3.1 + 4.1

Question 1

what do carbohydrates, proteins, lipids all contain?

Answer 1

carbon, hydrogen, and oxygen.

Question 2

What do all proteins contain?

Answer 2

nitrogen. some also contain sulfur.

Question 3

what are carbohydrates made up of?

Answer 3

simple sugars (ex. glucose)

Question 4

what is the ‘sugar’ we use in food called?

Answer 4

sucrose

Question 5

what are proteins made up of?

Answer 5

long chains of amino acids

Question 6

what are lipids made up of?

Answer 6

fatty acids and glycerol. there are 3 fatty acids in each lipid and the number of fatty acids vary in different lipids.

Question 7

draw carbohydrates, lipids, and proteins

Answer 7

(see textbook pg 45)

Question 8

what are the differences in structure of proteins and carbohydrates?

Answer 8

proteins are usually made up of several different kinds of amino acids but carbohydrates are usually made from one kind of simple sugar.

Question 9

why is water essential to living organisms?

Answer 9

water is the main part of the cytoplasm of the cell and the plasma of the blood.

Question 10

water is a good ____. why is it a good _____?

Answer 10

solvent. because many substances can dissolve in it.

Question 11

starch is the ______ for plants?

Answer 11

storage molecule

Question 12

what will happen when iodine/potassium iodide solution is mixed with a solution that contains starch?

Answer 12

the color of the iodide will change from brown —–> dark blue.

Question 13

what is the test for glucose called? what happens during it?

Answer 13

Benedict’s reagent. the Benedict’s solution is added to the sample (food) and heated to 95degrees Celsius (or in our class we did 80degrees Celsius).

if it changes color or forms a precipitate, this indicates the presence of reducing sugars (glucose).

green color: small amount of glucose
yellow color: medium amount of glucose
orange-red color: large amounts of glucose

Question 14

what to be careful of when testing for glucose?

Answer 14

Benedict’s solution will cause the sample to change color for any reducing sugar. not just glucose. but glucose is the most common sugar so it’s okay.

Question 15

what is the test for protein and how is it conducted?

Answer 15

the biuret test. a sample of food is placed in a test tube and then an equal volume of buret solution is added. if it contains protein a blue ring will form. when it is shaken it will turn form blue to purple.

Question 16

what is used to test for fat? how does it work?

Answer 16

ethanol is used (after being mixed with water). the test depends on the fact that fats and oils don’t dissolve in water. if there is fat present it will create cloudy solution when mixed with the ethanol.

Question 17

what is a catalyst?

Answer 17

a substance that changes the speed of a reaction, usually making it faster

Question 18

what are enzymes?

Answer 18

catalysts that control metabolic reactions (biological catalysts). they are proteins.

Question 19

what is a biological catalyst?

Answer 19

a chemical that is found in living organisms and that changes the speed of a reaction.

Question 20

define substrate and product.

Answer 20

a substrate is a molecule that an enzyme joins with at the start of a reaction. substrate molecules are changed to product molecules during a reaction.

Question 21

what do we call the enzyme and the substrate?

Answer 21

they are complementary since they fit perfectly.

Question 22

what is the active site?

Answer 22

the space in the enzyme’s shape where the substrate fits. it makes it easier for the bonds inside the substrates to be rearranged to form the product.

Question 23

why does the enzyme not change after reacting with a substrate

Answer 23

because when the substrate changes to form a product the active sight does not change. the products gets released and the enzyme is free to bond with another substrate.

Question 24

enzymes are ___? and what does it mean?

Answer 24

enzymes are specific. it means that each enzyme only works with one substrate or a group of similar substrates.

Question 25

what is amylase, proteases, lipases?

Answer 25

amylase is a type of carbohydrate enzyme produced in the mouth proteases are digestive enzymes that break down proteins into smaller units lipases are digestive enzymes that break down lipids in foods

Question 26

how does an enzyme cause a substrate molecule to change into product molecules?

Answer 26

the sequence of amino acids in the amino acid chain determines the way the chain will fold up to make the three dimensional structure of the protein.

Question 27

what is the particular temp. at which enzymes work best called?

Answer 27

optimum temperature.

Question 28

what is the usual optimum temperature for enzymes in the core (center) of the body such as the liver, kidneys, and lungs?

Answer 28

around 37degrees C

Question 29

what happens when an enzyme is far form it's optimum temp.

Answer 29

when it's too low, the enzymes work more slowly, and when it's too high the enzyme changes so it won't work. it is called being denatured.

Question 30

how to investigate the effect of temp. on enzymes?

Answer 30

do the iodine solution experiment but this time put the solutions in different temp. water baths and see what happens.

Question 31

what is kinetic energy?

Answer 31

it is the energy of moving particles. particles that have a greater kinetic energy move faster. the kinetic energy of atoms held within larger molecules will cause them to vibrate.

Question 32

an enzyme and a substrate molecule can only form an enzyme-substrate bond when...

Answer 32

they bump into each other with sufficient energy (how high their kinetic energy is) and the substrate fits into the active site. so at a low temp they both move slowly so it's harder for them to join to start the reaction and if it's too high than the enzyme could be damaged because of ecssesive bumping.

Question 32

an enzyme and a substrate molecule can only form an enzyme-substrate bond when...

Answer 32

they bump into each other with sufficient energy (how high their kinetic energy is) and the substrate fits into the active site. so at a low temp they both move slowly so it's harder for them to join to start the reaction. If it is beyond the optimum temp than they are vibrating so much they change the shape of the active site which lowers the rate of reaction and chances of them bonding. And if it's too high than the enzyme could be damaged because of too much bumping, breaking.

Question 33

enzymes and pH (basic stuff)

Answer 33

enzymes also often work best at a particular pH, called their optimum pH.

Question 34

what can pH do?

Answer 34

pH can slow down the rate of action of the enzyme or even denature (destroy) it.

Question 35

different enzymes have different ___

Answer 35

pHs (based on where they are normally found in the body)

Question 36

know the experiments for pH

Answer 36

on classroom and on page 57-58

Question 37

what causes the enzyme's 3D shape? (that the substrate can fit into) and what does pH have to do with it (effect of pH)

Answer 37

proteins are made up of amino acids and the amino acids are joined together in a chain with folds up to cause the 3D shape of an enzyme. some of the interactions between amino acids in the enzyme depend on the pH of the surround solvent (ex. water is a solvent) so if the pH changes too much from the optimum than the enzyme is in danger of denaturing or the substrate not fitting well so the reaction being slow or not being able to occur.