Amino Acids + Proteins

Question 1

What are Proteins?

Answer 1

• Linear polymers of amino acids.

Question 2

Amino Acids (Read)

Answer 2

• 20 diff common AA
• 10 essential
• 10 non - essential
• Conc of free AA in cell is low.

Question 3

Can amino acids be stored in the body?

Answer 3

• No

Question 4

What are Amino Acids needed for?

Answer 4

• To meet the body’s requirement for protein.
• Synthesize new proteins
  synthesis as precursors for other compounds.

Question 5

What can the bacteria E.coli do?

Answer 5

• Synthesize a set of standard AA.

Question 6

• How does the body convert proteins to AA’s in the digestive system?

Answer 6

• By releasing proteolytic enzymes.

Question 7

What does the basic structure of an Amino Acid contain?

C.A.H.R

Answer 7

• Carboxyl Group
• Amino Group
• Hydrogen atom
• Side Chain ( R group)

All are attached to a central carbon atom known as the α-carbon.

Question 8

How does the R Group (side chain) vary?

Answer 8

• Size
• Shape
• Charge
• Solubility

The properties of the side chain(s) influence the overall 3D shape (configuration of a protein). The 3 D shape plays an integral part in protein functionality.

Question 9

What can the R Group (side chain) be?

Answer 9

▪ Aliphatic (non-polar)
▪ Aromatic (ring structure, generally non-polar)
▪ Polar
▪ Negatively charged
▪ Positively charged

Question 10

What is an Aromatic Compound?

Answer 10

• An organic compound made of C + H, contains an aromatic ring configuration of atoms.

Question 11

Give an example of an Aromatic compound.

Answer 11

• Benzene

Question 12

What is an Aliphatic Compound?

Answer 12

• An organic compound made of C + H, it is Non- Aromatic.

Question 13

Give examples of Aromatic Amino Acids. (P.T.T)

Answer 13

• Tyrosine
• Tryptophan
• Phenylalanine

Question 14

How do you test for the detection of proteins?

Answer 14

• Spectrophotometry @ λ max 280

Question 15

What is a Peptide?

Answer 15

• Short chain of AA monomer.
• Linked by peptide bonds
• 2 - 20 AA’s

Shortest peptide is a dipeptide, then tripeptide, tetrapeptide etc.

Question 16

What are Peptide bonds also called?

Answer 16

• Amide Bonds

Question 17

What is a Polypeptide?

Answer 17

• Long, continuous, unbranched peptide chain

- 20 - 50 AA’S

Question 18

What is a protein?

Answer 18

• One or more polypeptides arranged in a biologically functional way.
• 50 - ? AA’s

Question 19

How are Amino Acids added added to a linear polymer in a stepwise manner?

Answer 19

• By a Condensation Rxn ( loss of H2O).

Question 20

Read

Answer 20

▪ As H2O is removed, the carboxyl
carbon of one AA and the amino nitrogen of a second are linked directly.

▪ This covalent C—N bond linking two AA’s is known as a peptide bond, shown below in bold.

▪ Formation consumes energy – living systems – ATP.

▪ Bond can be broken by hydrolysis (the adding of water) which releases
energy.

Question 21

Give 5 examples of the biological functions of Peptides. ( V.O.L.A.B)

Answer 21

• Vasopressin (H20 Reabsorption)
• Oxytocin ( Uterine Contraction)
• LHRH (Fertility)
• Angiotensin II (Reg. Blood Pressure)
• Bradykinin ( Inhibits Inflammation)

Question 22

How are Amino Acids linked?

Answer 22

• Covalently linked by peptide bond

- Linear sequence

Question 23

How many levels of structure do proteins have?

Name these levels.

Answer 23

• 4
• Primary
• Secondary
• Tertiary
• Quaternary

Question 24

What is the primary structure of a protein?

Answer 24

• The linear sequence of amino acids within a protein.

- Dictated by the Genetic Code.

Question 25

What is the Secondary Structure of a protein?

Answer 25

- Occurs due to Hydrogen Bonding between peptide bonds along the length of the protein. - Causing a Localized Helix to form + sheet structure.

Question 26

What do hydrogen bonds do to the secondary protein structure?

Answer 26

- They stabilize the structure.

Question 27

What is the Tertiary structure of a protein?

Answer 27

- Caused from extensive folding a polypeptide chain into a closely packed (almost) spherical shape.

Question 28

What is the extensive folding in the tertiary structure caused by?

Answer 28

- Chemical interactions between the side chains of the amino acids.

Question 29

What is the most protein structure/Conformation and why?

Answer 29

- Tertiary Structure | - Bc of the chemical interactions between the side chains of the amino acids stabilize the structure.

Question 30

Read

Answer 30

▪ H bonding between side chains ▪ Ionic bonding between side chains with ionizable groups. ▪ Disulphide bonds between 2 cysteine residues (Cys - S - S - Cys) ▪ Hydrophobic interactions ; this is the most significant tertiary structure stabilization force. It constitutes a non covalent interaction between the non polar R Groups.

Question 31

Quaternary structure?

Answer 31

▪ Limited to proteins with multiple polypeptide sub units . Each sub unit is a separate polypeptide chain. ▪ The bonds and forces that maintain quaternary structure are the same as those responsible for tertiary structure.

Question 32

Give an example of a protein with a Quaternary structure?

Answer 32

- Hemoglobin, the oxygen carrying | protein in blood.

Question 33

Biological Functions of Proteins.

Answer 33

- Enzymes - many proteins function as enzymes i.e. biochemical catalysts. - Hormones; many regulate biological/biochemical functions in target tissue e.g. hormones. - Some bind other molecules for storage and transport e.g. hemoglobin binds 0 2 , CO 2 in erythrocyte cells (red blood cells). - Structural proteins provide support and shape to cells & therefore to tissue and organisms (skin, tendons, hair (Elastin, Collagen , Keratin). - Assemblies of proteins perform mechanical work ( flagella, cilia , Some proteins are hormones they regulate biochemical activities in target cells or tissue. - Proteins also serve a range of other specialized functions including their defense functions as immunoglobulin (antibodies).

Question 34

Industrial Uses of Proteins.

Answer 34

- Enzymes: (proteases) meat tenderization, cheese manufacture rennin, contact lens cleaner. - Regulatory Protein medical uses, insulin diabetes, growth hormone treat dwarfism, FSH treat infertility. - Antibodies covid 19 test, HIV test, pregnancy test, Ovulation test.