BIO120 Chpt 7 Cell Division, Mitosis & Sexual Reproduction: Meiosis

why does cell division takes place?

- Cells die and need to be replaced.- Cells can only grow so large before they become dysfunctional.- There are times in which an organism needs quantities of new cells above "replacement" level.- The duplication of DNA (replication), which must occur before a cell divides- Cell division occur to keep the cell size small as multicellular organisms grow.

what are the stages of mitosis?

prophase, metaphase, anaphase, and telophase

what are the two main phases of the cell cycle?

interphase and mitotic phase

what occurs during interphase?

the cell carries out its work, grows, and duplicates its chromosomes in preparation for division

what occurs during the mitotic phase?

the duplicated chromosomes separate (mitosis) and the cell splits in two (cytokinesis)

what does cytokinesis in animal cells do?

works through a ring of protein filaments that tightens at the middle of a dividing cell. membranes on the portions of the cell being pinched together then fuse, resulting in two daughter cells.

what are diploid cells?

2n in which 2 of each type of chromosome are present (2 sets)

what is meiosis?

the process by which a single diploid cell divides to produce four genetically different haploid cells

what are haploid cells?

n, which only 1 of each type of chromosome is present (1 set)

what are gametes?

the haploid cells produced through meiosis, Female gametes (eggs) Male gametes (sperm)

when is a diploid fertilized egg (or zygote) is produced?

when the haploid sperm and haploid egg fuse

how does meiosis generates diversity?

by ensuring that the gametes it gives rise to will differ genetically from one another

what does meiosis produce?

daughter cells that are exact genetic copies of parent cells

human females have

23 matched pairs of chromosomes—22 pairs of autosomes (non sex chromosomes) & one pair of sex-determining chromosomes, which in females are X chromosomes

human males have

22 autosomes one X chromosome, & one Y (has very few genes) chromosome

what occurs during prophase I of meiosis?

homologous chromosomes pair with each other, they exchange reciprocal chromosomal segments with one another

what is recombination (crossing over)?

the process of creating chromosomes that are a new combination of paternal and maternal material

how is sex determined?

each egg that a female produces has a single X chromosome in it & each sperm that a male produces has either an X or a Y chromosome within it. if a sperm with a Y chromosome fertilizes an egg, the offspring will be male & if a sperm with an X chromosome fertilizes the egg, the offspring will be female

how much larger are eggs than sperm?

200,000 times larger

what are types of asexual reproduction?

binary fission, vegetative reproduction, & regeneration

what occurs during binary fission?

a given bacterial cell replicates its single chromosome and then divides in two

prokaryotic cells (bacteria) have

a single chromosomes & no nuclear membrane

what occurs during regeneration?

in which a new, complete organism can be formed from a portion of an existing one