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Nat 5 Cell Biology Pupil Notes Doon Academy Cell Bio 2013 1 (a) Cell structure / transport Cell Structure You have already learned about the basic structures Remember? that are found in plant & animal cells. Complete the diagrams below. Identify three structures that are common to both plant and animal cells: _______________________________________________________ Identify three structures that are found only in plant cells. ______________________________________________________ Doon Academy Cell Bio 2013 Cell structures and functions Your teacher will introduce a few more structures found within a cell and Cell organelle Cell wall Function Mitochondria Maintains cell shape / Fully permeable / Made of cellulose Site of aerobic respiration Chloroplasts Site of photosynthesis Cell membrane Controls entry and exit of material / Semi permeable Vacuole Contains cell sap Cytoplasm Site of chemical reactions Nucleus Controls cell activity Ribosomes Site of protein synthesis Plasmids Ring of DNA within a bacterial cell Doon Academy Cell Bio 2013 Structure of the Plasma Membrane The plasma membrane is referred to as the FLUID MOSAIC MODEL The reason for the name is that the phospholipids are constantly moving (fluid) and has a scattered (mosaic) arrangement of proteins. The proteins can function as: Doon Academy hormones, antibodies, enzymes structural support Cell Bio 2013 Fungi The cells of fungi are similar to plant cells. They have a nucleus, cytoplasm, ribosomes and mitochondria. They are however not green – they don’t photosynthesise and so don’t contain chloroplasts. Fungi need to feed on other organisms to obtain their energy source. Fungi are involved in decomposition - recycling nutrients from dead organisms back into the ecosystem. Humans have made great use of fungi, e.g. yeast are single-celled fungi and are used to make wine, beer and bread. Bacteria Bacteria have a much simpler structure than either plant or animal cells. They do not have an enclosed nucleus or mitochondria. The bacterial cell contains a cell wall. ALL their chemical reactions, including aerobic respiration occur in the cytoplasm. In the cytoplasm, bacteria also have ribosomes, upon which bacterial proteins are made. The bacterial cell also contains a cell wall. Bacteria keep their genetic information in a structure called a nucleoid, which is a large ring of DNA. In addition, they also have extra genetic information in a small ring of DNA called a plasmid. Doon Academy Cell Bio 2013 Diffusion Diffusion is the movement of molecules from a high concentration to a low concentration until they are evenly spread. Oxygen: Will diffuse from the lungs into the blood and then into the cells Carbon dioxide Will diffuse from the cells into the blood and then into the lungs Starch Will not diffuse because it is too large Water Water does not diffuse. It moves by osmosis Osmosis – A special kind of diffusion Osmosis is the movement of water from a high concentration to a low concentration through a selectively permeable membrane. Some new words • Hypertonic – LOW Water Conc • Isotonic – SAME Water Conc • Hypotonic – HIGH Water Conc Doon Academy Cell Bio 2013 What happens to cells in different solutions? Doon Academy Cell Bio 2013 Explaining the changes in cell appearance Plant cell placed in pure Plant cell placed in water strong salt solution The high water concentration The high water concentration is _________ the cell. Water is _________ the cell. Water will move _________ the cell will move _________ the cell from a _________ to a from a _________ to a _________ water _________ water concentation. The cell will concentation. The cell will become ____________ become ____________ Draw what the cell would look Draw what the cell would look like like Animal cell placed in pure water Animal cell placed in strong salt solution The high water concentration is _________ the cell. Water will move _________ the cell from a _________ to a _________ water concentation. The cell will _____________ The high water concentration is _________ the cell. Water will move _________ the cell from a _________ to a _________ water concentation. The cell will _____________ Draw what the cell would look like Draw what the cell would look like Doon Academy Cell Bio 2013 Active transport Active transport is when substances are absorbed against a concentration gradient (like a ball being rolled up a hill). Like nitrates being taken in by root hair cells Active transport always requires energy. The sodium/ potassium pump (which always requires active transport) is a carrier protein which exchanges sodium and potassium across the membrane to maintain nerve function. Active transport is dependent upon several factors including; temperature availability of oxygen availability of respiratory substrate Doon Academy Cell Bio 2013 1 (b) Producing new cells/Genetic engineering Cell division Cell division is a means of increasing the number of cell for ______________ organism. Single cell organisms use cell division as a menas of reproducing _________. It is the _________ that controls cell division. Each of our cells (except our ______ cells) contains two matching sets of chromomosomes. Each cell is therefore said to be d___________. Human cells have 2 sets of _____ chromomosomes. Cell division ensures that each daughter cell has the i______________ g______________ information to that of the parent cell. The process of cell division is called _________ We use cell division for 1) Growth, 2) Repair, 3) Therapeutic uses Doon Academy Cell Bio 2013 Stages of Mitosis There are two main stages in mitosis 1: The __________ divides 2: The cytoplasm divides These two stages can be further broken down into smaller steps, as shown below: Stage 1 Stage 2 Stage 3. The chromosomes shorten and duplicate. The chromosomes are now visible No chromosomes are visible The chromosomes line up along the equator of the cell. The membrane around the nucleus has disappeared Stage 5. Stage 6. The identical chromatids arrive at opposite poles The cytoplasm is now starting to divide Doon Academy Cell Bio •The nuclear membrane reappears. •The cell now divides into two identical daughter cells. 2013 Growing Micro-organisms Different types of micro-organisms require specific conditions to grow. These conditions include appropriate temperature and an appropriate food supply Antibiotics can be used to treat bacterial infections A range of antibiotics is required because: 1) Some people are allergic to certain antibiotics 2) Bacteria can become resistant to a particular antibiotic. Watch this link from the Wellcome Trust to give you an insight into the cell culturing process http://www.wellcome.ac.uk/Education-resources/Teaching-andeducation/Big-Picture/All-issues/The-Cell/WTDV030777.htm Doon Academy Cell Bio 2013 Your turn - Streaking agar plates Instructions Disinfect your work surface Light bunsen burner Open sample bottle using your pinky and heat the neck of the bottle Heat the inoculating loop until it glows and then allow to cool Dip the loop into the water Gently streak the agar plate in a zigzag fashion Reason To limits cross contamination. Bacterial spores may be present on surface To destroy any bacteria present in the air that may land on the agar plates To destroy any bacteria present on the bottle top and stops cross contamination from your hands To destroy any bacteria present on the loop To collect a water sample To separate different bacterial colonies Seal the petri dish using To avoid spread of germs cellotape Label your dish on the To avoid confusion if the lids fall off. bottom Leave for 3-5 days To allow bacterial growth to occur Doon Academy Cell Bio 2013 Genetic Engineering Genetic engineering is the transfer of genetic material from one organism to another. Microorganisms, e.g bacteria and yeast are often reprogrammed during genetic engineering to produce substances such as insulin for the following reasons: 1) They multiply quickly 2)They are inexpensive and 3) They are easier to reprogramme than other organisms.. Stages of genetic engineering 1. An enzyme is used to cut the human gene out of the chromosome. 2. Plasmids are then removed from bacterial cells. 3. The plasmids are cut open with an enzyme. 4. A human gene is inserted into each plasmid. 5. Plasmids are inserted back into the bacteria. 6. Bacteria with the human gene are then multiplied. 7. Each bacterium will produce a tiny volume of insulin 8. By culturing the genetically engineered bacteria limitless supplies of the useful product may be produced. Doon Academy Cell Bio 2013 Doon Academy Cell Bio 2013 1 (c) DNA and Proteins DNA STRUCTURE 1. DNA is made up of nucleotides. 2. Each nucleotide is made up of a phosphate, a deoxyribose sugar and an organic base. phosphate organic base deoxyribose sugar 3. There are 4 types of organic base – adenine, thymine, cytosine and guanine. 4. adenine thymine guanine ytosine 5. Nucleotides are joined to form long strands – a covalent bond forms between the deoxyribose sugar of one nucleotide and the phosphate of the next nucleotide. strong covalent bond Doon Academy Cell Bio 2013 6. DNA is made of 2 strands of nucleotides joined together by the organic bases. 7. Adenine pairs with thymine and cytosine pairs with guanine. 8. The base pairs are held together by weak hydrogen bonds. A G T C Adenine always pairs with Thymine Hydrogen bond Cytosine always pairs with Guanine They are “Complementary Base Pairs” 9. The two strands are coiled round to form a double helix. Doon Academy Cell Bio 2013 Sequence of DNA Bases The chemical components of DNA are the same in all species. However, the DNA of one species differs from another species in _____________ and in the _____________ in which the bases (A, T, G and C) occur. It is this __________________ of bases along the DNA strand which is unique to the organism. The base sequence contains the GENETIC instructions which control the organism’s ____________ characteristics. The Genetic Code and Protein Synthesis The genetic code is the information present in a molecule of DNA. It is like a molecular code language. The sequence of bases along a DNA strand represents a sequence of ‘codewords’. A molecule called Messenger RNA carries a copy of this code from the _________________ to the ________________ where protein is synthesised. Proteins are made up of one or more Polypeptide chains, and the building blocks for this chain are _________ ___________. Doon Academy Cell Bio 2013 Each amino acid is coded for by THREE bases (a “triplet”) called a CODON The instructions for protein synthesis are coded by the triplet code (_____________) of DNA bases. This is because each codon corresponds to a specific _________ _____ e.g. DNA codon AAT codes for the amino acid Leucine. So Codons are the basic units of the genetic code because each strand of DNA has codons arranged in a particular order. In other words, the order of amino acids is determined by the base sequence on the DNA. Doon Academy Cell Bio 2013 Variety of Proteins Proteins consist of long chains of AMINO ACIDS. There are ______ different amino acids. As the 26 letters of the alphabet permit the construction of an infinite number of words, so the 20 different amino acids allow for an infinite variety of proteins. The amino acids form long chains which can fold in various ways. These chains are called ______________. A particular protein might consist of two or more polypeptides. All amino acids (and hence proteins) contain carbon, hydrogen, oxygen, and ______________ Some amino acids also have sulphur. A protein might have hundreds or even thousands of amino acids. VARIETY OF PROTEINS. There are many functions which are undertaken by a variety of proteins Complete the following table Name Collagen Keratin Enzymes Antibodies Haemoglobin Actin and Myosin Insulin Doon Academy Function Cell Bio 2013 1 (d) Enzymes How do enzymes work? Every reaction requires a certain level of energy to allow it to happen. This energy is called the ACTIVATION ENERGY. An enzyme LOWERS the activation energy required, hence allowing the reaction to take place. Enzyme Equations Substrate Enzyme Products Catalase Hydrogen Peroxide Amylase Starch Protein Pepsin Phosphorylase Glucose 1 Phosphate Doon Academy Lipase Cell Bio O2 and H20 Maltose Amino Acids Starch 2013 Biological Catalysts Are in all living cells Fits with substrate like a Lock & Key OPTIMUM means best Have active sites Speed up chemical reactions DENATURED means destroyed ENZYMES Made of protein Specific Unchanged by reaction. Specificity of Enzymes During an enzyme controlled reaction the substances involved – the substrates – become joined to the surface of the enzyme molecule. The chemical reaction then takes place very rapidly. The spot on the enzyme molecule where the catalytic activity takes place is called the ___________ SITE. Enzyme molecules, that fit the active sites exactly, react on the surface of the enzyme. Substrate molecules fit into these active sites rather like a key fitting into a lock. The enzyme is said to be “SPECIFIC” to the __________. Doon Academy Cell Bio 2013 Synthesis Reactions Active sites Enzyme Molecule Stage 1 Substrate Molecules Substrate and enzyme join together Stage 2 Unchanged enzyme molecule now free to react with more substrate Stage 3 Product Molecule Colour in using the following key Enzyme Molecule Substrate Molecules Product Molecules Doon Academy Cell Bio Blue Red and Yellow Orange 2013 Using class room resources, find definitions of the following a) Specific b) Enzyme c) End Product d) Substrate e) Synthesis f) Active Site Doon Academy Cell Bio 2013 Optimum Enzyme Activity and working ranges Enzymes work best at certain temperatures and pH’s. The condition in which the enzyme works best is known as the ‘Optimum’ condition. Enzyme activity Enzymes can however work at other temps and PH’s other than the optimum one, however not as efficiently. The range of conditions in which an enzyme can work is known as the working range. At high temperatures the shape of the enzymes active site is permanently altered, and is Denatured. Doon Academy Cell Bio 2013 1 (e) Respiration Energy from food Method 1) Set up the experiment as shown below. Thermometer Boiling tube Clamp Stand Burning spoon Burning food 2. Measure 20cm3 of water into a boiling tube. 3. Record the starting temp of the water in the boiling tube. Leave the thermometer in the boiling tube. 4. Measure out 1g of each food using the balance. You should have a carbohydrate, a protein and a fat food to test. 5. Using the deflagrating spoon as shown by your teacher, heat the first piece of food until it catches fire. 6. Hold the burning food underneath the boiling tube of water until it stops burning. 7. Record in your jotter the final temperature of the water. 8. Repeat the above for the 2nd and 3rd piece of food Doon Academy Cell Bio 2013 Results Food Starting Final temp Change in sample temp (oC) (oC) temp (oC) Pasta 20 49 Cereal 24 12 Rice 26 15 Conclusion The food that contains the most energy is _________________________ Evaluation The above experiment may indicate less energy than is actually present in the food because ______________________________________________________________ _______________________________________________________________ Doon Academy Cell Bio 2013 Respiration Doon Academy Cell Bio 2013 Respiration All organisms require energy. Respiration is the release of ____________ (in the form of ATP) from ___________ in a series of ________________ controlled reactions. ATP • ATP is an immediate source of energy for your cells particularly your muscles that need it when they are contracting. ATP is required by our cells as an energy source for: • Muscle contraction • Cell division Synthesis of ATP • Building up (synthesis) of proteins • Transmission of nerve impulses Adenosine diphosphsate phosphate Adenosine tri-phosphate Energy in adenosine P P P adenosine P P Energy out Types of respiration There are two kinds of respiration: 1. Aerobic respiration 2 . Anaerobic respiration Doon Academy Cell Bio 2013 P 1. Aerobic respiration Aerobic respiration is broken down into 2 stages: 1 . In the cytoplasm, glucose is partially broken down into a molecule called pyruvic acid. Only a little energy is released to form 2 molecules of ATP. GLUCOSE 2ADP + 2Pi 2ATP 2 x PYRUVIC ACID 3C 2 . Pyruvic acid enters the mitochondria where it is completely broken down to form carbon dioxide and water and enough energy is released to form 36 molecules of ATP. • Therefore a total of ______molecules of ______are made when 1 molecule of _________ is broken down in the presence of __________ . Doon Academy Cell Bio 2013 Simple respirometer - Measuring the oxygen uptake The sodium hydroxide absorbs ___________ ______________ produced by the snail during respiration. This means that carbon dioxide does not interfere with the movement of the coloured liquid. The coloured liquid moved upwards to replace the space the ___________ molecules once took up. There is a ____________in pressure ____________ the apparatus since oxygen is being used up. There is a ___________ pressure ___________ container pushing on liquid resulting in it moving upwards towards the snail. Doon Academy Cell Bio 2013 2) Anaerobic respiration • Anaerobic respiration is known as _________________. • It is the incomplete breakdown of glucose in the absence of ____________ and occurs only in the cytoplasm of the cells. a) In animals Glucose is broken down into pyruvic acid which is then converted into _______________. Only ___ ATP are made. A build up of lactic acid can cause muscle ___________________. Doon Academy Cell Bio 2013 b) In plants and yeast Glucose is broken down into ______________ __________ which is then converted into ____________ _____________ and _____________. This occurs in the absence of ____________. Yeast is used in baking and brewing. The __________ _____________ causes the dough to rise in bread. Doon Academy Cell Bio 2013 1 (f) Photosynthesis Conditions required for photosynthesis 1. Is light needed? Experiment Result Conclusion 2. Is carbon dioxide needed? Experiment Result Conclusion 3. Is chlorophyll needed? Experiment Result Conclusion Part with chlorophyll Part without chlorophyll Doon Academy Cell Bio 2013 Raw Materials Green plants use simple chemicals – _____________ & __________ from the environment as raw materials to make food. Water is absorbed by the plant from the soil and it travels through the plant to the leaves where photosynthesis takes place. Carbon dioxide enters the plant through small pores in the leaf called ____________. Sunlight provides the energy to drive this process. The light energy is absorbed by ___________________, the green pigment found in chloroplasts in the leaf. Photosynthesis Equation + water chlorophyll Word bank Sugar carbon dioxide xygen raw materials Doon Academy Products Cell Bio + light energy essential requirements 2013 Photosynthesis Carbon dioxide + water Light energy Glucose + Oxygen Chlorophyll Starch (storage) Cellulose (structural) Photosynthesis is a series of ______________ controlled reactions. There are two stages : 1) Photolysis 2) Carbon Fixation Both stages occur within the _______________ of a plant cell. 1) Photolysis Light Trapped by ____________ Splits water _________ (by-product) ADP + Pi Doon Academy ________ Photophosphorylation Cell Bio 2013 2) Carbon Fixation Carbon dioxide Glucose (6C) Starch (storage) Cellulose (structural) Starch Starch molecules are long chains of glucose molecules. Starch is a plant’s store of food and can be converted back to glucose sugar for energy when needed. Starch is therefore called a ____________ carbohydrate. Cellulose Cellulose molecules are also long chains of glucose molecules, but they are arranged differently to Starch – every other glucose is “upside down” Cellulose is therefore called a _____________ carbohydrate. Doon Academy Cell Bio 2013 Limiting factors A limiting factor is any factor that is restricting the rate of photosynthesis. The rate of photosynthesis is usually measured by the number of _________ bubbles produced or the _______ of food produced. The limiting factor at A is: ______________________ The limiting factor at B is: ______________________ The limiting factor at C is: ______________________ At point D the rate if photosynthesis may have levelled out for 2 reasons: 1) 2) Doon Academy Cell Bio 2013 Measuring the rate of photosynthesis in Elodea What must be done to the Elodea sample before carrying out the experiment? _______________________________________________ The rate of photosynthesis is measured by the ____________________________________ The sheet of glass is placed between the light and elodea to ensure ________________________________________ Doon Academy Cell Bio 2013