Lecture 3 - introduction to proteins

Question 1

Proteins intro

Answer 1

Polymers of amino acids 
Proteins carry out or catalyse almost all of the processes required to sense and respond to the environment, to make and breakdown molecules, to grow and replicate and to acquire needed energy to fuel all these processes 
Some proteins (structural proteins) form much of our physical make up such as muscle, ligaments, hair, nails and tendons

Question 2

Primer on proteins

Answer 2

Proteins are non-branching polymers that form macromolecules about 50-100 Å in size (1 Å = 10^-10 m)
Each protein is composed of a specific sequence of amino acids joined together by chemical bonds called peptide bonds

Each protein has a distinct sequence that is unique to them

There are only 20 different amino acids used to make proteins

Question 3

Number of amino acids

Answer 3

20 different amino acids

Question 4

Amstrung

Answer 4

(1 Å = 10^-10 m)

Question 5

Amino acid sequence held together by

Answer 5

Peptide bonds

Question 6

Why do we need to know the structure of proteins?

Answer 6

Structure determines function

Question 7

Different ways of depicting chemical structure

Answer 7

Skeletal (lines)
Ball and stick
Space-filling

Question 8

Functions of proteins

Answer 8

Structural - collagen (protein in skin and bones)

Regulatory - insulin (peptide hormone)

Contractile - myosin and actin (muscle proteins)

Transport - Haemoglobin carries oxygen

Storage - Egg white, seed proteins

Protective - antibodies (immune proteins)

Catalytic - hydrolytic in lysosomes

Toxic - Botulinum toxin, diphtheria toxin

Question 9

Cell signalling - hormone

Answer 9

Insulin - after a meal, insulin is generated and binds to the insulin receptor to signal cells to take up glucose in order to decrease blood glucose levels

Question 10

Digestion (2)

Answer 10

Trypsin - an enzyme that breaks down proteins during digestion. Enzymes that breakdown proteins are called proteases

Amylase - an enzymes that breaks down starch into sugars. It is found in saliva as well as pancreatic juices

Question 11

HIV protease

Answer 11

Viruses and bacteria make proteins. They use the same amino acid building blocks. HIV make a protease that is essential for HIV replication

Question 12

Metabolism (2)

Answer 12

Alcohol dehydrogenase - An enzyme that helps to metabolise ethanol. Enzymes catalyse biochemical reactions (it is a dimer but can function as a monomer)

Hexokinase - an enzyme that adds a phosphate to glucose, after glucose is taken up by the cell. Kinases are enzymes that usually add phosphate to molecules

Question 13

Oxygen transport (metabolism)

Answer 13

Haemoglobin - binds oxygen in the lungs and carries it in the blood to tissues for use in metabolism (4 chains and each one bings oxygen through a heme group)

Question 14

Metabolism and energetics - membrane proteins

Answer 14

ATP synthase - membrane protein that generates ATP for use in cellular functions (part membrane proteins and part globular therefore it is part hydrophobic and part hydrophilic)

Question 15

Immune protection

Answer 15

Antibodies - bind to cellular invaders like bacteria and viruses to help protect the body from infection

Question 16

Replication and maintenance

Answer 16

DNA polymerase - binds to one strand of DNA and adds the complementary strand to it

RNA polymerase - creates a single strand of RNA that is complementary to one of the strands of duplex DNA

Question 17

Cell as a bag of…

Answer 17

proteins, lipids, and nucleic acids

Question 18

Name a protein that is involved in DNA replication

Answer 18

DNA polymerase

Question 19

Name a protein that is involved in RNA replication

Answer 19

RNA polymerase

Question 20

Name a protein that is involved in oxygen transport

Answer 20

Haemoglobin

Question 21

Name a protein that is involved in immune protection

Answer 21

Antibodies

Question 22

Name a protein that is involved in digestion

Answer 22

Amylase

Trypsin

Question 23

Name a protein that is involved in metabolism

Answer 23

Alcohol dehydrogenase

Hexokinase

Question 24

Regular components of amino acids

Answer 24

An amino group, a hydrocarbon, a carboxyl group, and a side chain which determines which amino acid it is and the properties it posesses

Question 25

Enzymes that break down proteins are called

Answer 25

Proteases

Question 26

Enzymes that add phosphates to molecules are called

Answer 26

Kinases