1041SCG Lecture Notes - Lecture 1: Sister Chromatids, Spindle Apparatus, Lysosome
19 Jun 2018
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1041SCG Biology Systems Notes
Weeks 1-3
Week 1 - 1st March
Endosymbiosis: a small cell being engulfed by a larger one
Eukaryotic: distinct nucleus, many organelles within
Prokaryotic: single-celled, no nucleus, no specialised organelles
Positive feedback: adrenaline, giving birth
Negative feedback: breaking a fever
Genetic code: made up of Adenine, Thymine, Guanine, Cytosine in DNA
made up of Adenine, Uracil, Guanine,Cytosine in RNA
Week 2 - 11th March
ATP AND REDUCED COENZYMES PLAY IMPORTANT ROLES IN BIOLOGICAL ENERGY
METABOLISM
Energy is stored in chemical bonds in molecules and it can be released
Free energy: chemical energy that is available to use
The Five Principles that govern metabolism pathways:
Chemical transformations occur in a series of intermediate reactions that form a metabolic
pathway
Each reaction is catalysed by a specific enzyme
Most metabolic pathways are similar in all organisms
Eukaryotes: many metabolic pathways occur inside specific organelle
Each metabolic pathway is controlled by enzymes that can be inhibited or activated
In cells, energy transforming reactions are often coupled
Energy releasing (exergonic) reaction (a catabolic reaction) is coupled to an energy required
(endergonic) reaction (anabolic reaction)
Two coupling molecules are coenzymes ATP and NADH
Energy can be transferred by the transfer of electrons in reduction-oxidation or redox reactions
Reduction: gain of one of more electrons (reduced molecules have the most free energy)
Oxidation: loss of one or more electrons (very little free energy in molecule)
(refer to Reduction-Oxidation image)
Energy released in catabolism by oxidation
Energy trapped by reduction enzymes such as NADH
Most energy releasing reactions produce NADH
Energy from anabolic reactions is supplied by ATP
Most reactions that require energy use ATP
Oxidative phosphorylation (chemical process) transfers energy from NADH to ATP
ATP hydrolysis: releases energy
Redox reactions: transfer electrons and energy
CARBOHYDRATE CATABOLISM IN THE PRESENCE OF OXYGEN RELEASES A LARGE
AMOUNT OF ENERGY
Aerobic Respiration
find more resources at oneclass.com
find more resources at oneclass.com
Cellular respiration: set of metabolic reactions used by cells to harvest energy in food
Many C-C and C-H bonds fully oxidised to CO2 release large amounts of energy
Overall, 35% of energy released is harvested by the cell
Coenzymes capture the energy that is released
Oxidation occurs in a series of small steps
(refer to PoL Figure 6.5 (ch. 6))
Three biochemical catabolic (energy releasing) pathways (under aerobic conditions)!
Glycosis: glucose converted to pyruvate (results in 2 molecules of each: pyruvate, ATP
and NADP)
Pyruvate oxidation: pyruvate oxidised to acetyl Coenzyme A (bound to acetate) and CO2.
Citric acid cycle: acetyl Coenzyme A is oxidised into CO2 (8 cycles)
Remember outputs and then inputs of each step
It then goes on to do electron transport and ATP synthesis in the mitochondrial membrane from the
mitochondrial matrix (where the second and third pathways are undertaken). Glycolysis occurs in
the cytoplasm
Week 3 - 14th March
Anaerobic Respiration
ELECTRON TRANSPORT AND ATP SYNTHESIS
Mitochondria: double celled (outer and inner membrane)
Chemiosmosis: uses proven gradient to generate ATP
Oxidative phosphorylation and chemiosmosis yield a lot of ATP
Anaerobic: no oxygen
Fermentation: the process that allows NAD+ to be regenerated in anaerobic conditions
Alcoholic fermentation: ethanol is the end product
Lactic acid fermentation: one end product is lactic acid
CATABOLIC AND ANABOLIC PATHWAYS ARE INTEGRATED
Polysaccharides: broken down into glucose which enters glycolysis
Glycerol from fats enters glycolysis
Acetate from fatty acid degradation forms coenzyme A to enter citric acid cycle
Proteins enter glycolysis and the citric acid cycle via amino acids
Diagrams of the above are valuable on 03.1 Other Metabolic Pathways
Gluconegenesis: new formation of glucose
Week 3 - 15th March
PHOTOSYNTHESIS
Photosynthesis: process in plant cells from turning light energy into chemical energy
Light energy absorbed by chlorophyll
Light absorption results in photochemical change
Reduction leads to ATP and NADPH formation
Anabolic pathway. Involves two pathways:
Light reactions convert light into chemical energy
Carbon-Filiation reactions use ATP and NADPH to produce carbohydrates
Inside a chloroplast:
Electron transport (including chlorophyll and thylakoid lumen). Sorts out light reaction
Rest of chloroplast sorts out carbon-filiation
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Endosymbiosis: a small cell being engulfed by a larger one. Genetic code: made up of adenine, thymine, guanine, cytosine in dna made up of adenine, uracil, guanine,cytosine in rna. Atp and reduced coenzymes play important roles in biological energy. Energy is stored in chemical bonds in molecules and it can be released. Free energy: chemical energy that is available to use. Chemical transformations occur in a series of intermediate reactions that form a metabolic pathway. Each reaction is catalysed by a speci c enzyme. Most metabolic pathways are similar in all organisms. Eukaryotes: many metabolic pathways occur inside speci c organelle. Each metabolic pathway is controlled by enzymes that can be inhibited or activated. In cells, energy transforming reactions are often coupled. Energy releasing (exergonic) reaction (a catabolic reaction) is coupled to an energy required (endergonic) reaction (anabolic reaction) Two coupling molecules are coenzymes atp and nadh.
