y

In pea plants, tall is dominant over short. The letter used to represent the tall gene is T. The short gene is represented by t. Tall =T Short = t Tall =T Short = t

In humans, brown eyes are dominant over blue. Brown = B Blue = b

5. Dominant genes hide recessive genes when both are inherited by an organism. Y + y = yellow seeds (yellow is dominant) T + t = tall plant (tall is dominant) B+ b = brown eyes (brown is dominant)

A PUREBRED organism has two of the same genes for a trait. TT = purebred TALL tt = purebred SHORT

A HYBRID organism has two different genes for a trait. Tt = hybrid TALL (tall is dominant.) Bb = hybrid for black feathers (black is dominant.)

Will a hybrid human with the genes Bb have brown or blue eyes? Bb = Brown eyes The dominant gene (brown), will be expressed in a hybrid.

Why must all blue eyed people be PUREBRED for that trait? If the dominant gene is present, it will always be expressed. The only possible gene combination for blue eyes is bb.

These basic laws of inheritance control the traits of all living organisms on Earth.

Can behavior be inherited too? Scenario 1 – Chimpanzee A has a very good technique for getting a banana out of a tree. This chimpanzee has an offspring which is taken away and raised in isolation. The offspring is not able to get the banana out of the tree. Scenario 2 – Bird A has a very specific way that it makes its nest. The bird has several offspring. One of the offspring is taken away and raised in isolation. The offspring begins making a nest in the exact same way as its parent.

Scenario 1 is a learned behavior that a parent would pass on through teaching. Scenario 2 is an example of a behavior being inherited genetically Can you think of any examples of INHERITED behavior?