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UNIT THREE

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

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UNIT THREE

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  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

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

  4. 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 + Pi. 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

  5. ATP (Adenosine Triphosphate) NH2 Base (adenine) C N N C CH HC C N N O- O- O- O P O P O P OCH2 - O C C O O O H H C H C C OH OH 3 phosphate groups Ribose

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

  7. CHP 3 TOPIC 3: CELLULAR RESPIRATION • Glucose (C6H12O6) 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 cytosolof 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

  8. 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.

  9. CHP 3 TOPIC 3: CELLULAR RESPIRATION Aerobic Respiration

  10. CYTOPLASMGLYCOLOSIS HAPPENS HERE! RESPIRATION PROTEINS CARBS (SUGARS) FATS (LIPIDS) GLUCOSE C6H12O6 AMINO ACIDS MAKES 2 ATPS GLYCOLOSIS IN CYTOPLASM NO OXYGEN! ATP TOTALS GLYCOLOSIS=2 Krebs + ETC =36 minus 2 Overall =36! PYRUVIC ACID CO2 IS RELEASED ACETYL-CoA O2 ENTERS HERE KREBS CYCLE AND ELECTRON TANSPORT MAKES 36 ATPS MITOCHONDRIARESPIRATION HAPPENS IN THIS ORGANELLE!

  11. Remember: Aerobic Cellular Respiration CARBON DIOXIDE 36 – 38 ATP GLUCOSE C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY OXYGEN WATER

  12. 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 + CO2 • anaerobic Respiration in yeasts is called Fermentation.

  13. Anaerobic Vs Aerobicreading page80 (Table 3.2) Biozone: Page 50

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

  15. violetbluegreenyelloworangered 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 Absorption

  16. 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: CO2 and H2O • 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 Thylakoid Membrane Granum Thylakoid Space

  17. Site of Photosynthesis • takes place in chloroplast

  18. CHP 3 TOPIC 4: PHOTOSYNTHESIS

  19. CHP 3 TOPIC 4: PHOTOSYNTHESIS

  20. CHP 3 TOPIC 4: PHOTOSYNTHESIS

  21. CHP 3 TOPIC 4: PHOTOSYNTHESIS • 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.

  22. Topic CHP3.4 Questions: • Light energy is also known as what: _____________ • A chemical formula for photosynthesis is: _______ +________ ______ + ________+ ____ • A example of a plastid in plant cells is a: ____________ • Green plants deflect ____________________ coloured light • The two stages of photosynthesis are: 1. ___________________ + 2.___________________ • Stage 1 takes place in: _____________________ Stage 2 in: _____________________ • True/ False: all plant cells photosynthesise • CO2 enters a leaf through which key structure: _________________ • Loaded acceptor molecules of photosynthesis include: _____________ • Carbon fixation is also known as: _______________________ • PGAL has how many carbons? ___________________

  23. 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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