Chapter 8 I Energy and Life Energy ability
Chapter 8
I. Energy and Life • • Energy = ability to do work A. Autotrophs and Heterotrophs – Originally most all energy comes from ____ Plants and some other organisms use the sun’s energy to produce______. food sun
– ________make their own food. – _________obtain energy from food they consumer – Some obtain energy as decomposers autotrophs heterotrophs
B. Chemical Energy and ATP – – When electrons in bonds are shifted from higher to lower energy levels, ________is released as heat and light __________is one of the principal chemical compounds used to store and release energy The extra energy Adenosine triphosphate
The 3 Phosphate groups are the key to ATP’s ability to store and release energy
1) Storing energy • ____________is a compound that looks a lot like ATP, except it has 2 phosphate groups and this difference is the key to storing energy. When a cell has energy available it can store small amounts by adding a phosphate to ADP, making ATP (think of ATP like a fully charged battery) Adenosine diphosphate (ADP)
2) Releasing Energy • Energy stored in ATP is released by breaking the bond between the 2 nd and 3 rd phosphates, releasing energy as needed. This can power such things as ________across the membrane of the cell, protein synthesis and muscle contraction Active transport
• ATP is exceptionally useful as the _______________. Basic energy source of all cells
C. Using Biochemical Energy – For active transport---______________that pumps Na+ out of cell and K+ into the cell. ATP keeps the pump working and keep ions balanced A sodium-potassium pumpa membrane protein
• ATP powers synthesis of proteins, _________ and responses to ___________. Nucleic acids Chemical signals @ cell surface
• Cells only have a small amount of ATP, to last seconds…. . not good for long term storage(1 molecule glucose stores 90 x the chemical energy of ATP ). Cells can regenerate ATP from ADP as needed by the energy in foods like glucose
II. Photosynthesis: An Overview – Plants use the energy of sunlight to convert water and CO 2 into sugars and starches, as well as O 2
A. Investigating Photosynthesis – Centuries ago the simple question was did the increase in tree’s mass come from soil, water or air? • • 1) Van Helmont’s Experiment 1600’s-Belgian physician did an experiment to see if the soil caused plants to grow, by trying to grow w/o soil…. he concluded most of the gain in mass was from water…. . this accounts for ½ the products of photosynthesis.
2) Priestly’s Experiment – – Candle w/jar over it-concluded that air enabled it to burn He put a sprig of a plant under the jar and waited a few days, …The candle could burn briefly under the jar…So he concluded the plant ____________ Produced oxygen
3) Jan Ingenhoutz • —showed the plant produced oxygen only if exposed to light » In conclusion to all 3 experiments, it is concluded that plants exposed to CO 2 and light and water, produce O 2 and carb’s
B. The Photosynthesis Equation light • 6 CO 2 + 6 H 2 O--- C 6 H 12 O 6 + O 2
• Plants use the sugars to produce complex carb’s such as _______ starches
C. Light and pigments • • • Photosynthesis also requires light and Chlorophyll (found in Chloroplasts) White light is a mixture of different wavelengths of light---seen as _____ Plants gather the sun’s energy with light absorbing molecules called______. Color pigments
• The principal plant pigment is_________. -chlorophyll a and b • Chlorophyll absorbs light well in the blue-violet and regions, but not well in the ________region, which is reflected by leaves green Chlorophyll
• Contain red and orange pigments like _________, that absorb light in other regions • When chlorophyll absorbs light, much of the energy is transferred directly to electrons in Chlorophyll , raising _____________which make photosynthesis work!!! carotenes The energy levels
Figure 8 -5 Chlorophyll Light Absorption Section 8 -2 Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll a V Go to Section: B G YO R
III. The Reactions of Photosynthesis • A. Inside a Chloroplast – Photosynthesis takes place in the _______. – The chloroplasts contain saclike membranes called _________ which are arranged in stacks known as ________ chloroplasts THYLAKOIDS grana
– Proteins in the Thylakoid membrane organize chlorophyll and other pigments into clusters known as __________-These are the light –collecting units of the chloroplast – Light dependent reaction happens in ___________. photosystems Thylakoid membrane
• Light-independent (Calvin-cycle) reaction happens in _______-region outside thylakoid membranes stroma
Figure 8 -7 Photosynthesis: An Overview Section 8 -3 water CO 2 Light Chloroplast NADP+ ADP + P Light. Dependent Reactions ATP Calvin Cycle NADPH O 2 Go to Section: Sugars
B. Electron Carriers • When sunlight excites electrons in chlorophyll, the electrons gain a great deal of energy…. . They require a carrier---_________by electron transport chain – ____nicotinamide adenine dinucleotide phosphate-accepts 2 high energy electrons along w/ a H+, converting it into _____. This is one way some of energy of sunlight is trapped in chemical form Compound that can accept a pair of high energy electrons and transfer w/ most of the energy to another molecule NADP+ NADPH
• ___________-then becomes an electron carrier NADPH
C. Light –Dependent Reactions – Require light – Light is used to produce ATP and NADPH
Figure 8 -10 Light-Dependent Reactions Section 8 -3 Photosystem II Hydrogen Ion Movement Chloroplast ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma Electron Transport Chain Go to Section: Photosystem I ATP Formation
– 1 -Photosynthesis begins when pigments in photosystem II absorb light. Energy is absorbed by high energy electrons and passed on to electron transport chain. New electrons come from the water, and O 2 is released into air – 2 -High –energy electrons move from electron transport chain from photosystem II to photosystem I. Energy from electrons is used by molecules in electron transport chain to transport H+ ions from stroma into the inner thylakoid space.
• 3 --Pigments in __________use energy from light to regenerate electrons. NADP+ picks up high energy electrons, along w/ H+ ions, at outer surface of thylakoid membrane…+ H+ ion=NADPH Photosystem I
• 4 - As electrons pass from chlorophyll to NADP+, more________are pumped along the membrane…. Eventually , the inside of the membrane fills w/ H+ ions……outside of membrane is ____________charged…The difference in charges produces energy for ATP…. This is why H+ ions are so important. H+ ions negatively
• 5 --H+ ions cannot cross membrane directly…. . But, the membrane contains a protein called _____that goes across the membrane and allows H+ ions to pass through it. As H+ passes through , ATP synthase, the protein rotates, binding w/ ADP and a phosphate group to make_________ So…. . lightdependent part makes high energy electrons and also ATP synthase ATP
D. The Calvin Cycle – – The ATP and NADPH from light-dependent part are not stable enough to store energy for more than a few moments…. these are used in _______to make high energy compounds that can last a long time----it makes ________. Does not require light so is called ___________ sugars Calvin Cycle Light-independent
Figure 8 -11 Calvin Cycle CO 2 Enters the Cycle Energy Input Chlorop. Iast 5 -Carbon Molecules Regenerated 6 -Carbon Sugar Produced Sugars and other compounds Go to Section:
• • 1) 6 CO 2 molecules enter from the atmosphere. They combine w/ 6 __________. The result is 12 3 -C molecules. 2) 12 3 -C molecules convert to higher energy forms…. The energy for this comes from ATP and __________. 5 -Carbon atoms High energy electrons from NADPH
• 3) 2 3 -C molecules removed from cycle…these are used to produce____________________ needed for plant metabolism and growth Sugars, lipids, amino acids and other compounds
• • Remaining 10 3 -C are converted back into 6 5 -C molecules. They combine w/ 6 new CO 2 molecules to begin cycle again. ***** 2 sets of photosynthetic reactions work together-light-dependent traps energy of sunlight in ______ and light –independent reactions(Calvin Cycle) use that chemical energy to produce stable, high energy sugars from CO 2 and water…. also O 2 is produced 4) Chemical form
E. Factors affecting Photosynthesis • • • Water supply Temperature---affects enzymes Light intensity----it does reach a maximum-or optimal level of light, depending on plant type--eg. conifers only photosynthesize on _____________. Warm. sunny days
- Slides: 41