Cellular Reproduction

I. The Cell Cycle and Mitosis
    Cell cycle consists of growth, development, and cell division.
	A. Interphase
		1. Longest period in a cells life
		2. Carries out the everyday functions of the cell
		3. In late interphase chromosomes are replicated (sister dafonnoltids are formed) and organelles doubled.
	B. Mitosis
		1. Phases where the nucleus of the cell divides into two nuclei with identical genetic material.
	C. Cytokinesis
		1. The division of the cytoplasm into two new cells called daughter cells.
	D. Test Tube Skin
		1. Material that is made of cowhide and shark cartilage is used to cover burned area in humans until new skin grows.
II. Mitotic Cell Division & Cytokinesis
     Originally described by Walther Fleming
	A. Interphase
		1. G1 - Cell grows	
		2. S - Chromosomes replicate become paired
		3. G2 - Makes new organelles
	B. Prophase
          	1.  Chromotids become visible                 
		2.  Nuclear membrane disappears
		3.  Spindle fibers form (microtubules)
	C. Metaphase
		1. Sister chromotids line up at equator
	D. Anaphase
		1. Chromotids separate and move to opposite poles
	E. Telophase
		1. Two new nuclear membranes begin to form
		2. Cell membrane pinches in animals, cell plate forms in plants, cytokinesis takes place.
		3. Two daughter cells form
III. Control of Mitosis
	A. Normal Growth and Repair
		1. Mitosis is needed for growth, repair, and replacement of cells.
		2. Differentiation is the changes, in shape or function, that take place in cells as they develop.
		3. Growth factors are chemicals that stimulate the division and differentiation of new cells
		4. Regeneration is the process of growing back lost body parts, (lizard's tail)
	 B. Asexual Reproduction
		1. Process where one parent produces offspring by cell division
			a) DNA in offspring is identical to parent
			b) Bacteria, fungi, plants, and some unicellular organisms
		2. Budding is when the parent grows a tiny replica (bud) on its body, which separates to form a new organism (yeast)
		3. Fragmentation is when body pieces can grow into new organisms (starfish)
		4. Vegetative Reproduction is when new plants grow from stems, roots, or leaves, (strawberries)
	C. Tumors and Cancer	
		1. Tumors are abnormal growth and replication of abnormal cells
	   		a) Benign tumors stay together and cause little harm	
			b) Malignant tumors (cancer) have cells that break free and spread the
			   abnormal cells 
				(1) able to invade normal tissues and replace healthy cells
IV. Meiosis and Sexual Reproduction
     Sexual reproduction is when the chromosomes of two parents combine to produce offspring. The chromosomes are contained in gametes. Females produce eggs (large cytoplasm) and males produce sperm that have flagella for movement. Gametes have 1/2 the chromosome number.
	A. Introduction to Meiosis
		1. Meiosis produces gametes (sex cells)
			a) Described as mitosis twice without replication the second time
			b) Four daughter cells with 1/2 the number of chromosomes in each.
			c) Daughter cells have different chromosomes
	B. Chromosome Number
		1. Body cells have 46 chromosomes (2N), 23 from each parent. (Biploid cells)
		2. Gametes have 23 chromosomes (IN). (Haploid cells)
		3. When the egg and sperm join (fertilization) the single cell formed (zygote) has 46 chromosomes (23 + 23 = 46). This is the original cell you came from. Body cells develop from this cell by mitosis.
		4. If you numbered the chromosomes from 1 thru 23, you would get 1-23 from each parent, thus your would have two #1, #2, #3 ect. These pairs are called homologous pairs.
		5. Chromosomes #23 determine your sex.
V. The Phrases of Meiosis
	A. Meiosis I
	   Replication of chromosomes and organdies late iaterphase.
		1. Prophase I
		2. Metaphase I
		3. Anaphase I
		4. Telophase I
			a) Two daughter cells form
	B. Meiosis II
	   No replication
		1. Prophase II
		2. Metaphase II
		3. Anaphase II
		4. Telophase II
			a) Four sperm form in male, one egg and 3 polar bodies in female
	C. Crossing Over
		1. Chromosomes are made of genes
		2. Crossing over is the exchange of genes between like chromosomes.
			a) Occurs during Prophase I
			b) Changes gene combination in chromosomes and gives variation in offspring.
VI. Meiosis and Evolution
	A. Meiosis (crossing over)and sexual reproduction (fertilization) results in new combinations of characteristics.
		1. Evolution is the change in living pop. over time.
		2. Differences in members of a population are called variations.
			a) Variations allow certain individuals in the pop. to survive changing conditions in the environment. These individuals will reproduce.
		   	b) Genes of surviving individuals get passed to the next generation