Unit 4 Review - Biology

goal of mitosis

a single cell divides into two daughter cells
- is for growth and to replace worn out cells
- SOMATIC cells

Mitosis: chromosome number of the parent or starter cell

46 = 2n

Mitosis: chromosome arrangement during metaphase

sister chromatids align in the middle

Mitosis: number of cells produced

2 cells

Mitosis: chromosome number of cell/s produced

both cells create 46
- 2n or diploid

goal of Meiosis

to create reproductive cells (gametes)

Meiosis: chromosome number of the parent or starter cell

46 = 2n

Meiosis: chromosome arrangement during metaphase

synapsis forming a tetrad
- crossing over occurs here when homologous pairs of chromosomes align in the middle

Meiosis: number of cells produced

4 cells

Meiosis: chromosome number of cell/s produced

23 = n
haploid

Goal of the Fertilization

making sure both adults contribute (egg and sperm) to form a zygote

Fertilization: chromosome number of the parent or starter cell

egg and sperm
are n or haploid

Fertilization: chromosome arrangement during metaphase

not applicable

Fertilization: number of cells produced

1 cell

Fertilization: chromosome number of cell/s produced

fertilized cell 46
2n or diploid

Suppose a cell skipped metaphase during metaphase during mitosis. How might this affect the two daughter cells?

If metaphase was skipped during Mitosis then the spindle fibers are not able to ensure that the sister chromatids separate and go the different daughter cells. It could cause the daughter cells to be different than their parent cells.

chromosome

has our genes (genetic information)

gene

our characteristics (such as hair color, fingerprint)

chromatin

a complex of macromolecules found in cells, consisting of DNA, protein, and RNA
- copy of the chromosome

prophase

chromosomes from two centrioles form and move to the two sides of the cell

metaphase

sister chromatids line up in the center of the cell

anaphase

copied chromosomes separate to opposite sides of the cell

telophase

nuclear membrane reforms, chromosome become chromatin

centriole

makes spindle fibers (microtubes) that will separate sister chromatids (copies from original)

centromere

holds copied chromosomes (sister chromatids) together

sister chromatids

the identical copies (chromatids) formed by the replication of a chromosome, with both copies joined together by a common centromere.

Homologous Chromosomes

the cell has two sets of each chromosome; one of the pair is derived from the mother and the other form the father

spindle fibers

fibers that pull on the chromosomes

Chromosomes number (2n, n)

2n = 46 (diploid)
n = 23 (haploid)

Meiosis

to create reproductive cells (make egg and sperm cells or Gametes)
- specialized type of cell division that reduces the chromosomes number by half , creating four haploid cells.

Tetrad

a group or set of four (align)

gamete

haploid reproductive cells, egg or sperm

gametogenesis

the process in which cells undergo meiosis to form gametes

oogenesis

producing eggs

spermatogenesis

producing sperm (formation)

Metaphase II

sister chromatids separate. in each of the two daughter cells produced by the first meiotic division (which are known as secondary germ cells), the spindle again draws the chromosomes to the metaphase plate

Genetic variation

multiple variants of any given gene with different set of DNA

random fertilization

- chromosomes are sorted into daughter randomly
-egg and sperm

independent assortment

random separate cells (genes)

crossing over

the exchange of genes between homologous chromosomes that result in a mixture of parental characteristics in offspring