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First Law of Thermodynamics
Energy in the universe can not be created or destroyed
it only can change form
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.
sunlight energy
water+
carbondioxide
PHOTOSYNTHESIS
AEROBICRESPIRATION
sugarmolecules
oxygen
ENERGY FLOW THROUGH LIVING THINGS
occurs in the mitochondria
occurs in the chloroplasts
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.
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…
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