Proteins

Question 1

What are the 4 levels of a protein structure?

Answer 1

Primary
Secondary
Tertiary
Quaternary

Question 2

What do all the 4 levels do?

Answer 2

Interact, as well as attract or repell

Question 3

What is the primary structure of proteins?

Answer 3

The polypeptide.

Question 4

What is the polypeptide?

Answer 4

Amino acid sequence. Peptide bonds

Question 5

Why are there infinite possibilities of polypeptides?

Answer 5

20 different amino acids 
Could be at any length
Amino acids can be in any order
They all have different properties
Some are polar, non polar
Some are (+) or (-) charged
Contain sulfur
Properties of amino acids determine polypeptide folds up into a protein

Question 6

What is the secondary structure of proteins?

Answer 6

Repeated units

Question 7

What are the repeated units? What are they held together by?

Answer 7

Alpha helixes and beta pleated sheets. H-bonds

Question 8

What is the tertiary structure of proteins?

Answer 8

3D folded structure

Question 9

What does the 3D folded structure have and do?

Answer 9

A hydrophobic core and folds a single protein into a 3D structure

Question 10

What does the 3D structure give proteins?

Answer 10

Their functional properties, such as active sites on enzymes.

Question 11

What are the R-group interactions?

Answer 11

• Hydrophilic polar amino acids orient to the outside
• hydrophobic non polar amino acids are protected in the core
• oppositely-charged ions attract
• disulfide bridges formed between sulfur-containing amino acids

Question 12

How does the 3D create its structure?

Answer 12

With 2 or more alpha helixes, 2 or more beta pleated sheets, or one of each

Question 13

What is the quaternary structure of proteins?

Answer 13

Multiple subunits

Question 14

Name 3 examples of quaternary structures

Answer 14

Haemoglobin
DNA polymerase
Ion channels in the plasma membrane

Question 15

What are fibrous proteins?

Answer 15

Insoluble on water structure
They support and strengthen
Help support the cell
The water can’t dissolve the amino acids
It’s a long and narrow structure exposing hydrophobic and hydrophilic properties

Question 16

Name 3 examples of fibrous proteins

Answer 16

Keratin 
-hair/nails
Elastin
-skin
Collagen
-tissue strengthening

Question 17

What are globular proteins?

Answer 17

Soluble in water 
Functional 
Works as enzymes and antibodies
They can float around the cell
Amino acids stick together
They will move around the water freely

Question 18

Name 5 examples of globular proteins

Answer 18

Amylase
-digest starch
Insulin
-blood sugar regulation 
Haemoglobin 
-carries oxygen and red blood cells 
Immunoglobulins 
-immune system/defense
Na+ / K+ pump
-membrane transport

Question 19

What are some uses of proteins?

Answer 19

Hormones
-insulin
Immunoglobulin 
-antibodies
Enzymes
-catalase 
Gas transport
-haemoglobin

Question 20

What are the polar and non polar amino acids used in what kinds of channels?

Answer 20

Membrane channels

Question 21

What die the polar sections allow?

Answer 21

It allows ions to pass through. Charged or polar molecules cannot normally pass through the hydrophobic

Question 22

Where does the polar amino acids position themselves?

Answer 22

On the outside and line the protein channels for facilitate diffusion

Question 23

Where do the non polar amino acids position themselves?

Answer 23

The position themselves with the hydrophobic tails

Question 24

What does non gated mean? What does gated mean?

Answer 24

Non gated- tunnel

Gated- will cause a shape change to let things through

Question 25

What do the non polar amino acids help do?

Answer 25

Bond proteins to the plasma membrane

Question 26

What do the polar amino acids help do?

Answer 26

Help bind the substrates for reaction