Unit 1-Lesson 6 Proteins

Question 1

List the characteristics of a Protein

Answer 1

• amino acids make up proteins
• structural building blocks
• extremely divers
• make up 50% of dry mass in cells

Question 2

List some examples of where proteins can be found

Answer 2

Examples: hair, nails, muscle tissue, enzymes, bone, cartilage, hormones, nerves tissues. etc.

Question 3

What is a amino acid?

Answer 3

An organic molecule with a central carbon atom to which an amino group, carboxyl group, hydrogen atom and a variable (“R”) group of atoms are attached

Question 4

Define Amphiprotic

Answer 4

a molecule that have both acidic and basic functional groups

Question 5

How many amino acids are there?

Answer 5

20 different groups; 8 are essential, your body cannot synthesize them, and you can only get them through diet only

Question 6

What are some characteristics for amino acids?

Answer 6

• can be polar, non polar, charged, all depends on the nature of their side chain or “R” group
• when dissolved in water, the carboxyl group donates an H+ ion to the amino group (carboxyl side becomes negatively charged + amino side becomes positively charged)

Question 7

Where are proteins made?

Answer 7

Proteins are made in the Ribosomes

Question 8

How are polypeptides formed?

Answer 8

The long chains of amino acids are linked together by dehydration synthesis to create a polypeptide

Question 9

What are peptide bonds?

Answer 9

Peptide bonds: are formed between the amino group of one amino acid and the carboxyl group of the adjacent amino acid

Question 10

The sequence of amino acids in a protein does not determine the function of that proteins T/F

Answer 10

False. The sequence of amino acids in a protein does determine the function of that proteins

Question 11

What is sickle cell anemia?

Answer 11

Hemoglobin protein that has one different amino acid from the normal
- Glutamic acid is replaced by valine

Question 12

What are the 4 levels of protein structure?

Answer 12

1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

Question 13

What is/happens in the primary structure?

Answer 13

• it has a unique sequence of amino acids in a polypeptide chain
• each amino acid is called a residue
• the DNA governs the order in which the individual amino acids are linked to form the chain (the most important structure, the order of amino acids determines the type of protein that is built)

Question 14

What is/happens in the secondary structure?

Answer 14

• as the amino acids are added to the polypeptide chain, it coils and folds at various locations along its length
• there are types of secondary structure
  1. Alpha helix
  2. Beta pleated sheets

Question 14

Describe what happens in a alpha helix secondary structure

Answer 14

• At certain regions of the polypeptide a hydrogen bond forms between the carboxyl group of one peptide and the amino group four peptide bonds away
• after repeating these action the chain will form into a coil
• e.g. Alpha - keratin (protein in hair)

Question 15

Describe what happens in a beta pleated sheet secondary structure

Answer 15

• when two parts of the polypeptide chain lie parallel to one another, hydrogen bonds between the oxygen atoms of the carboxyl group on one strand and hydrogen atoms from the amino group on the adjacent strain
• e.g. spider silk: large amounts of H bonding - super strong!

Question 16

What is/happens in tertiary structure?

Answer 16

• strong forces of attraction and repulsion between the polypeptide and its environment forces it to undergo additional folding
• ionic bonds and van deer waals forces keep the polypeptide folded
• when sulfur containing “R” groups are brought close together a covalent bond called a di sulfide bridge may form

Question 17

What is/happens in quaternary structure?

Answer 17

• not all proteins this structure
• in some cases, 2 or more polypeptide units must come together to form a functional protein
• Example: collagen (skin), keratin (hair), hemoglobin

Question 18

What is protein denaturation?

Answer 18

• Denaturation: changes in the 3D shape of a protein caused by changes in the temperature, pH, etc
• causes the protein to lose its tertiary or quaternary shape by disrupting the bonds of the proteins structure.

Question 19

Can a denatured protein carry out its function?

Answer 19

• a denatured protein cannot carry out its functions
• it will usually return to its normal shape and function (as long as the primary structure remains intact)
• Example: straightening hair

Question 20

What are the uses for proteins?

Answer 20

• style hair
• curing meats by denaturing protein that would cause them to brown

Question 21

What are the dangers for proteins?

Answer 21

• prolonged fever could denature critical enzymes in brain
• If primary structure is damaged, protein can no longer return to its normal shape: protein is considered dead