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