science

• cell - basic unit of life
• what are the limits of cell growth?

  volume grows faster than the surface are

  a larger cell has a more difficult time getting stuff in and out of the cell (oxygen & nutrients)

  so the solution is: cell division
• rates of cell growth are:

  -vary depending on cell type

  -coli every 30 minutes
• chromosome

  "colored body"

  seen only when cells divide

  contain genetic information in the form of DNA
• composition of chromatin

  composed of DNA and protein called histones (helps condensed the DNA)

  the dna in chromosome is 10,000x larger than the chromosome itself
• Chromosome structure

  can only see chromosome during division

  each chromosome replicates and is paired as sister chromatids joined at a centromere

  human cell has 46 chromosome (2n)
• 3 parts of cell cycle

  -interphase

  -mitosis (pmat) - few mins to several days

  -cytokinesis
• 23= haploid

  46=diploid

  92=during interphase

  body cells (somatic cells)

  46=mitosis

  23=meiosis
• PROCESS OF CELL DIVISION

  growth prepares for division, divides of cells (6hr-100 days)
• INTERPHASE

  90% of cycle is spent in this phase

  G1 = cell growth, development, and protein production (longest)
• mitosis - prophase

  -prophase-longest phase of mitosis (50-60% time)

  -chromosome condense (become visible) - see as 2 identical chromatids
• cytokinesis

  -it forms 2 identical cells when membrane moves inward and pinches in the middle

  cell plate becomes the cell wall and cell membrane appear separating 2 new cells
• MITOSIS PHASES:

  INTERPHASE

  PROPHASE

  METAPHASE

  ANAPHASE

  TELOPHASE

  CYTOKINESIS
• CHROMOSOMES CAN BE GROUPED IN PAIRS CALLED HOMOLOGOUS CHROMOSOMES
• homologous pair - inherited from the mother and the other one is inherited from the father
• when ova are produced in the ovaries in female, tis process called ogenesis
• sperm are produced in the testes of males
• GENETIC MATERIAL- when cells divide it is essential that genes are copied into the new cells

  genes- basic unit of inheritance

  genes are located in chromosomes, which is made from a very long coiled molecule called DNA
• CHROMOSOMES REACTION

  the centrioles do not break
• MEIOSIS 2

  -chromosomes randomly line up like along metaphase plate like regular mitosis

  -during anaphase 2, centrioles break

  -nuclei reform and cytokinesis usually occurs
• MEIOSIS 1 -segration homologous pairs are seperated reducing chromosome number by half
• MEIOSIS 2 - sister chromatids are seperated producing 4 haploid gametes
• diploid (2n) - normal amount of genetic material
• haploid(N) - 1/2 of the genetic material
• meiosis results in the formation of haploid cells