Unit 1 Study Guide

Covalent Bonds

a chemical bond where atoms share one or more pairs of electrons

• formed in dehydration synthesis

Ionic Bonds

Electrostatic attraction between atoms where one atom transfers an electron to another atom.

• in proteins (enzymes, tertiary and quaternary structures) and nucleic acids (DNA, RNA)

Hydrogen Bonds

A weak chemical bond formed when a slightly positive hydrogen atom of a polar covalent bond is attracted to a slightly negative atom of a polar covalent bond

• opposites attract

Isotopes

A version of a chemical element that has the same number of protons but a different number of neutrons in its nucleus; number of neutrons can differ between atoms of an element

• ex. C14 = 6P + 8N

How many bonds can the main 4 elements form?

C - 4 bonds

H - 1 bond

O - 2 bonds

N - 3 bonds

H2O is cohesive

water molecules are attracted to each other due to hydrogen bonding, causing them to stick together and create surface tension

H2O is adhesive

The polar nature of water molecules and the resulting hydrogen bonds they form with other polar or charged molecules causes water to stick to other surfaces or substances.

• however, cannot stick to nonpolar or waxy surfaces/substances

H2O is used for photosynthesis

• vascular tissue (xylem) acts as a pipeline for water and mineral transport from the roots to the rest of the plant

• In narrow tubes like the xylem, the adhesive forces between water and the tube walls, combined with the cohesive forces between water molecules, can cause water to move upward against gravity towards the leaves (capillary action)

H2O expands when it cools

When frozen, water molecules become spaced further apart in a rigid crystalline structure, forming ice and insulating the water below it, floating on top of the water surface as ice is less dense.

Carbs Elements

C, H, O

Carb monomers (monosaccharides)

Glucose - fuels cells in the body

Fructose - bonds with glucose to make sucrose; found in fruits, veggies, and honey

Galactose - bonds with glucose to make lactose; found in dairy products

Protein Elements

C, H O, N and sometimes S

Protein Polymers and Monomers

Monomers - amino acid

Polymers - enzymes, hormones, and antibodies

Lipid Elements

C, H, O, and sometimes P

Lipid monomers

Glycerol and fatty acids

Phospholipids

A type of fat that make up the phospholipid bilayer, a primary component of the cell membrane.

• hydrophilic head and hydrophobic tail create a semi-permeable layer that regulates what moves in and out of the cell.

Steroids

Hormones that act as chemical messengers used for communication to coordinate activites in the organism

Cortisol/Cortisone

a steroid hormone produced by the adrenal glands that regulates the body’s stress response, metabolism, and immune function

• hydrolyzes glycogen into glucose

Sex Hormones

steroid hormones, primarily produced by the gonads that regulate sexul development, function, and reproduction in vertebrates

• estrogen, testosterone, progesterone

Nucleic Acid Elements

C, H, O, N, P

NA monomers

Nucleotides with three parts; a phosphate group, a five-carbon sugar molecule, and a nitrogen base

• deoxyribose in DNA, ribose in RNA

• five nucleotides

Dehydration Synthesis

A chemical process where H2O is removed in order to join two molecules together into a polymer

• water is a product

Hydrolysis

A chemical process where H2O is added in order to break down a polymer into two molecules

• water is a reactant

• aka, digestion

What should you look for when determining the atomic number of a monosaccharide?

If oxygen is half of hydrogen, as it will always be half in a monosaccharide

Polysaccharide Types

Starch - carbs stored in plants for energy storage

Glycogen - carbs stored in animals and fungi for energy storage

Cellulose - main component of the plant cell wall, giving it structure

Chitin - exoskeleton of insects and cell walls of fungi, providing structure, protection, and support

Saturated Fats

a type of fatty acids chains that are composed only of single bonds between carbon atoms

• solid fats

Unsaturated fats

fatty acids with one or more double bonds between carbon atoms

• liquid fats

Level of Protein Structure

1. Primary - linear sequence of amino acids in a polypeptide chain that are joined by covalent bonds through dehydration synthesis

2. Secondary - folded structures that form within a polypeptide due to hydrogen bonds within the atoms of a back bone, commonly forming an alpha helix or beta pleated sheet

3. Tertiary - the complete, three dimensional shape of a single peptide chain, arising from folding and bending of secondary structures. If this level were denatured, it would lead to a loss of function

4. Quaternary - Some proteins will reach a fourth level, in which the arrangement and interaction of two or more individual polypeptide chains form a larger, more complex proteins.

Purines

adenine and guanine; double rings

Pyrimidines

cytosine, thymine (DNA), and uracil (RNA); single ring

What will adenine bond to?

thymine in DNA, uracil in RNA

What will cytosine bond to?

guanine