Cellular Respiration and Photosynthesis

Vocabulary practice flashcards covering cellular respiration, photosynthesis, ATP cycle, and metabolic pathways.

Describe the relationship between ATP and ADP

ATP contains three phosphate groups

ADP is the partially drained version with only two

• Hydrolysis strips a phosphate from ATP to release energy for cellular work, and a series of chem. reactions can add a phosphate group back onto ADP to recharge it back into ATP

Explain why ATP is referred to as the “energy currency” of cells

ATP provides immediate, universally accepted energy

that can be directly spent on cellular work.

ATP Hydrolysis

The process that strips a phosphate group from ATP to release energy for cellular work.

Exergonic process vs. Endergonic process

Exergonic:                                                               

Net release of free energy

Reactants hold more energy than products  

Endergonic:

Net release of free energy

Reactants hold more energy than products   Net absorption of free energy.                                    

Products hold more energy than reactants.    

Explain how endergonic and exergonic reactions are linked in biological systems

• Cells pair non-spontaneous endergonic reactions with spontaneous exergonic reactions so they can occur together.

• An enzyme usually transfers a highly reactive phosphate group from ATP directly onto a reactant, giving it the necessary energy boost to complete the reaction.

Explain why photosynthetic organisms must perform cellular respiration in addition to photosynthesis

Because photosynthesis just makes the food via sunlight, it cannot break it down into energy like ATP, so cellular respiration is helpful because it breaks down the food into energy. It does that during night when it is dark out and the plant cannot perform photosynthesis.

Cellular Respiration (Formula)

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}$$

Glycolysis

The first step of cellular respiration

-in the cytoplasm

-splits a 6-carbon molecule into two 3-carbon pyruvate molecules

produces 2 ATP and 2 NADH.

Pyruvate Oxidation

second step of cellular respiration

In the mitochondrial matrix

• Each 3 carbon molecule from step one lose one carbon

• The new 2 carbon molecules bond to a coenzyme

• Gains 2 NADH- one per molecule

Krebs Cycle

• In the mitochondrial matrix

• Product of step 3 combines with a 4 carbon molecule

• It then loses 2 carbon molecules in the form of CO2 in exchange for:

• 2 ATP, 2 FADH2, and 6 NADH

Oxidative Phosphorylation (ETC)

• In the inner mitochondrial membrane

• High energy electrons from the FADH2 and NADH pass thru membrane proteins

• Powers ATP synthase

• Produces 26-28 ATP

Aerobic Respiration

• Needs oxygen

• In cytosol and mitochondria

• Produces most ATP (36-38)

• ex.) cellular respiration

Anaerobic Respiration

• No oxygen

• In cytosol only

• Produces little ATP (2)

• ex.) lactic acid fermentation

Lactic Acid Fermentation

• Turns sugars into lactic acid (converts pyruvates)

• No CO2 produced

• Used for energy production

Ethanol Fermentation

• Breaks down sugars/pyruvates into ethanol(alcohol)

• CO2 is produced

• Used for energy production

the role of electron carriers in cellular respiration

They move high energy electrons thru the inner mitochondrial membrane, and this movement extracts energy which is then used to make ATP

Photosynthesis (Formula)

$$6CO_2 + 6H_2O + \text{Light Energy} \rightarrow C_6H_{12}O_6 + 6O_2$$

Light-Dependent Reactions (photosynthesis phase 1)

•  In the Thylakoid membranes of the chloroplast. 

• Its where chlorophyll absorbs sunlight and light energy splits water,

• Oxygen gets released into the atmosphere as a byproduct

• ATP and NADPH is produced

Light-Independent Reactions (Calvin Cycle)

second phase of photosynthesis,

• In the stroma of the chloroplast

• Does not require sunlight

• Uses the ATP and NADPH from the first step and CO2 from the air to make carbohydrates molecules like glucose

Explain the role of electron carriers in photosynthesis

They move high energy electrons thru the cell membrane of the chloroplast, and this movement allows the plant to capture light energy.

Identify domains and kingdoms of organisms which undergo photosynthesis

There are 2 main domains: bacteria and eukarya but split into 3 kingdoms where bacteria stays bacteria but eukarya is split into 2; plantae and protisita. Eukarya uses chloroplasts to undergo photosynthesis while bacteria doesn’t because it has internal membranes.