Genetics & Heredity Genetics & Heredity

Sex CellsSex Cells

Female Female Ovum or EggOvum or Egg

Male Male Sperm Sperm

ChromosomesChromosomes

A.A. Chromosomes are Chromosomes are rod shaped chemical rod shaped chemical compounds that compounds that carry genetic coding.carry genetic coding.

B. The genetic coding B. The genetic coding transmits transmits characteristics from characteristics from the parent to the the parent to the child.child.

ChromosomesChromosomes

C.C. Found in both sperm and ovumFound in both sperm and ovum

D.D. Every cell has 23 pairs of Every cell has 23 pairs of chromosomes, 46 totalchromosomes, 46 total

E.E. Sperm and ovum contain 23 Sperm and ovum contain 23 chromosomes each.chromosomes each.

GenesGenes

A.A. There are There are hundreds of hundreds of genes on each genes on each chromosome. chromosome.

B. They carry B. They carry individual, individual, specific traits.specific traits.

GenesGenes

C.C. They are the They are the building blocks building blocks of of chromosomes.chromosomes.

D. They are bead-D. They are bead-like structures.like structures.

GenesGenes

E. E. They can be They can be dominant dominant (stronger) (stronger) genes which genes which produce the produce the characteristic characteristic in the in the individualindividual

Blue Eyes

GenesGenes

F. F. They can be They can be recessive recessive (weaker) genes (weaker) genes which do not which do not produce the produce the characteristic characteristic unless unless transmitted by transmitted by both parents.both parents.Red Hair

Genetic InformationGenetic Information

A.A. An XY An XY combination will combination will produce a male produce a male child.child.

B.B. An XX An XX combination will combination will produce a female produce a female child.child.

Genetic InformationGenetic Information

C. The father C. The father determines determines the sex of the sex of the child. the child.

Genetic InformationGenetic Information

D.D. Sex linked Sex linked defects defects

Female is Female is carrier but carrier but defect appears defect appears in male.in male.

Color Blindness

Can you trace a line from one x to the other

x?

MULTIPLE BIRTHSMULTIPLE BIRTHS

FRATERNAL TWINSFRATERNAL TWINS

Form when Form when two eggstwo eggs are are

released at the same time released at the same time andand

each is each is fertilizedfertilized. They grow . They grow

side by side in the uterus. side by side in the uterus.

Because they are the result of Because they are the result of

two different two different ovumovum and and

spermsperm they are no more alike they are no more alike

in terms of heredity than in terms of heredity than

other siblings. They may be other siblings. They may be

of opposite of opposite sexes.sexes.

IDENTICAL TWINSIDENTICAL TWINS

A A fertilized eggfertilized egg starts growing by starts growing by

dividing into dividing into two cells.two cells. These cells These cells

continue to divide. Sometimes, continue to divide. Sometimes,

the cell mass splits in half soon the cell mass splits in half soon

after fertilization. Each cell mass after fertilization. Each cell mass

grows into a separate grows into a separate embryoembryo. .

They are always the They are always the same sexsame sex, and , and

have very similar characteristics have very similar characteristics

because they began as one zygote.because they began as one zygote.

TRIPLETSTRIPLETS

* Triplets can occur through * Triplets can occur through several combinations. several combinations. ThreeThree separate ovum could be separate ovum could be releasedreleased and and fertilizedfertilized. .

* Two ovum could be released, * Two ovum could be released, fertilized and then one ovum fertilized and then one ovum splitssplits into separate into separate embryoembryo, , resulting in a set of identical resulting in a set of identical twins and one fraternal twin.twins and one fraternal twin.

* One * One ovumovum could split into could split into twotwo parts resulting in identical parts resulting in identical triplets triplets

CONJOINED TWINSCONJOINED TWINS

Conjoined twins result Conjoined twins result when when

a a fertilizedfertilized ovum begins to ovum begins to

split into split into twotwo parts, but parts, but does does

not fully not fully completecomplete the the

process. The babies are process. The babies are joined joined

at whatever location does at whatever location does

not not completecomplete the the splittingsplitting

process.process.

THE END!!THE END!!