Biology exam 1 me

Element

A pure substance made of only one kind of atom

The number of protons(atomic number)

Identifies an element

Number of protons and electrons

determines how an element behaves in chemical reactions

Mass number

neutrons+protons

Isotopes

forms of an element with different numbers of neutrons(different mass numbers)

The ratio of isotopes varies with location

Valence shell

outer most shell

Atoms in the same column

have the same number of electrons in their valence shell and similar chemical properties

Orbitals

where electrons spend most of their time

Atoms with unfilled orbitals are

reactive

When the orbitals of the valence shell is filled the atom is

stable

Ionic

grabs

Covalent

shares

The valences shell determines how the atom

behaves

Octet rule

tendency of atoms to form stable molecules resulting in full valence shells (First rule an atom tries)

Chemical bond

attractive force that links atoms together to form molecules

Atoms bonded together are a

molecule

Compound

a molecule made up of 2 or more elements bonded together in a fixed ratio

Molecular weight of a compound

sum of atomic weight of ALL atoms in the molecule

Covalent bonds can be

Single=sharing 1 pair of electrons

Double= sharing 2 pairs of electrons

Triple=sharing 3 pairs of electrons

Sharing of electrons in covalent bonds is not always

equal

Electronegativity

attractive force that an atomic nucleus exerts on electrons

electronegativity depends on

1. On number of protons

2. Distance between the nucleus and electrons

Polar covalent bond:

one atom has greater electronegativity, so electrons are drawn more to that nucleus (not equal sharing)

Non-polar covalent bond:

Electrons are shared equally (atoms have similar electronegativity)

Ionic attraction

when one atom is much more electronegative than the other a complete transfer of electrons may occur

Hydrogen bond

Attraction between the delta negative end of one molecule and the other delta positive hydrogen end of another molecule WEAK

Polar molecules that form hydrogen bonds with water are

hydrophilic

non-polar molecules are

hydrophobic

Van der Waals bonds are

attraction between non-polar molecules that are close together

Combustion of propane is an

oxidation-reduction(redox) reaction

In an redoc reaction you have an

electron acceptor

electron donor

electron acceptor

(oxidizing agent) gains electrons and becomes reduced

electron donor

loses electrons becomes oxidazided

Energy

capacity to do work

Ice floats

Each molecule is hydrogen-bonded to 4 other molecules in a rigid crystalline structure

Solid water(ice)

LESS DENSE than liquid water.

In ice, water molecules are held in a rigid state by

hydrogen bonds

In gas, water does NOT form

hydrogen bonds

In liquid water, the hydrogen bonds

break and make as water molecules move

water has

high heat capacity

cohesion

hydrogen bonds between water molecules cause them to stick together (water to water)

adhesion

attraction of water molecules to other molecules (water to other)

A solution is a substance (solute) dissolved in a liquid (solution)

Mole

amount of a substance (in grams) that is numerically equal to its molecular weight

Molecules that make up organisms

proteins

lipids

carbohydrates

Nucleic acids

All except_____ are polymers of smaller molecules called monomers

lipids

Largest amount of molecule that make up organisms

Proteins(polypeptides)

Proteins consist of one or more

polypeptide chains

Polypeptide chain

single, unbranched chains of amino acids

Protein functions

• Amino-acids have carboxyl and amino groups (they function as both acid and base)

• The side chains or R-groups also have functional groups

• Amino-acids can be grouped based on the side chain

The primary structure of a protein is the sequence of

amino acids

the secondary structure

right handed coil resulting from hydrogen bonding between N-H groups and C=O groups (2 ways they fold)

the tertiary structure

folding results in the specific 3-D shape. Determined by interactions between R-groups (disulfide bonds, hydrogen bonds)

the quaternary structure

results from interactions of subunits of by hydrophobic interactions, Van der Waals forces, ionic attractions and hydrogen bonds (2 aminoacids chains)

Denatured protein

When a protein in heated 2ndary and 3teriary structure break down

When the protein cools back down it goes back to

primary structure

Conditions that affect 3tertiary and 2ndary structures

1. High Temp

2. pH levels

3. High concentrations of polar molecules

4. Non-polar substances

Proteins bond

Non-covalentes to specific molecules

Specificity of proteins is determined by

• Shape=fit

• Chemistry=surface R-groups interact with other molecule

Protein shape can change as a result of:

• Interactions with other molecules=ex. enzyme changes with reactant

• Covalent modification= addition of a chemical group to an amino-acid

Proteins can bond to the wrong molecules after

denaturation

Chaperones

proteins that help prevent wrongful bonds to incorrect molecules(capsule like)

Carbohydrates(C1H2O1)

• Sources of stored energy

• used to transport stored energy

• carbon skeletons for many other molecules

• form extracellular structures such as cell walls

monosacharides

one simple sugar

disacharides

2 simple sugars linked by covalent bonds

oligosacharides

3 to 20 monosacharides

polysacharides

100+ of monosacharides

all cells use ____ as energy

glucose

glucose is always

• straight chain or ring form(more stable)

• ring form is alpha negative or b-glucose which can interconvert

monosacharides can be

• pentoses= 5 carbons

• hexoses= 6 carbons

pentoses

• ribose

• deoxyribose

hexoses

• mannose

• glucose

• fructose(different)

Monosacharides bind together in a condensation reaction (two monomers bonding) and form

glycosidic linkages

Polysacharides are large polymers and some are branched like

• starch=storage of glucose in plants

• glycogen=storage of glucose in animals

• cellulose= stable; good for structural components

Carbohydrates can be modified by the addition of functional groups to form

• sugar phosphates(p0000)

• amino sugars

• chitin

Types of Lipids(non-polar)

• Fats and oils store energy

• Phospholipids-structural role in cell membranes

• Cartemats and chlorophylls-capture light energy in plants

• Steroids and modified fatty acids-hormones and vitamins

• Animal fat- thermal insulation

• Lipid coating around nerves provides electrical insulation

• Oil and wax on skin, fur and feathers repels water

Fats and oils are

tryglycerides-3 fatty acids and glycerol

peptide bond

2 amino acids

glycosidic bond

2 sugars

ester bond

bond that connects fatty acids to glycerol

straight fatty acid

saturated with hydrogen(mm no)

bent fatty acid

unsaturated(good)

Phospholipids

fatty acids bond to glycerol; a phosphate group replaces 1 fatty acid

The head is

hydrophillic

The tail is

hydrophobic

Caratenoids

light-absorbing pigments

Nucleic acids are specialized for

• storage

• transmission

• use of genetic info

DNA

deoxyribonucleidacid

RNA

ribonucleicacid

differences between RNA and DNA

1. the sugar (ribose and deoxyribose)

2. DNA has thymine and RNA has uracil

3. DNA is double stranded

DNA Bases

1. Adenine

2. Guanine

3. Cytosine

4. Thymine

Purines

1. Adenine

2. Guanine

Pyrimidines

1. Cytosine

2. Thymine

Phosphodiester bond

2 nucleotides

Nitrogen bases pair because

1. Hydrogen bonds

2. Size of the nitrogen bases

genome

the complete set of DNA is an organism

What are the theories on how life started?

1. Chemical evolution(Miller and Urey)

2. Life came from outside of Earth

Catalyst proteins

enzymes

Proteins are synthesized from information in

nucleic acids