Mitosis Flash Cards Ch 4

Why do cells divide rather than continuing to grow indefinitely? The larger the cell becomes, the more demands it places on the DNA The cell has trouble moving enough nutrients and wastes across the cell membrane What limits the maximum size a cell can get? Surface area to volume ratio What is cell division? The process by which 2 new cells are produced from one cell.

What are the 4 phases of the cell cycle? 1. G1 Phase 2. S Phase 3. G2 Phase 4. M Phase What happens during the G1 Phase? 1. Cell Growth – the cell increases in size 2. synthesizes new organelles. 3. Normal cell functions What happens during the S Phase? DNA Replication

What happens during the G2 phase? Additional cell growth What happens during the M phase? Mitosis and Cytokinesis - Cell division occurs What is Chromatin? DNA that is completely unwound “Spaghetti form” of DNA found during G1 of Interphase

During what phase of the cell cycle does cell growth occur? Interphase (G1) What are the three parts of Interphase? G1, S, and G2 phases What is mitosis? The division of the nuclear material (nucleus)

What are sister chromatids? 2 identical copies of a chromatid that have been replicated and connected together How are the two sides of sister chromatids joined together? centromere What are the building blocks of DNA? (Monomer) Nucleotides

What are the four phases of Mitosis? Prophase Metaphase Anaphase Telophase What happens during Prophase? The nucleolus and nuclear membrane “break up” and temporarily disappear. Centrioles duplicate and separate to opposite sides of the cell. The spindle fibers begin to form near the centrioles. What happens during Metaphase? The chromosomes line up across the center of the cell along the equator. Microtubules attach to the centromere of each chromosome from both poles of the spindle.

What happens during Anaphase? The spindle fibers shorten. The centromeres are broken and the sister chromatids separate. The chromosomes continue to move until they have separated into two groups near the poles of the spindle. What happens during Telophase? The nuclear envelope reforms around the chromosomes. a nucleolus becomes visible in each daughter nucleus Chromosomes begin to unwind back to chromatin. The spindle breaks apart. What is a histone? The protein that DNA coils around to start condensing to fit inside the nucleus

- mitosis is asexual reproduction so a new organism is created. What happens during cytokinesis for animal cells? - The cell membrane is pinched inward until the cytoplasm is separated into nearly equal halves. What happens during cytokinesis for plant cells? - A cell plate is formed in the center of the cell and grows outward to separate the two cells. What is the major function of mitosis for unicellular organisms? - mitosis is asexual reproduction so a new organism is created.

What is the major function of mitosis for multi-cellular organisms? 1. Mitosis increases the number of cells 2. help the organism grow 3. replace dying cells. What is this phase and what is happening? Interphase - G1, S, G2, Cell growth, normal cell functions, and replication of DNA and organelles. Prophase The nucleolus and nuclear membrane “break up” and temporarily disappear. Centrioles duplicate and separate to opposite sides of the cell. Sister chromatids are held together by centromeres The spindle fibers begin to form near the centrioles.

What is this phase and what is happening? Metaphase The sister chromatids line up across the center of the cell (equator) Spindles attach to the centromere of each chromosome from both poles of the spindle. Anaphase The centromeres are broken and the sister chromatids separate. Spindle fibers shorten The chromatids continue to move until they have separated into two groups near the poles of the spindle. Telophase The nuclear envelope reforms around the chromosomes. Chromosomes begin to unwind back to chromatin. a nucleolus becomes visible in each daughter nucleus The spindle breaks apart.

What is the role of the mitotic spindle (spindle fibers) in mitosis? To line up and divide the chromosomes What is the role of the centrioles in animal cells? To divide the chromosomes during mitosis