GENETICS HEREDITY w GENETICS The study of the

GENETICS & HEREDITY

w GENETICS - The study of the way Humans, animals & plants pass on to their offspring such as: w eye color, hair color, height, body build, blood types, intelligence, gender, etc. w HEREDITY - Characteristics that a child receives from both parents

w 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)

? ? ? ? How many chromosomes are there in each cell? w 46 CHROMOSOMES or 23 PAIRS w How many chromosomes are in Reproductive (egg & sperm) or Germ cells? w 23 CHROMOSOMES w • (combined = the 46 chromosomes)

CELL DIVISION w MITOSIS: Cell divides by copying the DNA cell splits - new cell with normal number of chromosomes (Cell growth & repair) w MEIOSIS: Creates 1/2 sets of chromosomes • Women = 23 Men = 23 Combined = 46

Female Sex Cells XX w Male Sex Cells XY w Baby Girl = XX Baby Boy = XY w (Ovum or Egg) (Sperm) • Conception is the union of an OVUM and the SPERM w Gender is determined by the father! • Someone should have told King Henry VIII!

DOMINATE Gene: More powerful - trait seen in person w RECESSIVE Gene: Weaker and hides in the background. w Trait can only determine when two of them are present - may show up in future generations. w CARRIER: Has a recessive gene that is not visible w SEX-LINKED: Mother passes the recessive X to son • Color-blind male receives the trait from his mother. • The mother is usually not color-blind herself. B = BROWN eyes (dominate) b = BLUE eyes (recessive) w BB = BROWN eyes w bb = BLUE eyes w Bb = BROWN eyes but carry the recessive BLUE eye gene w

MULTIPLE BIRTHS w ZYGOT: the cell that is formed when a sperm fertilized an egg (ovum) w MONOZYGOT: Identical Twins 1 Egg + 1 Sperm • Fertilized ovum splits into 2 identical cells - Always the same gender w DIZYGOT: Fraternal Twins 2 Eggs + different Sperm • Will look different - May be different or the same gender w MULTIPLE BIRTHS: More than 2 • May be identical, fraternal or both - May be different or the same gender w CONJOINED (Siamese) TWINS: Ovum splits apart, but the separation is not completed. Babies are joined at some part of their bodies.

What 4 FACTORS may contribute to Multiple Births? 1) History in the family w 2) Increased hormones naturally w – More than 1 egg released w 3) Fertility Drugs – More than 1 egg released w 4) Age 32 -36 w Likelihood of multiple pregnancies in the United States • Twins: Blacks- 1 in 73 Whites 1 in 93 • Triplets: 1 in 10, 000 • Quadruples: 1 in 620, 000

w Sex - Linked or X - Linked Defect: When an X-gene from the mother is faulty. There is a 50/50 chance of the child inheriting the disorder. w Syndrome: When a group of signs and symptoms occur together and characterize a particular problem. Congenital Malformation: A condition that is present at birth. w Multi-factorial Defects: Interaction of genes with other genes w OR with environmental factors. w Chromosomal Error: The fertilized egg cell that contains chromosomes in an abnormal number, structure or arrangement.

w *Heredity – The passing on of physical or mental characteristics genetically from one generation to another. w *DNA – Deoxyribonucleic acid; a large molecule that contains all the genetic information needed to form and sustain life. w *Cells – Highly organized units that are microscopic and make up all living things.

*Chromosome – A threadlike structure that carries genes. w *Gene – A unit of heredity material. w *Dominant Gene – A gene that overrides the expression of the other gene. w *Recessive Gene – A gene whose expression is overridden by the other gene. w w Examples: Dark hair over blonde hair, curly hair over straight hair, brown eyes over blue eyes.

Which ones are dominant? w a. Dark hair b. Curly hair c. Brown eyes They are all the dominant gene w w XX – Female sex chromosome – Male sex chromosome XY w -When a sperm fertilizes an ovum, a full complement of 46 chromosomes (23 from the father and 23 from the mother) is present in the resulting cell.

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