Download 4.01 Heredity - Catawba County Schools

What are multiple births?
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GENETICS - The study of the way animals
& plants pass on to their offspring such as:
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eye color, hair color, height, body build, blood types,
intelligence, gender, etc.
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HEREDITY - Characteristics that a child
receives from both parents
????????
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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
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MEIOSIS: Creates 1/2 sets of chromosomes
• Women = 23
Men = 23
Combined = 46
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Female Sex Cells XX
Male Sex Cells
XY
Baby Girl = XX Baby Boy = XY
(Ovum or Egg)
(Sperm)
• Conception is the union of an OVUM and the SPERM

Gender is determined by the father!
• Someone should have told King Henry VIII!
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DOMINATE Gene: More powerful or strongest gene- 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
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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.
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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

Identical Twins – when a
fertilized egg splits into
two
• Fertilized ovum splits into 2
identical cells - Always the
same gender

Fraternal Twins - when
2 eggs are released and
fertilized at the same time
• Will look different - May be
different or the same gender
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
March 20: Agenda

Goal: Understand
environmental and
hereditary influences
on prenatal
development and longterm effects on health
of children.

Journal 11:
In your own words; what
is a birth defect, what
are twins and the two
types of twins we
discussed ( how does
this happen) what are
the 4 factors that
contribute to a birth
defect?
Environmental Influences on
Birth Defects

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Inadequate nutrition of mother
Exposure to diseases or infections
during pregnancy
Harmful substances consumed during
pregnancy
Environmental Influences on
Birth Defects
Inadequate nutrition of mother
Stunted
brain development of baby
Leads to mental retardation
Environmental Influences on
Birth Defects
Exposure to diseases or infections during
pregnancy

Rubella, or German Measles, can cause blindness,
deafness, heart disease, and mental retardation
 Toxoplasmosis, can cause hearing loss, learning
disabilities and death; found in cat litter and some
raw meats
 Chicken pox, scarring of babies’ skin, limb
defects, eye problems, and miscarriage
 STDs can be passed to unborn child and lead to
serious illness, physical disabilities, or death
Environmental Influences on
Birth Defects
Harmful substances consumed during pregnancy
 Nicotine from smoking tobacco or secondhand
smoke
 Smaller babies
 Miscarriages and premature births
 Respiratory infections or allergies
Environmental Influences on
Birth Defects
Harmful substances consumed during
pregnancy
 Alcohol can cause fetal alcohol syndrome
(FAS)
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20% of infants die
Facial deformities, delayed physical growth, heart defects, and
hyperactivity
Mental retardation or disabilities
Poor coordination
Difficulty controlling behavior
Environment Influences of Birth
Defects
Harmful substances consumed while pregnant
 Drugs
Over-the-the counter drugs
Drug addiction
Long-term learning and behavioral problems
Risk of miscarriages
Congenital heart problems
Environmental Influences on
Birth Defects
Exposure to hazards during pregnancy
 Chemicals
 X-rays
 Toxoplasmosis – extreme high blood
pressure
Environmental Influences on
Birth Defects
Accidental injuries
 Cerebral palsy caused
by damage to brain
before, during, or
shortly after birth
 Falls lead to a variety
of complications
Hereditary Influences on
Birth Defects
Dominant genes?
Recessive genes?
Can you explain the difference?
Hereditary Influences on
Birth Defects
1. Defective recessive genes inherited from both parents
•
•
•
Cystic fibrosis
Tay-Sachs disease
Sickle cell anemia
2. Defective dominant gene inherited from one parent
•
•
•
•
Hemophilia
Huntington’s disease
Duchenne muscular dystrophy
Color blindness
3. Errors in chromosomes
•
Down syndrome
Tay-Sachs

Tay-Sachs disease is an
untreatable disorder that is
always fatal. Children
born with Tay-Sachs
appear normal at birth but
lack an enzyme needed to
break down certain fats.
The fats build up and
destroy brain and nerve
cells, leading to rapid
mental and physical
deterioration and death in
early childhood.
Combined Influence of Heredity and
Environment Birth Defects


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Drugs + virus = heart defect
Cleft lip/cleft palate
Spina Bifida – reduce risk by taking folic
acid
Individual Activity
In the blanks place an H if the factor is
influenced by heredity, an E if the factor is
environment, and B if it is both.
Case Study : Partner Activity
Read case study and list the various
influences in the correctly column
Scrapbook Page # 7
Family Tree

Create your family tree.

Begin with your grandparents and add
on all your family members, include eye
color and hair color.
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BE NEAT!
Scrapbook Page 8
TWINS
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Your twins:
Will they boys, girls, both
Will they be Identical or Fraternal and why?
Tell me what you will have to do to prepare
for them….childcare choice etc…
Draw them!!