Exam #1
a phospholipid molecule has a polar and nonpolar end. because of their, water molecules form
hydrogen bonds with the polar end of the phospholipid molecule
The part of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are
non-polar
a distinctive feature of eukaryotes is the organization of tightly packaged chromosomal DNA with proteins into a membrane-bound structure
nucleus
the "X" shaped chromosomal hereditary material can be packaged in this organelle in eukaryotic cells but not in the prokaryotic cells. this organelle is:
nucleus
the cytoplasmic space in eukaryotic cells is occupied by many diverse membrane-bound structures with specific cellular functions
organelles
based on the function of mitochondria, what substance is able to pass through the outer membrane of the mitochondria easily?
oxygen
Matthew noticed that his house plants were wilting badly. What cell structure had most likely had contracted?
vacuole
Osmosis occurs as water can cross the lipid bilayer through specialized channels for water movement called
aquaporins
receptor-mediated endocytosis brings in specific material by engulfing it in vesicles. what factors directly or indirectly affect this process?
-RME helps to increase membrane fluidity by helping to transport cholesterol into the cell -it is an active process -a clathrin coat is present
if ATP production is blocked, decreased transport of material across a membrane occurs. which type of transport is affected?
-active transport -endocytosis
insulin stimulates an increase in number of glucose carrier proteins at a cell membrane's surface. what effect will insulin have on cell function?
-an increase in insulin, which will increase the diffusion rate -low insulin levels will decrease the number of available carrier proteins -lack of membrane receptors for insulin will decrease amount of glucose taken in
a symporter is moving glucose and sodium levels are being depleted in extracellular fluids. what can be concluded about the movement of glucose?
-glucose would be moving against its gradient into the cell -glucose follows the gradient of sodium into the cell -ATP is not required to to move sodium down its concentration gradient -energy is needed to move glucose down its concentration gradient -glucose movement is considered a part of coupled transport
the cell's plasma membrane mediates the following transactions with the environment
-ingesting food molecules and sometimes entire cells -returning waste and other molecules back to the environment -responding to a host of chemical cues -passing messages to other cells
As ATP moves from the matrix of the mitochondrion to the cytoplasm of a cell, how many membranes will it pass?
2
If a water molecule passes through the outer membrane of a chloroplast, how many more membranes will it have to move through to be in the stroma?
2
carrier proteins are saturated at which point?
4; the plateau
mitochondria and chloroplasts are the other organelles besides the nucleus that contain
DNA
the organelle that can collect, package, modify, and transport molecules
Golgi apparatus
the eukaryotic organelle that is directly involved in the transport of proteins synthesized on the surface of the rough ER is called
Golgi body
Who first described cells?
Hooke
Kinases are enzymes that can phosphorylate (transfer phosphate groups onto) macromolecules such as proteins. A particular kinase, Kinase 1 is known to promote cell division. It promotes cell division by phosphorylating Protein X. Phosphorylation of Protein X activates Protein X. Once activated, Protein X stimulates the production of other proteins such as Protein Y and Z that directly promote cell division. In order to function, Kinase 1 requires the presence of Metal A. However, in the presence of Protein A, Kinase 1 is nonfunctional. From the description, what is considered the cofactor of Kinase 1?
Metal A
During neuronal signaling, a change in membrane potential will cause sodium channels to open and let Na+ ions diffuse down their concentration gradient into the cell. Which of the following helps establish the concentration gradient necessary for this process to occur?
Na+/K+ pump
Incubation of cells at 20C blocks the release of proteins from the trans-Golgi. Under such conditions, you would expect to see A. an increase in exocytosis. B. a decrease in exocytosis. C. an increase in endocytosis. D. a decrease in endocytosis.
b. a decrease in exocytosis
which of the following protein classes are not found as membrane proteins? a. transport channels b. hormones c. receptors d. enzymes e. identity markers
b. hormones
Kinases are enzymes that can phosphorylate (transfer phosphate groups onto) macromolecules such as proteins. A particular kinase, Kinase 1 is known to promote cell division. It promotes cell division by phosphorylating Protein X. Phosphorylation of Protein X activates Protein X. Once activated, Protein X stimulates the production of other proteins such as Protein Y and Z that directly promote cell division. In order to function, Kinase 1 requires the presence of Metal A. However, in the presence of Protein A, Kinase 1 is nonfunctional. From the description, what is considered the substrate of Kinase 1?
Protein X
If the function of centrioles was impaired in a cell, it could not:
divide
A calorie is the commonly used unit of chemical energy. It is also the unit of
heat
A particular reaction has a negative delta G. However, this reaction takes many years to proceed in the absence of enzyme. Why is this the case?
a certain amount of activation energy is required for the reaction to proceed
the energy needed to destabilize existing chemical bonds and start a chemical reaction is called:
activation energy
A type of transport of a solute across a membrane, up its concentration gradient, using protein carriers driven by the expenditure of chemical energy is known as
active transport
membrane proteins serve many functions. one of the functions is transportation of substances across the membrane. if a cell biologist placed cells into an environment in which a chemical has been added that blocks the function of only carrier proteins, the process that will be affected is.....
active transport
the type of movement that is specific and requires carrier molecules and energy is
active transport
Schleiden and Schwann stated the "cell theory", which in its modern form says:
all organisms are composed of one or more cells, all cells are the smallest living things and all cells arise by division of other cells
While eating lobster for dinner one night your friend asks what you think might happen if this marine invertebrate, which is normally isosmotic with respect to the surrounding seawater, were to be moved to a bay with a slightly lower salt concentration instead of being caught. You reply that, in order for the lobster to be isosmotic with respect to new environment, A. it must move water in to match the solute concentration of its new environment. B. it regulates its internal concentration of solutes to match that of its new environment. C. it must move water out to match the solute concentration of its new environment. D. it moves water in or out and regulates its internal concentration of water as needed.
b. it regulates its internal concentration of solutes to match that of its new environment.
On the outer surface of the plasma membrane there are marker molecules that identify the cell type. Often these molecules are
carbohydrate chains
which type of proteins is embedded in the cell membrane in both active transport and facilitated transport?
carrier
Plants, fungi and bacterial all have:
cell walls
in bacteria, fungi, and plants in high internal pressure generated by osmosis is counteracted by the mechanical strength of their.....
cell walls
Plant cells often have a large membrane-bound sac that is used for storing water and other substances called a:
central vacuole
a distinctive feature of chloroplasts is that they contain a green pigment called:
chlorophyll
individuals that are heavy smokers may eventually have trouble clearing the mucous from their lungs because the structures that move fluid along the epithelial lining of the lung become damaged over time. What are these structures?
cilia
the organic non-protein components that aid in enzyme functioning are called
coenzymes
the inorganic non-protein components that participate in enzyme catalysis are known as:
cofactors
a drug binds to the active site of an enzyme. if it is bound to the active site of the enzyme, it prevents substrate binding. this drug would be considered a:
competitive inhibitor
a molecule that closely resembles the shape of a substrate for an enzyme would most likely serve as a:
competitive inhibitor
The actual transport of protons by the proton pump is mediated by a transmembrane protein which undergoes a change in its
conformation
the accumulation of amino acids and sugars in animal cells can occur through
coupled transport
the semi-fluid matrix that surrounds organelles in a cell
cytoplasm
microfilaments such as actin, microtubules, and the intermediate filaments for the cell supporting structure called the:
cytoskeleton
Small cells function more effectively, because as cells become larger their surface area to volume ratio
decreases
What is the net movement of substances to regions of lower concentration called?
diffusion
to test for the presence of starch, iodine can be used. a positive reaction results in a black color. a dialysis bag filled with starch solution and secured on both ends is placed in iodine solution. after 30 mins the dialysis bag appears black. based on this info, what most accurately describes what happened?
due to its size and polarity, iodine was able to enter the dialysis bag and interact with starch
Chromosomes can be condensed into compact structures, visible with the light microscope, but usually only:
during cell division
When a vesicle moves along microtubules toward the center of the cell, the molecular motor(s) _____ are used?
dynein
Three (3) eggs are boiled and all weigh 2g. The eggs are placed in a 15% solution of NaCl and reweighed after 30 minutes. which egg is isotonic to the solution?
egg 2= 2 grams
Three (3) eggs are boiled and all weigh 2g. The eggs are placed in a 15% solution of NaCl and reweighed after 30 minutes. The solution in the container is hypertonic to which egg?
egg 3= 1.8 grams
oxidation and reduction reactions are chemical processes that result in the gain or loss of:
electrons
the synthesis of sugar molecules through the process of photosynthesis requires energy absorbed from sunlight. what kind of reaction is photosynthesis?
endergonic
organisms with a cell wall cannot carry out
endocytosis
the evolutionary process that created chloroplasts and mitochondria
endosymbiosis
in eukaryotes, mitochondria are the organelles primarily involved in
energy release/capture
Protein X contains four transmembrane domains, a short N-terminus and a long C-terminus. Following protein synthesis, the N-terminus of the protein faces the lumen (the inside) of the ER. After protein X is transported to the cell surface via exocytosis, you would expect the N-terminus of protein X to be
extracellular
the type of movement of molecules that is specific and passive, and which becomes saturated if all the protein carriers are in use is
facilitated diffusion
Hexokinase is an enzyme that binds specifically to glucose and converts it into glucose 6-phosphate. The activity of hexokinase is suppressed by glucose 6-phosphate, which binds to hexokinase at a location that is distinct from the active site. This is an example of what?
feedback inhibition
prokaryotic cell movement is attributed to
flagella
While water continually orients phospholipids into a lipid bilayer, it does not fix the lipids permanently into position. Thus, the bilayer is considered to be _______.
fluid
the amount of energy available to do work is called:
free energy
Three (3) eggs are boiled and all weigh 2g. The eggs are placed in a 15% solution of NaCl and reweighed after 30 minutes. when compared to the solution, the egg that gained that weight was....
hypertonic
a research laboratory is attempting to collect the content of human red blood cells. the type of solution researchers should use to cause blood cell to lyse (burst) would be
hypoosmotic
When looking at plant and animal cells with an electron microscope, you notice that the plant cells have more Golgi membranes than the animal cells. How might you explain this?
in plant cells, the Golgi apparatus is involved in the production of cell walls
the rate of diffusion of molecules would be fastest in a cells with an a. internal concentration of 45% and an external concentration of 50% in cold temperatures b. internal concentration of 50% and an external concentration of 12% in cold temperatures c. internal concentration of 50% and an external concentration of 12% in warm temperatures d. internal concentration of 40% and an external concentration of 35% in warm temperatures
internal concentration of 50% and an external concentration of 12% in warm temperatures
If a cell has the same concentration of dissolved molecules as its outside environment, the cell's condition is referred to as being
isotonic
alcohol consumption adversely affect the synthesis of molecules involved in protein degradation, which can eventually lead to liver damage. given this info, which organelle in liver cells is most directly affected by alcohol consumption?
lysosome
the chemistry of living systems representing all chemical reactions
metabolism
Peroxisomes are examples of
microbodies
The cilia and flagella of eukaryotic cells are composed of:
microtubules in a 9 + 2 arrangement
the organelle involved in the oxygen-requiring process by which the energy harvest from macromolecules is used to generate ATP is the:
mitochondria
what is the difference between mitochondria and chloroplasts?
mitochondria are oxidative metabolic bacteria derivatives and chloroplasts are photosynthetic bacteria derivatives
For the process of diffusion to occur, molecules must
move from areas of high concentration to areas of lesser concentration until an equilibrium is reached
a doctor diagnoses a child with ALD, a disorder in which there is an accumulation of long fatty acid chains accumulating in the cells of the central nervous system. the issue arise with malfunctions in enzymes associated with what organelle?
peroxisomes
organelles that breakdown hydrogen peroxide into water and oxygen
peroxisomes
The process often referred to as "cellular eating" is
phagocytosis
The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called
phospholipids
ribosomes are made up of
protein and RNA
during which cellular process do all three forms of RNA associate?
protein synthesis
the plasma membrane is a thin sheet of lipid embedded with
proteins
Matt is studying how the protein transferrin enters cells. He examines cells that have taken up transferrin, and finds clathrin-coated vesicles. What mechanism was used to take transferrin into the cell?
receptor-mediator endocytosis
the nucleolus is the site of
ribosome assembly
osmosis can only occur if water travels through the
semi-permeable membrane
osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the......
solutes
Membrane fluidity is affected by
temperature, cholesterol, types of fatty acids.
energy is defined as
the capacity to do work
the fluid mosaic model proposed by Singer and Nicolson in 1972 explained that
the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer
a cell biologist has developed a new drug that blocks vesicles transports at the cis face of the Golgi apparatus. what will this drug prevent from happening inside a cell
the movement of the lipids and protein from the endoplasmic reticulum to the Golgi apparatus
a particular chemical reaction is exergonic. what can you say about the relationship between the reactants and the products in this exergonic reaction?
the reactants have more free energy than the products
a cytologist is examining a tissue under an electron microscope. he notices that the endoplasmic reticulum of each cell is extremely rough in appearance and he knows that the rough appearance is because of the ribosomes embedded there. he asks why there are so many ribosomes?
this tissue exports proteins to other areas of the body
If you were to replace the phosphate group of a phospholipid with a fatty acid chain, you would have
triglyceride
a group of scientists perform an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. they inject a 5M solution of glucose into the cell and then place the cell into a beaker of water. after an hour, what effect do you expect to observe?
water moves into the cells
A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker containing 10M glucose. What effect do you expect to observe?
water moves out of the cell
why do we have storage macromolecules, such as fats, in our bodies?
we can break down the macromolecules to provide energy for the endergonic reactions in our bodies
