AP BIO Unit 1: College Board Videos

Covalent Bond

The bond type in which atoms share electrons

Polarity

-When there are differences in atomic electronegativities

-Since oxygen is more electronegative compared to hydrogen, there is an unequal sharing of electrons between oxygen and hydrogen

Hydrogen bond

A weak bond interaction between the negative and positive regions of two separate molecules.

Cohesion

When two of the same molecules for hydrogen bonds with each other.

Adhesion

When two different molecules form hydrogen bonds with each other

Surface tension

Results from increased hydrogen bonding forces between water molecules at the surface

-Example: water droplet on a penny

Properties of water

-Adhesive property gives water a high solvency ability in it’s liquid state

-Cohesive property causes water to be less dense as a solid(ice) compared to as a liquid (explains why ice is able to float).

-High heat capacity

Caplillary action

The movement of water within the spaces of a porous material as a result of both the adhesive and cohesive properties of water

The law of the conservation of energy

Energy cannot be created or destroyed only transformed

What molecules require carbon?

-Carbohydrates

-Proteins

-Nucleic acids

-Lipids

What molecules require nitrogen?

-Proteins

-Nucleic acids

What molecules require phosphorus?

Nucleic acids and certain lipids

Monomers

Chemical subunits used to create polymers

Polymer

A Macromolecule made of many monomers

Dehydration Synthesis reaction

-The subcomponents of a water molecule (H and OH) are removed from interacting monomers and a covalent bond forms between them.

-Used to create macromolecules

-The H and OH join together to for a molecule of water, water is a byproduct of this reaction

Hydrolysis reaction

-Polymers are hydrolyzed (broken down) into monomers

-Covalent bonds between the monomers are cleaved (broken)

-A water molecule s hydrolyzed into subcomponents (H and OH) and each subcomponent is added to a different monomer.

Nucleic acids

Polymers comprised of monomers called nucleotides

Nucleotides basic structure

-5-carbon sugar

-Phosphate group

-Nitrogen base

Amino Acids

• Monomers that make up proteins

• Directionality with an amino (NH2) terminus and a carboxyl (COOH) terminus

Polypeptide

-The primary structure of a protein

-Consists of a specific order of amino acids and determines the overall shape the protein can achieve

R group

-The atoms attached to the central carbon

-Can be hydrophobic, hydrophilic, or ionic

Lipids

Nonpolar macromolecules that do not have true monomers but are comprised of subunits such as fatty acids and glycerol

Phospholipid

-Contain hydrophilic(polar head)and hydrophobic(non polar tail) regions that determine their interactions with other molecules

Directionality of nucleic acids

3’ hydroxyl and 5’ phosphate of the sugar in the nucleotide

Direction of DNA strands

Antiparalleel 5’-3’ direction

Where can nucleotides be added during the synthesis of nucleic acid polymers

The 3’ end

Primary Structure of a Protein

Determined by the sequence of amino acids held together by covalent bonds, called peptide bonds

Secondary Structure of a Protein

Arises through local folding of the amino acid chain into elements such as alpha-helices and beta-sheets.

Tertiary Structure of a Protein

-The overall 3D shape of the protein and often minimizes free energy; -Various types of bonds and interactions stabilize the protein at this level.

Quaternary structure of a Protein

Arises from the interactions between multiple polypeptide units.