Science Chpt 4 Sect 1 & 2

cell division

increase the number of cells and causes many-celled organisms to grow

life cycle

cells have periods of formation, growth, development and death which is called the _____________

interphase

a cell cycle begins with ______________

MITOSIS

INTERPHASE PROCEEDS THE STEPS OF ____________

growth and development

In mitosis most of the life of any eukaryotic cell is spent in a period of ______________________

chromosomes

structure in the nucleus that contains hereditary material-DNA

cell division

during interphase, a cell duplicates its chromosomes or hereditary material and prepares for _______________

mitosis

process in which the nucleus divides to form TWO IDENTICAL NUCLEI with identical chromosomes

divide

Body cells _______ through Mitosis.

prophase
metaphase
anaphase
telophase

what are the 4 phases of mitosis in order:

Prophase

- nucleolus and nuclear membrane disintegrate
-centrioles move to opposite ends of the cell

Metaphase

-pairs of chromatids line up across the center (middle) of the cell
-spindle fibers stretch across the cell (spindle fibers are also found in plant cells)

Anaphase (away)

- each centromere divides
-each pair of chromatids separates and moves to opposite ends of the cell
- the separated chromatids are now called identical chromosomes

Telophase

-spindle fibers disappear and a new nucleus forms
- then the cytoplasm separates and 2 new cells are formed

Results of mitosis:
46
23

each cell in your body, except for sex cells, has the same number of ____ chromosomes, which is ____ pairs of chromosomes

worn out or damaged cells

Mitosis allows growth and replaces ___ ____ or ____ ___

Asexual reproduction

a new organism is produced from one parent organism

fission

divides into two identical organisms, happens with an organism with no nucleus
Example: bacteria

budding

a small, exact copy of the adult grows from the body of the parent
Example: Hydra

regeneration

in __________________, a whole new organism grows from each piece of the parent
Example: sponge

Sexual reproduction

Two sex cells, usually an egg and a sperm, come together a new organism is produced

Fertilization

The joining of an egg and a sperm, generally from two different organisms of the same species

male

Sperms are formed in the ______ reproductive organs.

female

Eggs are formed in the ______ reproductive organs.

Zygote

A cell that forms from fertilization is a _________

Mitosis

Following fertilization, ___________ begins and a new organism develops

Meiosis

A nuclear division that forms sex cells

nucleus

Meiosis consist of 2 divisions of the _____

In meiosis 1 (one)

the nucleus divides and produces two new cells with Same number of chromosomes in each.

In meiosis 2 (two)

the nuclei divides and produces four new cells with half the number of chromosomes of the original nucleus

Diploid

Body cells are ___________, because they have 23 pairs of similar chromosomes. (46)

Haploid

Sex cells are ___________ because they have 23 single chromosomes

23
46

A sex cell has ____ single chromosomes so that when it joins another sex cell, the two sets of single chromosomes can pair up and produce an organism with ____ chromosomes and unique traits