Lec 9: Intro To PROTEINS

Question 1

Building blocks of proteins

Answer 1

Amino acid

Question 2

General Structure of Amino Acids

1. An acid that is able to donate protons
2. A base that is able to accept a proton
3. Responsible for the function of the amino acid within the protein

Answer 2

1. Carboxyl group
2. Amino group
3. R or sidechain

Question 3

Smallest amino acid

Answer 3

Glycine

Question 4

An imino acid

Answer 4

Proline

Question 5

Amino acids which can’t be synthesized in the body

Answer 5

Essential

Question 6

Examples of essential AA

Answer 6

• isoleucine
• methionine
• threonine
• histidine
• valine
• phenylalanine
• lysine
• leucine

Question 7

Amino acids which can be synthesized in the boxy

Answer 7

Non-essential

Question 8

Example of non-essential AA

Answer 8

Arginine

Question 9

Amino acids which are required in growing children and pregnancy, but not essential in healthy adults

Answer 9

Semi-essential

Question 10

• Inherited errors of metabolism
• an enzyme defect that inhibits the body’s ability to metabolize certain amino acids

Answer 10

Aminoacidopathies

Question 11

The absence of the activity of phenylalanine hydroxylase enzyme.

Answer 11

Phenylketonuria

Question 12

1. Action of phenylalanine hydroxylase
2. Effect of high levels of phenylalanine
3. Describe urine of PKU patients

Answer 12

1. PAH catalyzes conversion of phenylalanine to tyrosine
2. High levels of Phenylalanine:
   • retards mental development
   • causes microcephaly
   • leads to hypopigmentation
   • become prone to seizures & eczema
3. Musty/Mousy odor

Question 13

Low levels of enzyme fumarylacetoacetate hydrolase

Answer 13

Type 1 Tyrosinemia

Question 14

What type of tyrosinemia?

• jaundice
• cabbage-like odor
• distended abdomen
• swelling of legs

Answer 14

Type 1 Tyrosinemia

Question 15

Tyrosine aminotransferase deficiency

Answer 15

Type 2 Tyrosinemia

Question 16

What type of tyrosinemia?

• mental retardation
• excessive tearing
• photophobia
• eye pain & redness
• painful skin lesions (palms & soles)

Answer 16

Type 2 Tyrosinemia

Question 17

Deficiency of 4-hydroxyphenylpyruvate dioxygenase

Answer 17

Type 3 Tyrosinemia

Question 18

What type of tyrosinemia?

• mental retardation
• periodic loss of balance and coordination

Answer 18

Type 3 Tyrosinemia

Question 19

What type of tyrosinemia?

1. Mild form
2. Most severe form

Answer 19

1. Type III
2. Type I

Question 20

For detection of Tyrosinemia

Answer 20

Tandem Mass Spectrometry

Question 21

Deficiency of homogentisate oxidase

Answer 21

Alkaptonuria

Question 22

• urine turns black when mixed with air
• dark spots on sclera
• ochronosis

Answer 22

Alkaptonuria

• high levels of thyroxine and phenylalanine —> secreted in urine
• ochronosis: darkening of cartilage tissues due to deposition of pigment

Question 23

Action of Homogentisate oxidase

Answer 23

For the metabolism of thyroxine & phenylalanine

Question 24

Absence of branched-chain alpha keto acid decarboxylase

Answer 24

Maple Syrup Urine Disease

Question 25

**Maple Syrup Urine Disease** 1. Describe urine 2. Infants born with this develop ___ (symptoms). 3. Treatment 4. Test for detection

Answer 25

1. Burnt sugar odor (including skin & breath) 2. Lethargy, vomiting, lack of appetite, failure to thrive 3. Avoidance of _branched-chain keto acid_ in diet 4. Modified Guthrie Test • inhibitor: _4-azaleucine_

Question 26

Linear polymers of amino acids

Answer 26

Protein

Question 27

Functions of Protein

Answer 27

- regulate metabolism - facilitate muscle contraction - provide structural framework - as transport proteins - component of the immune system - acid-base balance - water distribution maintenance

Question 28

- DNA produces RNA template - formation of mRNA strand - mRNA is sent to cytoplasm - *process takes place in nucleus*

Answer 28

Transcription

Question 29

- formation of RNA into protein - *takes place in cytoplasm*

Answer 29

Translation

Question 30

**Protein Structures** 1. Folding of short contiguous segments of polypeptide into *geometrically ordered units* 2. A sequence of a chain of amino acids 3. Results from the interaction of *more than one* protein molecule/sub-units. 4. Three-dimensional shape of protein. Either globular or fibrous.

Answer 30

1. Secondary structure 2. Primary structure 3. Quarternary structure 4. Tertiary structure

Question 31

**Secondary structure** 1. Most common secondary structure. Spiral structure. 2. A zigzag or pleated pattern.

Answer 31

1. Alpha helix 2. Beta-pleated sheet

Question 32

Four major types of plasma proteins

Answer 32

- albumin - globulin - fibrinogen - others..

Question 33

- it migrates before albumin in electrophoresis - transport protein for t3 and t4

Answer 33

Pre-Albumin

Question 34

- Synthesized in the liver - responsible for most of the colloid osmotic pressure - present in highest concentration in the plasma

Answer 34

Albumin

Question 35

A protein for: - cell adhesion - tissue differentiation - growth - wound healing

Answer 35

Fibronectin

Question 36

- Insoluble fibrous protein aggregates that are formed due to the alteration in their secondary structure (beta pleated sheets) - an abnormal protein found in different diseases

Answer 36

Amyloid