Chapter 2: Chemistry of Life
Endothermic
An endothermic reaction absorbs more energy than it releases
Exothermic
An exothermic chemical reaction releases more energy than it absorbs
Why does an ion form?
An ion forms because an atom is more stable when its outermost energy shell is full; the gain or loss of electrons results in a full outermost energy level.
Carbon, hydrogen, and oxygen are my building blocks; sometimes I am broken down as a source of energy, and sometimes I make up plant cell walls.
carbohydrate
1. substances that decreases activation energy 2. increases rate of a chemical reaction
catalyst
Chemical Reaction
changes substances into different substances by breaking and forming chemical bonds
Which property causes water to form beads?
cohesion
Chemical bonds hold me together; I always contain atoms of more than one element.
compound
Base
compound that removes hydrogen ions from a solution
Water and Carbon Dioxide, are examples of what?
compounds
A molecule is held together by _____.
covalent bonds
Nucleus
dense center of an atom
Monomer
each smaller molecule is a subunit called this
Two atoms may form several covalent bonds to share several pairs of ___.
electrons
What is made up of only one type of atom?
elements
1. reactants have greater bond energy than products 2. photosynthesis
endothermic
I am a chemical reaction that absorbs more energy than I release; my products have a higher bond energy than my reactants.
endothermic
I allow chemical reactions to take place under the tightly controlled conditions in living things; in almost all cases I am a protein.
enzyme
A solution is a mixture of substances that is __ distributed throughout the entire mixture.
evenly
Equilibrium EXAMPLE:
evenly matched tug-of-war
Polar molecules have two regions with a slight positive charge.
false; to make it true, add " and a slight negative charge" to the end of the statement.
I am a carbon chain found in many lipids; I can be either saturated or unsaturated.
fatty acid
Ionic Bond
forms through the electrical force between oppositely charged ions
Covalent Bond
forms when atoms share a pair of electrons
Solute EXAMPLE:
getting lost in a crowd
Which property allows water to resist changes in temperature?
high specific heat
I am an attraction between a slightly positive hydrogen atom and a slightly negative atom, such as oxygen or nitrogen.
hydrogen bond
1. atom that has gained or lost electrons 2. results in a full outermost energy level
ion
I have a positive charge if I lose an electron, or I have a negative charge if I gain an electron.
ion
Acid
is a compound that releases a proton - a hydrogen ion - when it dissolves in water
Solution
is a mixture of substances that is the same throughout - it is a homogeneous mixture
Polymer
is a molecule that contains many monomers bonded together
Protein
is a polymer made of monomers called amino acids
Compound
is a substance made of atoms of different elements, bonded together in a certain ratio
Catalyst
is a substance that decreases the activation energy needed to start a chemical reaction, and, as a result, also increases the rate of the chemical reaction
Solute
is a substance that dissolves in a solvent
Ion
is an atom that has gained or lost one or more electrons
Hydrogen Bond
is an attraction between a slightly positive hydrogen atom and a slightly negative atom
Element
is one particular type of atom, and it cannot be broken down into a simpler substance by ordinary chemical means
Activation Energy
is the amount of energy that needs to be absorbed for a chemical reaction to start
Bond Energy
is the amount of energy that will break a bond between two atoms
Atom
is the smallest basic unit of matter
Solvent
is the substance that is present in greater amounts and that dissolves another substance
Molecule
is two or more atoms held together by covalent bonds
Activation Energy EXAMPLE:
kick-starting a motor cycle
Covalent Bond EXAMPLE:
linking hands in a human chain
1. held together by covalent bonds 2. can be of the same element
molecule
I am held together by covalent bonds; I can be made of atoms of just one element.
molecule
"Oil and water don't mix" because a ___ molecule can't easily dissolve in a polar solvent.
nonpolar
I am the type of molecule that stores genetic information in living things; I include DNA and RNA.
nucleic acid
Amino Acid EXAMPLE:
one of many beads on a string
Shared pairs of electrons fill the ___ energy levels of bonded atoms.
outermost
I measure the hydrogen ion concentration in a solution; when I am low a solution is very acidic.
pH
Electron
particle with a negative charge
Proton
particle with a positive charge
Neutron
particle with no electrical charge
Ionic Bond EXAMPLE:
passing a basketball
Many different types of me have many different functions in living things; I am made of amino acids.
protein
1. enters a chemical reaction 2. thing that is changed during a chemical reaction
reactant
A ___ dissolves in a solution.
solute
Blood plasma is an example of a ___.
solute
I am a certain type of mixture; I am formed when one substance, such as water, dissolves other substances.
solution
1. dissovles a solute 2. substance that is present in greater amounts
solvent
Covalent bonds are generally very ____.
strong
I am a reactant an enzyme acts on; I bind to an enzyme's active site.
substrate
Atom
the smallest basic unit of matter
Equilibrium
When a reaction takes place at an equal rate in both directions, the reactant and product concentrations stay the same
On the pH table, which side is more acidic. more basic, and which pH is neutral?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 < more acidic more basic > The pH 7 is neutral
Carbohydrates
Carbohydrates are molecules composed of carbon, hydrogen, and oxygen, and they include sugars and starches. Carbohydrates can be broken down to provide a source of usable energy for cells. Carbohydrates are also a major part of plant cell structure. The most basic carbohydrates are simple sugars, or monosaccharides. many simple sugars have either five or six carbon atoms. Fruits contain a six carbon sugar called fructose, Glucose, one of the sugars made by plant cells during photosynthesis, is another six carbon sugar. Simple sugars can be bonded to make larger carbohydrates. Starches, glycogen, and cellulose are polysaccharaides.
High Specific Heat
Hydrogen bonds give water an abnormally high specific heat. This means that water resists changes in temperature. Compared ti many other compounds, water must absorb more heat energy to increase in temperature. This property is very important to cells. The processes that produce usable chemical energy in cells release a great deal of heat. Water absorbs the heat, which helps regulate cell temperatures.
Nucleic Acid
Nucleic acids are polymers that are made up of monomers called nucleotides. The two general types are: DNA and RNA
Cohesion
The attraction among molecules of a substance is cohesion. Cohesion from hydrogen bonds makes water molecules stick to each other. You can see this when water forms beads, such as on a recently washed car. Cohesion also produces surface tension, which makes a kind of skin on water.
Adhesion
The attraction among molecules of different substances is called adhesion. In other words, water molecules stick to other things. Adhesion is responsible for the upward curve on the surface of the water because water molecules are attracted to the glass of the test tube in figure 2.3. Adhesion helps plants transport water from their roots to their leaves because water molecules stick to the sides o the vessels that carry water.
1. includes sugars and starches 2. sometimes is broken down as an energy source
carbohydrate
Substrate
The specific reactants that an enzyme acts on is called this
Some ions are positively charged, and some ions have no charge.
This is false, To make this statement true, change "no charge" with "negative charge".
An atom becomes an ion when its number of protons changes.
This is false. To make it true, change "protons" with "electrons".
Ions usually form when electrons are transferred from one atom to another.
This statement is true.
The formation of an ion results in a full outermost energy level.
This statement is true.
Ionic Bond
a bond formed by the electrical force between two ions of opposite charge
Covalent Bond
a bond formed when two atoms share a pair of electrons
Lipid EXAMPLE:
a car's gas tank
Element
a particular type of atom
pH
a solution's acidity, or hydrogen ion concentration, is measured by this scale
Compound
a substance made of atoms of different elements bonded together in a certain ratio
1. releases hydrogen ion into a solution 2. increases the concentration of hydrogen ion in a solution
acid
I am the amount of energy that is needed for a chemical reaction to start; after I am added, the reaction can take place on it's own.
activation energy
Which property of water helps plants transport water from their roots to their leaves?
adhesion
Enzymes
are catalysts for chemical reactions in living things
Fatty Acid
are chains of carbon atoms bonded to hydrogen atoms
Amino Acids
are molecules that contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. Organisms use 20 different amino acids to build proteins. Your body can make 12 of the amino acids, the rest comes from foods that you eat such as meat, beans, nuts.
Lipid
are nonpolar molecules that include fats, oils, and cholesterol. Like carbohydrates, most lipids contain chains of carbon atoms bonded to oxygen and hydrogen atoms. Some lipids are broken down as a source of usable energy for cells. Other lipids are part of a cell's structure. Fats and oils store large amounts of chemical energy in organisms. They both consist of molecule called glycerol bonded to molecules called fatty acids.
Products
are the substances made by a chemical reaction
Reactants
are the substances that are changed during a chemical reaction
1.smallest basic unit of matter 2.contains protons, neutrons, and electrons
atom
I am the amount of energy needed to break a chemical bond; I am also the amount of energy released when a bond forms.
bond energy
Slightly charged regions of water molecules form hydrogen bonds.
true
Water is a polar molecule.
true
Molecule
two or more atoms held together by covalent bonds
Atom EXAMPLE:
unicellular organism