Cells divide to maintain a workable ratio of volume to surface area. The original cell is called the ____________ cell and the offspring are called ______________ cells. The offspring receive a portion of the cytoplasm, organelles, and hereditary information from the parent.
Limits to Cell Growth:
1. ____________________ - more demands are placed on the cells DNA
2. ____________________ - the rate at which food & oxygen are used up & waste products are produced become too much for the cell
3. ____________________ - volume increases more rapidly that surface area
4. ____________________ - 2 new daughter cells form
________________ cells are also known as 2n because they have the full set of chromosomes. ____________ cells are diploid. The diploid number for humans is _________. _____________ cells are also known as n because they have half of the cells found in a typical somatic cell. The haploid number for humans is _________. An example of a haploid cells in humans would be ________________. Diploid cells undergo cell division known as ________________ while haploid cells undergo cell division known as ___________________. All cells that undergo mitosis have daughter cells with the same number of chromosomes as the parent cell, while cells that undergo meiosis have half the number of chromosomes as the parent cell. Every body cell contains _____ chromosomes bearing genes for the same set of characteristics, & the 2 members usually have the same size & shape. The members of a pair are called ________________________ chromosomes one from the mother & one from the father.
Chromosome drawing:
THE CELL CYCLE
1. ________________________ - time in between divisions cell carries on its usual life activities- 3 Stages: 1) __________ - growth phase the cell decides if it will divide again cellular differentiation occurs
2) ________ - DNA replication occurs
3) ________ - another growth phase organelles reproduce prepares for _________
2. _______________________ - EARLY centrioles begin to migrate to opposite sides of the nucleus, chromatin may become denser, MIDDLE nuclear membrane starts to break down, nucleolus begins to disasppear, chromosomes appear, centrioles migrate to poles & produce the aster complex that makes the spindle, LATE no nucleolus or nuclear membrane, chromosomes are floating within the cell, spindle apparatus has formed
3. _______________________ - chromosomes align themselves along the equator they are attached to the spindle fibers at the ____________________
4. _________________________ - splitting of the centromeres , spindle fibers contract & chromatids are divided, these become chromosomes & are pulled to the poles, the chromosomes are V-shaped in middle anaphase & J-shaped in late anaphase, this stage is over when __________________________
5. __________________________ - this is the reverse of prophase, MIDDLE begins the formation of the nuclear membrane, the nucleolus reappears, granular chromatin reappears, LATE there is a complete nuclear membrane, the aster complex disappears, centrioles disappear
CYTOKINESIS:
The result of cell division is the production of _____________________________. In animals a cleavage furrow occurs that pinches in the cell. This begins during _______________________. In plants a __________ __________ forms in the middle of the dividing cell this eventually forms the cell wall.
MEIOSIS
Meiosis occurs in sex cells. It is composed of 2 stages: Meiosis I & Meiosis II. Meiosis consists of _____ nuclear divisions in which the chromosomes divide only once. The result is that mature gametes have only _____ member of each homologous chromosome pair (haploid). When the gametes unite, a ____________ is formed.
MEIOSIS I
1. ____________ -the 2 members of each pair of homologous chromosomes come into side-by-side contact (synapsis). Each chromosome has already replicated to form 2 chromatids, each of which will become a new chromosome. The 2 chromatids are joined at 1 point, the ________________, so that each will become _______ future chromosomes, & is thus called a __________________.
2. ____________ - the chromosomes align on the equator of the cell
3. ____________ - unlike mitosis, the centromeres holding the chromatids together do NOT divide each chromatid is pulled toward each pole (1st Reductive Division occurs)
4. ____________ - the daughter cells contain 1 of each of the homologous chromosomes - total chromosome number is now __________
MEIOSIS II
The second meiotic division more closely resembles the events in mitosis. The chromosomes are split at the beginning of ____________ by division of the centromeres, & single-stranded chromosomes move toward each pole. Each chromatid now exists in a separate ______________. ________ cells are now formed. In the male, all 4 cells are functional sperm, but in the female, only 1 is functional & the others become _________ ______________.
All cells contain the same DNA. In ______________________________, some of the DNA is repressed and some is expressed. This allows cells to have different functions.
Cell cycle regulators:
1. __________________ - proteins respond to events inside the cell to determine when mitosis occurs
2. __________________ - proteins respond to events outside the cell direct cell to speed up or slow down the cell cycle cells grow until they touch each other
_______________________ - cells increase in size
_______________________ - cells increase in number
_______________________ - cells change their shape (atypical cells)
______________________ - producing new cells
_______________________ - is programmed cellular death