DNA from this type of cells is passed to offspring

 sperm cell, egg cell

nerve cell, bone cell, muscle cell

Humans have ____ total chromosomes in each body cell

Offspring receives ____ chromosomes from each parent

chromosomes 1-22

Contain genes not directly related to sex of organism

eye color genes, hair color genes

chromosomes X and Y

Contain genes that control development of sexual characteristics

sperm production genes

Sex chromosomes determine whether someone is male or female

XX

Sex chromosomes determine whether someone is male or female

XY

a pair of chromosomes that carry the same type of information (genes) but are not genetically identical

process of creating offspring (children) from two parents

the fusion (union) of an egg cell and a sperm cell, which creates a fertilized egg

a fertilized egg

a cell with 2 sets of chromosomes (2n)

Zygotes and all body cells are ______

In humans, the diploid number is

a cell with 1 set of chromosomes (n)

In humans, the haploid number is

Only sperm cells and egg cells are ______

Each pair of chromosomes has the same structure and holds the same genes.

Every female has ____ pairs of homologous chromosomes.

Every male has ____ pairs of homologous chromosomes

makes exact copies of cells

o create a diploid zygote (fertilized egg) with 46 chromosomes, every sperm cell and egg cell must be ________

a type of cell division that divides one diploid cell into four haploid cells

Meiosis has ___ round(s) of divisions

homologous chromosomes separate

sister chromatids separate

DNA is replicated (copied) during S stage

Homologous chromosomes find each other and form a union called a tetrad (4 chromatids)

Crossing Over mixes up the DNA, which adds to genetic variation (differences)

an exchange of genes between tetrads

Tetrads (homologous chromosomes) line up at the middle randomly;

also known as the Law of Independent Assortment (adds to genetic variation)

Tetrads (homologous chromosomes) are pulled apart and sister chromatids move to poles; also known as the Law of Segregation (separation)

Nuclear envelope and nucleolus reappear; Cytokinesis occurs.

Nuclear envelope and nucleolus disappear

Sister chromatids line up at the middle

Sister chromatids are pulled apart

The end results of meiosis

Meiosis by itself makes sperm and eggs

the cells made during meiosis that do not become the egg

4 sperm are produced

(Sperm are composed of mitochondria, a flagellum, and a head which contains DNA)

1 large egg and 3 polar bodies are formed

Takes place only at certain times in an organism's life cycle

Involved in sexual reproduction

Results in haploid cells

Produces genetically unique cells

Involved in asexual reproduction

Results in diploid cells

Takes place throughout an organism's life cycle

 In humans, with 23 pairs, there are over ______ possible combination of genes that the cells can have.

where sperm are produced

a sac which encloses a testis

a tube that transports both urine and sperm to outside of body

where eggs are produced

where fertilization occurs

where fetus grows and develops

What allows sperm cells to enter the egg cell

Once one sperm cell enters, the egg changes and more sperm can enter

the first diploid cell (day 1)

a solid ball of cells (day 4-5)

A hollow ball of cells that implants onto the wall of the uterus (days 5-6)

the formation of three germ layers which will ultimately differentiate into body parts (day 7)

internal layer (organ cells, etc.)

middle layer (muscle cells, blood cells etc.)

external layer (skin cells, brain cells, pigment cells, etc.)

organ where nutrients and waste are exchanged (passed) between mother and fetus

[allows a mother to nourish (feed) the developing fetus for 9 months; no blood is shared]

cells specialize and get jobs

rapid division of cells in early embryo

joining of sex cells

creates sex cells

Important steps to creating and developing human life