1-3 Protein structure and function

Question 1

What determines the folding of a polypeptide to form a protein?

Answer 1

The sequence of amino acids.

Question 2

What are the four levels of protein structure?

Answer 2

• Primary
• Secondary
• Tertiary
• Quaternary

Question 3

What is the primary structure of a protein?

Answer 3

The unique sequence of amino acids.

Question 4

What characterizes the secondary structure of a protein?

Answer 4

Coiling or folding of sections of the polypeptide (alpha helix or beta sheet) due to hydrogen bonds.

Question 5

What is the tertiary structure of a protein?

Answer 5

The 3D shape of a single polypeptide chain due to disulphide and hydrogen bonds.

Question 6

What is the quaternary structure of a protein?

Answer 6

The 3D shape of two or more polypeptides.

Question 7

How many different amino acids are there?

Answer 7

20 different amino acids.

Question 8

What type of bond links amino acids together?

Answer 8

Covalent peptide bonds.

Question 9

What are proteins also known as?

Answer 9

Polypeptides.

Question 10

What is the polypeptide backbone?

Answer 10

The repeating sequence along the core of the polypeptide chain.

Question 11

What are the building blocks of proteins?

Answer 11

Amino acids.

Question 12

What elements do proteins contain?

Answer 12

• Carbon
• Nitrogen
• Oxygen
• Hydrogen
• Some contain sulphur

Question 13

Which two amino acids contain sulphur?

Answer 13

• Methionine
• Cysteine

Question 14

Why is precise folding essential for proteins?

Answer 14

Nearly all proteins carry out their function by recognizing and binding to a specific molecule.

Question 15

Fill in the blank: Proteins are long unbranched chains of _______.

Answer 15

Amino acids.

Question 16

Fill in the blank: From smallest to largest, the order is Amino acid, Peptide, _______ , Protein.

Answer 16

Polypeptide

Question 17

Why are proteins essential to cell structure and function?

Answer 17

Proteins are essential because they play key roles in cell structure and function.

Question 18

What are examples of proteins with specific shapes?

Answer 18

• Enzymes
• Some hormones
• Receptor proteins
• Antibodies

Question 19

Why is the three-dimensional shape of a protein critical to its function?

Answer 19

The three-dimensional shape determines how a protein recognizes, binds, and responds to other molecules.

Question 20

What is the role of enzymes in biochemical reactions?

Answer 20

Enzymes are specific for their substrate and increase reaction rates by lowering activation energy.

Question 21

What does the induced-fit model of enzyme-substrate binding describe?

Answer 21

The induced-fit model describes how the active site of the enzyme changes shape to fit the substrate.

Question 22

What is molecular recognition?

Answer 22

Molecular recognition is the specific interaction between two or more molecules exhibiting molecular complementarity.

Question 23

What forces are involved in molecular recognition?

Answer 23

• Hydrogen bonding
• Other weak intermolecular interactions

Question 24

What is a hormone?

Answer 24

A hormone is a chemical released by cells that affects other cells in the organism.

Question 25

How do hormones work?

Answer 25

1. Secreted into the bloodstream 2. Act on target cells with complementary receptors 3. Trigger a cellular response

Question 26

What are transport proteins?

Answer 26

Transport proteins are located in the cell membrane and allow specific molecules to pass through.

Question 27

What is the importance of protein structure and shape?

Answer 27

Protein structure and shape are essential for their function, including binding and interaction with other molecules.

Question 28

What are some conditions associated with abnormal 3D protein structures?

Answer 28

* Cystic fibrosis * Sickle cell anemia

Question 29

Define enzymes.

Answer 29

Enzymes are biological catalysts that speed up reactions without being used up.

Question 30

What is the active site of an enzyme?

Answer 30

The active site is the part of the enzyme where the substrate binds and undergoes a reaction.

Question 31

What is activation energy?

Answer 31

Activation energy is the amount of energy required for a chemical reaction to take place.

Question 32

How do enzymes affect activation energy?

Answer 32

Enzymes lower the amount of energy required for a reaction.

Question 33

What are the two models for enzyme action?

Answer 33

* Lock-and-Key Model * Induced-Fit Model

Question 34

What does the Lock-and-Key Model suggest?

Answer 34

It suggests that the enzyme and substrate have identical matching shapes.

Question 35

What does the Induced-Fit Model propose?

Answer 35

It proposes that the enzyme changes shape slightly to allow binding with the substrate.

Question 36

What happens during the induced-fit mechanism?

Answer 36

The substrate is drawn into the active site, causing a conformational change in the enzyme.

Question 37

What is released after the substrate reaction in enzymes?

Answer 37

The resulting end product/s is released, and the enzyme returns to its normal shape.

Question 38

True or False: Enzymes are used up in the reactions they catalyze.

Answer 38

False

Question 39

Fill in the blank: Enzymes are biological catalysts that speed up reactions by lowering _______.

Answer 39

activation energy