Week 2-3 Lectures

What are ~96% of the elements in the human body composed of?

Oxygen, carbon, nitrogen, hydrogen

What are the other ~4% of elements in the human body?

Calcium, phosphorus, potassium, sulfur

What are the trace elements of the human body?

Iron, iodide

What makes up atoms?

Neutrons, electrons, protons

What is the atomic number?

# of protons/electrons in the atom

What is the atomic mass number?

# of protons + # of neutrons

How can you find the # of neutrons in an atom?

Mass # - Atomic #

What is an isotope?

An element that has more neutrons than normal

• Carbon 13, Carbon 14

Why does the shape and size of molecules matter?

Size and shape determine how molecules interact with one another.

• Ex: Morphine has a similar structure to naturally occurring endorphins. This similarity allows it to bind to the same type of receptor and have successful interactions.

What is a covalent bond?

The sharing of a pair of valence electrons by two atoms

What is a nonpolar covalent bond?

A covalent bond between atoms with equal or very similar electronegativities, resulting in equal electron sharing and no significant dipole moment.

What is a polar covalent bond?

A covalent bond between atoms where one atom is more electronegative than the other, resulting in unequal electron sharing and a dipole moment

Ex: Water

What is an ionic bond?

Where atoms with opposite charges are attracted to one another

What is an ion with a positive charge? A negative charge?

Cation, Anion

Pharmaceutical comapnies construst drugs with ionic bonds. Why?

Ionic interactions are strong in dry/solid environments but become much weaker in water

• This allows ionic compounds to form stable solid formulations such as tablets and capsules

• When exposed to water in the digestive tract, the ionic interactions are disrupted, allowing the compound to dissolve and become available for absorption

What is an hydrogen bond?

A reversible, weakish bond within a molecule that invovles highly electronegative atoms, primarily:

• N—H

• O—H

What are van der waals attractions?

Weak attractions that occur when atoms and molecules are very close together

What is steric hindrance?

The slowing or prevention of a chemical reaction caused by the physical crowding of bulky groups of atoms around a reactive site

What is a chemical reaction?

Where atoms are rearranged to form new substances

• Can be the breaking or forming of chemical bonds

What is Cohesion?

Where two particles of the same substance are attracted to one another

• Water droplets clinging together

What is Adhesion?

Particles of one substance being attracted to particles of a different substance

• Water droplets clinging to a tupperware lid

How does water move up a tree?

Occurs within the xylem:

• Via adhesion of the water molecules to the cell wall

• Via cohesion of water molecules together

  • Overall, allows a transport-driven tension that helps move the water upward

What atom is the centerpiece of all organic compounds? Why?

Carbon — it is very stable and very versatile

How many electrons does carbon have? Where are they located?

6 e^-

• 2 within the inner shell

• 4 within outer shell

Due to carbon only have 6 e^-, how many bonds can it form?

4 total

• It is capable of completing its outer shell by sharing its 4 electrons with other atoms via single or double bonds

  • Wants an outer shell of 8 electrons!

What are isomers?

Molecules that have the same composition but vary in architecture

What is a structural isomer?

Molecules that share the exact same molecular formula but differ in how those atoms are connected to one another

What is a geometric isomer?

Molecules that have the same chemical formula and atom connections, but a different spatial arrangement in three-dimensional space

• Also called cis-trans isomers

What are enantiomers?

Molecules that have the same chemical formula and atom connections, but are non-superimposable mirror images of each other

• Much like our right and left hands!

What type of isomer is this?

Enantiomers

Why is it important than we understand the existence of isomers?

Particularly relevant to cis-trans isomers, two molecules can have the same molecular formula and even connectivity, but their difference in 3D arrangements will can cause them to interact differently with other molecules and therefore produce vastly different biological effects

• Ex: D-methamphetamine acts on the CNS and triggers a massive dopamine release while L-methamphetamine has no effect on the CNS

  • The D-isomer is highly addictive while the L-isomer helps clear congestion

What makes up macromolecules?

Polymers, which are made from monomers

What is the name of the process for synthesizing a polymer?

Dehydration

What is the name of the process for breaking down a polymer?

Hydrolysis

What are monomers?

Small molecules that serve as building blocks

What are polymers?

Long chains of monomers

What are carbohydrates?

Sugars and the polymers of sugars

How are carbohydrates formed?

Via dehydration

What are monosaccharides?

The simplest forms of sugar and the basic building blocks of all carbohydrates

Monosaccharides have formulas that are multiples of what?

CH₂O

• Ex: 6 x (CH₂O) = C₆H₁₂O₆

  • Glucose!

What are disaccharides?

Formed via 2 covalently bonded monosaccharides

• Glucose + Fructose = Sucrose

• Glucose + Galactose = Lactose

What are polyaccharides?

Large, complex carbohydrates made of long chains of simple sugar molecules

What two types of polyaccharides exist?

• Storage

  • Glycogen — animals

  • Starch — plants

• Structural

  • Cellulose — found in plant cell walls; the most abundant organic polymer on Earth

What are Lipids?

Hydrophobic compounds composed mostly of hydrocarbons

• Very hydrophobic

  • Insoluble in H2O

What are some examples of Lipids?

Fats, phospholiids, steroids, and waxes

What are Fats composed of?

Glycerol and 3 fatty acids

What two types of fats are there?

Unsaturated and Saturated Fats

Unsaturated Fats

• Found primarily in animal fats

• Solid at room temperature

• Fully hydrogenated

  • No double bonds

Saturated Fats

• Found primarily in fish and plant fats

• Liquid at room temperature

• Not fully hydrogenated

  • Contains double bonds

    • Has a “kink” in the structure

What are phospholipids a major part of?

The plasma membrane of cells and organelles

What is the composition of phospholipids?

• Phosphate head

• Glycerol body

• Fatty acid tails

What are steroids composed of? How are they differentiated? What is this important for?

Composed of 4 fused rings with different functional groups

• Important in terms of membrane fluidity

(t/f) — All proteins are polypeptides and all polypeptides are proteins

False. All proteins are polypeptides, but not all polypeptides are proteins

• Proteins are folded, polypeptides are not

What key factor allows for the wide range of protein functions?

The way it folds/creates its shape

Enzymatic protein function

Selective acceleration of chemical reactions

Defensive protein function

Protection against disease

Storage protein function

Storage of amino acids

Transport protein function

Transport substances

Hormonal protein function

Coordination of an organism’s activities

Receptor protein function

Response of a cell to chemical stimuli

Contractile and motor protein function

Movement

Structural protein function

Support

What is the primary structure of proteins?

Their chain of amino acid monomers

In the primary structure of proteins, what type of bond binds the monomers together?

Peptide bonds

• Type of covalent bond