Cellular Respiration

NRG from Food

Cellular Respiration

The breakdown of food to release stored chemical energy and thus make ATP for use in the cell

Formulas to know and love

Where? When? Who?

mitochondria of eukaryotic cells As long as food is available and

an organism requires energy ALL living things – plants,

animals, fungi, bacteria, protists

Cellular Respiration

Follows these 3 easy steps…that follow either one of two pathways…

1st step of Respiration

Glycolysis Occurs in cytoplasm (w/wo

Oxygen) Break glucose into 2 pieces of

pyruvic acid (pyruvate)Protons (H+) stripped (and e-) &

“loaded” onto NAD

Oxygen availability determines next step

NO “O” Anaerobic

respiration or Fermentation

Oxygen available Oxidative

metabolism Kreb’s

cycle/citric acid cycle

ETC (electron transport chain)

Anaerobic Fermentation

When oxygen is low or unavailable Occurs in cytoplasm NO NRG made Only purpose is to regenerates

NAD needed for glycolysis Byproducts depend on organism

Alcohol, propionic acid, lactic acid

Aerobic Respiration Two steps

Kreb’s cycleThe complete breakdown of glucose

Harvesting of H+ and e- (potential energy)

Makes a little bit of ATP Electron Transport Chain

Where most ATP is made in chemiosmosis

Kreb’s Cycle

Mitochondrial matrix Pyruvate further ripped apart:

release of CO2 Acetyl-CoA enters Kreb’s cycle Hooks up with a starting molecule

(oxaloacetate) to make a 6C sugar

Complete breakdown of glucose harvest protons (H+) and electrons

(e-) NAD and FAD “wagons” pick up the

H+/e- Beginning molecule (Oxaloacetate)

is regenerated for cycle

ETC – Electron Transport Chain

Occurs on cristae of mitochondria Passing of H+/e- sets up

concentration gradient of protons ATP made by chemiosmosis MOST energy of respiration is

made here Final electron acceptor – oxygen H+/e- plus O2 equals H2O

Comparison of respiration

Anaerobic No O Starts with glycolysis Only makes 2 ATP Waste products of

lactic acid, alcohol or propionic acid & CO2

Aerobic Oxygen available Starts with glycolysis 2 further steps Generates 34-36 ATP CO2 is waste product

It takes energy to make energy…

Flow of energy in universe is constantly cycledStored in chemical bondsReleased from chemical bonds