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Transcript
11/8/16 Unit 5 Cellular Processes Bio 1.2.1,1.2.2,1.2.3, 4.2.1 & 4.2.2 Euglena • Environment: fresh and salt water • Movement/locomotion: flagella (long whip-like tails) • Food: Unicellular Organisms Notes Page ___ Objective: Compare the structures and functions of the following single-celled organisms: 1. Euglena 2. Amoeba 3. Paramecium Euglena http://www.youtube.com/watch?v=ZHZZKwrYm4g – Heterotrophic- engulfs full cell & absorb them – Autotrophic- make their own food using chlorophyll • Reproduction: asexual • Additional Organelle: – Eye spot- detects light & guides Euglena in its direction for photosynthesis to occur 1 11/8/16 Amoeba • Environment: Fresh and salt water • Movement: Pseudopod “false feet” (sends out a slender extension of itself (like a foot) & then the rest of the body flows into this extension Cytoplasmic streaming – free flowing cytoplasm; changes shape • Food: heterotrophic – They surround their prey and engulf it with a pseudopodium • Reproduction: asexual Paramecium • Environment: Fresh water • Movement/Locomotion: Cilia (hair-like projections) – Bend and straighten helping propel organism through water (forward or backward) • Food: Heterotrophic – Uses cilia to sweep the food into the cell. • Reproduction: sexual and asexual • Additional Info: Most complex and specialized Amoeba Eating Paramecium http://www.youtube.com/watch?v=pvOz4V699gk Brain Eating Amoeba http://www.cbsnews.com/news/what-you-need-toknow-about-the-brain-eating-amoeba/ Paramecium http://www.youtube.com/watch?v=l9ymaSzcsdY 2 11/8/16 Euglena Amoeba Paramecium Environment Fresh and salt water Fresh and salt water Fresh water Movement Flagella Cytoplasmic streaming (tail-like) Cilia (hair-like) (changing shape) Food Additional Information Autotrophic and Heterotrophic Heterotrophic Heterotrophic Eye spot Pseudopod Most specialized and complex (light sensitive) (False foot) Diagram Quiz Be sure you have these in your notes!!! Structures & Behaviors • Contractile vacuole-pumps excess water out of the cell • Cilia- tiny hair like projections that are used in locomotion & nutrition • Flagella- long whip like tails that are used in locomotion • Pseudopods- extensions of the cytoplasm that are used in locomotion & nutrition • Eyespots- a photo sensitive area that detects light • Phototaxis- a movement toward/away from light • Chemotaxis- a movement toward/away from food molecules, poisons, etc. 1. Which single-celled organisms moves by flagellum? A. Euglena B. Amoeba C. Paramecium A. Euglena 3 11/8/16 2. Which single-celled organism moves by cilia or hairlike projections? A. Euglena B. Amoeba C. Paramecium C. Paramecium 4. Which single-celled organism has a unique feature of an eye spot? A. Euglena B. Amoeba C. Paramecium A. Euglena 3. Which single-celled organism uses pseudopods to surround and engulf their food? A. Euglena B. Amoeba C. Paramecium B. Amoeba 5. Which single-celled organism moves by cytoplasmic streaming? A. Euglena B. Amoeba C. Paramecium B. Amoeba 4 11/8/16 6. Which types of single-celled organisms may contain chlorophyll? Which organism appears in the photos? A. Euglena and Amoeba B. Amoeba and Paramecium C. Paramecium D. Euglena D. Euglena Look at the picture. Be able to answer the questions on the following slide! • paramecium 7. What organelle engulfs food? A. cytoplasm B. pseudopods C. vacuoles D. nucleus 8. What organelle digests the food? A. cytoplasm B. pseudopods C. food vacuole D. nucleus 5 11/8/16 A. B. pseudopods C. food vacuoles A. Is the nucleus B. Is the cytoplasm B. Name the organelles located at A. and B. Cell/Plasma Membrane Notes Page ___ 6 11/8/16 Plasma/Cell Membrane “Gatekeeper” Cellular Transport Notes Ch. 7.2 Plasma Membrane (p.175-178) Ch. 8.1 Cellular Transport (p.195-200) 1. ALL cells have a Cell Membrane 2. Functions: a. Controls what enters and exits the cell to maintain homeostasis (example: body temperature, pH, blood sugar, water balance) b. Provides protection and support for the cell Cell Membranes (continued) Polar heads Fluid Mosaic love water Model of the & dissolve. cell membrane 3. Structure of cell membrane (LIPIDS & PROTEINS) Lipid Bilayer -2 layers of phospholipids a. Phosphate head is polar (water loving) b. Fatty acid tails non-polar (water fearing) c. Proteins embedded in membrane TEM picture of a real cell membrane. Non-polar tails hide from water. Phospholipid Membrane Movement animation Carbohydrate cell markers Lipid Bilayer Proteins 7 11/8/16 Cell Membranes (continued) Structure of the Cell Membrane • 4. Cell membranes have pores (holes) in it which makes it Selectively Permeable: Allows some molecules in and out the cell Outside of cell Lipid Bilayer Transport Protein Animations of membrane Go to structure Carbohydrate chains Proteins Phospholipids Inside of cell (cytoplasm) Section: Cell Membrane Quiz “Use Notes” Cell Membrane Drawing & Questions Notebook Page ____ Front---Draw, Color, Label & Descriptions • Page 177 Figure 7.4 ANSWER THE FOLLOWING: 1. What is the function of the cell membrane? 2. Describe the structure of the cell membrane? 3. How many layers of lipids are there in the plasma membrane? 4. What does selective permeable mean? 5. True or False: ALL cells have cell membranes. Back---Write questions & answers 1. The cell membrane is selectively permeable. Define selectively permeability. 2. Why do the polar heads of the phospholipids face the outside of the membrane? 8 11/8/16 Cell Concentrations Solutions Notes Page ___ Cell Concentrations • A solution is a mixture of two or more substances. – Solute – dissolved substance (salt/sugar) – Solvent – dissolves solute (water) • Cells are surrounded and filled with a liquid environment • The cytoplasm contains a solution of different substances. Cell Concentrations Substances will move across the cell membrane if their concentrations are unequal. 9 11/8/16 ! Isotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. A cell in an isotonic solution Water moves in and out at the same rate Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) Hypotonic Solution ! 10% Solute How much solvent inside? 90% solvent 10% Solute How much solvent outside? 90% solvent Cell remains the same! Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) A cell in a hypotonic solution Water moves in 20% Solute How much solvent inside? 80% solvent Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)! 10% Solute How much solvent outside? 90% solvent Cell swells! 10 11/8/16 ! Hypertonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) A cell in an hypertonic solution Water moves out 10% Solute How much solvent inside? 90% solvent shrinks Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! What type of solution are these cells in? 20% Solute How much solvent outside? 80% solvent Cell shrinks! Solutions Drawing & Questions Notebook Page __8__ Front--- Draw, Color, Label & Descriptions. A B C Hypertonic Isotonic Hypotonic • (Fig. 8.2 A,B,C) p. 197 • (Fig. 8.3 A,B,C) p. 197 • (Fig. 8.4 A,B,C) p. 197 Back---Write questions & answers 1. Define isotonic solution, hypotonic solution, and hypertonic solution. 2. Explain why plant cells do not burst when in a hypotonic solution. 3. What happens to an animal cell in a hypertonic solution? 11 11/8/16 Osmosis Drawing & Questions Notebook Page __9__ Draw, Color, Label & Descriptions. • (Fig. 8.1) p. 196 Write questions & answers. 1. The diffusion of water across a selectively permeable membrane is called ___. 2. Water flows to the side of the membrane where the water concentration is (higher/lower). 3. (True/False) In a cell, water always moves to reach an equal concentration on both sides of the membrane. Types of Cellular Transport 1. Diffusion 2. Facilitated Diffusion 3. Osmosis high low • Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis Page ____ • Animations of Active Transport & Passive Transport Wee!!! • Passive Transport cell doesn t use energy Passive & Active Transport Notes This is gonna be hard work!! high Passive Transport • • • cell uses no energy molecules move randomly Molecules spread out from an area of high concentration to an area of low concentration. (High"Low) low 12 11/8/16 Passive Transport: 1. Diffusion 3 Types of Passive Transport 1. Diffusion: random movement of particles from an area of high concentration to an area of low concentration. 1. Diffusion- diffusion of particles 2. Facilitative Diffusion – diffusion with the help of transport proteins 3. Osmosis – diffusion of water Passive Transport: 2. Facilitated Diffusion Simple Diffusion Animation (High to Low) • Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-Note: molecules will still move around but stay spread out. Passive Transport: 2. Facilitated Diffusion A 2. Facilitated diffusion: diffusion of specific particles with HELP from a transport proteins a. Transport Proteins are Facilitated specific – they select diffusion only certain molecules (Channel to cross the membrane Protein) b. Transports larger or charged molecules (sugar) Carrier Protein B Glucose molecules Cellular Transport From aHigh Concentration High ! Channel Proteins animations Cell Membrane Diffusion (Lipid Bilayer) Low Concentration Protein channel Low Transport Go to Section: Through a Protein " 13 11/8/16 Passive Transport: 3. Osmosis Osmosis animation • Paramecium (protist) removing excess water video • Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure. • 3.Osmosis: diffusion of water through a selectively permeable membrane • Water moves from high to low concentrations • A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. • Water moves freely through pores. • Solute (green) to large to move across. Active Transport How Organisms Deal with Osmotic Pressure • Salt water fish pump salt out of their specialized gills so they do not dehydrate. • Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water. 3 Types of Active Transport • cell uses energy (ATP) • actively moves molecules to where they are needed • Movement from an area of low concentration to an area of high concentration 1. Protein Pumps- transport macromolecules across the cell membrane 2. Endocytosis- material ENTERING the cell 3. Exocytosis- material EXITING the cell (Low " High) 14 11/8/16 Types of Active Transport 1. Protein Pumps transport proteins that require energy to do work • Example: Sodium / Potassium Pumps are important in nerve responses. Sodium Potassium Pumps (Active Transport using proteins) Protein changes shape to move molecules: this requires energy! Types of Active Transport 2. Endocytosis: taking bulky material into a cell • Uses energy • Cell membrane in-folds around food particle Aka: cell eating • forms food vacuole & digests food (This is how white blood cells eat bacteria!) Types of Active Transport 2 Types of Endocytosis… 1) Phagocytosis: large PARTICLES are engulfed 2) Pinocytosis: WATER drops are engulfed 3. Exocytosis: Forces material out of cell in Endocytosis & Exocytosis animations bulk • membrane surrounding the material fuses with cell membrane • Cell changes shape – requires energy EX: Hormones or wastes released from cell 15 11/8/16 Compare: Passive to Active Transport • Passive Transport -Moves from HIGH to LOW 3 Types: 1) Diffusion- particles move from H to L 2) Osmosis- water moves from H to L 3) Facilitated Diffusionparticles move from H to L with the HELP of transport protein REQUIRES NO ENERGY (ATP) • Active Transport Moves from LOW to HIGH 3 Types: 1) Endocytosis- particles into the cell 2) Exocytosis- particles exists the cell 3) Protein Pump- particles moves with HELP of a transport protein with ATP REQUIRES ENERGY (ATP) Exit Ticket 1. (Passive/Active) Transport is from High to Low. 2. (Passive/Active) Transport requires Energy. 3. ______________ transports proteins across a membrane and requires energy. 4. (Osmosis/Diffusion) water moves from High to Low. 5. (Osmosis/Diffusion) particles moves from High to Low. Passive and Active Transport Drawing & Questions Notebook Page ____ Front: Draw, Color, Label & Descriptions. • (Fig. 8.5 & 8.6) p. 199-200 Back: Write questions & answers. 1. Passive transport (does/does not) require energy. 2. List 2 examples of passive transport. 3. Transport proteins help substances move through the _____ _____. 16 11/8/16 Photosynthesis Notes Page _12_ Photosynthesis: Life from Light and Air 2006-2007 Plants are energy producers • Like animals, plants need energy to live How do plants make energy & food? PHOTOSYNTHESIS – unlike animals, plants don t need to eat food to make that energy • Plants make both FOOD & ENERGY – animals are consumers/heterotrophs – plants are producers/autotrophs 17 11/8/16 • Photosynthesis Photosynthesis: Cellular Respiration: – using sun s energy to make ATP – using CO2 & water to make sugar – occurs in chloroplasts – allows plants to grow – makes a waste product Chloroplasts are only in plants Mitochondria in animals animal cells plant cells • oxygen (O2) carbon sun + water + energy dioxide (ATP) = used to build the sugar → glucose + oxygen 6CO2 + 6H2O + sun → C6H12O6 + 6O2 energy Chloroplasts absorb sunlight & CO2 Leaf Leaves sun CO2 So what does a plant need? • Bring In (Reactants) – light – CO2 – H2O leaves • Let Out (Product) Chloroplasts in cell • Move Around (Product) Chloroplast Chloroplasts contain Chlorophyll shoot – O2 Chloroplast make ENERGY & SUGAR – sugars roots 6CO2 + 6H2O + light → C6H12O6 + 6O2 energy 18 11/8/16 Leaf Structure vascular bundle (vein) Transpiration xylem (water) xylem (water) cuticle epidermis phloem (sugar) palisades layer O2 H O 2 CO2 spongy layer epidermis cuticle Transpiration • Water evaporates from the stomates in the leaves – pulls water up from roots • water molecules stick to each other – more water is pulled up tree from ground stomate guard cells stomate # CO2 in # O2 out # water out O2 H2O CO2 guard cells # so it gets to leaves from roots Function of Leaf Structures • Cuticle – waxy coating reduces water loss • Epidermis – skin protecting leaf tissues • Palisades layer – high concentration of chloroplasts • collecting sun s energy – photosynthesis • making ATP & sugars • Spongy layer – air spaces • gas exchange – CO2 in for sugar production, remove waste O2 19 11/8/16 Stomates & Guard Cells • Function of stomates • Homeostasis – CO2 in – O2 out – H2O out – keeping the internal environment of the plant balanced • Stomates open • gets to leaves for photosynthesis – let CO2 in • Function of guard cells – open & close stomates Guard cells & Homeostasis guard cell • needed to make sugars – let H2O out • needed for photosynthesis stomate – let O2 out • get rid of waste product • Stomates close – if too much H2O evaporating Xylem Phloem: food-conducting cells carry water up from roots # carry sugars around the plant wherever they are needed $ new leaves $ fruit & seeds $ roots 20 11/8/16 How are they connected? Energy cycle sun Respiration glucose + oxygen → carbon + water + energy dioxide C6H12O6 + 6O2 Photosynthesis Plants, producers, autotrophs → 6CO2 + 6H2O + ATP CO2 Photosynthesis carbon sun + water + energy → glucose + oxygen dioxide 6CO2 + 6H2O + light → C6H12O6 + 6O2 energy Another view… waste organic molecules H2O waste O2 animals, plants, consumers, heterotrophs Cellular Respiration The Great Circle of Life! Mufasa? ATP synthesis producers, autotrophs CO2 sugars sun capture light energy Photosynthesis glucose H2O food consumers, heterotrophs O2 waste digestion Cellular Respiration release chemical energy Got the energy… Ask Questions!! ATP 21 11/8/16 Burn fuels to make energy Cellular Respiration Harvesting Chemical Energy aerobic respiration making ATP energy (& some heat) by burning fuels in many small steps ATP ATP + CO2 + H2O (+ heat) food (carbohydrates) O2 ATP 2009-2010 Energy needs of life • Animals are energy consumers – What do we need energy for? • synthesis (building for growth) • reproduction • active transport • movement • temperature control (making heat) Where do we get energy? • Energy is stored in organic molecules – carbohydrates, fats, proteins • Animals eat these organic molecules → food – digest food to get • fuels for energy (ATP) • raw materials for building more molecules ATP – carbohydrates, fats, proteins, nucleic acids 22 11/8/16 What is energy in biology? Harvesting energy stored in food • Cellular respiration – breaking down food to produce ATP ATP • in mitochondria • using oxygen food ATP – aerobic respiration – usually digesting glucose • but could be other sugars, fats, or proteins Adenosine TriPhosphate glucose + oxygen → energy + carbon + water dioxide Whoa! HOT stuff! 2009-2010 C6H12O6 + What do we need to make energy? • Fuel – food: carbohydrates, fats, proteins • Helpers – oxygen – enzymes 6O2 → ATP + 6CO2 + 6H2O Mitochondria are everywhere!! animal cells • The Furnace for making energy – mitochondria O2 plant cells Make ATP! Make ATP! All I do all day… And no one even notices! food • Product enzymes – ATP • Waste products – carbon dioxide • then used by plants – water O2 ATP CO2 H2O 23 11/8/16 A Body s Energy Budget Using ATP to do work? Can t store ATP # carbohydrates & fats are long term energy storage 1 ATP # too unstable # only used in cell that produces it # only short term energy storage Adenosine TriPhosphate work Adenosine DiPhosphate eat food make energy ATP ADP 2 A working muscle recycles over 10 million ATPs per second Whoa! Pass me the glucose & oxygen! What if oxygen is missing? • No oxygen available = can t complete aerobic respiration • Anaerobic respiration 3 O2 – no oxygen or no mitochondria (bacteria) – can only make very little ATP – large animals cannot survive storage Anaerobic Respiration • growth • reproduction • repair • glycogen (animal starch) • fat O2 • Fermentation – alcohol fermentation • yeast – glucose → ATP + CO2+ alcohol – make beer, wine, bread – also known as fermentation • alcohol fermentation • lactic acid fermentation synthesis (building) { { { • energy needed even at rest • activity • temperature control – lactic acid fermentation yeast • bacteria, animals – glucose → ATP + lactic acid – bacteria make yogurt – animals feel muscle fatigue bacteria Tastes good… but not enough energy for me! 24 11/8/16 Comparing Photosynthesis and Cellular Respiration Photosynthesis Cellular Respiration Function Stores Energy Energy release Location Chloroplast Mitochondria Reactants Carbon dioxide and Glucose and oxygen water Glucose and oxygen Carbon dioxide and water Products Equation 6CO2+6H2O+light % 6O2+C6H12O6 Got the energy… Ask Questions!! 6O2+C6H12O6 % 6CO2+6H2O+energy Comparing Photosynthesis and Cellular Respiration Photosynthesis Cellular Respiration Requires CO2, H20, & Sun Light Requires O2 & C6H12O6 Occurs in the Chloroplast located in Occurs in the Mitochondria of plant the Leaf and animal cells Attach the comparison chart and diagram in your notebook on Page _____ Stores energy in the form of glucose molecule 2 types: aerobic & anaerobic Releases 6O2+C6H12O6 Releases CO2, H2O & energy(ATP) Uses solar energy to produce chemical energy Breaks down glucose to release ATP Equation: Equation: 6CO2+6H2O+light %6O2+C6H12O6 6O2+C6H12O6 %6CO2+6H2O+energy 25 11/8/16 Photosynthesis & Respiration Diagram Attach the Chloroplast & Mitochondria/ Photosynthesis & Respiration Diagram in your Notebook on Page ____ The Cell Cycle and Mitosis Notes Page ___ Biology is the only subject in which multiplication is the same thing as division… THE CELL CYCLE • Series of events that cells go through as they grow and divide • Consists of four phases: – G1 PHASE – CELL GROWTH – S PHASE – CHROMOSOME REPLICATION – G2 PHASE – PREPARATION FOR MITOSIS – M PHASE – MITOSIS AND CYTOKINESIS 26 11/8/16 Cell Cycle: order does matter& • Remember: Cell Cycle phases as IPMAT • I= Interphase (G1, S, G2 phases) • P= Prophase (M phase) • M= Metaphase (M phase) • A= Anaphase (M phase) • T= Telophase (M phase) Where it all began… MITOSIS: Making New Body Cells Making New DNA And now look at you… You started as a cell smaller than a period at the end of a sentence… How did you get from there to here? 27 11/8/16 Getting from there to here… Why do cells divide… # One-celled organisms • Going from egg to baby…. the original fertilized egg has to divide… and divide… and divide… and divide… ' ' for reproduction asexual reproduction (clones) amoeba # Multi-celled organisms ' for growth & development ' for repair & replacement # from fertilized egg to adult starfish # replace cells that die from normal wear & tear or from injury Dividing cells… Copying DNA • What has to be copied • A dividing cell duplicates its DNA – DNA – organelles – cell membrane – lots of other molecules – creates 2 copies of all DNA – separates the 2 copies to opposite ends of the cell – splits into 2 daughter cells DNA • enzymes cell plant cell animal cell nucleus # But the DNA starts loosely wound in the nucleus # If you tried to divide it like that, it could tangle & break 28 11/8/16 Organizing & packaging DNA Chromosomes of Human Female DNA 46 chromosomes 23 pairs cell DNA has been wound up nucleus DNA in chromosomes in everyday working cell cell nucleus 4 chromosomes in this organism DNA in chromosomes in cell getting ready to divide Chromosomes of Human Male double-stranded human chromosomes ready for mitosis 46 chromosomes 23 pairs 29 11/8/16 MITOSIS=body cells DNA must be duplicated… chromosomes in cell DNA in chromosomes cell nucleus • Asexual reproduction for single cells (remember: My toe needs to grow; this does not need a partner &) 4 single-stranded chromosomes • Growth & development for multicellular organisms • Four phases of Mitosis: (Hint: PMAT) 1st P= Prophase duplicated chromosomes duplicated chromosomes cell 2nd M= Metaphase 3rd A= Anaphase 4th T= Telophase nucleus 4 double-stranded chromosomes Mitosis: Dividing DNA & cells • Stage 2: DNA winds into chromosomes • Stage 1: cell copies DNA – DNA is wound up into chromosomes to keep it organized Copy DNA! DNA Mitosis: Dividing DNA & cells duplicated chromosomes Wind up! cell cell nucleus (prophase) Cells spend the most time in Interphase nucleus (interphase) 30 11/8/16 Mitosis: Dividing DNA & cells • Stage 3: Chromosomes line up – chromosomes line up in middle – attached to protein cables that will help them move Line up! duplicated chromosomes lined up in middle of cell Mitosis: Dividing DNA & cells • Stage 4: Chromosomes separate – chromosomes split, separating pairs – start moving to opposite ends Separate! chromosomes split & move to opposite ends (pull apart) (metaphase) Mitosis: Dividing DNA & cells • Stage 5: Cell starts to divide (anaphase) Mitosis: Dividing DNA & cells • Stage 6: DNA unwinds again – cells start to divide – nucleus forms again – cells separate – now they can do their every day jobs Divide! Makes 2 new cells (telophase) Bye Bye! (cytokinesis) 31 11/8/16 New daughter cells Cell division in Animals • Get 2 exact copies of original cells – same DNA – clones Mitosis in whitefish embryo Mitosis in plant cell 32 11/8/16 Overview of mitosis interphase I.P.M.A.T.C. prophase Please Make Another Two Cells cytokinesis metaphase REGULATING THE CELL CYCLE • REGULATORY PROTEINS (Cyclins) – CONTROL CELL GROWTH – STIMULATES THE CELL TO PRODUCE SPINDLE AND BEGIN CELL DIVISION – NORMAL CELLS STOP GROWING WHEN THEY COME INTO CONTACT WITH EACH OTHER anaphase telophase What happens when there is Cancer Cells? • Cancer Cells – Don t respond to signals that control the cell cycle – Do not stop dividing – Can form tumors • Carcinogens – Damage DNA, results in cancer – Radiation – Cigarette smoke – Environmental chemicals 33 11/8/16 Mitosis Drawing & Questions Notebook Page ____ Draw, Color, Label & Descriptions. • (Fig. 8.13 A, B, C, D) Page 207 Cell Cycle & Chromosomes Drawing & Questions Notebook Page ____ Draw, Color, Label & Descriptions. Write questions & answers. • (Fig. 8.11 & 8.12) Page 206 1. What are the four phases of mitosis? 2. When does mitosis begin? 3. Describe metaphase. 4. How many daughter cells are formed during telophase? Write questions & answers. 1. In which phase does a cell spend most of its time? 2. What holds the two sister chromatids together? 3. Explain what happens during interphase. 34