2.5 Enzymes

KEY CONCEPTEnzymes are catalysts for chemical reactions in living things

• Some chemical reactions that make life possible are too slow or have activation energies that are too high to make them practical for living tissue…(in other words they take TOO LONG)

• Solution Your body has a protein that lowers the amount of energy needed at the beginning of a reaction, so you have more energy to complete your metabolic processes needed to live your life!

• These proteins are called enzymes.

2.5 Enzymes

A catalyst lowers activation energy.• Catalysts are substances that speed up chemical

reactions.– decrease activation energy– increase reaction rate

2.5 Enzymes

Enzymes allow chemical reactions to occur under tightly controlled conditions.

• Enzymes are proteins that act as catalysts in living things. They speed up the reactions!– Enzymes are needed for almost all processes.– Most enzymes end in “ase”.

Amylase = in saliva/spit break down starches Lipase = ? Protease = ?

2.5 Enzymes

• Enzymes are involved in almost every process in organisms– Digestion of foods– Building proteins

• An enzyme’s function depends on its structure• Enzymes function best in a small range of conditions, so

disruptions in homeostasis will effect the enzymes function

2.5 Enzymes

• Conditions affecting the function of an enzyme

• Temperature and pH break hydrogen bonds– Denaturation

• Cell activators and Inhibitors

2.5 Enzymes

An enzyme’s structure allows only certain reactants to bind to the enzyme.

• Enzymes act as an Active Site of a reaction and are not used up

• Enzymes have very specific active sites where only certain substrates can bind to reduce activation energy

• Enzymes release products and can repeat process over again

substrates (reactants)

enzyme

Substrates bind to anenzyme at certain places called active sites.

2.5 Enzymes

The Enzyme Substrate Complex

• Can be represented by the lock-and-key model which helps illustrate how enzymes function.– substrates brought together at active sites– bonds in substrates weakened and product released

from enzyme– VIDEO

Substrates bind to anenzyme at certain places called active sites.

The enzyme bringssubstrates together and weakens their bonds.

The catalyzed reaction formsa product that is releasedfrom the enzyme.

2.5 Enzymes

Remember…

• Enzymes are a type of PROTEIN!!!

• There job is to regulate the body’s activities WITHOUT using too much energy.

• When you damage a protein, so it no longer works it becomes DENATURED.