MGD S1 - Amino acids, Proteins and Protein folding

Question 1

Golgi body is important for what?

Answer 1

Export of proteins

Detoxification reactions

Question 2

Cytoplasm is involved in?

Answer 2

Metabolism of carbohydrates, amino acids and lipids

Fatty acid synthesis

Question 3

Function of lysosomes?

Answer 3

Cellular digestion

Question 4

Mitochondria perform what function?

Answer 4

ATP synthesis

Question 5

Endoplasmic reticulum functions?

Answer 5

Export of proteins
Membrane synthesis
Detoxification reactions
Protein synthesis (rER)

Question 6

Nucleus does what now?

Answer 6

DNA synthesis and repair

Question 7

What’s the function of the Nucleolus?

Answer 7

RNA processing and ribosome assembly

Question 8

Plasma membrane is for?

Answer 8

Cell morphology and movement

Question 9

What’s the function of Ribosomes?

Answer 9

Protein synthesis

Question 10

Is it hydrophobic or hydrophillic molecules that can pass through a cell membrane unassisted?

Answer 10

Hydrophobic

Question 11

How does a prokaryote differ from eukaryotes?

Answer 11

No membrane bound organelles
One circular strand of DNA + plasmids
Flagella
Smaller ribosomes (70s not 80s)
Bacteria only, can't form multicellular organisms

Question 12

pH refers to what?

Answer 12

Measurement of the concentration of H+ ions in a solution.

Question 13

What’s a buffer?

Answer 13

A mix of an acid and its conjugate base that resists change in pH

Question 14

What is the isoelectric point (pI)?

Answer 14

The pH point at which the Protein has no overall charge

Question 15

When pH of solution > pK of amino acid then?

And what happens vice versa?

Answer 15

Molecule will be deprotonation

Vice versa: molecule is protonated

Question 16

Amino acids can be classified by what criteria?

Answer 16

Aromatic or aliphatic
Polar or non-polar
Charged or uncharged
Positive or negative (@pH7)

Question 17

Acidic proteins contain?

Basic proteins contain?

Answer 17

Many negatively charged aa

Many positively charged aa

Question 18

Acidic proteins have a ______ pI.

Basic proteins have a ______ pI.

Answer 18

Low

High

Question 19

A peptide bond is formed between?

Answer 19

Two amino acids

Between a -COOH and a NH2 group

Question 20

Describe a peptide bond

Answer 20

Planar
Condensation reaction to form
No rotation due to double bond ‘characteristics’
Carbonyl oxygen and amide hydrogen in trans formation

Question 21

What is the primary structure of a protein?

What bonds are involved?

Answer 21

Chain of amino acids

Covalent peptide bonds

Question 22

What is the secondary structure of a protein?

What bonds are involved?

Answer 22

Stretches of alpha helix of beta sheet structures

Hydrogen bonds

Question 23

Tertiary structure is?

Bonds involved are?

Answer 23

Full 3D structure of protein, involves folding up of secondary structures
Covalent (disulphide bridges)
Ionic
Van der waals
Hydrogen
Hydrophobic interactions

Question 24

Quaternary structure is?

Answer 24

Interactions between multiple polypeptide chains within the same protein

Question 25

Tertiary folding sometimes requires the help of?

Answer 25

Molecular chaperones

Question 26

Quaternary proteins can be heteromeric or homomeric, explain the difference.

Answer 26

Homomeric proteins made up of all the same subunits

Heteromeric proteins have at least 2 different types of subunit eg. Haemoglobin.

Question 27

Describe structure and functions of globular proteins

Answer 27

Several types of secondary structure Small and compact

Enzymes, regulatory proteins

Question 28

Describe the structure and functions of fibrous proteins

Answer 28

One type of secondary structure
Long fibres
Structure support and protection

Question 29

Major structural elements of alpha helices?

Answer 29

Right handed

3. 6 aa per turn
4. 54nm pitch

Question 30

Describe the key feature of beta sheet structures.

Answer 30

Extended conformation
Parallel or anti parallel
Multiple inter strand h bonds

Question 31

Name and explain why particular aa are strong helix formers or breakers.

Answer 31

Small hydrophobic aa such as ala or leu good formers
Pro acts as helix breaker due to rotation around the N-C bond being impossible
Gly acts as breaker because the tiny R group supports other conformations

Question 32

Improper folding of protein’s tertiary structure is characteristic of what class of diseases?

Answer 32

Amyloidoses