Introduction to MetabolismSBI4U Biology

What does Metabolism mean?

• The overall process by which an organism obtains nutrients, deals with them, and extracts energy from them.

• How the organism uses that energy.

• The specific biochemical processes that happen at the cellular level to allow this.

• Energy Balance

Metabolism has two phases:

• ANABOLISM:• ‘building up’• forming cells,

tissues…• going from simpler

molecules to more complex ones.

• synthesis of polymers

• CATABOLISM:• ‘breaking down’• digesting nutrients,

ingesting food…• going from more

complex molecules to simpler ones

• hydrolysis of polymers

Catabolism!

• Ingestion• Digestion• Hydrolysis• You eat an

egg so that you can obtain amino acids for your own body’s use.

Anabolism!

• Growth• Repair• Polymerization• Using the

amino acids from that egg you ate to build muscle.

It’s a big give & take:

BMR: Basal Metabolic Rate

• Basal = most basic, lowest

• Genetically determined

• The metabolic cost of staying alive

• i.e., the energy for life processes such as breathing, circulation, nerve function, body heat, etc.

• Can be increased temporarily

BMR: Basal Metabolic Rate

• BMR changes with age:

Factors affecting Metabolism:

• Highest in infancy, Lowest in old age• Level of activity & Exercise• Stress• Fever• Dietary choices

Factors affecting Metabolism:

• Thyroid gland = one of our main organs regulating metabolic rate.• Hyperactive = weight loss• Hypoactive = weight gain

Balance matters:

Energy in > Energy out = weight gain

Energy out > Energy in = weight loss

Eating disorders can complicate matters.

We think this is a recent, or modern-day problem, but look at this Kellogg’s advertisement from the early 1900’s

Where do we extract the energy?

• Cell Metabolism• Mitochondrion• Different molecules are processed by different

reactions• Some cells are specialized to one or two ‘jobs’.

How is metabolism studied?

• In metabolism experiments, rats are fed radioactively tagged sugars, and their carbon dioxide output is measured.

• Glucose + Oxygen Water + Carbon Dioxide + Energy

What do you mean, ‘energy’?

• Specifically the energy is obtained as Adenosine Triposphate, or ATP.

• This is the energy currency of all living things.

• C6H12O6 + O2 H2O + CO2 + ATP

Example: What happens to Glucose

The details: three major nutrients

The Big Picture… don’t panic!