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Get fill-in the blank notes from the front and your spiral. I EXPECT FOR ALL STUDENTS TO BE IN THEIR CHAIRS WHEN THE BELL RINGS!. The Cell Cycle. Interphase , Mitosis and Cytokinesis. Cell Reproduction- Intro Infromation. - PowerPoint PPT PresentationTRANSCRIPT
• Get fill-in the blank notes from the front and your spiral.
• I EXPECT FOR ALL STUDENTS TO BE IN THEIR CHAIRS WHEN THE BELL RINGS!
The Cell Cycle
Interphase, Mitosis and Cytokinesis
Cell Reproduction- Intro Infromation
• Recall that the cell theory states that all cells come from preexisting cells.
• Cellular division is the process by which new cells are produced from one cell.
• This results in two cells that are identical to the original, parent cell.
• Right now, as you are reading this page, many of the cells in your body are growing, dividing, and dying.
• Old skin cells are being shed and replaced, cuts and bruises are healing.
• Worn-out tissues are repaired or replaced by newly produced cells.
Discovery of Chromosomes• Early biologists observed that just before
cellular division, several short, stringy structures suddenly appeared in the nucleus.
• Scientists also noticed that these structures seemed to vanish soon after division of the cell.
• These structures arechromosomes.
• Chromosomes are the carriers of the genetic material (DNA) that is copied through DNA replication so that each new cell has the correct genetic material in it.
Anatomy of a Chromosome
• For most of a cell’s lifetime, chromosomes exist as chromatin, long strands of DNA wrapped around proteins called histones.
• Under a microscope, chromatin looks like beads on a string.
Anatomy of a Chromosome• An unduplicated
chromosome is called a chromatid.
• When two identical chromatids are together (sister chromatids), this is called a duplicated chromosome.
• These sister chromatids are held together by a centromere
• In the body cells of animals and most plants, chromosomes occur in pairs. With the sister chromatids together.
• One chromosome in each pair came from the male parent, and the other came from the female parent.
• Humans have 46 chromosomes or 23 pairs.
• The 23rd pair are our sex chromosomes that make you male or female.
• Cells with two of each kind of chromosome are called diploid cells.
• The prefix dipl- means double• These are said to contain a diploid, or 2n,
number of chromosomes.• “n” stands for the number of duplicated
chromosomes. • This number multiplied by the 2 =the total
number of chromosomes for the cell.
• Organisms produce gametes or reproductive cells.– Ex. Humans produce gamete cells which are eggs for
females and sperm for males.
• These cells contain one of each kind of chromosome and are called haploid cells said to contain a haploid, or n, number of chromosomes.
• The prefix hapl- means single• Look at table 10.1 in your book on p. 265.
• This process of making gametes or reproductive cells is called meiosis.
• We will talk in detail about meiosis later.• For now you just need to understand the
following:– Our body cells (non-reproductive cells) are diploid
cells– Our egg and sperm (reproductive cells) are
haploid cells
Cell Cycle
• During the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each of which then begins the cycle again.
• There are three main parts to the cell cycle.1. Interphase
a. G1, S, G2
2. Mitosisa. Prophase, Metaphase, Anaphase and Telophase
3. Cytokinesis
1. Interphase
• Interphase – Most of the cells life is spent in interphase.– G1 (Gap 1)=• Rapid growth and metabolic activity• Check point to make sure the conditions are correct to
support DNA replication– S (Synthesis)=DNA replicates– G2 (Gap 2)=• Cell prepares to divide• Second check point where the cell makes sure that the
DNA and other cell parts were replicated correctly.
2. Mitosis
• The division of somatic or regular cells.• Its divided into 4 phases.– PMAT• Prophase (prefix Pro- means 1st)• Metaphase (prefix Meta- means middle)• Anaphase (prefix Ana- means opposite)• Telophase (prefix Telo- means end)
Prophase
• First stage • Chromatin condenses
into chromosomes• Centrioles separate and
spindle fibers begin to form.
• Nuclear membrane breaks down
Metaphase
• Second Phase of Mitosis• Chromosomes line up in
the middle of the cell.• Each chromosome is
connected to a spindle fiber.
Anaphase
• Third Phase of Mitosis• The sister chromatids
separate into individual chromosomes and move apart to opposite ends of the cell.
Telophase
• The end or Final Stage of Mitosis
• Chromosomes gathered at opposite ends of the cell and lose their distinct shapes
• Two new nuclear membranes have formed.
3. Cytokinesis
• The cytoplasm pinches in half.
• Each daughter cell has an identical set of duplicate chromosomes