AP Bio Midterm (Biochem Cell)
the following characteristics of water are a result of hydrogen bonding
- adhesive strength - capillarity - cohesive strength
the endocrine and nervous systems are alike in which of the following ways?
- both utilize feedback - several chemicals serve as both hormones and neurotransmitters - nerve impulses can cause endocrine glands to release hormones - some structures can both release hormones and generate nerve impulses
ions diffuse across membranes down their
- concentration gradients - electrochemical gradients
two most important characteristics of the lipid bilayers found in cell membranes
- most polar molecules cannot go across the cell membrane - their phospholipid and protein molecules are not rigidly fixed in place
all of the following are functions of membrane proteins
- signal transduction - cell-cell recognition - intercellular joining - transport
the maximum number of covalent bonds an element with atomic number 16 can make with hydrogen
2
how many electrons does carbon gain through covalent bonding in order to complete its valence?
4
receptor molecule
B
Which of these receptors is NOT a membrane receptor?
E (know receptors)
Up to 60% of all medicines used today exert their effects by influencing what structure in the cell membrane?
G protein-linked receptors
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane. If these molecules can enter all cells, why do only specific cells respond to their presence?
Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell's nucleus
A + B yields AB
anabolic reaction
the main male hormones
androgens
Cell biologists sue the term "ligand" to refer to
any small molecule that can bind to a larger one
a substance that produces a high number of hydrogen ions when added to water is
atom
the total number of protons and neutrons in an atom is
atomic mass
a solution with a pH of 11 is
basic
radioactive iodine is often used as a treatment for tumors of this gland
because only the thyroid gland uses iodine to make its hormones
the active site of an enzyme is the region that
binds with substrate
the active site of an enzyme is the region that
binds with the substrate
Which hormone opposes the action of parathyroid hormone?
calcitonin
when substances are changed by the breaking and for forming of chemical bonds
chemical reaction has occurred
what is an organic, nonprotein component of an enzyme molecule called?
coenzyme
when a drug attaches to the enzyme's active site, stopping the reaction is an example of
competitive inhibition
which of the following is the term for two or more elements joined by chemical bonds?
compounds
a chemical bond in which both atoms share an electron
covalent bond
which of the following is NOT considered to be a weak intermolecular interaction?
covalent bond
a change in a protein's three dimensional shape or conformation due to the disruption of the hydrogen bonds, disulfide bridges and ionic bonds is termed
denaturation
the movement of substances from an area of higher concentration to an area of lower concentration is
diffusion
a small, negative subatomic particle is
electron
which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor?
estrogen
a substance that acts at a relatively long distance from the site at which it is secreted is classified as
hormone
what kind of chemical bond involves a hydrogen atom that is attracted to a larger atom in another molecule?
hydrogen
when atom of a water molecule is attracted to the oxygen atom of another water molecule
hydrogen bond is formed
an atom with an electrical charge
ion
what kind of chemical bond involves one atom that donates an electron to another?
ionic
a substance with only one kind of atom is
isotope
an atom of the same element that has a different number of neutrons is known as
isotope
which disorder is correctly matched with its cause?
low blood calcium: hypersecretion of parathyroid hormone
An enzyme accelerate a metabolic reaction by
lowering the activation energy
what hormone does the pineal gland produce to chemically identify day and season length
melatonin
tyrosine kinase receptor
membrane proteins that attach phosphates to protein tyrokinases C
the smallest unit of a compound
molecule
the smallest particle of a compound is
molecule/formula unit
what are the two most important characteristics of the lipid bilayers found in cell membranes?
most polar molecules cannot go across the cell membrane
anabolic steroids, sometimes taken illegally by athletes and body builders, are synthetic substitutes for
natural androgens from the gonads
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane. If these molecules can enter all cells, why do only specific cells respond to their presence?
nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cells nucleus
A covalent bond is most likely to be polar when
one of the atoms sharing electrons is much more electronegative than the other atom
a substance made of 2 or more different elements chemically combined in definite proportions is
organic compound
Which of the following hormones is sometimes given to strengthen contractions of the uterus during childbirth?
oxytocin
membrane activity most nearly opposite to exocytosis
phagocytosis
white blood cells engulf bacteria through what process?
phagocytosis
which organisms can convert light energy into chemical energy?
plants
G-protein linked receptor
plasma membrane receptor protein that receives a ligand and transmits the signal into the cell A
a molecule that has a partial + charge on one side and a partial - charge on the other is
polar
which of the following is NOT an endocrine gland?
salivary gland
the a-helix and the b-pleated sheet are both common forms found in
secondary structure
a signal transduction pathway is initiated when
signal molecule binds to a receptor
due to an uneven distribution of its electrons, a water molecule is
slightly charged at both ends
What is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off
steroid
when you dissolve salt into water, you produce a mixture called
suspension
if red blood cells grown in an isotonic medium are then placed into distilled water, they will most likely
swell and lyse
a cell that contains membrane proteins enabling a hormone to selectively bind to its plasma membrane is called
target cell
why don't red blood cells pop in the bloodstream?
the blood provides an isotonic solution
molecular biologists believe that signal-transduction pathways evolved early in the history of life because
the molecular details of cell signaling are quite similar in organisms whose last common ancestor was a billion years ago
evidence that cell signaling evolved early in the history of life comes from
the similarity of the mechanisms in organisms that have a very distant common ancestor
a signal molecule can cause different responses in different cells because
the transduction process is unique to each cell type; to respond to a signal, different cells require only a similar membrane receptor
Some bacteria are metabolically
their enzymes have high optimal temperatures
which of the following is the most randomized form of energy?
thermal energy
catabolic pathways
they release energy as they degrade polymers to monomers
which of these is the second of the three stages of cell signaling?
transduction
Is there any movement of water between two isotonic solutions
yes
metabolism of which of the following molecules result in the greatest amount of usable energy per gram of molecule?
a triglyceride
Molecules capable of interacting must first overcome a thermodynamic barrier known as the reaction's
activation energy
the movement of a substance across a biological membrane against its concentration gradient with the help of energy input is
active transport
every hormone
acts as a signal between cells
If an enzyme solution is saturated with substrate, the most effective way to obtain an even faster yield of products is to
add more of the enzyme
which of the following is an example of a base?
ammonia in animal wastes
the concentration of a solution is
amount of a solute that is dissolved in a fixed amount of a solution
