Study Guide B pt 2 Flashcards
What is a polar molecule?
a molecule with a slightly positively charged region and a slightly negatively charged region
Explain why water is a polar molecule.
the oxygen nucleus pulls the electrons in the molecule more strongly than the hydrogen atoms. The hydrogen atoms have a slight positive charge and the oxygen atom has a slight negative charge.
What is a hydrogen bond?
an attraction between a slightly positive hydrogen and a slightly negative atom
Describe where a hydrogen bond can form among water molecules.
between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another water molecule.
describe high specific heat
a large amount of energy is needed to produce an increase in water temperature; water resists changes in temperature
describe cohesion
water molecules “stick” to each other
describe adhesion
water molecules “stick” to other substances
What is the difference between a solvent and a solute?
a solvent is present in greater concentration and dissolves the solute
What types of substances dissolve easily in water?
polar molecules and ions
What types of substances do not dissolve easily in water?
Nonpolar molecules (such as fats & oils)
Effect an acid has on H+ concentration in a solution
increases H+ concentration
Effect a base has on H+ concentration in a solution
decreases H+ concentration
Effect an acid has on pH
lower pH
Effect a base has on pH
raise pH
define solution
a homogeneous mixture of substanes
define solvent
substance present in greater amount in which other substances dissolve
define solute
substance that dissolves in a solvent
Why is carbon often called the building block of life?
carbon atoms are the basis of the molecules that make up most living things
What ability allows carbon atoms to form a large number of molecules?
carbon atoms can form covalent bonds with up to four other atoms, including other carbon atoms
function of carbohydrates
broken down as a source of chemical energy (short term energy); part of cell structure
function of lipids
broken down as a source of chemical energy (long term energy); part of cell structure
function of proteins
many functions, including movement, transport, chemical catalysts
function of nucleic acids
store genetic information, build proteins
examples of carbohydrates
sugars, starches, cellulose
examples of lipids
fats, oils, phospholipids
examples of proteins
enzymes, hemoglobin
examples of nucleic acids
DNA, RNA
What determines a protein’s structure and function?
The order of amino acids and interactions between amino acids (hydrogen bonds + sulfer-sulfer bonds)
What are nucleic acids made of?
Nucleotides, which are composed of a sugar, a phosphate group, and a nitrogen-containing base
The prefix mono- means “one,” and the prefix poly- means “many.” How are these meanings related to the terms monomer and polymer?
a monomer is a single subunit; a polymer is a molecule made of many monomers
define reactants
substances that are changed during a chemical reactions
define products
substances made by a chemical reaction
What causes chemical bonds to break during a reaction?
the addition of energy to the reactants
What is bond energy?
the energy required to break a bond between 2 atoms
In a chemical equation, what symbol is used to show that a chemical reaction goes in both directions?
one arrow on top of another, pointing in opposite directions
When does a chemical reaction reach equilibrium?
when a reaction takes place at equal rates in both directions
The bond energy of the reactants and products determines whether …
energy will be released or absorbed during a chemical reaction
before a chemical reaction can start, _____ must be absorbed by reactants.
energy
What is the amount of energy that must be absorbed to start a reaction called?
activation energy
In an exothermic reaction, the products have …
a lower bond energy than the reactants. overall, energy is released.
In an endothermic reaction, the products have …
a higher bond energy than the reactants. Overall, energy is absorbed.
A chemical reaction changes ______ into ______.
reactants into products
analogy for activation energy example
the energy it takes to get out of bed in the morning before you can start your day.
The term equilibrium is based on two Latin roots that mean “equal” and “balance.” How do these meanings tell you the meaning of equilibrium in a chemical reaction?
The reactants and products formed equally; the reaction is in a balanced state.
The prefix exo- means “out,” and the prefix endo- means “in.” What do these prefixes tell you about exothermic and endothermic reactions?
Energy goes out of an exothermic reaction and goes into an endothermic reaction.
What is activation energy?
the amount of energy required to start a chemical reaction.
A catalyst _____ activation energy.
lowers
main functions of catalysts
- catalysts decrease activation energy for a chemical reaction
- catalysts increase the rate of a chemical reaction
detail about another characteristic of catalysts
catalysts are neither reactants nor products because they are not changed or used up
When a catalyst is present, more/less activation energy is needed to start a chemical reaction.
less activation energy
Why are enzymes necessary?
because reactions in organisms have to occur at a low temperature (body temp), with low concentrations of reactants and at a high rate.
How does the structure of enzymes affect their function?
if structure changes, substrates will not be able to bind an enzyme’s active sites
Lock and key model for enzymes
only certain substrates bind to an enzyme’s active sites; when bound to the enzyme the chemical reaction can occur
Important factors in enzyme structure
order of amino acids and hydrogen bonding between the amino acids
How do enzymes weaken the bonds in substrates?
the enzyme’s shape changes slightly, which strains the bonds inside the substrate. the strain on the bonds weakens them.
The word catalyst comes from the Greek word meaning “to dissolve.” How does this definition relate to the meaning of catalyst?
A catalyst “dissolves” or “gets rids of” some of the activation energy needed to start a reaction.
How are substrates like keys and enzymes like locks?
specific substrates fit exactly into the active sites for specific enzymes, in a similar way that only a certain key will open any given lock
Why is the size of a cell important when looking at surface area?
cells need a high surface area to volume ratio because of food, waste, and metabolic reactions
Why is the cell membrane described using the fluid mosaic model?
fluid means moving and that relates to the cell membrane
water is ____ , oil is ________, and phospholipids are _______.
hydrophilic; hydrophobic; amphiphilic
How is cholesterol used by cells?
cholesterol can function to connect phosopholipids to keep them from getting too warm
What is the difference between peripheral and integral proteins?
integral proteins are embedded in the membrane, whereas peripheral proteins are on the surface of the membrane
name 1 integral protein
channel proteins
name 1 peripheral protein
receptor/signal proteins
When carbohydrates bind to proteins, they are known as …
glycoproteins
When carbohydrates bind to lipids, they are known as…
glycolipids
