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