Lecture 4

Question 1

Proteins

Answer 1

Function: support, storage, transport, signaling, receptors, movement, catalysis, defense
Structure: Amino Acids (monomers that combine to form polymers) to Polypeptides (polymers of AAs in specific sequence) to Protein (one or more polypeptides with specific 3D conformation)
Most proteins are enzymes

Question 2

Amino Acid

Answer 2

Building blocks of proteins
Made up of an Amino group, hydrogen, carboxyl group, and R group
20 of them

Question 3

R Group

Answer 3

A way to abbreviate parts of a molecule or to describe groups of similar molecules
Variable side chain
- Nonpolar; hydrophobic (9/20)
- Polar; Hydrophilic (6/20)
- Ionized (charged at cellular pH) acids and bases; Hydrophilic (5/20)

Question 4

Polypeptides

Answer 4

AA are joined by dehydration reactions (covalent peptide bonds)
Consists of an Amino end (N terminus), Carboxy end (C terminus)
Few to thousands of monomers (aa)

Question 5

Primary Structure

Answer 5

Determined by AA sequence
Consists of an amino acid chain held together by peptide bonds

Question 6

Secondary Structure

Answer 6

Hydrogen bonding by atoms in the polypeptide backbone
Consists of either an Alpha helix (coils) or Beta pleated sheets (folds)

Question 7

Tertiary Structure
(overall shape of polypeptide)

Answer 7

Consists of a full folded protein subunit held together by R groups
Coils and Folds

Question 8

R group interactions

Answer 8

Weak: Hydrogen bonds, Ionic bonds, Hydrophobic, and van der Waals interactions
Strong: Disulfide bridges (covalent)

Question 9

Quaternary Structure

Answer 9

Overall protein structure resulting from 2 or more combined polypeptides
Stabilized by R group interactions

Question 10

Effect of Changes in Primary Structure

Answer 10

Single change in primary structure can have pleiotropic consequences

Question 11

Sickle Cell Anemia Causes

Answer 11

Caused by a single base change in DNA, a single base change in mRNA, or a single AA change in protein (primary structure)

Question 12

Protein Conformation

Answer 12

Influenced by pH, a high salt conc, or temperature
Facilitated by Chaperone proteins by providing an appropriate environment in the cell

Question 13

Proteosomes

Answer 13

Degrades denatured, misfolded, or damaged proteins into short peptides for recycling
Proteins are tagged with ubiquitin (kiss of death) and delivered to proteosomes to be degraded

Question 14

Nucleic Acids

Answer 14

Function: to store and transmit hereditary info
Structure: polymers of nucleotide monomers and nucleotide monomers (pentose sugar, nitrogen base, and phosphate group)
Two types: Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
Form via dehydration rxn

Question 15

DNA vs. RNA

Answer 15

DNA:
- Double stranded
- deoxyribose sugar
- Nitrogen bases are C,G,A,T

RNA:
- Single stranded
- ribose sugar
- Nitrogen bases are C,G,A,U

Both have a Phosphate group

Question 16

Purines and Pyrimidines

Answer 16

Purines consist of either guanine (G) or adenine (A) which contains 2 carbon rings
Pyrimidines consist of either cytosine (C), thymine (T), or uracil (U) which contains 1 carbon ring
Uracil only in DNA while Thymine is only in RNA