Cellular Metabolism Chapter 4

Metabolism All the chemical reactions that occur in a cell

Two general types of metabolism Anabolic reactions- making larger molecules from smaller ones Catabolic reactions- breaking down larger molecules into smaller ones Anabolism + catabolism = metabolism

Anabolic Ex: dehydration synthesis, combines smaller molecules into bigger molecules (plus water)

Anabolic steroids Reaction that increases production of proteins (and can inhibit catabolism of proteins)

Catabolic Example: hydrolysis, breaking down larger molecules by adding water, produces smaller molecules

Control of metabolic reactions Most reactions proceed at a particular rate/speed Must put in energy to cause a reaction Amount of energy put in to start reaction is called “Activation energy”

Speeding up reactions

Speeding up reactions Enzymes- produced by our bodies, proteins that speed up reactions by lowering activation energy, identified by –ase suffix (e.g., protease) Not consumed in chemical reactions, so your body can reuse them Highly specific- typically only one enzyme type only recognizes one molecule

Enzymes Makes it easier to break the bonds between molecules Substrate is molecule(s) involved in the reaction Active site is part of the enzyme that combines with the substrate Substrate Enzyme Sucrose Fructose Glucose Active site

Optimal conditions for enzymes pH and temperature have dramatic effects on enzymes Ex: Too high a temp denatures enzymes and they can’t work

Getting energy from metabolism…

Energy Capacity to change something, ability to do work Common forms: heat, light, sound, electrical, chemical energy Can transform from one form to another

Why do we eat?. . . To make ATP ATP (Adenosine triphosphate)—the energy currency of the cell Foods are metabolized (chemical bonds are broken) to produce ATP ATP ATP Eat food. Digest food. Transport food to cell. Use to make ATP.

Cellular Respiration Cellular Respiration—the process of making ATP C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 38 ATPs (Glucose) Cellular Respiration—the process of making ATP Carbohydrates, fats and proteins are all metabolized and fed into biochemical pathways that make ATP.