Regents Biology

Proteins – Multipurpose molecules Function:

many, many functions Hormones - Regulation

signals from one body system to anotherInsulin – blood sugar levels

movementmuscle and skin

immune system - antibodiesprotect against germs

enzymes - written over the arrowhelp chemical reactions (metabolism)

Regents Biology

Proteins

Building block =

—N—H

H

H|

—C—|

C—OH

||O

variable group

amino acids

20 different amino acids

Amino group

Carboxyl group (“acid”)

“R” group (20 different ones)

Regents Biology

Amino acid chains Proteins – also called polypeptides

amino acids chained into a polymer by peptide bonds

Each amino acid is different – “R group” some “like” water & dissolve in it

some “fear” water & separate from it

amino acid amino acid amino acid amino acid amino acid

Regents Biology

Water-fearing amino acids Hydrophobic

“water fearing” amino acids try to get away from water in cell

the protein folds

Regents Biology

Water-loving amino acids Hydrophillic

“water loving” amino acids try to stay in water in cell

the protein folds

Regents Biologypepsin

(stomach)

For proteins: SHAPE matters!

collagen (skin)

Proteins fold & twist into 3-D shape that’s what happens in the cell!

Different shapes = different jobs/functions Shape is determined by the order of the

amino acids

hemoglobinred blood cellscarries oxygen

growthhormone

Regents Biology

It’s SHAPE that matters! Proteins do their jobs, because of their 3-D

shape Unfolding a protein destroys its shape

wrong shape = can’t do its job unfolding proteins = “denature”

temperature (high) pH (acidity)

folded

unfolded“denatured”

In Biology,it’s not the size,it’s the SHAPEthat matters!

Regents Biology

Nothing works without enzymes! ALL chemical reactions (metabolism) in

living organisms require enzymes to do work (GRRSNERT) building molecules

Synthesis enzymes

breaking down molecules digestive enzymes

enzymes speed up reactions “catalysts” – lower activation energy

+

+

enzyme

enzymeWe can’t live

without enzymes!

Regents Biology

Examples Synthesis

Digestion - N

+

+

enzyme

enzyme

Same enzyme for BOTH reactions

Regents Biology

Enzymes are proteins Each enzyme is the specific helper to

a specific reaction each enzyme needs to be the right 3-D

shape for the job enzymes are named for the reaction

they help – usually end in -ase sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA

Oh, I get it!They end

in -ase

Regents Biology

Enzymes aren’t used up Enzymes are not changed by the reaction

used only temporarily - reusable re-used again for the same reaction with

other molecules – written over the arrow very little enzyme needed to help in many

reactions

enzyme

substrateor reactant

product

active siteenzyme-substrate

complex

Regents Biology

Enzyme vocabulary Enzyme

helper protein molecule

Co-enzyme Usually a vitamin; NOT protein

Substrate molecule that enzymes work on

Products what the enzyme helps produce from the reaction

Active site part of enzyme that substrate

molecule fits into

Regents Biology

The “Key”

It’s Shape that Matters!!!

• Lock & Key model• Shape of protein allows enzyme & substrate to fit

togetherSHAPE of enzyme for each specific reaction

Regents Biology 2009-2010

For enzymes…What matters?

SHAPE!Correct protein determined by:• Correct order of amino acids –

determined by DNA

• Temperature• pH (acids & bases)• Substrate Concentration (amount of

substrate)

Regents Biology

Order of amino acids Wrong order = wrong shape = can’t do its job!

DNA

DNA

chain ofamino acids

chain ofamino acids

foldedprotein

foldedprotein

right shape!

wrong shape!

Regents Biology

Sickle Cells vs Normal RBC’s

Regents Biology

Temperature Effect on rates of enzyme activity

Optimum (best) temperature greatest number of collisions between

enzyme & substrate human enzymes

35°- 40°C (body temp = 37°C) Raise temperature (boiling) - fever

denature protein = unfold = lose shape Lower temperature T°

molecules move slower fewer collisions between enzyme &

substrate

Regents Biology

37°

Temperature

temperature

reac

tio

n r

ate

What’s happening here?!

humanenzymes

Enzyme is denaturing or

unfolding

Regents Biology

7

pH

pH

reac

tio

n r

ate

20 1 3 4 5 6 8 9 10

stomachpepsin

intestinestrypsin What’s

happening here?!

11 12 13 14

acid baseneutral

Regents Biology

Also Substrate concentration Lucy and the candy factory

http://www.youtube.com/watch?v=4wp3m1vg06Q

ALL enzymes are in use; can’t go any faster unless more enzymes are added

Substrate concentration

reaction rate