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Storing and Harvesting Energy Photosynthesis and Respiration

Storing and Harvesting Energy Photosynthesis and Respiration

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Storing and Harvesting Energy

Photosynthesis and Respiration

First Law of Thermodynamics

Energy in the universe can not be created or destroyed

it only can change form

What are some different forms of E?

radiation (light)

chemical E

thermal E

mechanical E (work)

fireflies: chemical E light E

hand warmers

chemical E thermal E

RADIATION E

CHEMICAL E

Photosynthesisconverts the sun’s radiation E into the chemical E of glucose

H2O + CO2 O2 + C6H12O6 + H2OWATER CARBON

DIOXIDEOXYGEN GLUCOSE WATER

LIGHT ENERGY

Ps is an ENDERGONIC reaction: it takes in E

ENERGY

Ps is done by plants, algae, and some bacteria (and a sea slug) that contain chlorophyll-

green pigments that can capture E from the sun

leaf’s upper surface photosynthetic cells

two outer layers of membrane

inner membrane system (thylakoids, all interconnecting bychannels) stroma

chloroplast

Respirationall living things do some type of respiration

respiration = cells harvest E from chemical bonds by degrading complex organic molecules (eg. sugar) intosimpler molecules and extracting the stored bond E.

6O2 + C6H12O6 6CO2 + 6 H2O + E

this reaction gives off E = EXERGONIC

sunlight energy

water+

carbondioxide

PHOTOSYNTHESIS

AEROBICRESPIRATION

sugarmolecules

oxygen

ENERGY FLOW THROUGH LIVING THINGS

occurs in the mitochondria

occurs in the chloroplasts

Cells can do respiration either:

A. with oxygen (O2) = aerobic

B. without oxygen = anaerobic

Aerobic Respiration

Step 1: Glycolysis = “cutting glucose” occurs in the cytoplasm of cell

glucose (6 C) 2 pyruvate (3 C)

Step 2: Krebs cycle occurs in the mitochondria

pyruvate breaks down into CO2 + electrons

Step 3: Electron transport phosphorylation occurs across the mitochondrial membrane

2 ATP

2 ATP

32 ATPthe big E producer!

ATP = a molecule that is the currency of energy for cells

GLYCOLYSIS

glucose

pyruvate

To second stage of aerobic pathway (or to additional reactions of another energy-releasing patway).

animal cell (eukaryotic)

plant cell (eukaryotic)

bacterial cell (prokaryotic)

Krebs Cycle

NADH

NADH

NADH

ATP ATP

ATP

ATP

ADP + Pi

INNER COMPARTMENT

OUTER COMPARTMENT

acetyl-CoA

free oxygen

6 Following its gradients, H+ flows back into inner compartment, through ATP synthases. The flow drives ATP formation.

1 Pyruvate from cytoplasm enters inner mitochondrial compartment.

3 NADH and FADH2 give up electrons and H+ to membrane-bound electron transport systems.

2 Krebs cycle and preparatory steps: NAD+ and FADH2

accept electrons and hydrogen stripped from the pyruvate. ATP forms. Carbon dioxide forms.

5 Oxygen accepts electrons, joins with H+ to form water.

4 As electrons move through the transport system, H+ is pumped to outer compartment.

ELECTRON TRANSPORT PHOSPHORYLATION

glucose

pyruvate

KREBS CYCLE

GLYCOLYSIS

Anaerobic Respiration

typically found in bacteria & some fungi that live in low-oxygen environments

swamps, bogs, marshes, deep sea, animal guts

Anaerobic Respiration

1. Lactate fermentation

• happens in our muscles when we run out of oxygen

• glucose is broken down to lactate (instead of pyruvate)

LACTATE LACTIC ACID

causes “burn” in muscles

• same process occurs in milk spoilageLactobacillus (bacteria) using lactate fermentation

use to make buttermilk, sourcream, yoghurt…

** make sure to read section 7.6 on p. 117 in bookabout slow-twitch vs. fast-twitch muscle fibers

Anaerobic Respiration

2. Alcoholic fermentation

• done by yeast make beer, wineex. Saccharomyces

• pyruvate converts to acetaldehyde converts to ethanol

• CO2 is also a biproduct (carbonation)

Energy Sources for Humans

eat pasta

enzymes in mouth and enzymes & acids in stomach break down starch into glucose molecules

glucose is absorbed across lining of gut into blood- blood glucose levels rise

increased glucose triggers pancreas to release INSULIN

insulin tells your cells to take up glucose

once glucose is inside cells, respiration occurs– releases ATP -- increased ATP tells liver and muscle cells to store glucose

short-term glucose storage = GLYCOGENglycogen storage in avg. humans only about 2 cups pasta worth of E

2/3 of the free sugar in the body is needed by the ____________at any given time

BRAIN

sugar crash!

long-term energy storage = fatapprox. 78% of E storage in average adult is in fat