The Cell Cycle Biology
Standards you are responsible for mastering. SB1a: Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction. SB2b: Explain the role of DNA in storing and transmitting cellular information.
The next two slides aren t for the notes just pay attention. A Question for you Cells need to be small. That s a fact. But, WHY do they need to be small? Why is it better to have many small cells than just a couple of big cells?
Ok, good. So, how do organisms get more cells and prevent cells from getting too large?? Cell Division.
Two main reasons why cells divide: 1.) To prevent DNA overload if the cell grows too big, there will be an information crisis. 2.) Bigger is not better if the cell grows too large, it would take too long for nutrients and wastes to travel through the cell.
Cell Division A.) the cell divides forming 2 daughter cells before growing too big. B.) solves the problems of: 1.) Information crisis 2.) Increasing size
Cell Division A.) Chromosomes: 1.) pass on genetic information 2.) made of DNA and proteins 3.) every organism has a specific number of chromosomes. (Humans = 46) 4.) are only visible during cell division 5.) are replicated BEFORE cell division a.) chromatids 2 identical sister parts of a duplicated chromosome. 1.) are attached at the centromere
Chromosome
Chromosome
The Cell Cycle 1.) The cell cycle is a series of events that the cell goes through as it grows and divides. 2.) During the cell cycle, the cell grows, prepares for division, and divides to form two daughter cells.
The 2 phases of the cell cycle A.) Interphase B.) Cell Division Mitosis & cytokinesis
Interphase - NOT A PART OF MITOSIS; NOT CELL DIVISION! 1.) contains the G-1, S, and G-2 phases. 2.) G-1 phase the cells grow in size and make new molecules and organelles. 3.) S phase chromosomes are replicated 4.) G-2 phase shortest phase, molecules & organelles needed for cell division are made.
Cell Cycle
Interphase
Interphase
Mitosis 1.) part of the cell cycle when the chromosomes separate from each other and the cell splits in half. 2.) This is how somatic cells reproduce. Somatic cells are normal body cells (i.e., not sperm and egg) 3.) Mitosis has 4 phases: Prophase - Nucleus breaks down, chromosomes become thick (visible) and pair up. Metaphase - Chromosomes line up in the middle of the cell Anaphase - Chromosomes move to the opposite ends of the cell Telophase - Chromosomes unwind (become invisible) and nucleus reforms.
Prophase
Prophase
Prophase Draw This in the Box Nuclear Membrane Spindle Fibers Centriole Cell Membrane
Metaphase
Metaphase
Metaphase
Metaphase Draw this in the box
Anaphase
Anaphase
Anaphase
Anaphase Draw this in the box
Telophase
Telophase
Telophase
Telophase Draw this in the box
Cytokinesis - Starts during Telophase 1.) Cytoplasm divides separating the two identical nuclei. 2.) in animals the cell membrane is pulled inward until the cytoplasm is pinched into 2 almost equal parts. 3.) in plants a cell plate forms half way between the two new nuclei.
Animal Cell Cytokinesis Cleavage furrow 100 µm Contractile ring of microfilaments Daughter cells Figure 12.9 A (a) Cleavage of an animal cell (SEM)
Plant cell cytokinesis Vesicles forming cell plate Wall of patent cell Cell plate 1 µm New cell wall Figure 12.9 B (b) Cell plate formation in a plant cell (SEM) Daughter cells
End result of Mitosis 2 genetically identical daughter cells.
Review Questions
Review 1 During which part of interphase is the DNA copied? A.) G1 B.) S C.) G2 D.) Mitosis
Review 2 Which stage in a cell s life cycle is the longest? A.) mitosis B.) metaphase C.) interphase D.) cytokinesis
3 Which of the following is the correct name of DNA when it is uncoiled (not in a chromosome form)? A.) Chromatid B.) Chromatin C.) Chromosome D.) Spindle Fiber
4 If a cell has 32 chromosomes in G1 of interphase, how many chromosomes will each daughter cell have after mitosis & cytokinesis? A.) 16 B.) 32 C.) 64 D.) 128
5 During which stage of mitosis do the chromosomes line up at the equator of the cell? A.) prophase B.) metaphase C.) anaphase D.) telophase
6 Each side of a copied chromosome is called: A.) a chromosome B.) a sister chromatid C.) chromatin D.) centromere
7 The part of a copied chromosome where the two sides are linked together is called the: A.) centriole B.) centromere C.) chromatid D.) spindle fiber
8 During which stage of mitosis do the sister chromatids separate? A.) prophase B.) metaphase C.) anaphase D.) telophase
9 Division of the nucleus is called: A.) interphase B.) cell cycle C.) mitosis D.) cytokinesis
10 Division of the cytoplasm is called: A.) interphase B.) cell cycle C.) mitosis D.) cytokinesis
11 What organelle has the job of pulling on the spindle fibers to separate the chromatids? A.) DNA B.) ribosome C.) centromere D.) centriole