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

cycleLight-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