Download forming a new life - Jess Roel Q. Pesole

12/7/2013
FERTILIZATION
FORMING A NEW
LIFE
Prepared by:
Jess Roel Q. Pesole
MULTIPLE BIRTHS
GENETIC PROCESS
GENETIC PROCESS
GENETIC PROCESS
CELL DIVISION
Mitosis – two new cells are formed, each containing
the same DNA as the original cell
- nonsex cells divide through this process
Meiosis – two new cells are formed, but each
contain half the chromosomes of the original cell
- gametes (sperm and egg cells) divide through
this process
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WHAT DETERMINES SEX?
WHAT DETERMINES SEX?
MOTHER
FATHER
X
X
X
Y
Contains
SRY gene
(for
maleness)
GIRL
BOY
SEX CHROMOSOMES (2)
AUTOSOMES (44)
PATTERNS OF GENETIC
TRANSMISSION
PATTERNS OF GENETIC
TRANSMISSION
Genotype
Genetic makeup
Phenotype
Observable characteristics
Allele
Two or more alternative forms of a
gene that can occupy the same
position on paired chromosomes
and affect the same trait
PATTERNS OF GENETIC
TRANSMISSION
GENETIC PRINCIPLES
Mother’s genotype: Bb
Father’s genotype: Bb
B sperm
B ova
b ova
BB
Homozygous dominant
Bb
Heterozygous
b sperm
Bb
Heterozygous
bb
Homozygous recessive
B – brown eyes allele b – non-brown eyes allele
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GENETIC PRINCIPLES
ABNORMALITIES
Polygenic Inheritance - Traits are inherited due to
interaction of several genes
Multifactorial transmission – Traits are expressed
due to environment and genetic factors
Defects due to
Dominant or
Recessive
Inheritance
Sex-linked inheritance – Mutated gene (altered
segment of DNA) is carried on the X chromosome;
more likely among males who only have one X
chromosome
ABNORMALITIES
ABNORMALITIES
Sex-linked
Inheritance
Example:
Hemophilia
NOTE:
Most mutated
genes are
recessive.
ABNORMALITIES
CHROMOSOME ABNORMALITIES
Down
syndrome
Name
Pattern
Characteristics
Down
syndrome
Extra 21st
chromosome
Mental retardation and physical
abnormalities
Klinefelter
syndrome
XXY
Physical abnormalities among
males
Fragile X
syndrome
Abnormal X
chromosome
Mental retardation and learning
disabilities
Turner
syndrome
X0
Mental retardation, sexual
underdevelopment
XYY
syndrome
XYY
Above-average height; tendency
for low IQ
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CHROMOSOME ABNORMALITIES
KLINEFELTER SYNDROME
FRAGILE X SYNDROME
TURNER SYNDROME
HEREDITY-ENVIRONMENT
INTERACTION
Behavioral genetics – focuses on how much
heredity and environment affect certain traits
Methods of study
1.
Family study – common traits among family
members
2.
Twin study – identical and same-sex fraternal
twins
3.
Adoption study – similarities between adopted
children and (a) their adoptive families, and (b)
their biological families
STAGES OF PRENATAL DEVELOPMENT
GENE-LINKED ABNORMALITIES
Phenylketonuria (PKU)
- inability to metabolize the amino acid
phenylalanine (found in protein-rich foods);
can cause mental retardation and
hyperactivity; autosomal recessive
Huntington’s disease
– central nervous system deteriorates; can
cause mental deterioration; autosomal
dominant
HEREDITY-ENVIRONMENT
INTERACTION
a.
b.
c.
Genotype-Environment Interaction
Genotype-Environment Correlation
Passive – environment influences, child has no
control
Reactive/Evocative – child’s traits evoke responses
from environment
Active – niche-picking; child actively seeks
experiences consistent with one’s genetic
tendencies
STAGES OF PRENATAL DEVELOPMENT
Germinal stage - first two weeks after conception
- Creation of the fertilized egg
- Mitosis (rapid cell division) takes place
- Ball of cells turn into a blastocyst, consisting of three
layers:
a.
Ectoderm – will become the skin and nervous system
b.
Endoderm – will become the digestive and respiratory
system
c.
Mesoderm – will become the muscle and skeletal
system
- Implantation – attachment of zygote to uterine wall
1.
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STAGES OF PRENATAL DEVELOPMENT
STAGES OF PRENATAL DEVELOPMENT
1.
Germinal stage
- Life-support
systems/organs for the
embryo:
a.
Amniotic sac
b.
Placenta
c.
Umbilical cord
2.
STAGES OF PRENATAL DEVELOPMENT
STAGES OF PRENATAL DEVELOPMENT
Embryonic stage – two to eight weeks after
conception
- organs and major body systems develop rapidly
- Organogenesis – process of organ formation during
first two months of conception
- Spontaneous abortion (miscarriage) – expulsion of
embryo/fetus that could not survive outside the
womb; usually within first trimester
Fetal stage – eight weeks after conception until
birth
- marked by appearance of first bone cells
- fetus grows to 20 times its previous length
- actively moves arms, legs, mouth, and head
- finishing touches (fingernails, toenails) develop
- fetus becomes viable (able to survive outside the
womb) by the end of the seventh month
3.
STAGES VERSUS TRIMESTERS
GERMINAL STAGE
(first two weeks after conception)
FIRST TRIMESTER
(first 3 months)
EMBRYONIC STAGE
(two to eight weeks after conception)
FETAL STAGE
(eight weeks after conception until
birth)
HAZARDS TO PRENATAL
DEVELOPMENT
1.
SECOND TRIMESTER
(3-6 months)
2.
3.
THIRD TRIMESTER
(6-9 months)
Teratogen – any agent that can potentially cause
birth defects or abnormalities
Factors that influence the severity of a teratogen
Dose – the greater the dose, the greater the effect
Genetic susceptibility – linked to the genotype of
the mother and the child
Time of exposure – more damage is done when
they occur at critical periods of development
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HAZARDS TO PRENATAL
DEVELOPMENT
1.
2.
3.
Forms of Teratogens
Nutrition and Maternal Weight – children born to
malnourished and overweight mothers
- lack of folic acid (a B-complex vitamin) is
related to defects in nervous system
Physical Activity and Strenuous Work – moderate
exercise is good; demanding workload poses a risk
Emotional States and Stress – intense emotions
may lead to physiological changes that may affect
her fetus
HAZARDS TO PRENATAL
DEVELOPMENT
5.
5.
6.
7.
HAZARDS TO PRENATAL
DEVELOPMENT
4.
Forms of Teratogens
Drug Intake
a.
Prescription and nonprescription drugs – includes
antibiotics, antidepressants, diet pills, aspirin
b.
Alcohol – may lead to a child with fetal alcohol
syndrome (FAS)
c.
Nicotine
d.
Caffeine
e.
Cocaine, Methamphetamine (shabu), Marijuana,
Heroin
HAZARDS TO PRENATAL
DEVELOPMENT
Forms of Teratogens
Maternal illnesses
a.
HIV/AIDS
b.
Rubella (German measles)
Maternal age – (A) adolescent mothers and (B)
mothers who are 35 years old and above are at
risk
Paternal factors
Environmental hazards
PRENATAL TESTS
Anencephaly
PRENATAL TESTS
Ultrasound
Maternal blood screening
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