Genetics & heredity

GENETICS & HEREDITY

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

• CELL: Basic unit of all living matter (Adult = over 10 trillion cells)

• NUCLEUS: Central point of cell / contains genetic coding for maintaining life systems and issuing commands for growth & reproduction

• CYTOPLASM: Substance of a cell outside of the nucleus

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

CELL DIVISION

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

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

• DOMINATE Gene: More powerful - trait seen in person
• RECESSIVE Gene: Weaker and hides in the background. Trait can only determine when two of them are present - may show up in future generations.
• CARRIER: Has a recessive gene that is not visible
• 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)
• BB = BROWN eyes
• bb = BLUE eyes
• Bb = BROWN eyes but carry the recessive BLUE eye gene

MULTIPLE BIRTHS

• ZYGOT: the cell that is formed when a sperm fertilized an egg (ovum)
• MONOZYGOT: Identical Twins 1 Egg + 1 Sperm
• Fertilized ovum splits into 2 identical cells - Always the same gender
• DIZYGOT: Fraternal Twins 2 Eggs + different Sperm
• Will look different - May be different or the same gender
• MULTIPLE BIRTHS: More than 2
• May be identical, fraternal or both - May be different or the same gender
• 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
• 2) Increased hormones naturally
• More than 1 egg released
• 3) Fertility Drugs
• More than 1 egg released
• 4) Age 32-36
• 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

• 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.
• Syndrome: When a group of signs and symptoms occur together and characterize a particular problem.
• Congenital Malformation: A condition that is present at birth.
• Multi-factorial Defects: Interaction of genes with other genes OR with environmental factors.
• Chromosomal Error: The fertilized egg cell that contains chromosomes in an abnormal number, structure or arrangement.