AP Bio: Unit 2
Endocytosis
"Cellular eating" When cells take in material by wrapping their cell membranes around it - this forms vesicles that transports the large molecules into the cell
ATP
(adenosine triphosphate) main energy source that cells use for most of their work
guard cells and stomata
- GUARD CELLS open STOMATA (pores in a leaf) which allow carbon dioxide, oxygen, and water vapor to pass. - The stoma and guard cells help to maintain water homeostasis plants use active transport of K+ and the process of osmosis to open and close their stomata.
How does the sodium potassium pump work?
1 - pump first binds to Na+. 2 - ATP comes along, "phosphorylates" pump, pumo changes shape. 3 - pump then releases Na+ to outside 4 - pump now open out, only has configuration to fit K+. Pump binds K+. 5 - Pump reverts back to original conformation (like a spring bottle, no atp needed this way) and releases K+ into cell, ready to start again. The sodium-potassium pump system moves sodium and potassium ions against large concentration gradients. It moves two potassium ions into the cell where potassium levels are high, and pumps three sodium ions out of the cell and into the extracellular fluid.
unicellular
1 single cell, simple, bacteria
cell membrane structures
75% phospholipids 5% glycolipids 20% cholesterol phospholipid( phosphate, fatty acid tails (c-h bonds) transport channel carrier protein atp cell receptor transmembrane protein peripheral protein
molarity
A common measure of solute concentration, referring to the number of moles of solute per liter of solution.
electrochemical gradient
A difference in charge between the outside and inside of the cell due to uneven concentrations of ions in those two areas
concentration gradient
A difference in the concentration of a substance across a distance.
contractile vacuoles
A membranous sac that helps move excess water out of the cell.
endomembrane system
A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. conssits of the rough ER and golgi apparatus and modifies and ships proteins that belong in a specific destination like the membrane, outside the cell, or in a lysosome.
organelle
A tiny cell structure that carries out a specific function within the cell
Stomata are pores on the surfaces of the leaves and stems of plants that regulate gas exchange between the plants and the atmosphere. Researchers found that the stomata density on the leaves of a species of plant change as the concentration of CO2 in the atmosphere changes. When grown at 350 ppm CO2 the plant has an average density of 300 stomata per mm2, but when grown at 400 ppm CO2 the plant has an average density of 250 stomata per mm2. Which of the following best describes how the ratio of the density of stomata (stomata per mm2) per CO2 concentration (ppm CO2) changes as the CO2 concentration increases? A The ratio decreases from 0.86 to 0.63, because fewer stomata are needed at higher CO2 concentrations. B The ratio decreases from 1.6 to 1.2, because fewer stomata are needed at higher CO2 concentrations. C The ratio increases from 0.63 to 0.86, because more stomata are needed at higher CO2 concentrations. D The ratio increases from 1.2 to 1.6, because more stomata are needed at higher CO2 concentrations.
A. The ratio decreases from 0.86 to 0.63, because fewer stomata are needed at higher C02 concentrations.
active transport
Active transport is the process of moving molecules across a cellular membrane through the use of cellular energy.
A study was conducted to understand the factors controlling the rate at which molecules or ions travel across cell membranes. An artificial membrane was created that was composed of a phospholipid bilayer only. The speed at which various substances crossed this membrane was measured. Some substances can pass through an actual cell membrane much faster than they passed through the artificial membrane in this study. Which of the following statements best explains this finding?
Actual cell membranes have a variety of proteins embedded in the membrane that are absent in the artificial membrane.
surface area to volume ratio
As cells grow larger; their surface area and volume both increase but the volume increases at a faster rate than the surface area. This makes their surface area to volume ratio smaller. Cells stay reltively small to maintain higher surface area to volume ratios.
diagram of active transport
Atp is being used, is it going up or down the gradinet, is it a pump or a channel
Beetroot cells contain a family of dark red pigments called betalains. The selectively permeable nature of the beetroot cells keeps the internal environment of the cell separate from the external environment of the cell. Researchers are interested in determining whether the selective permeability of beetroot cells is due to the cell membrane or if it is due to the cell wall. Exposure to cellulase is known to damage the structure of the cell wall. An experiment is set up in which beetroot cells are placed in an aqueous solution with cellulase and in one without cellulase. Which of the following results best refutes the alternative hypothesis that selective permeability is a consequence of the cell wall? A When beetroot cells are placed in a solution with cellulase, the solution turns dark red. B When beetroot cells are placed in a solution with cellulase, the solution remains clear. C When beetroot cells are placed in a solution, it turns dark red with or without cellulase present. D Since plant cells contain cell membranes, not cell walls, the alternate hypothesis cannot be tested.
B. When beetroot cells are placed in a solution with cellulase, the solution remains clear.
hydrolysis
Breaking down complex molecules by the chemical addition of water
A magnesium sulfate solution taken orally can cause a net movement of water into the large intestine, which results from water molecules diffusing through aquaporins embedded in the cells of the intestinal lining. By which of the following mechanisms do the water molecules most likely move into the large intestine.
By passive transport from an area of low osmolarity to an area of high osmolarity.
Aldosterone (a steroid hormone) is a small, nonpolar, hydrophobic molecule that enters a target cell by moving across the plasma membrane, down a concentration gradient. Based on the information presented, how does aldosterone most likely enter target cells?
By simple diffusion because aldersterone can enter a cell by moving across the plasma membrane and moving down the concentration gradient.
The cell membrane is selectively permeable due to its structure. Thus, the internal environment of the cell is distinct from the external environment of the cell. One biologist hypothesizes that small nonpolar molecules readily pass through membrane. Another biologist alternatively hypothesizes that these types of molecules require channel and transport proteins that are embedded in the membrane in order to move across the membrane.
CO2 and N2 movement in and out of cells unaffected when membrane protein activity is blocked.
chloroplasts
Captures energy from the sunlight and uses it to produce food in plant cells; found only in plant cells
Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. Which of the following data would support the alternative hypothesis?
Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.
Researchers have proposed a model of chloroplast evolution. According to the model, chloroplasts evolved from a small prokarytotic organism that was engulfed by an ancestral eukaryote. The engulfed prokaryote then formed an endosymbiotic relationship with the eukaryotic host.
Chloroplasts and some prokarytes share similar photosynthetic reactions.
cell membrane
Controls what comes into and out of a cell; found in plant and animal cells. gives structure and shape to the cell
cytoplasm
Gel-like fluid where the organelles are found; found in plant and animal cells. allows things to move through out the cell.
A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe the genes the code for the hydrolytic enzymes that are normally found in lysosomes and continues to translate the mRNAs for those proteins on membrane- bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures.
Golgi complex
Larger surface area to volume ratios =
Greater efficiency of diffusion of materials in and out of cells
Endoplasmic Reticulum (ER)
Has passageways that carry proteins and other materials from one part of the cell to another; found in plant and animal cells.
hypertonic
Having a higher concentration of solute than another solution.
Some viral infections can lead to the rupture of the lysosome membrane. Which prediction of the effect of this disruption of cellular compartmentalization is most likely correct?
Hydrolytic enzymes will be released, which will cause cell death.
hypertonic, isotonic, and hypotonic cell
Hypotonic has a lower concentration of fluid, sugars and salt than blood. Hypertonic has a higher concentration of fluid, sugars and salt than blood. Isotonic has similar concentration of fluid, sugars and salt to blood.
simple diffusion
In simple diffusion, small noncharged molecules or lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration (they move down their concentration gradient).
Reasearchers investiagate the transport of a certain protein into cells by endocytosis. In an experiment, the reasearchers incubate the cells in the presence of the protein and measure the amount of the protein that is absorbed into the cells over a five- minute period. Based on their observations, what should the researchers do to further clarify how the availability of the protein outside the cell affects the rate of endocytosis of the protein.
Incubate the cells in the presence of several different concentrations of the protein.
how is the NA/ K pump used efficiently to absorb glucose into your bloodstream
It acts to transport sodium and potassium ions across the cell membrane in a ratio of 3 sodium ions out for every 2 potassium ions brought in. In the process, the pump helps to stabilize membrane potential, and thus is essential in creating the conditions necessary for the firing of action potentials. The Na+K+ ATPase moves Na+ out of the epithelial cells lining the intestine and into the blood. The reduced concentration of Na+ inside the cell coupled with high Na+ inside the lumen of the intestine provides a driving force for the movement of Na+ into the cell.
In an experiment, researchers compared the growth of two different plants, plant X and plant Y. The researchers maintained the plants under nearly identical conditions and observed that plant X grew faster than plant Y. The researchers also observed that the inner mitochondrial membranes of plant X had more folds than did those of plant Y. Which of the following conclusions about increasing the number of folds in the inner mitochondrial membrane is best supported by the results of the experiment?
It increases the surface area available for ATP production, which results in faster cell growth.
glycolipid
Membrane phospholipids with carbohydrate chaings attached. Can be enzymes, cell receptors, or simply structural.
glycoprotein
Membrane proteins with carbohydrate chains attached that act as cell recognition markers and help attach cells to form tissues
Which of the following observations best supports the claim that mitochondria evolved from once- free living prokaryotic cells by the process of endocytosis.
Mitochondria are surrounded by a double membrane.
understand the difference between moving substances up their concentration gradients vs. down
Moving against a concentration gradient means that the substance is moving from a low concentration to a high concentration. Moving down (descending) a concentration gradient means that the substance is moving from high concentration area to a low concentration area.
proteins
Nutrients the body uses to build and maintain its cells and tissues
mitochondria
Produces the energy a cell needs to carry out its functions; found in plant and animal cells
Which component of the cell membrane is responsible for active transport?
Protein
Organic Macromolecules
Proteins, carbohydrates, nucleic acids, and lipids are the four major classes of biological macromolecules—large molecules necessary for life that are built from smaller organic molecules. Macromolecules are made up of single units known as monomers that are joined by covalent bonds to form larger polymers.
cell wall
Ridged outer layer of a plant cell; found in only plant cells. helps give structure to the cell
secondary active transport/ cotransport
Secondary active transport is when active transport is used direclty to create a gradient of some substance (usually an ion) and then the ion gradient is used to pull another molecule (like glucose) UP it's gradient as the ion flows down its gradient.
what are forms of passive transport
Simple Diffusion. Facilitated Diffusion. Filtration. Osmosis.
Carbon dioxide most likely enters a cell through what process?
Simple diffusion through the membrane
rough endoplasmic reticulum
System of internal membranes within the cytoplasm. Membranes are rough due to the presence of ribosomes. functions in transport of substances such as proteins within the cytoplasm
Cholesterol is an important component of animal cell membranes. Cholesterol molecules are often delivered to body cells by the blood, which transports the molecules in the form of cholesterol- protein complexes. The complexes must be moved into the body cells before the cholesterol molecules can be incorporated into the phospholipid bilayers of cell membranes.
The animals body cells are defective in endocytosis.
Which of the following cellular deficiencies would most likely be related to mutations in mitochondrial proteins?
The cell is unable to complete reactions related to electron transport and ATP production.
Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation for the data?
The contraction rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
Lysosomes digest food particles brought into a cell by endocytosis. After a vesicle containing food particles fuses with a lysosome, H+ ions are transported into the lysosome from the cytosol. This significantly lowers the pH of the lysosome relative to the cytosol and activates the enzymes that digest the particles. Which of the following best predicts what will happen to the lysosomal enzymes if the proteins that transport H+ ions from the cytosol into the lysosome are damaged?
The lysosomal enzymes will not become active, since there will be no active transport of H+ ions.
Gaucher disease is an inherited disorder in which cells of the body are unable to break down a particular type of lipid, resulting in a buildup of the lipid in some tissues and organs. Based on the information provided, Gaucher disease results most directly from a defect in the function of which of the following organelles.
The lysosome
Why can't water pass directly through the lipid bilayer?
The membrane is called semipermeable, meaning that some things can pass through without assistance, while other things cannot. Water is a charged molecule, so it cannot get through the lipid part of the bilayer. In order to allow water to move in and out, cells have special proteins that act as a doorway.
A human kidney filters about 200 liters of blood each day. Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water. If ADH secretion is inhibited, which of the following would initially result? If ADH secretion is inhibited, which of the following would initially result?
The person would produce greater amounts of dilute urine.
A certain type of specialized cell contains an usually large amount of rough endoplasmic reticulum. (ER) Which of the following functions is this cell type most likely specialized to perform?
The production and secretion of proteins.
Hereditary spherocytosis (HS) is a disorder of red blood cells that causes the cells to be smaller and spherical instead of having the usual flattened, biconcave shape. The average diameter of normal red blood cells is 7.2 um, and the average diameter of red blood cells in a person with HS was found to be 6.7 um. The normal red blood cell has an average surface area of 136 um^2 and an average volume of 91 um^3. What provides an accurate calculation of the surface area to volume ratio of an HS red blood cell, as well as a prediction of its effect on the efficient transferring of oxygen compared to a normal red blood cell?
The ratio is 0.89, and the cells are less efficient at transferring oxygen.
A scientist is studying the various prokarytoic and eukarytoic species found floating in a sample of water taken from a marine ecosystem. Which cellular component will be found in the widest range of organisms in the sample?
The ribosomes, since all organisms need to synthesize proteins.
lumen (internal space)
The space in the interior of a tubular structure, such as an artery or the intestine.
Which of the following transport mechanisms will be affected most directly by a temporary of ATP molecules inside the cell?
The transport of glucose molecules against a concentration gradient.
Exoytosis
Vesicles from the cells interior fuse with the cell membrane, expelling their contents
water potential
Water potential is a measure of the differences in potential energy between a water sample with solutes and pure water.
fat soluble
doesn't disolve in water, hydrophobic, can move directly though the lipid bilayer.
cotransport
a carrier protein that allows the transport of two different species (a solute and an ion) from one side of the membrane to the other at the same time
water potential
adding solute decreases solute potential adding pressure decreases solute potential decreasing pressure increases pressure potential
ribosomes
assembles amino acids to create proteins, found in plant and animal cells
lipid bilayer
double-layered sheet that forms the core of nearly all cell membranes
Smaller surface area to volume ratio=
cell that is better at a function like storage
nucleus
contains DNA, which controls the functions of the cell and production of proteins, found in plant or animal cells. Directs all activies in the cell.
water soluble
dissolve in water, hydrophilic, can't move directly through the lipid bilayer
aqueous
dissolved in water
animal cells
does not have a cell wall or chloroplast
When a substance moves across the plasma membrane along a concentration gradient at a rate faster than would be expected by simple diffusion alone but without the expenditure of metabolic energy, the process is best described as:
facilitated diffusion
lipids
fats and oils
plant cell
has a cell wall, chloroplasts, and large vacuole
ATP/ ADP cycle
has three phosphate groups and to release energy from ATP the last phosphate group (terminal phosphate) is broken off the chain (hydrolysis/ digestion reaction) to form ADP+Pi. Then energy from food/ glucose can be used to reattach that phosphate back, forming ATP again.
water always moves from
hypotonic to hypertonic higher to lower water potential and higher to lower pressure
Contains hydrolytic enzymes associated with the intracellular digestion of macromolecules
lysosome
pH scale
measurement system used to indicate the concentration of hydrogen ions (H+) in solution; ranges from 0 to 14 higher concentrations of H+ ions means more acidic.
multicellular
more than 1 cell, complex, frog
osmosis
osmosis is the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell's partially permeable membrane.
Can pass through protein channel BUT NOT cell membrane
polar molcules (water, glucose) ions/ charged particles +, -
solute potential
pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.
golgi body
recieves proteins and materials from the ER, packages them and distributes them, found in plant and animal cells.
What can go through the cell membrane? In/ cytoplasmic
small non polar molecules. small lipids small uncharged molecules 02 and co2.
Osmolarity and molarity refer to:
solute concentration. high molarity and higher osmolarity both mean higher solute concentration. (lower solute potential and lower overall water potentiall.
vacuoles
stores food, water, wastes, and other materials; found in plant and animal cells. helps cells with digestion.
chromosomes
structures made of DNA molecules that contain the genes
Tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
salinity
the amount of salt in water
facilitated diffusion
the diffusion of solutes through transport proteins in the plasma membrane. Facilitated diffusion is a type of passive transport. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient
why can't charged particles pass through the membrane?
the plasma membrane surrounding the cell consits of a phospholipid bilayer as shown in the Fluid Mosaic Model. This membrane has two parts, the hydrophilic phosphate head and the hydrophobic phosphate tail. Charged molecules like ions repel the uncharged molecules within the hydrophobic tail and therefore are unable to pass through it into the cell by simple diffusion. However, cells have implemented protein channels in its plasma membrane so larger polar molecules and ions such as glucose and potassium ions respectively can pass into the cell.
turgor pressure
the pressure that is exerted on the inside of cell walls and that is caused by the movement of water into the cell
permeability
the state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.
what do hydrophobic membranes do
they compartmentalize cells meaning form small areas within cells that are seperated off from others this allows different pH levels or solute concentrations to be maintained in different areas of these cells. this allows eukaryotic cells to be much more efficient than prokaryotic cells
What do lipid based membranes do
they form the outer membrane, they surround many important organelles, and they are what some organelles are composed of entirely.
Where are lipid based membranes found
throughout eukarytoic cells
osmolarity
total concentration of all solute particles in a solution
turgor pressure
understand that the rigid cell walls of plant cells exerts a pressure back on the cell as they fill with water (become turgid) in hypotonic solutions
lysosome
used primarily for digestion and removal of excess or worn- out organelles, wastes; found in plant and animal cells. Breaks down food and recycles.
hydrophobic
water hating. non- polar.
hydrophilic
water loving (polar)
hypotonic
when comparing two solutions, the solution with the lesser concentration of solutes
isotonic
when the concentration of two solutions is the same