bioenergetics
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Bioenergetics. Chapter 8 & 9. The Big Picture. - energy flows through - matter recycles. The Big Picture…. Producers = Autotrophs - organisms which can make their food - plants, algae, some bacteria - most use photosynthesis Consumers = Heterotrophs - PowerPoint PPT PresentationTRANSCRIPT
BioenergeticsChapter 8 & 9
The Big Picture
- energy flows through
- matter recycles
The Big Picture….Producers = Autotrophs
- organisms which can make their food- plants, algae, some bacteria- most use photosynthesis
Consumers = Heterotrophs- organisms which get their food from other organisms- animals, fungi, most protists- most use cellular respiration
Venus Fly TrapsAlso called Dionaea muscipula, these plants often trap insects by eating them! For example, let's say a fly lands on a Venus Fly Trap, it would activate the "trap" by touching the plant's "hairs" and would be crushed by the plant. After doing so, a Venus Fly Trap receives nutrients from the insect. These plants are still autotrophic because they mainly receive food from sunlight.
ATP = Adenosine triphosphate- normal molecule that cells use to store and release energy- used to power all cellular work- stores small amounts of usable energy- cells must recycle it quickly
Photosynthesis- process by which plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates (sugars + carbs) and oxygen (a waste product) 6CO2 + 6H2O ---light--> C6H12O6 + 6O2
carbon dioxide + water ---light--> sugars + oxygen- chlorophyll is the primary light-gathering pigment of plants- chlorophyll reflects green light
Photosynthesis happens in mesophyll cells of a leaf.- contain chloroplasts which have thylakoids where reactions occur- two sets of reactions:1. Light-dependent reactions2. Light-independent reactions = Calvin cycle
Light-dependent reactions- require light- happen in photosystems on thylakoid
membranes- sunlight splits water into H+ and O2
- also forms ATP and NADPH-NADPH carries electrons (energy) to Calvin cycle
- excited electrons from photosystems give energy to pump H+ into thylakoid spaces and then form ATP
a concentration gradient of H+ in thylakoids is balanced by diffusion through ATP synthase
See diagram on page 211 of textbook
Light-Independent Reactions = Calvin Cycle
- occur in the stroma of the chloroplast
- use the ATP and NADPH from the light reactions to convert CO2 into C6H12O6
- six CO2 are needed to make one sugar molecule
Cellular Respiration – Ch. 9- the energy captured in photosynthesis is
released by organisms by several chemical pathways
- breaks down glucose and other food molecules in the presence of oxygen
6O2 + C6H12O6 6CO2 +6H2O + Energy Oxygen + glucose carbon dioxide + water + energy- energy of food is measured in calories
- food Calorie = 1 kilocalorie (1,000 calories)- energy of food must be released slowly and
captured in the bonds of ATP
See page 222 in textbook
Glycolysis- breaks a molecle of glucose into two pyruvic
acids- occurs in the cytoplasm of all cells with or
without oxygen- net gain of 2 ATP – not much, but very fast- also produces 2 NADH’s which carry electrons
and H+ to other reactions in the cellFermentation- when oxygen is not available fermentation occurs- yeasts and a few other organisms form alcohol - in our muscles fermentation forms lactic acid
Kreb’s Cycle = Citric Acid Cycle (pg. 227)
Krebs Cycle = Citric Acid Cycle- in the presence of oxygen, pyruvic acids are
modified and taken into the mitochondria- capture energy from bonds of pyruvates to
form ATP, NADH, and FADH2
- occurs in mitochondrial matrix- releases CO2
Electron Transport Chain (pg. 228)- NADH and FADH2 from glycolysis and Krebs
Cycle carry electrons (energy) to electron transport chains on inner membrane of mitochondria
- movement of electrons through E.T.C. pumps H+ into outer compartment of mitochondria to establish a concentration difference
- H+ can only diffuse out through ATP synthase and the energy of their diffusion is used to form ATPs
Summary of ATP production in Cellular Respiration