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1. Cell Ultrastructure 2. Transport Across The Membrane 3. Cell division 4. DNA & Protein Production 5. Enzymes 6. Genetic Engineering 7. Photosynthesis 8. Respiration Topic 1 Cell Functions and Structures Structure Function Cell Type Nucleus Controls cell activities All Cytoplasm Site of chemical reactions All Cell Membrane Controls exchange of materials in/out of the cell TASK! All Ribosomes All Mitochondria Site of protein synthesis Make Match Cards of the Site of Aerobic Respiration (ATP/ structures and functions. Chloroplasts Site of photosynthesis Green Plants Vacuole Stores cell sap Plant, Fungal Cell Wall Provides structure and prevents bursting Plant, Fungal, Bacteria Plasmid Extra ring of DNA Bacteria Energy Production) All Fungal Cell Bacterial Cell 3D Model Homework Choose 1 of the 4 cell types and create a 3D model with structures clearly labelled. Model is due 1 week today. Topic 2 Transport: Key Terms and Definitions Term Definition Passive Transport Movement of molecules without using ATP (energy) Diffusion The movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient Osmosis TASK The movement of water molecules from an area of Makehigh Match Cards ofarea these concentration to an of low concentration a concentration gradient key down terms and definitions. Active Transport The movement of molecules from an area of low concentration to an area of high concentration against a concentration gradient using ATP (energy) Hypertonic A solution which has a lower water concentration to that of the cell contents Isotonic A solution which has equal water concentration to that of the cells contents Hypotonic A solution which has greater water concentration to that of the cell contents. Structure of the Cell Membrane • The cell membrane is made of PROTEINS and LIPID molecules in a BI-LAYER known as the fluid mosaic model. TASK Use the worksheet provided to create your own model membrane. • Proteins are spaced randomly and can be embedded or span the entire width of the membrane. • These proteins can be CARRIERS during active transport or create protein CHANNELS/PORES for passive transport processes. Passive Transport: Diffusion • Diffusion is the passive transport of molecules from an area of high concentration to an area of low concentration down a concentration gradient.Experiment 1 does not require any energy as molecules Using visking tubing as a which are small enough will pass through protein channels in/out of the model membrane show cell as required. • Diffusion • Examples that only small molecules of molecules which move by this transport method can Dioxide pass through. include: Oxygen, Carbon and Glucose. Passive Transport: Osmosis • Osmosis is a special case of diffusion as it refers solely to the movement of WATER. • Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration down a concentration gradient. • Osmosis occurs continually to maintain balance in organisms as too much or too little water can have a detrimental effect on the cell. Osmotic Effects on Cells THINK! What do you think each of the terms isotonic, hypotonic and hypertonic mean in this context? Use the diagrams to help you and discuss with your partner. Experiment 2 Using identical cylinders of potato and various concentrations of salt, identify the ISOTONIC water concentration in plant tissue. Active Transport • Active transport involves the embedded protein molecules in the fluid membrane acting as carrier molecules to transport larger molecules across the membrane. • Active transport requires energy (ATP) as molecules are moved AGAINST a concentration gradient from a high concentration to a low concentration. • Examples of substances that enter a cell by active transport include ions such as Sodium and Potassium. Topic 3 Cell Division: Mitosis • MITOSIS is the term given to the process of cell division. • Cells must divide for GROWTH and REPAIR purposes in the body. • There are 6 key stages in this process which ends in 2 daughter cells being IDENTICAL to the parent cell. • They are genetically identical to prevent loss of information (sometimes written as maintaining the cells chromosome complement) Stage Description 1 Chromosomes become visible after undergoing DNA replication 2 3 4 Chromosomes shorten and pair up as TASK TASK chromatids Makethe Picture and Description Use resources provided to match cards.of Nuclear membrane draw out the 6 stages Mitosis.disappears and chromatidsexam line up at the cells Mitosis is a favourite equator question so you must know EVERYSpindle stage.fibres pull apart chromosomes to opposite poles in the cell 5 Nuclear membrane forms around groups of chromosomes and cytoplasm divides 6 2 identical daughter cells formed Cell Culturing • Cells can be grown in lab cultures for use in research or classroom practice. • In order for any cell culture to be grown, the right growing conditions must be present; - Nutrient growth medium - Optimum pH - Optimum temperature • Cell cultures can be grown on a variety of mediums including: - Agar plates - Agar slopes - Agar broths Aseptic Techniques • Aseptic techniques are used for all cell culturing experiment to AVOID CONTAMINATION. • Aseptic techniques and conditions ensure sterile conditions as far as possible. • Aseptic - conditions include: Hand washing Hair tied back Apron/Lab Coat Working close to a flame Disinfecting work area Flaming bottle neck/ metal loop Cell Culturing • When streaking an agar plate to grow a cell culture you must follow the zig zag pattern as shown on the Experiment 3 image. Use your knowledge of aseptic • The initial streak will betechniques to culture very dense with your yeast on an agar microbe so by streaking plate. it out a further 3 times you can identify a single colony to transfer for growth. THINK! What do you notice about the edge of each zig zag? Why do you think this is done? Topic 4 Deoxyribonucleic Acid (DNA) • D.N.A is found inside the nucleus of a cell on threadlike structures called chromosomes. • D.N.A. has a unique structure in that it consists of a 2 strands twisted together known as a double stranded helix. EXAM Favourite DNA questions often come up as problem solving questions. Nucleotides • D.N.A is made up of repeating units called NUCLEOTIDES. • Nucleotides are made up of a phosphate, a ribose sugar and 1 TASK TASK Use Use the the model sweets kitsprovided in pairs to to • The 4 bases are; create aanmodel edibleofDNA the DNA helix. - Adenosine create Ensure andyou complementary have the bases base in - Thymine helix - Cytosine complimentary pairs. fashion and can - Guanine explain the structure. Take a • The bases aresmiling COMPLIMENTARY always pairing with selfie with with yourAmodel T and G always pairing withyou C. eat it! before of 4 bases. Proteins • The order of the bases on a DNA strand provide a specific code for a particular type of protein to be made at the ribosome. • Examples table: of proteins and their functions are given in the Protein Function Enzyme Speeds up chemical reactions Hormone Carries signals to target tissues from another area of the body to bring about an appropriate response. Antibody Fights off infection/ foreign pathogens in the body Making Proteins • Stage 1: Free nucleotides in the nucleus of the cell make a copy of the coding region on DNA. This single stranded molecule contains the blueprint instructions for making the protein and is called messenger RNA (mRNA). • Stage 2: mRNA leaves the nucleus through pores and into the cytoplasm to a ribosome. • Stage 3: The ribosome reads 3 bases (called a codon) at a time and brings the amino acid associated with that codon into position to form a polypeptide chain. • Stage 4: This chain of amino acids is then folded into shape to form the new protein. Topic 5 What Are Enzymes? • Enzymes are BIOLOGICAL CATALYSTS found in all living organisms that: - speed up (or in some cases slow down) chemical reactions . - lower the activation energy required for the reaction to occur. - remain unchanged in the reaction. - are SPECIFIC. • Enzymes are protein molecules which have a structure suited to fit only one substrate molecule. This area which fits the substrate is called the ACTIVE SITE and ensures SPECIFICITY is achieved (lock and key theory). Enzyme Activity and Examples • Enzyme activity is greatest in the enzymes OPTIMUM conditions such as theExperiment right temperature and pH. Experiment 65 Experiment 74 Experiment Show that enzyme Investigate how enzyme Investigating which fruit Investigating enzyme • Anything belowactivity this will slow be activity reactions can be and anything above will can affected has the greatest content SPECIFICITY usingsite becoming stop activity entirely due to thereactions active SYNTHESIS by temperature and pH of the enzyme the enzyme misshapen. This is when anthe enzyme DENATURES. using enzyme using the enzyme CATALASE. AMYLASE. PHOSPHORYLASE. AMYLASE. • There are two types of enzyme reactions: SYNTHESIS DEGRADATION • Substrate Enzyme Product Starch Amylase Maltose Fats Lipase Fatty Acids and Glycerol Hydrogen Peroxide Catalase Water and Oxygen Enzyme Activity Graphs Enzymes Assignment • You will now be asked to write an assignment on the use of ENZYMES. • You will be asked to write this in EXAM CONDITIONS IN CLASS. • It is essential that you: - Have a clear aim - Have a minimum word count of 500 - Have two different sources (1 exp. & 1 other) - Process your sources into 2 different formats (tables to graphs) - Compare your sources - Can make a conclusion about your aim USING the info from your 2 sources. • RAW data i.e. line graph from source 1, MUST have gridlines and have the FULL URL or reference for it. Topic 6 Genetic Engineering • Genetic engineering is the process of ARTIFICIALLY altering the genome (Genetic make-up) of a cell. • Scientists use genetic engineering to alter a bacterial plasmid to produce useful substances QUICKLY. • 2 substances which are produced in this manner are : - Human Growth Hormone (HGH) - Insulin THINK! What do each of these substances treat? What other benefits are there of using Genetic Engineering to manufacture these substances? EXAM Favourite Stages of Genetic Engineering are always asked. Make sure you can identify each stage AND describe what is happening. You might want to make your own match cards to help with this. Genetically Modifying Organisms Has Science gone too far?? Research GM Crops on the iPads Topic 7 What is Photosynthesis? • Photosynthesis is the process which green plants undergo to create their own food using light energy. • Water and Carbon Dioxide are the RAW materials. • Glucose and Oxygen are the PRODUCTS. • Photosynthesis happens in two stages: 1. Light Dependant Reaction (occurs in the grana of the chloroplasts) 2. Carbon Fixation (occurs in the stroma of the chloroplasts) Light Water + Carbon Dioxide Glucose + Oxygen Chlorophyll Stage 1: Light Dependant • Water is absorbed into the plant by the roots. • Light energy trapped in the grana is used to SPLIT water into Oxygen and Hydrogen. • Oxygen is a WASTE product to plants and is released into the atmosphere through tiny pores called stomata. • Hydrogen is required for Stage 2 and is moved by a carrier into the Stroma. • ATP is also generated in this stage for use in Stage 2. Stage 2: Carbon Fixation • Carbon Dioxide enters the plant from the atmosphere through the stomata. • The ATP (energy) from stage 1 is used in a reaction to join the Carbon dioxide to the Hydrogen (again from stage 1) to form a sugar called GLUCOSE. • Photosynthesis is an ENZYME CONTROLLED reaction and is therefore affected by temperatures out with an enzymes optimum. Fates of Glucose • The glucose which is made during photosynthesis can be used by the plant in any 1 of the following 3 ways • Firstly it can be used straight away as ENERGY • Secondly it can be converted to CELLULOSE for the structural purpose of the cell wall. • Finally it can be converted to the storage carbohydrate STARCH. Limiting Factors of Photosynthesis • There are 3 limiting factors associated with the RATE of photosynthesis. 1. Carbon Dioxide Concentration Experiment 7 2. Light Intensity TASK 3. Temperature Test a leaf for starch in • Limiting Practice naming the limiting factors from prove that •certain Anytime a point is on the the graphs drawn on the factors can limitinitial glucose INCLINE the limiting board. factor is always what is production. factor questions always involve graphs various conditions toas shown below: written on the horizontal axis. • If a point is on the straight level-off line, then the factor limiting the photosynthesis is any of the other 2. Topic 7 What is Respiration? • Respiration is the process by which 1 molecule of glucose is broken down in the body to release ATP (energy) Glucose + Oxygen • There Carbon Dioxide + Water (+ENERGY) are 2 pathways for respiration: 1. AEROBIC (with Oxygen) 2. FERMENTATION (Without Oxygen) THINK! Do you notice anything about the Respiration equation? Linking Systems in Plants Understanding ATP • ATP is a high energy compound made of 1 Adenosine and 3 inorganic phosphate molecules. • The energy is stored in the third bond between the last 2 phosphates. When this bond is broken the energy is released forming the molecule ADP+Pi. Aerobic Respiration GLUCOSE 2 ATP 4 ATP There is a NET GAIN of 2 ATP 2x Pyruvic Acid • Aerobic Respiration occurs in two stages. The first stage is called GLYCOLOSIS and occurs in the CYTOPLASM. • Glucose is SPLIT into 2 molecules of Pyruvic Acid. • ATP (energy) has to be used to start this reaction, however the release of 4 ATP means that there is a NET GAIN of 2 ATP • No Oxygen is required for this stage to occur, therefore common to both Aerobic and Fermentation pathways . Aerobic Respiration Cont’d • The second stage of Aerobic respiration occurs in the MITOCHONDRIA and can only occur in the presence of oxygen. Pyruvate 36 ATP Made • The 2 Pyruvate molecules undergo a series of chemical reactions to release CARBON DIOXIDE as waste. • HYDROGEN is also released during this stage and is COMBINED with OXYGEN using the ATP to form water. is described as the last Hydrogen ACCEPTOR in this chain of events. Carbon Dioxide Hydrogen • Oxygen Oxygen Water Fermentation • The second pathway in respiration is called FERMENTATION and occurs in the absence of oxygen. • In animals, when there is a lack of Oxygen for complete breakdown of glucose the pyruvate is converted into a substance called LACTIC ACID. • Lactic Acid builds up in muscles causing fatigue. • When oxygen is available once again, the lactic acid is converted back into pyruvate for the aerobic cycle to continue. • We say that an OXYGEN DEBT has been paid. Fermentation • In plants/fungi etc, when there is a lack of oxygen for complete breakdown of glucose the pyruvate is converted 8 Experiment into ethanol and carbon dioxide. Investigate how carbon dioxide produced in fermentation of yeast can • This process is completely irreversible.be useful in the baking industry. • We can use fermentation to our advantage in certain industries such as brewing and baking. THINK! Why do you not taste alcohol in bakery products such as bread and cakes?