THE HUMAN LIFE THE HUMAN LIFE CYCLECYCLE

CELLS DIVIDING IN AN CELLS DIVIDING IN AN EARLY EMBRYOEARLY EMBRYO

THE THE CELL CYCLECELL CYCLE = = THE DAY-TO-DAY LIFE THE DAY-TO-DAY LIFE OF A CELLOF A CELL

CELL NUCLEICELL NUCLEI

CHROMOSOMESCHROMOSOMES IN THE CELL NUCLEUS IN THE CELL NUCLEUS- CHROMOSOMES ARE MADE OF DNA- CHROMOSOMES ARE MADE OF DNA

CHROMOSOMES CHROMOSOMES DUPLICATE BEFORE DUPLICATE BEFORE CELLS DIVIDECELLS DIVIDE

A DIVIDING CELLA DIVIDING CELL

CELL DIVISION - CELL DIVISION - MITOSISMITOSIS

CELL DIVISION - CELL DIVISION - MITOSISMITOSIS

INTERPHASEINTERPHASE

PROPHASEPROPHASE

METAPHASEMETAPHASE

ANAPHASEANAPHASE

TELOPHASETELOPHASE

CELL DIVISION - CELL DIVISION - MITOSISMITOSIS

SKIN CELLS ARE SKIN CELLS ARE CONSTANTLY DIVIDINGCONSTANTLY DIVIDING

BREAST CELLSBREAST CELLSNORMAL CANCEROUSNORMAL CANCEROUS

COMPARISON OF COMPARISON OF MITOSIS AND MEIOSISMITOSIS AND MEIOSIS

MEIOSISMEIOSIS – MEIOSIS I – MEIOSIS I

MEIOSIS – MEIOSIS IIMEIOSIS – MEIOSIS II

DOWN’S SYNDROMEDOWN’S SYNDROME

Characteristics of Down’s Characteristics of Down’s SyndromeSyndrome There are over 50 clinical signs of Down syndrome, but it is rare to find all or even most of them in There are over 50 clinical signs of Down syndrome, but it is rare to find all or even most of them in

one person. Some common characteristics and down syndrome facts include:one person. Some common characteristics and down syndrome facts include:

Poor muscle tonePoor muscle tone

Slanting eyes with folds of skin at the inner corners (called epicanthal folds)Slanting eyes with folds of skin at the inner corners (called epicanthal folds)

Hyperflexibility (excessive ability to extend the joints)Hyperflexibility (excessive ability to extend the joints)

Short, broad hands with a single crease across the palm on one or both handsShort, broad hands with a single crease across the palm on one or both hands

Broad feet with short toesBroad feet with short toes

Flat bridge of the noseFlat bridge of the nose

Short, low-set earsShort, low-set ears

Short neckShort neck

Small headSmall head

Small oral cavitySmall oral cavity

Short, high-pitched cries in infancy. Short, high-pitched cries in infancy.

MATERNAL AGE vs. MATERNAL AGE vs. RATE OF DOWN’S RATE OF DOWN’S

SYNDROMESYNDROME

KARYOTYPINGKARYOTYPING = a technique to visualize the = a technique to visualize the chromosomes and number of chromosomes in a chromosomes and number of chromosomes in a dividing celldividing cell

HUMAN FEMALE HUMAN FEMALE KARYOTYPEKARYOTYPE

HUMAN MALE HUMAN MALE KARYOTYPEKARYOTYPE

DOWN’S SYNDROME DOWN’S SYNDROME KARYOTYPEKARYOTYPE

COMPARISON OF COMPARISON OF MITOSIS AND MEIOSISMITOSIS AND MEIOSIS

NONDISJUNCTIONNONDISJUNCTION = failure of = failure of chromosomes to separate chromosomes to separate during meiosisduring meiosis

FERTILIZATION AFTER FERTILIZATION AFTER NONDISJUNCTION IN NONDISJUNCTION IN AN EGGAN EGG

AmniocentesisAmniocentesis = sampling the = sampling the amnionic fluid around the fetus amnionic fluid around the fetus for fetal cellsfor fetal cells

Chorionic Villi SamplingChorionic Villi Sampling = = sampling the placental cells sampling the placental cells which have the same DNA as which have the same DNA as fetal cellsfetal cells

KLINEFELTER’S SYNDROMEKLINEFELTER’S SYNDROME (XXY) = due to nondisjunction (XXY) = due to nondisjunction of sex chromosomesof sex chromosomes

Due to fertilization with an egg or sperm that has an extra X chromosome

TURNER’S SYNDROMETURNER’S SYNDROME (XO) = (XO) = due to nondisjunction of sex due to nondisjunction of sex chromosomeschromosomes

Due to fertilization with an egg or sperm lacking an X chromosome

Proteins Perform Most Proteins Perform Most Cell FunctionsCell Functions