1.5: Intro to Protein Networks

Lactase Lab

• Lactose sugar is composed of galactose and glucose

• Lactase enzyme breaks lactose into galactose and glucose

Lactose

Glucose

Lactase

Galactose

The arrows represent the action of the enzyme

Substrate

Products

Enzymes convert substrates into products

Substrate ProductEnzyme

lactose

lactase

glucose

lactoseGlucose

and Galactoselactase

galactose

Serotonin

• Serotonin is a molecule called a neurotransmitter used by cells in the brain to communicate

• Part of its function is to regulate emotions• Abnormally low amounts of serotonin in the

brain can cause depression

How is serotonin produced, and how can we use our understanding of it to treat depression?

Some enzymes involved in serotonin synthesisEnzyme: AAADSubstrate (start with): 5-HTPProduct (end up with): serotonin

Enzyme: TPHSubstrate: tryptophanProduct: 5-HTP

Enzyme: MAOSubstrate: serotoninProduct: 5-HIAA

5-HIAA

5-HTP

5-HIAA

5-HTP

TPH

AAAD

MAO

Your proteins determine your characteristics…

5-HIAA

5-HTP

TPH

AAAD

MAOLow amounts of AAAD –

more or less serotonin?

5-HIAA

5-HTP

TPH

AAAD

MAOLow amounts of MAO –

more or less serotonin?

5-HIAA

5-HTP

TPH

AAAD

MAOHigh amounts of MAO –

more or less serotonin?

So do you want lots of MAO or a little bit of

MAO?

Antidepressants

• One type of drug to treat depression works by decreasing the activity of the MAO enzyme. These are called MAO inhibitors or MAOI’s

• The drug molecules have a shape that fits into the active site of the MAO enzyme and blocks it

Guiding Question:

“How does variation exist between organisms?”

Vocab to know

• Pigment = A substance, such as chlorophyll or melanin, that produces a characteristic color in plant or animal tissue.

• Pigment molecules are often substrates for enzymes.

Pigment Metabolic Network for the Imaginary Bioflower

Blue Flower Purple Flower

Where is the variation in these flowers? Blue and Purple Flowers (Color)

Bioflowers

A colorless starting molecule is converted by enzyme X to blue pigment. Next, enzyme Y converts the blue pigment to purple pigment.

1.Diagram of the pathway. (include a key)

2.Give an explanation for a blue flower.

Colorless Compound Blue Pigment Purple Pigment

X Y

Colorless (white)molecule

Blue pigment molecule

Purple pigment molecule

Enzyme X Enzyme Y

pathway

Molecule cartoons

Colorless (white)molecule

Blue pigment molecule

Purple pigment molecule

Enzyme X Enzyme Y

pathway

Molecule cartoons

“Roundbuds”

RoundbudsIn another type of wildflower, the roundbud, red pigment is synthesized from a white precursor by enzyme Q.

1. Draw the enzyme pathway for the roundbud.

It was believed that all roundbuds were red until a knowledgeable, observant teenager discovered a meadow full of white-flowered roundbuds.

2. Using your knowledge of the synthesis pathway for red pigment, give an explanation for the white roundbud variety.

colorless (white) molecule

Red Pigment moleculeEnzyme Q

Colorless molecule

Enzyme Q

Red pigment molecule

It was believed that all roundbuds were red until a knowledgeable, observant teenager discovered a meadow full of white-flowered roundbuds.

2. Using your knowledge of the synthesis pathway for red pigment, give an explanation for the white roundbud variety.

White Precusor Red Pigment

Q

colorless (white) molecule

Red Pigment moleculeEnzyme Q

Colorless molecule

Enzyme Q

Red pigment molecule

Continue working on the back of the worksheet.

Introduce networks in cells

Idea Journal

• In the last box of your Proteins Idea Journal, draw a simple network showing enzymes and substrates in a cell.

• In the “Explain” box, describe how proteins determine the traits of a cell.