ability to replicate and by the presence of some sort of metabolic activity
variety and variability among all genes, species, and ecosystems
substance that can’t be broken down into any other substances
Everything (matter) is made up of:
a particle of matter that can’t be further subdivided without losing essential properties
what are the three parts of an atom?
nucleus, and three other parts: electrons, protons, and neutrons
The amount of matter in a particle
electrons weight almost:
nothing; they weight 1/20th of one percent
combined mass of all of the atom’s protons and neutrons
Particles that have the same charge ___ each other
Particles with opposite charges are _____ to each other
How can we tell elements apart?
by their atomic number, which means how many PROTONS are in the nucleus
Elements differ in their number of ____
abbreviation of the element’s name
The mass of an atom is often about double the element’s atomic number
Oxygen mass: 15.99
atomic number: 8
Atoms with the same atomic number (number of protons), but different numbers of neutrons
(extra neutrons or fewer neutrons than the number of protons)
(same protons, different neutrons)
in isotopes, does the charge change? Why?
-no because neutrons don’t have a charge
Does the atom’s mass change in isotopes?
yes, with the loss or addition of another particle in the nucleus
elements/isotopes having an unstable nucleus, breaking down spontaneously, releasing tiny, high-speed particles that carry a lot of energy.
Radioactive atoms turn out to be useful in determining what?
the age of fossils
Of all the elements found on earth, how many are found in your body?
The “Big 4” elements consist of:
oxygen, carbon, nitrogen, hydrogen
The “Big 4” make up how much of our body mass?
more than 96%
electrically charged atoms
-number of protons are same, but number of electrons are different
ions have a ___/___ bond
extra electrons mean __ charge and
extra protons mean __ charge
An atom’s ____ determine how and whether the atom will bond with other atoms
The first electron shell holds ___ electrons, and is ___ to the nucleus
the second electron shell is ___ away from the nucleus, and can hold up to ___ electrons
how many shells can there be total?
up to 7
If an element doesn’t have eight atoms, how can they get some?
Groups of atoms are held together by what?
STRONG bonds that form when atoms share electons
The sharing of two pairs of electrons between two atoms
Covalent bonds ..
transferring electrons (now called ions) –oppositely charged ions attract each other and form compound
link multi-atom MOLECULES togehter
Hydrogen bonds are important for bonding..
Ionic and covalent bonds link ___ together
link multiatom molecules together
-formed between a H in one molecule and another molecule, often O or N
Hydrogen bonds are formed between
the slightly positively charged hydrogen atoms of one molecule and the slightly negatively charged oxygen atom of another
-usually a polar atom and a hydrogen atom
oppositely charged atoms attract eachother to form a compound, TAKEN not shared (covalent)
electrons determine what?
HOW nd WHETHER the atom will bond with others
one side is positive, and one is negative
what are polar molecules attracted to?
other polar molecules
-ex: water is the most famous one
are hydrogen bonds strong or weak?
Ionic bonds form _______, while covalent bonds form ________
Because of their unequally shared electrons, water molecules are ..
hydrogen bonds make water
all life on earth depends on
cohesion allows tall trees to exist because
hydrogen bonds allow water molecules to pull up other molecules
water has four unusual properties that are critical, what are they?
cohesion, large heat capacity, low density as a solid, good solvent
When it’s a hot beach day, why is the sand hot but the water isn’t?
hydrogen bonds; hydrogen bonds help resist heating
attraction between two like things
attraction between two different things
heat capacity is like the ability to absorb heat well without reflecting it
low density as a solid
ice floats in water
Water pries apart ionic bonds, dissolving ionic compounds.
What allows us to remain at a stable temperature despite the weather outisde?
PH Scale: below 7
acidic; more h+ (Less OH-)
basic; fless h+ (more OH-)
the lower the ___ the greater the ____ on the ph scale
a decrease of 1 on the pH scale represents a ____-fold increase in the hydrogen ion concentration
a way of referring to the acidic, basic, or chemically neutral quality of a fluid.
chemicals that can quickly absorb excess H+ ions to keep a solution from becoming too acidic, and they can quickly release H+ ions to counteract any increases in OH− concentration.
when blood ph levels become too acidic, a buffer chemical absorbs excess what?
when a blood ph level becomes too basic..
a buffer chemical rleases h+ ions
The pH scale is a direct measure of:
the concentration of hydrogen ions in a solution.
The tendency of water molecules to stick together is called:
A chemical compound that releases H+ into a solution is called:
buffers help PH ..
get back to normal
a large molecule made up from smaller building blocks or subunits.:
what are the four types of macromolecules
lipids, carbohydrates, proteins, and nucleic acids
molecules that contain carbon, hydrogen, and oxygen: they are the primary fuel for running all of the cellular machinery and also form much of the structure of cells in all life forms.
-primary fuel for organisms
carbohydrates are classified by:
ex: glucose and fructose
Why do carbohydrate molecules function so well as fuels for the body?
Carbohydrates have many carbon-hydrogen bonds that store a great deal of energy. These bonds are easily broken, and the energy can be captured by organisms.
Carbs are the primary fuel for running all cellular machinery and also form much of the structure of cells in all life forms
glucose provides energy for..
the body’s cells
carbohydrates ultimately convert into what
glucose can be stored as what in the muscles and liver for later use, or can be converted to what
what are the three uses of glycogen?
1: fuel for cellular activity
2: stored temporarily as glycogen
3: converted to fat
glycogen is hydro..
What are the three basic tupes of carbohydrates?
monosaccharides, disaccharides, polysaccharides
fruit, milk, cake, candy
two sugars joined together
many simple sugars joined together
starch, glycogen,cellulose(structural support for plants)
energy received from braking down carbohydrates
some carbohydrates are stronger or weaker than others?
glucose that isn’t used turns into what?
To use sucrose, the body must first break the bond linking
glucose and fructose
A complex polysaccharide carbohydrate consisting of a large number of monosaccharides linked in line;
;the primary form of energy storage is a complex carbohydrate
Starch and glucose are both carbohydrates. So why does starch fail to provide you the quick burst of energy that glucose can provide?
Starch is a more complex carbohydrate, consisting of hundreds or more sugar molecules covalently linked together. You cannot directly use starch; your body must first break the covalent bonds connecting these sugar molecules, and this takes time.
which carbohydrates are not digestable by humans?
chitin and cellulose
orms the rigid outer skeleton of most insects
forms a huge variety of plant structures that are visible all around us
if humans can’t digest cellulose, why is it still so important for our diet?
Dietary cellulose is called fiber, and it helps move materials through the digestive system.
What is “carbo-loading”?
It is a method by which athletes can increase the usual amount of glycogen that is stored in their muscles and liver, increasing the amount of fuel available for extended exertion and delaying the onset of fatigue during an endurance event.
insoluble in water and greasy to the touch. Lipids are important in energy storage and insulation (fats), membrane formation (phospholipids), and regulating growth and development
lipids are primarily made up of what?
are made primarily from atoms of carbon, hydrogen, and oxygen, but the atoms are in different proportions
are lipids hydrophobic or hyrophilic?
lipids are used as an ___ source
why aren’t lipids soluable in water?
have long chains consisting only of carbon and hydrogen atoms
chains of carbon and hydrogen atoms are polar or nonpolar?
What are the three main types of lipids? What function do they serve in the body?
The three main types of lipids are:
- fats: store energy for long periods of time and insulate the body.
- sterols: such as cholesterol, regulate growth and development.
- phospholipids: form the membranes that enclose cells.
long term energy storage, insulation, mebrane formation, and as hormones
are lipids soluble in water?
no, greasy to touch
A long hydrocarbon (a chain of carbon-hydrogen molecules; form the tail region of triglyceride fat molecules
a chain of carbon atoms, often a dozen or more, linked together and with one or two hydrogen atoms attached to each carbon atom.
glycerol heads and fatty acid tails
A fat in which each carbon in the hydrocarbon chain forming the tail region of the molecule is bound to two hydrogen atoms; saturated fats are solid at room temperature.
some of the carbon atoms are bound to only a single hydrogen (and are connected to each other by a double bond
. Triglycerides that are solid at room temperature
liquid at room temperature
three types of lipids
fats, sterols, phospholipids
structures make lipids polar, which means..
lipid important in regulating growth and development.
cholesterol, estrogen, and testosterone are all types of which macromolecule?
major component of the membrane that surrounds the contents of a cell and controls the flow of chemicals into and out of the cell
phospholipid vs fat in structure
contain a phosphorus atom (hence phospholipids) and they have two fatty acid chains rather than thre
An unsaturated fatty acid is one in which:
carbon-carbon double bonds are present in the hydrocarbon chain
Saturated fatty acids have _________________ than unsaturated fatty acids, which is why they exist as a ____________ at room temperature.
fewer double bonds; solid
Unsaturated fatty acid chains in membrane phospholipids help to maintain fluidity because:
they are less likely to pack tightly at lower temperatures, and they have kinks induced by extra carbon-carbon double bonds
In a phospholipid, the head is _____, and the fatty acid is _____.
A. hydrophilic, hydrophilic
proteins are like bodybuilding macromolecules
constructed of unique combinations of 20 amino acids that result in unique structures and chemical behavior
t initiates and accelerates a chemical reaction in a living organism
One of 20 molecules built of an amino group, a carboxyl group, and a unique side chain. Proteins are constructed of combinations of amino acids linked together.
carbon atom bonded to two oxygen atoms (to one by a single bond and to the other by a double bond).
nitrogen atom bonded to hydrogen atoms (usually two or three).
amino acid structure
Amino acids are made up of a central carbon atom attached to a hydrogen atom, an amino group, a carboxyl group, and a side chain.
list six different functions of proteins
structural, protective, regulatory, contractile, transport, and enzyme roles for proteins
strucgtural protein function
s form hair, fingernails, feathers, and other structures in organisms
protective protein function
elp fight invading microorganisms
regulatory proteins function
control cell activity.
allow muscles to contract and the heart to pump
trasnport proteins ex
carry molecules such as oxygen around the body.
help clot blood
regulatory proteins control
contractile proteins help sperm
transport proteins carry molecules
around the body
proteins are built up of amino acids
how many different kinds of amino acids are there
amino acids all have what
amino acids, carboxyl groups (same backbone) but have different SIDE CHAINS
complex polymer built up of amino acids
If all twenty amino acids are necessary for proteins, then why are only about half of them called “essential”?
The essential amino acids are the ones that human cannot manufacture, so it is essential that they are supplied in our diet.
amino group of one amino acid is bonded to the carboxyl group of another.
The corkscrew-like twists or folds of a protein that are held in place by hydrogen bonds between amino acids in the polypeptide chain
complex three-dimensional shape of a protein formed by multiple twists of its secondary structure as amino acids come together to form hydrogen bonds or covalent sulfur-sulfur bonds
two or more polypeptide chains are held together by hydrogen bonds and other non-peptide bonds between amino acids in the different chains.
The overall shape of a protein molecule determines its
function (how it behaves and the other molecules it interacts)
For proteins to function properly, they must retain their
lose function when folding
The part of an enzyme to which reactants (or substrates) bind and undergo a chemical reaction.
molecule on which an enzyme acts. The active site on the enzyme binds to the substrate, initiating a chemical reaction
each enzyme has an active site that is perfect for its substance
like a key in a lock, what fits in the active site?
lactose; this bond between teh simple sugar is broken
the two simple sugars making up lactose are then released. which two sugars?
glucose and galactose
the little push in order to initiate a reaction in chemical reactions
how do enzymes act as catalysts?
lowering the activation energy
Only the substrate molecules are of the correct ___ and ____ to fit into the active-site groove
size and shape
Once a substrate molecule is bound to the active site, a reaction
can take place, and does so quickly
The chemical reactions that occur in organisms can either /or/ energy.
release or consume
enzymes bind to the substrate at the active site, positioning the atoms in the active site in a manner that weakens the bonds in the substrate, what does this do?
lowering the activation energy necessary for the chemical reaction to occur
The rate at which an enzyme catalyzes a reaction is influenced by several chemical and physical factors.
Enzyme and substrate concentration More stuff, more likely to run into each other Temperature (optimal) Gets molecules moving pH Have an optimal pH Presence of inhibitors or activators
For a given amount of substrate, an increase in the amount of enzyme ____the rate at which the reaction occurs
temperature: reaction rates will increase until optimum, and if there already, it’ll denature from that point
Interactions with PH
disrupt enzyme function (and sometimes structure) and decrease reaction rates.
One of the most common ways that cells can speed up or slow down their metabolic pathways is through
the binding of other chemicals to enzymes. This binding can alter enzyme shape in a way that increases or decreases the enzyme’s activity.
reduce enzyme activity and come in two types
bind to the active site, blocking substrate molecules from the site and thus from taking part in the reaction
do not compete for the active site but, rather, bind to another part of the enzyme, altering its shape in a way that changes the structure of the active site, thus reducing or blocking its ability to bind with substrate.
Enzyme activity is influenced by
physical factors: temperature & pH
chemical factors: enzyme & substrate concentrations
inhibitors & activators
A chemical within a cell that binds to an enzyme, altering the enzyme’s shape or structure in a way that causes the enzyme to catalyze a reaction.
Proteins are an essential component of a healthy diet for humans (and other animals). Their most common purpose is to serve as:
raw material for growth
dietary proteins are considered complete when
are considered “complete” only if they contain the eight essential amino acids required by humans.