BIO EXAM 2: First lecture!

What are the levels of protein structure?

Primary, secondary, tertiary, and quaternary

Primary

Sequence of amino acids(polypeptides)

Ex: protein containing 100 amino acids (20^100 or 10^130)

Secondary

Interaction of groups in peptide backbone

What are the two types of secondary structures?

a-helix(coiled spiral) and B-pleated sheet

Tertiary

Final folded shape of globular protein(Final level of structure for proteins + consists of single polypeptide chain)

Quaternary

arrangement of individual chains(2 or more polypeptide chains)

Transient dipole

(weak bond) temporary, uneven distribution of electric charge within a molecule- electron shift

What do the side chains(r-groups do)

They do not form hydrogen bonds, but they affect whether a helix or sheet is favorable by steric hindrance or chemical properties

Interactions depend only on?

Peptide backbone (C=O and N-H)

Hydrogen bond visual

Disulfide bridge

Ionic bond

van der Waals attraction

Hydrophobic exclusion

Perm chemistry-disulfide bridge

Perm: 1. reducing agent applied

Perm solution (ammonium thioglycolate) → Breaks disulfide
bridges (–S–S–) into free sulfhydryl (–SH) groups → Hair becomes soft and flexible, can be reshaped (curled around
rollers)

Perm: 2. Re-shaping

Hair is physically curled or straightened while bonds are broken →Keratin chains slide into new positions→New hair shape is
set mechanically

Perm: 3.Oxidizing agent applied

Neutralizer” (usually hydrogen peroxide, H₂O₂)→Re-oxidizes –SH
groups → reforms new disulfide bridges (–S–S–) between cysteines
in their new positions→ Hair retains the new curly or straight shape

How is perm chemistry related to cystic fibrosis?

Through the breaking of disulfide bonds in protein structure

Motifs

Short, recurring patterns of secondary structure (like α-helices
and β-sheets) that appear in many proteins→ provide clues about the overall fold or potential function of a protein

Domains

Larger, independently folding structural and functional units
within a protein→Most proteins contain multiple domains, and each domain usually carries out a specific part of the protein’s overall function

What motif is this?

Rossmann fold (important for binding nucleotides
like NAD⁺)

What motif is this?

Common in DNA-binding proteins

Which is larger? Motif or domain?

Domain! Domains are independently stable and functional, while
motifs are not→composed of multiple interacting motifs

Lipids

Loosely defined group of molecules that are insoluble in water

Are lipids polar or non polar?

High proportion of *nonpolar C-H bonds causes the
molecule to be hydrophobic

Which part of this is hydrophilic

HO

Triglycerides

composed of one glycerol and three fatty acids

Is this the structured formula for saturated or unsaturated fat?

Saturated→Hydrophobic/linear

Is this the structured formula for saturated or unsaturated fat?

Unsaturated→ double bond-kink

Van der Waals interaction make molecules more?

rigid

Is this a saturated or unsaturated filling model?

saturated!

Is this a saturated or unsaturated filling model?

unsaturated

What are the Lipid molecules that orient with polar(hydrophilic) head toward water and non polar(hydrophobic) tails away from water

Micelles(spheres)

what are the molecules that more complicated structure where two
layers form

• Hydrophilic heads point outward.
• Hydrophobic tails point inward toward each other.

Phospholipid bilayer

Enlgish natural philosopher. Cells were first observed
using a microscope in 1665

Robert Hooke

Cellulae

small rooms

Dutch Microscopist. First observed living cells, bacteria and
protozoa in 1674

Anton van Leeuwenhoek

Animalcules

little animals

Leeuwenhoek researches proved

provided empirical proof that tiny life form had their own reproductive cycles refuting the doctrine of spontaneous generation. Ex) maggots from rotting meat.