Protein structure and function

Question 1

What are proteins built from?

Answer 1

Amino Acids

Question 2

What is the equation for protein formation?

Answer 2

L - amin acid Protein

–> = condensation reaction

Question 3

What are the bonds between proteins?

Answer 3

Peptide

Question 4

What are the 2 processes that are required when initially building a protein?

Answer 4

Transcription and translation

Question 5

What is being translated when building a protein?

Answer 5

Genetic code

Question 6

Give a brief summary of transcription and translation: (2)

Answer 6

Genes are transcribed into mRNA by RNA polymerase

mRNA is translated by tRNA - ribosome

Question 7

What is the structure of an amino acid?

Answer 7

Alpha carbon, carboxyl group, amine group, R-group
.............. H
............... |
\+H3N -- C -- COO-
............... |
............  (R)

Question 8

What is a naturally occurring optical isomer called?

Answer 8

Enantiomers

Question 9

What type of mixture is formed by chemical synthesis of an amino acid?

Answer 9

A racemic mixture

Question 10

What type of isomers are amino acids always? (D or L)

Answer 10

L - isomers (homochirality)

Question 11

What does aliphatic mean?

Answer 11

R-group is NOT branched

Question 12

What does aromatic mean?

Answer 12

R-group is based on a benzene ring

Question 13

What does polar mean?

Answer 13

the R-group carries a small charge

Question 14

Which part of the amino acid can be ionised and what is that called? (2)

Answer 14

Carboxyl and amine

Amphoteric

Question 15

What is pKA?

Answer 15

pKa is the pH at which a group has equal amounts of protonated and unprotonated forms

Question 16

What is the point of pKa?

Answer 16

Proton binding affinity - low pKa means it has low pba

Question 17

What is a zwitterion?

Answer 17

The pH of the amino acid has no net overall charge - least soluble

Question 18

What is the hydropathy index and what do the values mean?

Answer 18

Hydropathy index is how hydrophobic/hydrophilic an R group is

Negative value = hydrophilic
Positive value = hydrophobic

Question 19

What are the fundamental forces in biology? (4)

Answer 19

Electrostatic interactions (ionic bonds)
Polar interactions (hydrogen bonds)
van der Waals interactions (dipole)
hydrophobic interactions

all NON-COVALENT

Question 20

What are the 4 forces crucial for? (2)

Answer 20

Chemical reactivity of proteins as enzymes

Ability of a protein to fold into the correct shape

Question 21

What are electrostatic/ionic attractions?

Answer 21

Occur between oppositely charged ions

Water weakens their strength

Question 22

What is Coulomb’s law?

Answer 22

Magnitude of the electrostatic force between 2 charges is directly proportional to the product of the 2 charges

Question 23

What is an example of an essential ionic bond in enzyme activity?

Answer 23

ATP - converting energy from food/sun to energy for cells

Question 24

What are polar bonds? (2)

Answer 24

Hydrogen bonding

Water

Question 25

What are van der Waals forces? (2)

Answer 25

Electron cloud alignment

Atoms never collide

Question 26

What are hydrophobic forces? (3)

Answer 26

Not polar
Useful for separation
Increase with increasing temp and salt