Biochemistry Exam Review - Proteins, Carbohydrates, and Membranes

These flashcards cover critical biochemical concepts related to protein structures, modifications, and the functions of carbohydrates and lipids, crucial for exam preparation.

Secondary Structure

Local backbone patterns in proteins, including α-helix, β-sheet, and random coil, stabilized by hydrogen bonds.

Tertiary Structure

Overall 3D fold of one polypeptide, stabilized by hydrophobic effects, ionic bridges, and disulfide bonds.

Quaternary Structure

Assembly of multiple subunits in proteins, either homo or hetero, stabilized by non-covalent forces.

Motif

A small, recurrent pattern of secondary structure that is not necessarily independently stable.

Domain

A large, independently folding and often functional unit of a protein that maintains stability when excised.

Isoelectric Point (pI)

The pH at which a protein carries no net charge, influencing its solubility and behavior in ion-exchange.

Hydropathy

A measure of a molecule's tendency to interact with water; hydrophobic amino acids are water-fearing.

Chaperone

A helper protein that prevents other proteins from misfolding during folding.

Disulfide Bonds

Covalent bonds formed between cysteine residues that stabilize protein structure in oxidizing environments.

Phosphorylation

A post-translational modification where a phosphate group is added to Ser/Thr/Tyr, affecting protein activity.

Glycosylation

The addition of carbohydrate moieties to proteins, crucial for protein folding and stability.

Lipidation

Post-translational modification involving the attachment of lipids to proteins for membrane targeting.

Glycosaminoglycan (GAG)

Repeating disaccharide units typically composed of uronic acid and hexosamine, often sulfated.

Fluid Mosaic Model

A model describing the structure of cell membranes as a fluid combination of lipids and proteins.

Simple Diffusion

The passive movement of small nonpolar molecules across a membrane down their concentration gradient.

Facilitated Diffusion

The process by which polar and charged molecules cross membranes via specific transport proteins.

Primary Active Transport

Transport that requires energy input (ATP) to move substances against their concentration gradient.

Secondary Active Transport

Transport that utilizes the energy from ion gradients established by primary active transport.

which of the following can undergo hydrolysis

triacylglyceride

degrees of unsaturation

• Degree of Unsaturation (DoU) = number of rings + π bonds.

• Each double bond = 1 DoU.

• Each triple bond = 2 DoU.

• Each ring = 1 DoU.

L

OH is on left side furthest away from the carboxylic acid

D

OH is on right side furthest away from the carboxylic acid

anomeric carbon

In sugars, the anomeric carbon is the carbon that was the carbonyl carbon (C=O) in the open-chain form. Carbon that is directly connected to 2 oxygens

saturated (no double bonds)

•Tight packing

•Higher inter molecular interactions

•Higher boiling point - solid at room temp

unsaturated (double bonds)

•Bending leads to less packing

•Weaker inter molecular interactions

•Lower boiling point - liquid at room temp

•Monounsaturated = 1 double bond

•Polyunsaturated = 2 or more double bonds

Different types of phospholipids

•Type 1: Glycerophospholipids

•Type 2: Sphingolipids

•Type 3: Cholesterol (Steroids)

•Type 1: Glycerophospholipids

•Tri-esters of G-3-P, and are essential components of cell membranes and important signaling molecules

•Type 2: Sphingolipids

•Functioning in signal transductions and cell recognition

•Type 3: Cholesterol (Steroids)

•Reinforce the phospholipid bilayer

Importance of cholesterol

•Membrane structure: Maintains membrane fluidity and stability across temperatures.

•Precursor molecule: Starting point for steroid hormones (estrogen, testosterone, cortisol).

•Bile acid synthesis: Essential for digestion and absorption of dietary fats.

•Vitamin D synthesis: Converted into vitamin D in the skin with UV light.