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UNIT THREE BIOLOGY AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 3: BIOCHEMICAL PROCESSES.

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Presentation on theme: "UNIT THREE BIOLOGY AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 3: BIOCHEMICAL PROCESSES."— Presentation transcript:

1 UNIT THREE BIOLOGY AREA OF STUDY #1: MOLECULES OF LIFE EXAM REVISION LECTURE CHP 3: BIOCHEMICAL PROCESSES

2 CHP 3 TOPIC 1: ENERGY IN CELLS Living organisms require energy in the form of organic compounds to survive” Heterotrophs: (= other feeding) – Rely on an external energy source – Uses organic matter from dead and living organisms or their products to obtain carbon Autotrophs: (= self feeding) – build organic compounds from simple inorganic compounds such as carbon dioxide and water. – Use an external source of energy, usually the sun, to build organic compounds. Reactions in Cells occur in the cytosol and cell organelles some total of a cells reactions is called cellular metabolism Anabolic (Endergonic) Reactions:Catabolic (Exergonic) Reactions energy taken in (cell must expend energy in process) example: building of macromolecules; synthesis of ATP reduction reactions are endergonic controlled by enzymes energy is released (net gain) most not spontaneous and require ‘activation energy’ (from ATP for example) oxidation reactions are exergonic examples: cellular respiration, ATP into ADP + Pi

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4 Topic CHP3.1 Questions: 1.Which of the following are heterotrophs? (circle) pigeon, amoeba (single celled protistan), yeast, algae, mushroom, horse 2.What percentage of energy is transferred to chemical energy from one trophic level to the next (on average)? _____________ 3.What happens to the rest of the energy? 4.What is the primary source of all energy? 5.Reduction reactions involve the removal of oxygen from organic compounds or the addition of electrons (i.e. H+). Reduction reactions are: endergonic/ exergonic 6.Give an example of a reduction reaction? ___________________ 7.Oxidation reactions involve the addition of oxygen (or the removal of electrons from) a substance. Give an example of an oxidation reaction? ____________________

5 CHP 3 TOPIC 2: ATP ATP- Energy Currency The immediate source of energy is the molecule ATP (remember: Coenzyme!) ATP: Adenosine Triphosphate Portable energy source that moves about the cell to where its needed (used within 1minute) ATP is synthesized from ADP + P i. The process of synthesizing ATP is called phosphorylation. Most ATP is produced in the mitochondria of eukaryotic cells At sites where energy is required ATP breaks down to form ADP + Pi (Pi is inorganic) Energy is released for: anabolic reactions; cell growth; tissue repair; movement; reproduction; active transport; active secretion Energy required to build up (anabolic/ endergonic reaction)- glucose etc

6 6 CH N C C C NH 2 N HC N N C C C C O C O P O P O P O CH 2 O O O O - O - O - - H OH H ATP (Adenosine Triphosphate) 3 phosphate groups Base (adenine) Ribose

7 Topic CHP3.2 Questions: 1.What is a coenzyme? 2.The addition of Pi to ADP is known as: _________________________ 3.ADP is: organic/ inorganic 4.Pi is : organic/ inorganic 5.Name one enzyme responsible for the production of ATP: ___________________ 6.How many phosphate atoms does ADP have? 7.What kind on bonds connect the phosphates together? ____________________

8 CHP 3 TOPIC 3: CELLULAR RESPIRATION Glucose (C 6 H 12 O 6 ) is broken down to release energy in the presence of oxygen, most cells carry out aerobic respiration aerobic respiration occurs in three stages: glycolysis, krebs cycle, electron transport chain aerobic respiration takes place in the mitochondria Mitochondria are membrane bound organelles suspended in the cytosol of eukaryotic cells are the site of some stages of aerobic respiration (double membrane bound!): have an outer membrane and a highly folded inner membrane, called cristae fluid inside called matrix contain respiration enzymes on the internal membranes are the production site of most ATP occur in larger numbers in cells with a higher energy requirement

9 Pyruvate (3 carbon molecule is converted to a 2 carbon molecule, Acetyle coenzyme A prior to stage 2 – Krebs Cycle. Carbon Dioxide is formed from this oxidation reaction.

10 CHP 3 TOPIC 3: CELLULAR RESPIRATION Aerobic Respiration Step/ ProcessLocationProducts Glycolysis Glucose, a 6 carbon molecule is spilt into two pyruvate (3 carbon molecule). Energy is released. Energy is used to form ATP and NADH in the cytosol of cells2 ATP molecules 2 NADH molecules which can be used later to produce more ATP 2 Pyruvate (3Cs) formed Intermediate molecule formed: Acetyl Coenzyme A (a 2 carbon molecule) see next slide! Krebs Cycles Each pyruvate is broken down to produce 3 molecules of C ATP and loaded (H+) acceptor molecules formed in the inner compartment of mitochondria 2 ATP molecules 8 NADH loaded acceptors 2 FADH 2 loaded acceptors 6 C0 2 Electron Transport (Chain) (H+) Electrons from the loaded molecules of NADH and FADH2 are transferred to oxygen to form water and produce 32 ATP on the inner membranes of mitochondria 32 ATP molecules in most cells (34 ATP in some cells) 6H 2 0

11 RESPIRATION CYTOPLASM GLYCOLOSIS HAPPENS HERE! MITOCHONDRIA RESPIRATION HAPPENS IN THIS ORGANELLE! PROTEINSCARBS(SUGARS) AMINOACIDS FATS(LIPIDS) GLUCOSE C 6 H 12 O 6 ACETYL-CoA PYRUVICACID GLYCOLOSIS IN CYTOPLASM NO OXYGEN! KREBS CYCLE AND ANDELECTRONTANSPORT MAKES 36 ATPS MAKES 2 ATPS O 2 ENTERS HERE CO 2 IS RELEASED ATP TOTALS GLYCOLOSIS=2 Krebs + ETC =36 minus 2 Overall =36!

12 Remember: Aerobic Cellular Respiration C 6 H 12 O 6 + GLUCOSE 6O 2 OXYGEN 6CO 2 + CARBON DIOXIDE 6H 2 O + ENERGY WATER 36 – 38 ATP

13 CHP 3 TOPIC 3: CELLULAR RESPIRATION Anaerobic Respiration: is an energy releasing cellular reaction which does no require oxygen in animal cells (anaerobic glycolysis): Glucose + 2 ADP + 2Pi 2 ATP + lactic acid does not require oxygen is a series of reactions in the cytosol transfers some of the chemical energy in glucose to chemical energy in ATP glucose is converted to pyruvate which in turn is converted into lactate acceptor molecule (nad) used in process of converting pyruvate produces a net gain of two atp molecules for each glucose molecule produces waste called lactate lactate is toxic and in excess causes pain and fatigue in the tissue. in plant cells/ yeast (fermentation) Glucose + 2 ADP + 2Pi 2 ATP + ethanol + CO 2 anaerobic Respiration in yeasts is called Fermentation.

14 Anaerobic Vs Aerobic reading page80 (Table 3.2) AnaerobicAerobic Oxygen not requiredOxygen required Rapid ATP ProductionSlow ATP Production Mammals sustain over a short period (60 secs) Sustain indefinitely Less efficient energy transferMore efficient energy transfer 2 mole of ATP produced per 1 mole of glucose used 36 mole of ATP produced per 1 mole of glucose used (some 38) Various waste products: lactic acid, water (Humans) Ethanol, CO2 (Yeasts) Butyl alcohol (bacteria) Waste Products: CO2 and water Biozone: Page 50

15 Topic CHP3.3 Questions: 1.Chemical formula for a glucose molecule: _______________________ 2.Chemical formula for aerobic respiration: _____________________________ 3.In the absence of oxygen most cells carry out: __________________ respiration 4.Aerobic respiration takes place in which organelle: ________________________ 5.True/ False: only animal cells aerobically respire 6.True/ False: anaerobic respiration only occurs in the absence of ozygen 7.The fluid inside the Mitochondria is called what: ________________ 8.The three stages of aerobic respiration (in order) include: ___________________, _____________________, & ___________________________ 9.Loaded acceptor molecules involved in aerobic respiration include: ______________, ______________________ 10.In glysolysis, one molecule of glucose produces two 3 carbon molecules called: __________ 11.Acetyl Coenzyme A has how many carbons? __________________ 12.One molecule of glucose produces how many molecules of CO2? __________ 13.How many molecules of ATP are produced from one molecule of glucose? ____________ 14.True/ False: Amino acids can be used for cellular respiration 15.True/ False: amino acids are converted directly into Acetyl co enzyme A and skip glycolysis 16.In the absence of oxygen, through the process of respiration plants convert glucose into what: ____________________________________-

16 CHP 3 TOPIC 4: PHOTOSYNTHESIS Photosynthesis is the conversion of light energy (photons) to stored chemical energy in glucose molecules Simple molecules water and CO2 are converted to glucose with oxygen as a waste product Reaction occurs when chlorophyll (plastid) is present.(carotenoids also absorb blue-violet light and appear orange yellow or red) Chlorophyll traps the light energy and converts it to a form of chemical energy (ATP & NADPH+) which can be used to make glucose Most plants contain two forms of chlorophyll, chlorophyll a & chlorophyll b, together these pigments absorb light at the violet/ blue and red ends of the spectrum violet blue green yellow orange red Absorption

17 CHP 3 TOPIC 4: PHOTOSYNTHESIS Rate of Photosynthesis influenced by available wave lengths of light Is also dependent upon light intensity; the stronger the light, the greater the rate Does not increase indefinitely: at high light intensities is limited by: availability of the reactants: CO 2 and H 2 O availability of enzymes which catalyse the reaction Process of Photosynthesis doesn’t take place in all plant cells, even not all leaf cells (i.e. most epidermis cells lack chloroplasts – exception: guard cells) occurs in a number of steps that can be divided into two stages: light dpendent stage & light independent stage (also referred to as dark stage, although they don’t require darkness, they simply don’t require light!) Site of Photosynthesis Chloroplasts Stage 1: Grana Stage 2: Stroma Granum Thylakoid Membrane Thylakoid Space

18 Site of Photosynthesis takes place in chloroplast

19 CHP 3 TOPIC 4: PHOTOSYNTHESIS Stage/ DescriptionLocationProducts Light- dependent Reactions Light energy is trapped by chlorophyll and used to produce ATP and to split water molecules into H= ions and oxygen. Oxygen given off as waste. H+ ions are taken by acceptor molecules NADP 12H 2 O + light energy 6O H+ (as NADPH) + stored ATP Role of ATP Synthase Within grana (thylakoid membranes) 6 O 2 (from the split water molecules; it is released by diffusion into atmosphere) ATP – net gain of 2 NADPH Light-independent Reactions CO 2 from the atmosphere is combined with hydrogen (from the loaded acceptor NADPH) to form sugar in a series of reactions known as Calvin cycle. ATP produced in light stage used for this Role of Enzyme – rubisco, PGAl In stroma: Glucose C 6 H 12 O 6 6 H2O

20 CHP 3 TOPIC 4: PHOTOSYNTHESIS

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22 one important product formed in the calvin cycle is PGAL (phosphoglceraldehyde), a compound that contains 3C atoms. PGAL can react to form various sugars, including glucose, fructose, sucrose. sucrose is the form in which carbohydrates are transported through the phloem. Starch (a polysaccharide) is the storage carbohydrate in plant cells. CHP 3 TOPIC 4: PHOTOSYNTHESIS

23 Topic CHP3.4 Questions: 1.Light energy is also known as what: _____________ 2.A chemical formula for photosynthesis is: _______ +________ ______ + ________+ ____ 3.A example of a plastid in plant cells is a: ____________ 4.Green plants deflect ____________________ coloured light 5.The two stages of photosynthesis are: 1. ___________________ + 2.___________________ 6.Stage 1 takes place in: _____________________ Stage 2 in: _____________________ 7.True/ False: all plant cells photosynthesise 8.CO 2 enters a leaf through which key structure: _________________ 9.Loaded acceptor molecules of photosynthesis include: _____________ 10.Carbon fixation is also known as: _______________________ 11.PGAL has how many carbons? ___________________

24 CHP 3 TOPIC 5: STARVATION animals require a continuous supply of energy and matter for survival when an animal is starved it uses energy from body tissue. after glucose is used up, fats and then proteins are used. during starvation people use up to 97% of fat tissue, 31% of skeletal muscle and 27% of blood. when an animal reaches this stage, it is called autophagia (feeding off self).


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