Exam 1 Beate BOLD TERMS

Nature of science

NOT mysterious, just a methodical, objective, rational way to discover and understand our world

cell

is a highly organized

compartment

The cell theory states that

All organisms are made of cells. All cells come from preexisting cells

A species

is a distinct, identifiable type of organism

The Central Dogma

DNA codes for ribonucleic acid (RNA), which

codes for proteins

The atomic number

The characteristic number of protons

in the nucleus of any atom

Atoms with the same atomic

number

Have the same chemical properties. Belong to the same element

The mass number is

The number of protons + neutrons in an atom

Each proton and each neutron has a mass of one

Dalton

Isotopes are

forms of an element with different numbers of

neutrons

The atomic weight of an element

Average of all the masses of the naturally occurring

isotopes based on their abundance

Most isotopes are stable, but some are unstable blank that decay over time

radioactive isotopes

Each orbital can hold up to

two electrons

Orbitals are grouped into levels of similar energies called

electron shells

Outermost shell

valence shell

The number of unpaired electrons in an atom's valence shel

valence

Octet rule

valence shell stable at 8 e-

Molecules

substances held together by covalent bonds

Compounds

molecules in which atoms of different elements are held together

electronegativities

the strength with which they pull electrons toward themselves

Nonpolar covalent bond

Electrons are evenly shared between two atoms. The bond is symmetrical

Polar covalent bond

Electrons are shared unevenly

ion

an atom or molecule that carries a charge

Cation

an atom that loses an electron and becomes

positively charged

Anion

atom that gains an electron and becomes

negatively charged

The degree to which electrons are shared in chemical

bonds forms a

continuum

Molecular formulas

Indicate the numbers and types of atoms in a molecule

Structural formulas

Which atoms are bonded together

Water is

Polar

These weak electrical attractions are called

hydrogen bonds

cohesion, adhesion

Hydrophobic

uncharged and nonpolar compounds

Covalent Bonds

Nonpolar: uncharged, hydrophobic. Polar: partial charges, hydrophilic

Ionic Bond

Atoms have full charges, hydrophilic

Acids

substances that give up protons during

chemical reactions

Bases

substances that acquire protons during

chemical reactions

acid-base reactions

A proton donor (acid) transfers a proton to a proton acceptor (base)

Buffers

compounds that minimize changes in

pH

The characteristics of an

organic molecule

can be

changed dramatically by

replacing one of the hydrogen

with one or more functional

groups.

Amino

Polar, weakly basic

Carboxyl

Polar, weakly acidic

Carbonyl

Polar

Hydroxyl

Polar, weakly acidic

Phosphate

Polar, weakly acidic

Sulfhydryl

Polar; does not participate in H-bonds; tends to bond with other sulfhydryl

Methyl

Non-polar

Essential amino acids

Nine of 20 are essential, and can't be produced by our bodies

Nonessential amino acids

Can be made by our bodies

Central carbon that bonds to

H, NH2, COOH, distinctive R-group

The 20 amino acids differ only in

unique R-group, or side chain, attached to the central carbon

Charged and polar side chains are

hydrophilic

Nonpolar side chains are

hydrophobic

Proteins

macromolecules

Subunits

monomers

Monomers link together (polymerize) to form

polymers

Monomers polymerize through

condensation (dehydration) reaction

Hydrolysis

is the reverse reaction of condensation

Condensation reactions bond the carboxyl

group of one amino acid to the amino group

of another

covalent peptide bond

Secondary Structure

Formed by hydrogen bonds between the carbonyl group of one a.a. and the amino group of another

a

helices

B

pleated sheets

Tertiary Structure

Results from interactions between R-groups or between R-groups and the peptide backbone

Quaternary Structure

The bonding of two or more distinct polypeptide subunits

denatured

unfolded protein that is unable to function

Cells contain proteins

molecular chaperones

molecular chaperones

Facilitate protein folding

Prions

They are misfolded proteins that can be infectious

Enzymes

Speed up chemical reactions without itself undergoing any permanent chemical change

Catalysts

increase the rate of a chemical reaction

Enzymes

Hold substrates in precise orientation

active site

location on an enzyme where substrates bind and react

nucleic acid

A polymer made of nucleotide monomers

Three components of a nucleotide

Phosphate group, 5-carbon sugar, 3. nitrogenous base

3' or 5'=

"3 prime or 5 prime"

"3 prime or 5 prime"

indicates carbon number in sugar

There are two groups of nitrogenous bases

Pyrimidines, purines

Pyrimidines

Cytosine (C), Thymine (T), Uracil (U)

Purines

Adenine (A), guanine (G)

What Pyrimidine is only found in DNA

Thymine (T)

What pyrimidine is only found in RNA

Uracil (U)

Nucleic acids polymerize via

condensation reactions

Covalent bond between

nucleotides is called

phosphodiester bond

The nucleic acid's primary

structure

nucleotide sequence

Polymerization of nucleic

acids is

endergonic process and requires energy

Energy for polymerization

comes from

phosphorylation of nucleotides

Phosphorylation

Phosphate adds two electrons to a molecule and alters the electron configuration and shape of the molecule

Kinases

phosphorylate

Removal of phosphates is

done by an enzyme called

phosphatase

"activated" nucleotide

ATP

negative charges

repel each other and a higher potential energy

Reactivity of a molecule that is not stable

more reactive

Double helix

Two anti-parallel strands connected by base pairing

Purines always pair with pyrimidines

Strands form complementary base pairs (bp)

The Tertiary Structure of DNA

DNA forms more compact three-dimensional structures in cells

How many forms of DNA tertiary structure

2

Histones

DNA wraps around DNA-binding proteins

Supercoils

DNA is wound too tightly or loosely; twists

primary structure

consists of a sugar-phosphate backbone

RNA is much less BLANK than DNA

stable

RNA's Secondary Structure

The RNA strand folds over, forming a hairpin structure

The bases align with a BLANK RNA segment on the other side of the fold

Antiparallel