This animation demonstrates the stages of mitosis in an animal cell. Use the control buttons along the bottom to run the complete animation. Click on any intermediate stage (for example, Anaphase), and see a representative still frame.
Events during Mitosis
Interphase: Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles divide, and proteins are actively produced. For a complete description of the events during Interphase, read about the Cell Cycle.
Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes. Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes.
Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center.
Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell.
Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles.
Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear.
Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the return to interphase.
Cancer cells reproduce relatively quickly in culture. In the Cancer Cell CAM compare the length of time these cells spend in interphase to that for mitosis to occur.
You may download this entire file in Microsoft Word Format, or you may preview the questions and standards by year through your web browser by selecting the appropriate yearCELL QUESTION 1983: L. PETERSON/ECHS Describe the fluid-mosaic model of a plasma membrane. Discuss the role of the membrane in the movement of materials through by each of the following processes. a. Active Transport b. Passive Transport STANDARDS: FLUID-MOSAIC MODEL: Max. = 9 points__ Singer/Nicholson or "differs from" Davson/Danielli__ Dynamic__ Phospholipid Bilayer__ Hydrophilic heads/hydrophobic tails and explanation__ Polar/Nonpolar__ Proteins - intrinsic/extrinsic__ Permeases (active + passive)__ Pores or apertures__ Functional "R" Groups__ Glycoproteins or carbohydrates (recognition)__ Diagrams appropriately used with explanation__ Selectivity TRANSPORT Max = 9 points PASSIVE TRANSPORT:__ Definition of Diffusion__ Osmosis__ Size of molecule / polarity__ Facilitated Diffusion__ Function of pores ACTIVE TRANSPORT:__ Definition__ ATP__ ATPase__ Na+/K+ Pump__ Substances diffuse in-need transport out__ Carrier molecules and specificity
CELL QUESTION 1984: L. PETERSON/ECHS Describe the structure of a generalized eukaryotic plant cell. Indicate the ways in which a nonphotosynthetic prokaryotic cell would differ in structure from this generalized eukaryotic plant cell. STANDARDS: STRUCTURE, as part of the eukaryotic cell: DESCRIPTION: (1/2 point each) (1 point each)__ Cell Wall __ Cellulose__ Cell Membrane __ Protein/phospholipid or phospholipid bilayer__ Cytoplasm __ Fluid with dissolved substances__ Vacuole __ Protein/phospholipid or water__ Mitochondria __ Cristae, folding convolutions__ Ribosomes __ Two Subunits__ Golgi Bodies __ Phospholipid/protein, cisternae, vesicles__ Chloroplasts __ Stroma, grana, thylakoids__ Lysosomes __ Phospholipid/protein membrane or digestive enzyme__ Nucleus __ Double nuclear membrane or envelope__ Nucleolus __ RNA present, fibrillar__ Chromosome __ Double strand, DNA and Protein__ Plasmodesmata __ Cytoplasmic bridge__ Peroxisomes __ Membrane Bound__ Flagella __ 9 + 2__ Microtubules, microfilaments __ Tubulin protein/actin proteinMAX. = 4 points MAX. = 7 pointsTOTAL MAXIMUM = 10 points II. STRUCTURE COMPARISONS/DIFFERENCES of a simple cell and a complex cell. (2 points each pair / structure and comparison) __ Cell Wall __ No cellulose; murein present__ Cell Membrane __ No cholesterol__ Membrane-bound organelles absent __ Name one organelle__ OR AT LEAST 2: vacuole, mitochondria, __ Absent nucleus, E.R., lysosome, peroxisome, chloroplast__ AT LEAST 2: microtubules, microfilaments, __ Absent plasmodesmata__ Ribosomes __ Smaller, few, free floating__ Nuclear membrane __ Absent__ Genetic material __ Single, no protein, circular, plasmids__ Flagella __ No 9 + 2BONUS: Elaboration: evolution, size, two additional structures and comparisons for each structure = one point eachMAXIMUM = 10 points in Section II.
AP CELL QUESTION 1987: L. PETERSON/ECHS Discuss the process of cell division in animals. Include a description of mitosis and cytokinesis, and of the other phases of the cell cyle. Do not include meiosis. STANDARDS:PART I. DESCRIPTION OF MITOSIS IN ANIMAL CELLS: Max. = 7 pointsGeneral__ division of nucleus__ daughter cells acquire the same number and kinds of chromosomes as in the mother cell__ process for growth or repair or asexual reproduction__ list phases in correct order (P,M,A.T)Prophase (one point each / max. 2)__ centrioles move apart__ chromosomes condense__ nucleolus is no longer visible__ nuclear envelope disappears__ asters and spindle formMetaphase__ sister chromatids (chromosomes) are in a line at the midpoint of the spindleAnaphase (one point each / max. 2)__ centromeres uncouple (split)__ chromosomes move to opposite poles__ microtubules involved in the push/pull movementTelophase (one point each / max. 2)__ reverse of prophase__ nuclear envelope reforms__ nucleolus reappears__ chromosomes become diffuse__ spindle and aster disappear__ centrioles are replicatedPoints less frequently mentioned:__ function of centrioles__ definition of kinetochores__ description of polar microtubules and kinetochore microtubules__ definition of chromatids*In order to obtain a score of 10, there must be points in all three sections. If only two sections are written the maximum is 9. PART II. CYTOKINESIS: __ division of cytoplasm__ formation of a cleavage furrow__ occurrence of cytokinesis in the cell cyclePoints less frequently mentioned:__ function of cytokinesis__ dense belt of actin and myosin microfilaments__ purse-string mechanism__ furrow occurs at location of equatorial plane__ cytochalasin blocks activity of microfilaments (stops cytokinesis) PART III. OTHER PHASES OF THE CELL CYCLE (INTERPHASE):General__ list G1, S, and G2 in correct order__ G1, S, and G2 are part of interphase__ chromosomes appear as a mass of chromatin materialG1__ synthesis of cell organelles or cell doubles in size__ restriction (decision) point or point of no returnS__ synthesis or replication of DNA or DNA replication occurs during interphaseG2__ synthesis of microtubular assembly, or prepare for mitosisPoints less frequently mentioned:__ description of nucleosomes__ times in each phase__ growth factors__ some cells do not go beyond G1__ after cell passes "S", mitosis will usually continue__ colchicine prevents the formation of microtubules