Function of Proteins in

Cells &Enzymes

PROTEINS

Copyright © 2009 Pearson Education, Inc.

Functions of Proteins in Cells

• There are THOUSANDS of proteins at work in most cells.

• A PROTEIN is a macromolecule made up of one or more chains of amino acids folded together into a complex three-dimensional structure.

Examples of Proteins

Functions of Proteins in Cells

• Each protein performs a certain function, such as• transporting a specific molecule in or out of the

cell (what type of diffusion could this be?)• or fighting disease• speeding up a chemical reaction. We could also

say that this molecule catalyzes the reaction! (what type of protein is this called?)

VOCAB ALERT! Catalyze = speed up the rate of a reaction

Eight is GREAT!

8 classes of proteins

Proteins

• Proteins are made of

N, C, H, O, S

• Proteins are made of monomers called amino

acids

Structure of Proteins

•The R(radical) group on amino acids is a variable like X in algebra

• It makes each amino acid different. There are 20 different amino acids

Structure of Proteins• The polymer of amino

acids bonded together is a polypeptide/ protein

• Proteins are used in our muscles and also to carry out all of our genes!

Protein Shape and Function

If for some reason a protein’s shape is altered, it can no longer

function

Denaturation: The loss of shape/unraveling of proteins which causes them to not function properly

Proteins can be denatured by changes in salt concentration,

temperature, and pHCopyright © 2009 Pearson Education, Inc.

Changes in primary structure can have

huge effects!• Example: Sickle cell anemia (one wrong

amino acid)

•Enzymes are a type of Protein

•Enzymes are workers in your cells that help chemical reactions happen!

Hey, let’s take a closer look at ENZYMES!

ENZYMES!

• Enzymes CATALYZE reactions

• These reactions sometimes SYNTHESIZE large biological molecules, including: DNA, RNA, proteins, fats, & complex carbohydrates (such as starch

• How does an enzyme work?

Chemical Reactions• When enzymes are

present, they lower the activation energy needed to run the reaction!

• This makes the reaction more likely to happen.

Enzyme Properties• Enzymes look like big

blobs of folded up protein!

• They have an active site where the reaction that they control happens.

Active Site

Enzyme Properties

Substrate: the substance that the enzyme works on

Product: the substance that is created at the end of the

reaction

VOCAB ALERT! Substrate = molecule being changed

Enzyme Properties•Enzymes are awesome

because they never get tired and never get used up!

•Enzymes will continue to work on their substrates until they run out of stuff to work on!

Enzyme Properties

• Things that prevent enzymes from working:• Temperature• pH change

• These things will denature the enzyme

• Enzymes have a pH and temperature where they work their best!

Anything outside of this temp. and pH range is bad for enzymes

Enzyme Properties

Enzymes are very specific!

Enzymes typically only work on 1 substrate, and are actually named after the things they

work on!

Lactase works on lactose

Sucrase works on sucrose