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MIDDLETOWN HIGH SCHOOL SOUTH BIOLOGY THE CELL AND TRANSPORT BOOKLET 13 NAME: _________________________________ CLASS: _____________ Miss Tagore MHSS April 2013 1 LEARNING OUTCOMES Cell Variety (a) There are variations in cell structure and different types of tissue (b) There are different types of cells; prokaryotic and eukaryotic cells (c) Unicellular organisms can be found. (d) The structural similarities and differences between animal and plant cells. (e) The relationship of structure to function Absorption and secretion of materials (a) Diffusion Osmosis and Active Transport as cell processes (b) Understand the terms/definitions Hypotonic, Hypertonic and Isotonic. (c) State what happens to animal and plant cells when placed in these solutions (d) The structure and function of the plant cell wall. (e) The structure and function of the cell membrane Miss Tagore MHSS April 2013 2 EUKAROTIC CELLS • All living things are composed of cells • Cells are the basic units of structures and function in living things • All cells come from preexisting cells. • Eukaryotic cells include both plant and animal cells. • They are referred to as eukaryotic because they contain membrane bound nuclei. • Prokaryotic cells include bacteria and their relatives. • These are usually unicellular organisms. • They are referred to as prokaryotic because they do not contain a membrane bound nucleus. Miss Tagore MHSS April 2013 3 CELL ORGANELLES Both plant and animal cells contain “mini organs” known as organelles. These organelles do specific jobs for the cell to ensure that normal functioning occurs for the whole organism. The diagrams below show the organelles present in animal and plant cells. You should recognize most of these from previous topics. Task 1: Collect the Cell Coloring sheets from your teacher and complete them both using this page to help you. Miss Tagore MHSS April 2013 4 Task 2: Label the organelles in the diagrams below. Try to do this without looking at the previous page. Plant cell THE FUNCTIONS OF CELL ORGANELLES Miss Tagore MHSS April 2013 5 Golgi apparatus • • Packages and secretes complex molecules. Form lysosomes Secretory vesicles • Move to the surface of a cell and discharge their contents Mitochondria • Site of aerobic respiration. Chloroplasts • Site of photosynthesis. Smooth endoplasmic reticulum • • Large surface area for transport of lipids. Detoxification of drugs, fat metabolism. Miss Tagore MHSS April 2013 6 Ribosomes • Site of protein synthesis. Nucleus: • Controls cell activities and contains DNA and mRNA Centrioles: • Involved in spindle fiber formation in meiosis/mitosis Lysosomes • Contains powerful enzymes which digest redundant structures. Cytoplasm: • Fluid in which many chemical reactions take place. Miss Tagore MHSS April 2013 7 Task 3: Complete the questions that follow. Make sure that you check with your teacher to ensure you have the correct answers. The following table contains a description of an organelle. Write in the name of the organelle that matches the description. Organelle Description I am surrounded by a doublemembrane, I am the site of respiration reactions called the Krebs' cycle and oxidative phosphorylation, I make ATP. I evolved from bacteria many millions of years ago. I have my own DNA. What am I? I am a membrane-bound organelle, I am involved in preparing protein for secretion, I am named after an Italian scientist. What am I? I am a membrane bound organelle, I contain water and dissolved substances, I enlarge if the cell is placed in a hypotonic solution. What am I? I am a formed when the ends of Golgi body pinches off, I move towards the cell membrane, I contain protein that is about to be secreted. What am I? I am membrane-bound, I am studded with ribosomes, I make protein that is locked inside my centre. What am I? Miss Tagore MHSS April 2013 8 I am a small pore around the control centre of the cell, I allow messages used to make protein to get into the cytoplasm. What am I? I am not really an organelle, I am flexible and surrounded by many organelles. What am I? I am used to separate chromosomes during mitosis and meiosis; I am set of two protein chains arranged at 90° to each other. What am I? I evolved from bacteria millions of years ago, I have a part that absorbs light and a part that turns carbon dioxide into sugar, I contain the pigment chlorophyll, I contain my own DNA. What am I? I am part of the nucleus, I make ribosomes. What am I? Miss Tagore MHSS April 2013 9 THE PLASMA MEMBRANE The cell membrane is not one solid piece. Everything in life is made of smaller pieces and a membrane is no different. Compounds called proteins and phospholipids make up most of the cell membrane. Scientists describe the organization of the phospholipids and proteins as the fluid mosaic model. This is because the structure is not hard or solid and the scattering of proteins throughout gives a mosaic effect. That model shows that the phospholipids are in a shape like a head and with two tails. The heads like water (hydrophilic) and the tails do not like water (hydrophobic). The tails bump up against each other and the heads are out facing the watery area surrounding the inside or outside of the cell. The two layers of cells are called the bilayer. There are various different proteins in the cell membrane. Some span the entire length of the membrane and some are partially embedded on one side. One of the most important functions of proteins in the cell membrane is to transport molecules into or out of the cell. There are two ways this can happen o Passive transport (does not require any energy) o Active transport (does require energy) Miss Tagore MHSS April 2013 10 Task 4: Complete the questions that follow. Make sure that you check with your teacher to ensure you have the correct answers. 1. Complete the descriptions in the diagram but adding in the appropriate word. 2. What are the two components that make up a cell membrane? 3. Proteins transport substances into and out of the cell. a. Name two substances that would be transported into a cell b. Name two substances that would be transported out of a cell 4. What is meant by the term “passive transport”? 5. Where to cells get the energy from to transport molecules across a cell membrane? Miss Tagore MHSS April 2013 11 6. Complete the diagram of a cell membrane using the labels below. Miss Tagore MHSS April 2013 12 TYPES OF TRANSPORT ACROSS THE CELL MEMBRANE DIFFUSION Diffusion is the movement of molecules in a liquid or gas from high to low concentration until they are evenly spread out. Diffusion will stop when all the molecules are evenly spread out. In animals, the gas oxygen diffuses into cells and the gas carbon dioxide diffuses out of cells. Other small molecules such as glucose and water also diffuse into our cells, while waste products diffuse out of cells. Diffusion is an important process to animals because it allows useful substances to enter cells and harmful ones to leave. Miss Tagore MHSS April 2013 13 Task 5: Complete the questions that follow. Make sure that you check with your teacher to ensure you have the correct answers. 1. Substances enter and leave cells by the process of A B C D dissolving evaporating breathing diffusing 2. Substances enter and leave cells by passing through the A B C D nucleus membrane cytoplasm vacuole 3. In diffusion, substances move from A B C D high concentration to low concentration high concentration to high concentration low concentration to low concentration low concentration to high concentration 4. Diffusion stops when molecules A B C D are at high concentration are a low concentration are at even concentration stop moving completely 5. In which diagram do the black molecules have the highest concentration? A B C D Miss Tagore MHSS April 2013 14 6. The diagram shows the concentrations of black molecules in four cells Cell 1 Cell 3 Cell 2 Cell 4 In which direction will the black molecules diffuse? A B C D From cell 1 to cell 2 From cell 2 to cell 4 From cell 4 to cell 3 From cell 3 to cell 1 7. Which of these can enter or leave cells by the process of diffusion? A B C D carbon dioxide only carbon dioxide and dissolved food only oxygen and dissolved food only oxygen, carbon dioxide, and dissolved food 8. Diffusion is important to animals. One reason is that A B C D they breathe by diffusion oxygen enters their blood by diffusion blood moves by diffusion carbon dioxide enters their cells by diffusion Miss Tagore MHSS April 2013 15 OSMOSIS Selectively permeable membranes allow certain molecules to pass through but not others. Pores in the cell membrane are small, so only small molecules such as water, glucose, oxygen and carbon dioxide can get through. Large molecules such as starch cannot pass through. Osmosis is the special diffusion of water from high water concentration to low water concentration through a selectively permeable membrane. CONCENTRATION GRADIENTS • Like the ball on the slope, water also moves down a gradient from high to low • Solutions are made up of a solute dissolved in a solvent ex. sugar dissolved in water. • Concentrations of the mass of solute are written in percentages. Ex. 1 % sugar solutions contain 1% sugar as the solute and 99% water as the solvent. Selectively permeable membrane • Water moves down a concentration gradient by osmosis from high to lower water concentration. The water will stop moving when the two concentrations are equal. Miss Tagore MHSS April 2013 Water Sugar molecule 16 WATER CONCENTRATIONS • If we think about solutions in terms of their water concentrations, it is easier to recognize which direction water molecules will flow in. • A dilute sugar solution will have a high concentration of water. • A concentrated sugar solution will have a lower water concentration. OSMOTIC EFFECTS ON CELLS A hypotonic solution has a higher water concentration than the water concentration within the cell. The water concentration outside the cell is greater than that inside the cell so water moves into the cell by osmosis. (HWC) 0.1% Salt Solution Cell 1% Salt A hypertonic solution has a lower water concentration than the water concentration within the cell. The water concentration outside the cell is lower than that inside the cell so water moves out of the cell by osmosis. Miss Tagore MHSS April 2013 17 (LWC) 15% Salt Solution Cell 1% Salt An isotonic solution has a water concentration that is equal to the water concentration within the cell. Water is constantly moving in both directions so there is no net gain of water molecules in either direction. H2O concentration 1% salt = Miss Tagore MHSS April 2013 Cell 1% Salt 18 PLANT CELLS AND OSMOSIS Hypotonic solution: more water outside of the cell than inside, therefore water will move into the cell by osmosis. This causes the cell to swell and become turgid. The cell wall prevents it swelling any further. Hypertonic solution: more water inside the cell than outside, therefore water will move out of the cell by osmosis. This causes the cell to become softer or flaccid. Total water loss from a plant cell is known as plasmolysis. If this happens, the plant cell is said to be plasmolyzed. Miss Tagore MHSS April 2013 19 ANIMAL CELLS AND OSMOSIS The effects of osmosis on animal cells are totally different to plant cells because animals cell structures are different. Animals cells do not have: o Cell walls o Vacuoles Red blood cells (RBCs) float in a solution called plasma which is isotonic. RBCs in isotonic plasma do not change size because the water has no concentration gradient to follow. RBCs in hypotonic and hypertonic plasma will change because there is a concentration gradient for water to follow. Miss Tagore MHSS April 2013 20 Task 6: Complete the questions that follow. Make sure that you check with your teacher to ensure you have the correct answers. 1. State what is meant by the term osmosis. 2. The cell membrane is described as “selectively permeable”. Describe what this means and give some examples of molecules that can and cannot pass across the cell membrane. 3. Describe what is meant by a concentration gradient. Give an example in your answer. 4. Using the words hypertonic, isotonic and hypotonic, decide which word best describes the following solutions when compared to a plant cell with 1% sugar in its vacuole. a) 15% sugar solution. b) 1% sugar solution. c) 100% pure water. 5. Why must red blood cells be kept in an isotonic plasma solution? 6. Look carefully at the diagram below. For each cell in the different solutions, write down a word from the list below to describe it. Turgid, Plasmolyzed, Shrunk, Burst, Normal Miss Tagore MHSS April 2013 21 Task 7: Complete the questions that follow. Make sure that you check with your teacher to ensure you have the correct answers. 1. Which term best describes how water enters and leaves cells? A B C D Diffusion Osmosis Evaporation Permeation 2. Which statement best describes a selectively permeable membrane? A B C D It lets all substances through It does not let any substances through It is equally permeable to all substances It lets some substances through but not others. 3. A concentration gradient exists between two solutions of A B C D equal concentration of the same substance equals concentrations of different substances different concentrations of the same substance different concentrations of different substances 4. Osmosis is special diffusion of water from A B C D high concentration to lower concentration through a selectively permeable membrane high concentration to lower concentration through a fully permeable membrane low concentration to higher concentration through a selectively permeable membrane low concentration to higher concentration through a fully permeable membrane 5. A 5% sugar solution contains A B C D 5% water and 95% sugar 95% sugar and 95% water 5% sugar and 95% water 5% sugar and 5% water 6. Osmotic effects are different on plant cells compared with animal cells because A B C D plant cells have cytoplasm animal cells have cell walls animal cells do not have chloroplasts plant cells have cell walls and vacuoles Miss Tagore MHSS April 2013 22 7. Solution X is hypertonic to solution Y. Which of these statements is true? A B C D X has higher water concentration than Y X has a lower water concentration than Y Y has the same water concentration as X Y has a lower water concentration than X 8. A plant cell is flaccid if its vacuole is A B C D swollen and pushing the cytoplasm against the cell wall shrunken and pulling the cytoplasm away from the cell wall shrunken and pushing the cytoplasm against the cell wall swollen and pulling the cytoplasm away from the cell wall 9. What solution should a plant cell be placed in to make it fully turgid? A B C D hypotonic very hypertonic isotonic slightly hypertonic 10. If blood plasma became hypertonic, the red blood cells would A B C D burst shrink become plasmolyzed show no change 11. Red blood cells placed in a solution are observed to burst. Which type of solution were they immersed in? A B C D hypotonic slightly hypertonic very hypertonic isotonic Miss Tagore MHSS April 2013 23 ACTIVE TRANSPORT Active transport is an energy requiring process. It involves the movement of molecules against a concentration gradient. In active transport, molecules cross the membrane by passing through protein channels or carriers in the membrane In the diagram above, molecules are crossing the plasma membrane in the opposite direction of diffusion. Here, molecules are moving from a low concentration to a high concentration. Imagine you are in a crowd of people all going in one direction and you are going the opposite way. It would be easier to get swept up in the crowd and it takes an extra effort to “go against the flow”. The same is true for molecules that travel by active transport. These molecules are able to travel against the concentration gradient by using energy in the form of ATP. ATP gives the protein pump energy to move these molecules in the opposite direction. Miss Tagore MHSS April 2013 24 Task 8: Learn the words and definitions listed below. Your teacher may test you on these. Word Description Cell Wall Protects and supports plant cells Cell membrane Protects the cell, performs active transport and passive transport, moves materials in and out of the cell, communication Cytoplasm Pads and supports organelles inside the cell. The site of many chemical reactions. Nucleus Controls all of the cell’s activities Nuclear membrane Covers and protects the nucleus. Allows genetic material to leave the nucleus Nucleolus Produces ribosome’s Smooth Endoplasmic Reticulum Transports materials like proteins around the cell Ribosome The site of protein synthesis. Mitochondria Supplies ATP for the cell through cell respiration using glucose and oxygen Vacuole Storage tank for food, water, wastes or enzymes. Provides structural support for plant cells. Chloroplast Captures sunlight and uses it to produce food through photosynthesis Miss Tagore MHSS April 2013 25 Golgi Body Packages and secrets proteins for use in and out of the cell Lysosome Digests older cell parts, food or other objects Centriole Used with the spindle apparatus during mitosis Osmosis The diffusion of water from an area of high water concentration to an area of lower water concentration Diffusion The movement of molecules in a gas or a liquid from an area of high concentration to an area of low concentration Hydrophobic Water fearing Hydrophilic Water loving Active transport The movement of molecules and ions across a cell membrane against the concentration gradient. This process requires energy. Phospholipid Molecules that make up the majority of the cell membrane. Made of a head region and a tail region. Isotonic A solution with an equal water and solute concentration Hypertonic A solution with a higher solute concentration and lower water concentration Hypotonic A solution with a higher water concentration and lower solute concentration. Miss Tagore MHSS April 2013 26