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HUMAN GROWTH AND DEVELOPMENTSSYM 1023
HEREDITERY INFLUENCES ON DEVELOPMENT
PRINCIPLES OF HEREDITERY TRANSMISSION
We must start at conception to understand the working of hereditery.
Ovum released by a women’s ovary and on its way to the uterus via the fallapion tube .
Then fertilized by a man’s sperm.
THE GENETIC MATERIAL
• Sperm cell begins to disintegrate and releasing genetic material.
• Ovum also release genetic material.• New cells nucleus (zygote) forms which
contain hereditery • Zygote is about 1/20th the size of the head
of pin.
What hereditery material is present in human zygote?
• Hereditery information provided by the father’s sperm n the mother’s ovum.
• Contains 46 elongated threadlike bodies called chromosomes.
CHROMOSOMES STRUCTURE
MALE OR FEMALE?
MALE
Genetic XY
FEMALE
M
Genetic XX
GROWTH OF THE ZYGOTE AND
PRODUCTION BODY CELLS
Zygote moves through fallopian tube
Towards uterus
Begins to replicate itself through process of mitosis
Zygote divides into two cells, then become four, become eight, become sixteen and so on.
New cells with has identical 23 pairs of chromosomes(46 in all).
Same genetic material as the original cell.
Makes up muscles, bones, organs and other bodily structures.
PRODUCTION OF GAMETES THROUGH MEIOSIS
Male germ cells in the testes produce
sperm.
Female germ cells in the ovaries produce
ova.
Undergo meiosis process.
Crossing over takes places
DOMINANT AND RECESSIVE TRAITS IN HUMAN HEREDITERY
DOMINANT TRAITS RECESSIVE TRAITSDark hair Blown hair
Full head of hair Pattern baldnessCurly hair Straight hair
Facial dimples No dimplesNormal vision Color blindness
Normal blood clotting HaemophiliaNormal blood cells Sickle-cell anemia
EXAMPLE:
HEREDITERY UNIQUENES: MULTIPLE BIRTH
• Two people share a genotype.• A zygote split into separate but identical cells.• Called as monozygotic ( or identical twins) because
developed from a single zygote and have identical genes.• Occurs in 1 of of every 125 births.
SOURCES OF CONGENITAL DEFECTSCongenital defects
Inherited defects Environmental defects
Chromosomal abnormalities
Complications of the birth process
Prenatal exposures to damaging effects
Too many 0r too few
chromosomes
Broken or damaged or
chromosomes
Genetic abnormalities
Recessive genes for a
disorder
Dominant genes for a
disorder
Genetic mutation
Four common sex chromosomes abnormalities
Female abnormalities
TURNER’S SINDROME( XO)
1 in 2500 births
POLY-X or “SUPERFEMALE”
SYNDROME( XXX, XXXX, XXXXX )
1 in 1000 births
Male abnormalities
KLINEFELTER’S SYNDROME( XXY, XXXY )
1 in 750 births
SUPERMALE SYNDROME( XYY, XYYY, XYYYY )
1 in 1000 births
DOWN SYNDROME
Once in every 800 births
Extra at 21st chromosomes
Mentally retarded-IQ average is 55
-normal children is 100
characteristicsSlopping forehead, protruding tongue,
short stubby
Congenital eye, ear and heart defects
Slightly flattened nose, and almond-shaped nose.
MAJOR RECESSIVE
HEREDITERY DISEASES
Diabetes
hemophilia
Sickle-cell anemia
Tay-Sachs disease
Phenylketonuria ( PKU )
Duchenne-type
muscular dystrophy
Cystis fibrosis (CF)