BISC1111 - Chapter 5 -Proteins and Lipids (Part 2)

Lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are NOT true polymers

What unifies all lipids?

They are all hydrophobic

What are the most important lipids?

Fats, phospholipids, and steroids

What are fats made out of?

Glycerol and fatty acids

Glycerol

A three-carbon alcohol with a hydroxyl attached to each carbon

Fatty acid

hydrocarbon chain with a carboxyl group attached to it

Tryglycerides

glycerol and 3 fatty acids bonded via an ester linkage

Ester linkage

The linkage formed between the glycerol molecule and the fatty acids in a fat

How do fatty acids vary?

In the number of carbons and the number and locations of double bonds

Saturated fatty acids

have the maximum number of hydrogen atoms possible and no double bonds

Unsaturated fatty acids

have one or more double bonds

Saturated fats

fats that are solid at room temperature; usually composed from animal fats

Unsaturated fats

A fat that is liquid at room temperature and found in vegetable oils, nuts, fish, and seeds.

Hydrogeneration

The process of converting unsaturated fats to saturated fats by adding hydrogen

What is the purpose of fats?

To store long-term energy

Adipose tissue

Tissues that insulate the body and cushion vital organs

Phospholipids

Two fatty acids and a phosphate group that are attached to a glycerol

amphipathetic molecules

Molecules (like phospholipids) that have both a polar end and a nonpolar end.

Hydrophilic "head"

The component of a phospholipid consisting of glycerol and phosphate. Attracted to water.

Hydrocarbon "tail"

The component of a phospholipid that is nonpolar and hydrophobic

Phospholipids assemble into ___ when they are added into water

bilayers

Hydrocarbon tails point towards the ___ of a cell when exposed to water

interior

What is the phospholipid bilayer's purpose?

To create a boundary between the cell and its environment

Steroids

lipids characterized by a carbon skeleton consisting of four fused rings

Cholesterol

Steroid that is a component in animal cell membranes and a precursor that allows other steroids to form

High cholesterol can lead to....

Cardiovascular disease

Proteins account for __ of dry mass in most cells

50%

Catalysis Function of proteins

the acceleration of a chemical reaction by a catalyst

Movement function of proteins

Motor proteins moving cells and molecules within them

Transport function of proteins

Allows molecules to enter and exit cells and move them through the body

Defense function of proteins

Antibodies attacking foreign and potentially harmful pathogens

Polypeptides

Unbranched polymers built from the same set of 20 amino acids that all proteins are made of

Peptide

Bonds that connect amino acids.

Protein

Functional molecule that consists of one or more polypeptides

Every protein has a...

Carboxyl end (C-terminus) and a amino end (N-terminus

amino

NH2; usually relates to nitrogen-based substances

What are amino acids made of?

A central carbon (C) connected to a carboxyl group (COOH), an amino group (NH2), a hydrogen atom (H) and a varying R-group

Nonpolar (hydrophobic) amino acids

Consist mostly of hydrogen and carbons. Hydrocarbons, if you will

Polar (hydrophilic) amino acids

Consists mostly of oxygen

Acidic amino acids

Have negative charges

What determines a protein's actions?

Their 3D structure

primary structure of protein

sequence of amino acids

Secondary structure of protein

Hydrogen bonds between alpha helix and beta pleated sheet

tertiary structure of protein

Overall shape of a protein that is indicated by the interactions between R-groups

Quaternary structure of protein

Two or more polypeptide chains forming a macromolecule

Collagen

Fibrous protein that consists of three polypeptides coiled like a rope. Found in animal skin and bones

Hemoglobin

Oxygen carrying pigment in red blood cells that is made up of four polypeptides; two alpha and two beta

subunits

Sickle cell disease

Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape.

What can can cause a protein to unravel?

pH alterations, salt concentration, and temperature

What diseases are associated with misfolded proteins?

Alzheimer's, Parkinson's, and Mad Cow

Why is predicting a protein's final structure based on its primary structure difficult?

Because many proteins go through many different stages as they try to achieve a stable struggle