The smallest unit of matter that cannot be broken down by chemical means.
the smallest unit of an element that maintains the chemical properties of that element.
Its has a pos. charged core surrounded by a neg. charged region.
Protons : Pos. charge.
Electrons: neg. charge.
neutrons: no charge
- Atoms have no overall charge because they have the same amount of + & -
- Protons & neutrons have about the same mass & make up the nucleus
- Electrons have very little mass & move around the nucleus in a cloud. Cloud is much larger then the nucleus.
whats is 99.9 % of a substances's weight?
one atom of a substance
cannot be separated or broken down into simpler substances by chemical means.
A substance made up of atoms that have the same number of protons.
what are isotopes?
Atoms of an element may have different #'s of neutrons.
the electrons in the outermost level. & that determines the atom's chemical properties.
How to atoms tend to combine with each other?
So that 8 electrons will be in the valence shell.
the force that holds atomic bonds. They form between groups of atoms because most atoms become stable w/ 8 electrons in the valence shell.
what is a compound?
a substance made of the bonded atoms of 2 or more different elements joined by chemical bonds.
what is a covalent bond?
the sharing of valence electrons an example is water.
what is a molecule?
a group of atoms held together by covalent bonds.
what is ionic bonding?
when atoms achieve a stable valence level by losing or gaining electrons. resulting in a positive or negative charge. The attractive force between oppositely charged ions.
salt ( sodium chloride) is an ionic compound
what is an ion?
an atom or group of atoms that has an electric charge because it has gained or lost electrons. it can be an atom, radical, or molecule.
what is a polar?
Molecules w/ partial charges on opposite ends. example is water.
why can water dissolve polar molecules, sugar, & ionic compounds,salt,.?
partially charged ends of polar molecules attract opposite charges.
nonpolar substances do not dissolve well in water.
Hydrogen bonding plays an important role in many of the molecules that make up living things.
When bonded to an oxygen, nitrogen, or fluorine atoms, a hydrogen atom has a partial charge nearly as great as a proton's charge.
It attracts the neg. pole of other nearby molecules. The hydrogen bond is stronger than attractions between other molecules, but not as strong as a covalent bond.
What are most of the unique properties of water a result of?
Water molecules form hydrogen bonds w/ each other.
Properties of water
Ice floats- Floating ice prevents rivers,lakes, & oceans from freezing solid, so life can exist in the water under the ice.
Water Absorbs & retains heat- Water cab absorb a large amount of heat without changing tempt. Why water takes a long time to cool. Large bodies of water help keep tempts. on earth from changing to fast. Can help organisms maintain a constant internal tempt.
Water molecules stick to each other- because of cohesion.
Water molecules stick to other polar substances- adhesion.
what is cohesion?
the attraction of particles of the same substance.
what is adhesion?
attraction between particles of different substances.
Adhesion & cohesion combine?
causes water to move upward through the stem of a plant from the root to the leaves.
what is a solution?
a mixture in which ions or molecules of one or more substances are evenly distributed in another substance.
many substances are transported throughout living things as solutions of water. Dissolved substances move more easily.
what can water dissolve?
many ionic & polar substances but not nonpolar substances.
solute (whats being put in) + Solvent ( whats being mixed into) = solution
homogenous- can't be separated
heterogeneous- can be separated
What are acids?
compounds that form extra hydronium ions when dissolved in water.
what are bases?
compounds that form extra hydroxide ions when dissolved in water. Many bases contain hydroxide ions others react w/ water molecules.
what happens when acids & bases mix?
the extra hydronium & hydroxide ions react to form water. Depending on the amount of extra ions the solution will be either less acidic less basic or neutral.
what is pH?
a measure of how acidic or basic a solution is. Each one-point increase in pH represents a 10 fold decrease in hydronium ion concentration.
What is a buffer?
For a stable pH to be maintained the solutions in living things contain buffers. Its a substance that reacts to prevent pH changes in a solution. An important buffer in living things is the bicarbonate ion HCO3
what are biomolecules?
The parts of a cell are made up large complex molecules. Biomolecules are built from a few smaller, simpler, repeating units arranged in an extremely precise way.
What is the basic unit of most biomolecules?
what are carbohydrates?
molecules made of sugars.a sugar contains carbon, hydrogen, & oxygen. CH2O
monosaccaride-a single sugar. example glucose. simple carb
Polysaccharide- many sugars linked together. Starch. complex carb
Glycogen- consists of many branched chains of glucose. ( found in animals)
how do cells use carb?
for sources of energy- Carbs are a major source of energy for many organisms including humans.
structural materials- Chitin & cellulose are two complex carbs that provide support.
& cellular identification- Cells may have short branched chains of varying sugar units on heir outer surface. In a complex organism celles recognize neighboring cells by these carbs.
what are lipids?
are another class of biomolecules, which includes fats, phospholipids, steriods, & waxes.
lipids consist of chains of carbon atoms bonded to each other and to hydrogen atoms. this makes lipids repel water
The main functions of lipids include storing energy & controlling water movement.
lipids also include steroid hormones used as signaling molecules & some pigments which absorb light.
the main purpose of fat?
to store energy. Fats can store energy even more efficiently then carbs.
what is a cell's boundary made of?
phospholipids, one end is attracted by water molecules & one end the one made of carbon is not.
what are proteins?
the workhorse molecules of all living things.
there are many types of proteins.
Proteins are chains of amino acids that twist & fold into certain shapes that determine what the proteins do.
some provide structure & support, enable movement, aid i communication or transportation, others help carry out important chemical reactions.
what are amino acids?
building blocks that link to form proteins.
every amino acid has an amino group, a carboxyl group, and a variable side group. the carboxyl group of one unit can link to the amino group of another ~ peptide bond.
the side group gives an amino acid its unique properties.
twenty amino different amino acids are found in proteins.
to get amino acids the body breaks apart the proteins in the food eaten.
for each type of protein amino acids are arranged i a specific order, this is the proteins primary order.
the various side groups interact to bend & twist the chain portions of the chain may form coils & folds, the proteins's secondary structure.
some small proteins only consist of one chain but most have 2 or more chains.
the teriary structure of proteins is the overall shape of a single chain of amino acids.
the quaternary structure is the overall shape that results from combining the chains to form the protein. This shape suits the function of each protein.
what is a nucleic acid?
a long chain of nucleotide units.
what is a nucleotide?
a molecle made up of three parts a sugar, a base, and a phosphate group.
what is DNA And RNA
DNA~ nucleotides of deoxyribonucleic acid contains the sugar deoxyribose the intructions for the processes of an organisms life. The genetic code depend on the oreder of bases in the nucleotides of the DNA molecule.
RNA~ nucleotides of ribonucleic acid~ contain the sugar ribose. also interacts w/ DNA to help decode the info.
What do cells need a steady supply of to function?
ATP a nucleotide that has three phosphate groups.
Energy is released in the reaction that breaks off the 3rd phosphate group. other single nucleotides transfer electrons or hydrogen atoms for other life processes.
what is energy
the ability to move or change matter.
energy can be converted from one form to another.
a physical change occurs when only the form or shape of the matter changes. the substance that make up the matter do not change into different substances.
a chemical change occurs when a substance change into a different substance. The identity of the matter changes.
the law of conservation of mass
matter is neither created nor destroyed in any change.
the law of the conservation of energy
energy may change from one form to another but the total amount of energy does not change. living things use different chemical reactions to get the energy needed for life processes.
what does changing a substance require?
a chemical reaction, bonds between atoms are broken & new ones are formed.
what is a reactant?
a substance that is changed in a chemical reaction.
what is a product?
a new substance that is formed.
what is activation energy
the minimum kinetic energy that colliding particles need to start a chemical reaction.
when can chemical reactions occur?
when the activation energy is available & the correct atoms are aligned.
what is an enzyme
a molecule that increases the speed of biochemical reactions. they hold molecules close together & in the right orientation. An enzyme lowers the activation energy of a reaction. By assisting in necessary biochemical reactions enzymes help organisms maintain homeostasis. without them chemical reactions would not occur quickly & easily enough 4 life to go on.
what is an active site?
the region where the reaction takes place. the shape of the active site determines which reactants or substrates will bind to it. each different enzyme acts only on specific substrates.