Core Idea 3: Energy and Equilibrium

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Core Idea 3: Energy and Equilibrium by Mind Map: Core Idea 3: Energy and Equilibrium

1. Blood glucose concentration increases above set point of 90mg/100ml

1.1. Change detected by B-cells of islets of Langerhans --> increased release of insulin into the bloodstream

1.1.1. Insulin binds to specific RTKs on target liver/muscle cells a. Accelerates rate of glucose uptake b. Accelerates glucose utilisation and storage - Stimulation of glycogenesis c. Stimulation of amino acid absorption and protein synthesis d. Stimulation of lipogenesis Down-regulates blood glucose concentration to set point

2. Similar to that of cellular respiration, just that (1) Protons accumulate in the thylakoid space (2) Thylakoid membrane is impermeable to protons (3) Protons move from stroma into thylakoid space

3. Cell Signalling

3.1. LO 3m: Main stages of cell signalling

3.1.1. Signal reception Target cell's detection of an extracellular signal molecule

3.1.2. Signal transduction Target cell converts an extra-cellular signal into an intracellular signal - Multistep signal transduction pathway - Phosphorlyation cascade

3.1.3. Cellular response Regulation of cellular activities

3.2. Insulin

3.3. LO 3n: Roles and nature of second messengers

3.3.1. Small, non-protein, water-soluble

3.3.2. Spread throughout the cytosol by diffusion

3.3.3. Mount a large-scale, coordinated response

3.3.4. cAMP AMP --> cAMP catalysed by adenylyl cyclase

3.4. LO 3o: Role of kinases and phosphatases in signal amplification

3.4.1. Kinases --> phosphorylation

3.4.2. Phosphatases --> dephosphorylation

3.4.3. Each kinase can phosphorylate multiple substrates, using a single ligand

3.5. LO 3p: Outline how insulin and glucagon regulate the concentration of blood glucose through the respective tyrosine kinase receptor and G-protein linked receptor

3.5.1. G-protein linked receptors (GPLR) Glucagon Change detected by a-cells of islets of Langerhans --> increased release of glucagon into the bloodstream Blood glucose concentration decreases below set point of 90mg/100ml

3.5.2. Receptor Tyrosine Kinase (RTK)

4. Photosynthesis

4.1. LO 3b: Absorption and action spectra of photosynthetic pigments

4.1.1. Chlorophylls Major and most abundant pigment, absorbs blue and red light

4.1.2. Carotenoids Accessory pigment, absorbs blue-violet light

4.1.3. Conclusions from the absorption and action spectra (1) Wavelengths of light absorbed by chlorophyll similar to wavelengths of light that drive photosynthesis Chlorophyll is mainly responsible for the absorption of light (2) Wavelengths optimally absorbed result in the highest rate of photosynthesis Both red and blue light are the energy source for photosynthesis

4.2. LO 3c: Light-dependent reactions with reference to chloroplast structure

4.2.1. (1) Light harvesting stage Location: thylakoid membrane Light of appropriate wavelength strikes pigment --> absorb --> excited

4.2.2. (2) Light dependent stage Location: thylakoid membrane Non-cyclic - Produce ATP - Produce NADPH Excitation energy transferred to other molecules via resonance energy transfer Cyclic - Produce ATP only Photosystem I / P700

4.3. LO 3d: Calvin cycle (Location: stroma)

4.3.1. (1) Carbon dioxide fixation - CO2 diffuses into chloroplast - CO2 (1C) combines with RuBP (5C) to form intermediate (6C) - Catalysed by rubisco - Intermediate breaks down into PGA/GP (3C) (2) Reduction of PGA - PGA is phosphorylated by ATP to form 1,3-bisphosphoglycerate (3C) - NADPH donates a pair of electrons to reduce 1,3-bisphosphoglycerate to TP/GALP/G3P (3C) (3) Regeneration of RuBP - 3 CO2 (1C) molecules carboxylate 3 RuBP (5C) to form 6 G3P (3C) - 1 G3P is net gain of carbohydrate - 5 G3P used to regenerate 3 RuBP LO 3a: Components of chloroplasts

4.4. LO 3d: Limiting factors of photosynthesis

4.4.1. Light

4.4.2. Carbon dioxide concentration

4.4.3. Temperature

4.4.4. Chlorophyll concentration

4.4.5. Specific inhibitors

4.4.6. Water

4.4.7. Oxygen

4.5. LO 3l: Chemiosmosis in photosynthesis

5. Cellular Respiration

5.1. LO 3a: Components of mitochondria

5.1.1. Outer membrane: permeable to ATP, ADP, etc

5.1.2. Inner membrane: -Selectively permeable and highly folded to form cristae -Increases surface are for embedding ETC and ATP synthase complexes -Site of oxidative phosphorylation

5.1.3. Matrix: Site of link reaction and Krebs cycle, contains enzymes

5.2. LO 3f: Glycolysis (Location: Cytoplasm)

5.2.1. Cytoplasm Glucose is respiratory substrate Converted in 2 3C pyruvate Substrate level phosphorylation 2 net ATP Dehydrogenation 2 NADH Waste product Water

5.3. Rate limiting step involving phosphofructokinase Allosterically inhibited by ATP

5.4. LO 3g: Link reaction and Kreb cycle

5.4.1. Link reaction (Location: Mitochondrial matrix) Occurs twice per glucose molecule Catalysed by pyruvate dehydrogenase Oxidative decarboxylation 2 Pyruvate + 2 NAD + 2 CoA --> 2 Acetyl CoA + 2 NADH + 2CO2

5.5. LO 3h: Oxidative phosphorylation

5.5.1. NADH & FADH2 transfer electrons to oxygen in an ETC, with succeeding electron carriers having increasing electron affinity

5.5.2. Exergonic transport of electrons coupled to endergonic process of ATP synthesis

5.6. LO 3l: Chemiosmosis in respiration

5.6.1. Inner mitochondrial membrane Electrons transferred along ETC, energy released Drive proton pumps to actively pump H+ unidirectionally from matrix to intermembrane space, against concentration gradient

5.6.2. Exergonic passage of H+ coupled to endergonic phosphorylatin of ADP

5.6.3. 3 ATP / NADH + 2ATP / FADH2

5.7. LO 3i: Explain production of a small yield of ATP from respiration in anaerobic conditions in yeast and in mammalian muscle tissue

5.7.1. Glycolysis produces pyruvate No further oxidation; no acetyl-CoA 2 net ATP

5.7.2. Lack of oxygen Mammalian muscle tissue Lactic acid fermentation Yeast Alcoholic fermentation

5.8. LO 3j: Significance of the formation of ethanol in yeast and lactate in mammals in the regeneration of NAD

5.8.1. Mammals 2NADH + C3H4O3 --> NAD + C3H6O3

5.8.2. Yeast 2NADH + C3H4O3 --> 2NAD + C2H5OH + CO2

5.8.3. NAD regenerated used for glycolysis to produce low yield of ATP

5.9. LO 3k: Effect of factors on rate of respiration

5.9.1. Substrate concentration Increase concentration --> increase respiration

5.9.2. Type of substrate Fatty acids Glucose Amino acids More energy per molecule than glucose

5.9.3. Investigation Method 1: Measure uptake of oxygen per unit time using respirometer - CO2 produced from respiration absorbed by absorbant so any decrease in volume of air results from oxygen consumption - Read manometer - Compensation (control tube) to compensate for changes in atmospheric pressure Method 2: Use redox dye (e.g. DCPIP, methylene blue) which turn from blue to colourless when reduced (like NADH) - Rate of change from blue to colourless is a measure of rate of respiration

5.9.4. Temperature Temperature coefficient Increase temperature --> increase rate of respiration, until optimum temperature Lower temperature higher rate (e.g. white potato)

6. Extension Topic B: Impact of Climate Change on Animals and Plants

7. Core Idea 2: Genetics and Inheritance - Genetics of Bacteria - The molecular biology of cancer - Inheritance

8. Core Idea 4: Biological Evolution - mtDNA - Cytochrome C

8.1. Core Idea 1: The Cell and Biomolecules of Life - Carbohydrates - Enzymes - Eukaryotic cell structure and function - Transport across membrane