Bio 20: Photosynthesis

Carotenoids

other pigments that act as accessory pigments in photosynthesis.

Chloroplasts

organelles where photosynthesis occurs, containing chlorophyll within photosynthetic membranes.

Grana

stacks of thylakoids in chloroplasts.

Thylakoid membrane

photosynthetic membrane containing light gathering pigment molecules and electron transport chains.

Thylakoid lumen

the fluid filled space inside a thylakoid.

Stroma

protein rich semiliquid material in the interior of the chloroplast.

Glucose

the end product of photosynthesis, used to store energy for later use by cells.

ATP

adenosine triphosphate, used by all living cells to provide immediate energy for cellular functions.

ADP

adenosine diphosphate, formed when ATP loses a phosphate group and releases energy.

NADPH

an electron donor involved in energy transfers during photosynthesis.

Light Dependent Reactions

reactions that require solar energy, capturing it and transferring it to electrons.

Light Independent Reactions

reactions that do not require solar energy and use energy stored in ATP and high-energy electrons carried by NADPH.

Calvin cycle

a cyclic sequence of enzyme catalyzed reactions that incorporate the carbon of CO2 into glucose.

Carbon fixation

the process of incorporating carbon from CO2 into glucose.

Electron transport chains

molecules necessary for photosynthesis that are located in the thylakoid membrane.

Electron Transport Chain

They are passed from one electron acceptor to another inside an electron transport chain in the thylakoid membrane.

NADPH and ATP

The end result of the electron transport chain is the production of NADPH and ATP.

O2 Production

The O2 that is released comes from H2O that the plant takes in.

Energy Requirement for Glucose

Building one simple sugar molecule (glucose) requires the energy from 18 ATP molecules and the electrons and H+ ions carried by 12 NADPH molecules!

Main Function of Photosynthesis

The main function of photosynthesis is to convert solar energy into glucose.

Storage of Glucose

Plants join many glucose molecules together to make starch for long term storage.

Glycogen Formation

Animal and fungal cells join glucose molecules obtained from their food to form the storage compound glycogen.

Usable Energy Form

When cells require energy for a particular process, it must be supplied in the usable form of ATP.

Cellular Respiration

The role of cellular respiration is to break the glucose down to produce ATP.

Energy Release in Cellular Respiration

The cells of plants and animals release the energy stored in the bonds of glucose molecules through cellular respiration.

Aerobic Cellular Respiration

Aerobic cellular respiration requires oxygen and involves the complete oxidation of glucose.

End Products of Aerobic Respiration

The end products are CO2, H2O, and 36 ATP.

Stages of Aerobic Respiration

There are 4 stages: Stage 1 = glycolysis, Stage 2 = pyruvate oxidation, Stage 3 = Krebs's cycle, Stage 4 = electron transport chain and chemiosmosis.

Anaerobic Cellular Respiration

Anaerobic cellular respiration takes place when oxygen is absent.

Lactic Acid Fermentation

Lactic acid fermentation occurs in human muscles during intense exercise.

Stages of Fermentation

Both types occur in 2 stages: Stage 1 = glycolysis, Stage 2 = fermentation.

Glycolysis

The first stage in the release of energy that comes from glucose is called glycolysis.

Glycolysis Definition

The word glycolysis literally means, 'splitting of sugar' and that is exactly what happens.

Stage 2: pyruvate

The 2 pyruvate molecules formed in glycolysis are transported from the cytoplasm into the mitochondria.

End of the Krebs cycle

All 6 C atoms from glucose have been oxidized to CO2 and released from the cell as waste.

Chlorophyll

a green pigment that absorbs photons from solar energy and starts photosynthesis.

Chlorophyll a

the primary light absorbing pigment used by all photosynthetic organisms.

Chlorophyll b

an accessory pigment that assists chlorophyll a in photosynthesis.

Solar energy

energy from the sun that is captured during photosynthesis.

Glucose Synthesis

The Calvin cycle needs to be completed 6 times in order to synthesize one molecule of glucose!

Cellular Respiration Equation

Equation for cellular respiration: Glucose + oxygen ® carbon dioxide + water + energy.

Cellular Respiration Products

C6H12O6(s) + 6O2(g) ® 6CO2(g) + 6H2O(l) + energy.

Energy Conversion Efficiency

At best, only approximately 36% of the energy content of one glucose molecule is converted into the energy of ATP.

Heat Release

The remaining 64% is released as heat.

Alcohol Fermentation

Alcohol fermentation produces ethanol (ethyl alcohol).

ATP Production in Fermentation

Both processes produce 2 ATP molecules.

Inefficiency of Glycolysis

Glycolysis is a very inefficient form of energy production because only 2 ATP are produced.

Stage 1 in respiration

The initial phase in both aerobic and anaerobic respiration.

Stage 3: Krebs Cycle

A series of reactions that transfer energy from organic molecules to ATP, NADH, and FADH2, and removes C atoms as CO2.

Energy storage after Krebs cycle

All that is left of the original glucose molecule is its energy, stored in NADH, FADH2, and ATP.

Stage 4: electron transport and chemiosmosis

NADH and FADH2 transfer electrons to the electron transport chain (ETC) in the inner mitochondrial membrane.

Electron transport chain (ETC)

A series of compounds in the inner mitochondrial membrane where electrons move from carrier molecule to carrier molecule.

Function of electrons in ETC

Electrons release energy at each step, transferring H+ ions into the mitochondrial matrix.

Final electron acceptor

Oxygen is the final electron acceptor in aerobic respiration.

Chemiosmosis

The process where H+ ions pass through ATP synthase, synthesizing ATP as they do.

Role of NADPH in photosynthesis

The gain and loss of electrons from NADP+ and NADPH contributes to the process of photosynthesis.