bio 3 chapter NSMO

Metabolism

Metabolism is the sum of all the biochemical processes that occur within the body of a living organism

Catabolism

releases energy, e.g. digestion and respiration

Anabolism

consumes energy, e.g. photosynthesis

Law of Energy Conservation

States that energy can be transformed from one form to another, but cannot be created or destroyed except by God’s will

Second law

States that energy is lost whenever it is transformed from one form to another

The lost energy is released as heat

The food chain is an example of this law

ATP

The cellular unit of energy

Consisting of adenine + ribose sugar + three phosphate groups

It stores chemical energy used by cells in their reactions

ATP releases energy when the bond between the second and third phosphate groups is broken

This produces ADP + a free phosphate group.

Energy is stored in the phosphate bond when ADP combines with a free phosphate group to form ATP again

Photosynthesis

The process of converting light energy into chemical energy

Photosynthesis takes place in chloroplasts

It’s a common process among all organisms that contain chloroplasts

It occurs through a series of reactions that produce a molecule of glucose

Structure of the Chloroplast

Large, disc-shaped organelles.

Contain the pigment chlorophyll, which absorbs light energy

Thylakoids

stacks of flattened membrane sacs (disc-like structures) that form the grana

Stroma

the fluid that fills the spaces surrounding the grana

Composition of Chloroplasts

1. Thylakoids: stacks of flattened membrane sacs (disc-like structures) that form the grana.

2. Stroma: the fluid that fills the spaces surrounding the grana

Chlorophyll

Main pigments in plants, absorbs light energy

Carotenoids

red, yellow, and orange pigments, these pigments become visible in autumn as chlorophyll molecules break down, giving leaves their different colors

Light Reactions (first stage)

Occur in the grana, where chlorophyll pigments absorb light energy and convert it into chemical energy in the form of NADPH and ATP, which are used to build glucose

Oxygen is released as a byproduct due to the splitting of water molecules

Dark Reactions (second stage)

Occur in the stroma, where the energy produced from the light reactions (ATP and NADPH) along with CO₂ is used to form a molecule of glucose

Take place through a series of reactions known as the Calvin Cycle

Do not require the presence of light

Cellular Respiration

The process of oxidizing nutrients to obtain energy

Involves the intake of O₂ and the release of CO₂

Takes place inside the mitochondria

Aerobic Respiration

Occurs in the presence of oxygen

Glycolysis

Glucose is broken down in the cytoplasm

Two molecules of pyruvic acid are produced

The net energy from this stage is 2 NADH + 2 ATP

Conversion of Pyruvic Acid to Acetyl CoA

This stage occurs in the mitochondrial membrane

When oxygen is available, pyruvic acid enters the mitochondrion

The acetyl group combines with coenzyme A (CoA) to form acetyl-CoA

The products of this stage (from 2 pyruvates) are: 2 Acetyl-CoA + 2 CO₂ + 2 NADH

Krebs cycle

Occurs in the mitochondrial matrix

A: The acetyl group from acetyl-CoA combines with a four-carbon compound to form a six-carbon compound (citric acid)

B: A series of oxidation reactions and atom rearrangements occur, allowing the cycle to repeat

Products from kerbs cycle

From one cycle: → 2 CO₂ + 1 ATP + 1 FADH₂ + 3 NADH

From two cycles: → 4 CO₂ + 2 ATP + 2 FADH₂ + 6 NADH

Electron transport chain

Occurs in the mitochondrial membrane

Final stage of aerobic respiration

In this stage, most ATP are produced

High energy electrons like NADH and FADH_{2 are used}

Each NADH molecule produces 3 ATP molecules

Each FADH₂ molecule produces 2 ATP molecules

Lactic acid fermentation

Glucose is converted into pyruvate, producing ATP and NADH

Through the action of enzymes, pyruvate is converted into lactic acid

This process occurs in muscles during fatigue and oxygen deficiency

No CO₂ is produced in this process

Final products: 2 Lactic acid + 2 ATP

Alcoholic fermentation

Glucose is converted into pyruvate, producing ATP and NADH

Pyruvate is then converted into ethanol

This process occurs in yeast and certain bacteria

CO₂ is produced during this process

Final products: 2 Ethanol + 2 ATP + 2 CO₂