ATP, Cellular

Respiration and

Photosynthesis

Energy for Cells

Free Energy: the energy available to do

work

Types of Reactions

Endergonic Reactions: require an input of energy

Exergonic Reactions: release energy (energy EXits)

ATP

Adenosine Triphosphate

3 Phosphate Groups

Goes into endergonic reactions

Released from exergonic reactions

Energy source

ATP + H2O ADP + P + Energy When the last phosphate bond (high energy bond)

is broken, energy is released

Hydrolysis reaction

Cellular Respiration

The process by which energy is made

available for biological work

C6H12O6 + 6O2 6CO2 + 6H2O + Energy

Exergonic

Occurs in both autotrophs & heterotrophs

Reactions occur in the cytoplasm and

mitochondria

Aerobic Respiration

Aerobic Respiration: cellular respiration

that uses O2

Releases 38ATP

Anaerobic Respiration

Anaerobic Respiration: cellular

respiration that occurs in the absence of

oxygen

Fermentation: another term used to

describe anaerobic respiration

Types:

Lactic Acid Fermentation

Alcoholic Fermentation

Anaerobic Respiration

Lactic Acid Fermentation: glucose is

broken down into 2 lactic acid molecules

in the absence of O2

Releases 4ATP

Occurs in human muscle cells

Allows muscles to keep working without oxygen,

but produces MUCH LESS ATP than aerobic

respiration

Anaerobic

Alcoholic Fermentation: glucose is broken down into 2 ethanol molecules and 2 carbon dioxide molecules in the absence of oxygen Releases 4ATP

Carried out by plant cells and microorganisms

Yeast in bread breaks down carbohydrates in the dough by alcoholic fermentation, the CO2 released causes the bread to rise

Yeast are used to produce ethanol in beer & wine

Photosynthesis

Process by which producers store energy

from sunlight as chemical energy in

organic molecules (glucose)

6CO2 + 6H2O + Energy C6H12O6 + 6O2

Endergonic (takes in sunlight)

Occurs in producers only (autotrophs)

Light

Light: radiant energy travels in waves

Visible Spectrum: the range of colors that make up white light Longest R O Y G B I V Shortest

Colors we see depend on what wavelengths are reflected

Chlorophyll & Other

Pigments

Organisms that carry out photosynthesis

contain colored pigments that absorb

light energy and convert it to chemical

energy

Chlorophyll

Most important pigment in photosynthesis

Eukaryotes: chlorophyll is in the chloroplasts

Prokaryotes: chlorophyll is in the cytoplasm

Chlorophyll

Appears green = reflects green & yellow wavelengths of light

Absorption Spectrum: a graph that shows the wavelengths of light absorbed

Absorbed wavelengths are transformed from light energy to chemical energy during photosynthesis

Absorbed wavelengths are USED

Carotenoids

Yellow, orange, and red pigments in chloroplasts

Absorb blue & green wavelengths

Pass energy to chlorophyll

Present in other plant parts (flowers, fruits)

Become visible in autumn because chlorophyll production stops

Chloroplasts

Contain chlorophyll & other pigments

Thylakoid membranes Internal membranes

Fluid mosaic

Chlorophyll & carotenoids embedded in bilayer with proteins

Where the light reactions occur

Grana: stacks of thylakoids

Stroma: fluid part of chloroplast Where the Calvin Cycle occurs

Light Reactions

Involve a series of changes that convert

light energy to chemical energy

“photo” means light – this is the “photo” in photosynthesis!

Occur in the thylakoid membranes

H2O split into Hydrogen ions (H+),

electrons, and O2

The Calvin Cycle (“Dark” Reactions)

Synthesis of sugars by the stroma &

molecules within it

“Synthesis” of photosynthesis

Produces 3 Carbon sugars

2 can be combined to form 6 Carbon sugars,

like glucose

Lack of Free Glucose in

Plants

Most plants contain little free glucose

because:

Glucose + fructose sucrose

Glucose + glucose starch

Glucose used for cellulose

Energy Relationships

Photosynthesis & Respiration are opposites &

interdependent

Respiration = exergonic

Photosynthesis = endergonic

One cannot occur without the

other – products of one are the

reactants of the other

6CO2 + 6H2O + Energy C6H12O6 + 6O2

C6H12O6 + 6O2 6CO2 + 6H2O + Energy

Photosynthesis only in autotrophs

Respiration in autotrophs AND heterotrophs