Proteins part 1

Question 1

What is a protein?

Answer 1

A protein is a macromolecule consisting of
amino acids arranged in a particular
structure that enables it to carry out a
specific function in a particular context

Question 2

What are the two types of proteins and their characteristics?

Answer 2

Proteins may be structural (e.g. actin
‘scaffold’ within a cell or keratin in skin) or
functional (e.g. catalytic function of
enzymes or antibodies in immune defence)

Question 3

Steps before protein synthesis (basic )?

Answer 3

DNA is both a blueprint and instruction
manual for different proteins
It tells cells how to make messenger
RNA (mRNA)
TRANSCRIPTION
mRNA is used by the cell as a code to
make chains of amino acids
TRANSLATION
These chains go on to form proteins!

Question 4

What are the nucleotides that make up DNA ?

Answer 4

adenine, cytosine, guanine and thymine

Question 5

Nucleotides that make up mRNA?

Answer 5

adenine ,cytosine, guanine and uracil

Question 6

Describe amino acid structure?

Answer 6

always a central carbon atom
always amine group (NH2) on left
carboxylic acid group on the right
always a hydrogen attached to second carbon
has a variable r group

Question 7

What does an amino acid being chiral mean?

Answer 7

distinct orientation in space despite common chemical constitution
-true for all except glycine (R is H )

Question 8

Why are amino acids affected by acid-base?

Answer 8

Have COOH - can lose hydrogen ions
amine group- can behave like a base

Question 9

What happens when amino acids are subjected to pH?

Answer 9

may take on positive or negative charge

Question 10

What happens to AA in low pH?

Answer 10

Lots of H+ ions
carboxylic acid group takes up hydrogen and becomes slightly positive
cation

Question 11

What happens to AA in high pH?

Answer 11

not many h+ ions
carboxylic acid loses hydrogen and becomes slightly negative
anion

Question 12

Amino acids at pH 7?

Answer 12

two charges

Question 13

What are aliphatic amino acids?

Answer 13

R group consisting of hydrocarbon chains
increasing long hydrocarbon - non polar properties

Question 14

What are aromatic amino acids?

Answer 14

r group consisting of hydrocarbon ring

Question 15

Why are there sulphur-containing amino acids?

Answer 15

The presence of sulphur allows interactions called disulphide bridge to form

Question 16

What are di- sulphide bridges?

Answer 16

Covalently bonded linkages that occur between two sulphur containing amino acids and help increase strength

Question 17

What are the acidic amino acids?

Answer 17

aspartate and glutamate

Question 18

What are the basic amino acids?

Answer 18

• Lysine
• Hisitidine
• Arginine

Question 19

What are polar amino acids?

Answer 19

Can carry charge at the end of R group

Question 20

What is the miscellaneous amino acid and why?

Answer 20

proline , unusual ring shape- which is very difficult to break

Question 21

Describe primary structure?

Answer 21

The sequence in which amino acid monomers are
bonded together to form a polypeptide chain

Question 22

What is a peptide bond?

Answer 22

amine and carboxylic acid groups both react together
dehydration reaction

Question 23

What is secondary structure?

Answer 23

This is the 3D spatial arrangement of amino acids
located near each other in the polypeptide chain
Relies on hydrogen bonding between the amino
hydrogen of one amino acid and the carboxyl oxygen of another amino acid in the same chain

Question 24

What are the types of secondary structure?

Answer 24

alpha helix
and beta pleated sheet

Question 25

Two examples of proteins with spiral alpha helices?

Answer 25

troponin - released from myocardium
myoglobin

Question 26

What do troponins tell us?

Answer 26

elevations in troponins can help determine if a patient has had a myocardial infarction.

Question 27

What are porin proteins?

Answer 27

porin proteins act as channels that allow water into cells

Question 28

What is the tertiary structure?

Answer 28

Results when functional groups of ‘R’ chains of amino
acids in the polypeptide chain interact with one another
Van der Waals, ionic, hydrogen, disulphide and
hydrophobic interactions can all be involved
Functional proteins exist as, at least, a tertiary structure

Question 29

What is the quaternary structure?

Answer 29

Sometimes several polypeptides interact with one
another to form a quaternary structure

Question 30

Describe structure of haemoglobin?

Answer 30

haemoglobin contains four highly-folded
polypeptide chains and four iron-containing heme
groups with one group tucked within the interior of
each folded polypeptide subunit

Question 31

What is denaturation?

Answer 31

Occurs when a protein’s chemical bonds are
disrupted (possibly destroyed) within its
secondary and tertiary structure
Biological functionality is LOST
Denaturation processes are rarely strong enough
to break the primary structure of individual
peptide bonds, so the primary structure remains
the same even after denaturation