BIO 110
Which of these is NOT a lipid? a) RNA b) phospholipid c) steroids d) cholesterol e) wax
b) RNA, because RNA is a nucleic acid
Cargo leaves the endoplasmic reticulum and is sent to the _____ Golgi cisterna, which then matures through the redistribution of enzymes to become a _____ Golgi cisterna and eventually the _____ Golgi cisterna.
cis; medial; trans
Palm oil and coconut oil are more like animal fats than are other plant oils. Because they _____ than other plant oils, they may contribute to cardiovascular disease.
contain fewer double bonds
Which of the following is least likely to be important in holding the components of a biological membrane together?
covalent interactions between the phospholipid and protein components of the membrane
glucose + glucose —> _____ by _____.
maltose + water ... dehydration synthesis, because Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis.
Beginning within the nucleus, the first step leading to the synthesis of a polypeptide is _____.
transferring of information from DNA to messenger RNA
Which of the following best describes the structure of a biological membrane?
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which statement is true of phospholipids?
(a) Their synthesis uses fatty acids. (b) Some of their tails have double bonds. (c) They all ionize.
A food company hydrogenated a barrel of fat. The treatment ... (a) made the fat less fluid. (b) made the fat less saturated. (c) lengthened the fat tails. (d) put more bends (kinks) in the fat tails. Both (a) and (d).
(a) made the fat less fluid, becuase Hydrogenation removes double bonds, so the tails can straighten. Do you know why that makes the fats less fluid?
Facilitated diffusion via channels and carrier proteins The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion. Diagram showing facilitated diffusion across the plasma membrane. A channel protein embedded in the membrane allows yellow balls to travel through a channel from the outside of the cell to the inside. A carrier protein embedded in the membrane undergoes a shape change allowing red balls to travel from the outside of the cell to the inside. http://session.masteringbiology.com/problemAsset/1119629/22/1119629_007.jpg Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers. -Provide a continuous path across the membrane, -undergo a change in shape to transport solutes across the membrane, -Are integral membrane proteins, -Allow water molecules and small ions to flow quickly across the membrane, -Transport solutes down a concentration or electrochemical gradient, -Transport primarily small polar organic molecules, -Provide a hydrophilic path across the membrane Only channels: Only carriers: Both channels and carriers:
-Only channels: -Provide a continuous path across the membrane, -Allow water molecules and small ions to flow quickly across the membrane -Only carriers: -Undergo a change in shape to transport solutes across the membrane, -Transport primarily small polar organic molecules -Both channels and carriers: -Transport solutes down a concentration or electrochemical gradient, -Are integral membrane proteins, -Provide a hydrophilic path across the membrane Carrier proteins and channels are both transport proteins involved in facilitated diffusion, the passive transport of solutes across a membrane down their concentration or electrochemical gradient. As integral membrane proteins, both carriers and channels protect polar or charged solutes from coming into contact with the hydrophobic interior of the lipid bilayer. Furthermore, all transport proteins are specific for the solutes they transport, owing to the specificity of the interactions between the solute and the transport protein. Channels are protein-lined pores across the membrane. A channel may be open at all times (non-gated), or may be gated such that the channel opens and closes under specific conditions. Channels transport inorganic ions or water http://session.masteringbiology.com/problemAsset/1119629/22/1119629_008.jpg In contrast, carrier proteins do not have a pore. Binding of the transported solute to the carrier protein on one side of the membrane induces a conformational change in the protein that exposes the solute binding site to the opposite side of the membrane, where the solute is released. Carriers transport small polar solutes such as sugars and amino acids. http://session.masteringbiology.com/problemAsset/1119629/22/1119629_009.jpg
Diffusion All molecules have energy that causes thermal motion. One result of thermal motion is diffusion: the tendency of substances to spread out evenly in the available space. Although the motion of each individual molecule is random, there can be directional motion of an entire population of molecules. Consider a chamber containing two different types of dye molecules, purple and orange. The chamber is divided into two compartments (A and B) by a membrane that is permeable to both types of dye. Initially (left image), the concentration of the orange dye is greater on side A, and the concentration of the purple dye is greater on side B. With time, the dye molecules diffuse to a final, equilibrium state (right image) where they are evenly distributed throughout the chamber. http://session.masteringbiology.com/problemAsset/1119629/22/1119629_001.jpg -(never),(always),(only before equilibrium is reached),(only at equilibrium) 1. orange dye moves independently of purple dye.___ 2. concentration of gradients exist that drive diffusion of both dyes.___ 3. there is a net movement of orange dye from side A to side B. ___ 4. purple dye ONLY moves from side B to side A.____ 5. there is no net movement of purple dye.____
1. (always) 2. (only before equilibrium is reached) 3. (only before equilibrium is reached) 4. (never) 5. (only at equilibrium) Each dye molecule and the water molecules that surround it are in constant motion due to their thermal energy. Any individual molecule's motion is random because of the frequent collisions among all of the molecules. If a concentration gradient exists for a population of molecules, the motion of the individual molecules in that population will result in a net (directional) movement from higher to lower concentration. For example, in the initial condition, there is a concentration gradient for the orange dye. As a result, the orange dye molecules diffuse down the concentration gradient, with net movement from side A to side B. Once diffusion has eliminated the concentration gradient and equilibrium is reached, net movement stops, but the random motion of each molecule continues (as indicated by the red arrows in the image below).
Because ions carry a charge (positive or negative), their transport across a membrane is governed not only by concentration gradients across the membrane but also by differences in charge across the membrane (also referred to as membrane potential). Together, the concentration (chemical) gradient and the charge difference (electrical gradient) across the plasma membrane make up the electrochemical gradient. Consider the plasma membrane of an animal cell that contains a sodium-potassium pump as well as two non-gated (always open) ion channels: a Na+ channel and a K+ channel. The effect of the sodium-potassium pump on the concentrations of Na+ and K+ as well as the distribution of charge across the plasma membrane is indicated in the figure bhttp://session.masteringbiology.com/problemAsset/1119630/24/1119630_010.jpgelow. Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply. 1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. 2. The diffusion of Na+ ions into the cell is impeded by the electrical gradient across the plasma membrane. 3. The diffusion of K+ ions out of the cell is impeded by the K+ concentration gradient across the plasma membrane. 4. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. 5.The electrochemical gradient is larger for Na+ than for K+.
1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. 4. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. 5.The electrochemical gradient is larger for Na+ than for K+. -The concentration gradient of Na+ ions across the membrane (higher Na+ concentration outside) facilitates the diffusion of Na+ into the cell. At the same time, the electrical gradient across the membrane (excess positive charge outside) drives Na+ into the cell. The concentration gradient of K+ ions across the membrane (higher K+ concentration inside) facilitates the diffusion of K+ out of the cell. However, the electrical gradient across the membrane (excess positive charge outside) impedes the diffusion of K+ out of the cell. The electrochemical gradient for an ion is the sum of the concentration (chemical) gradient and the electrical gradient (charge difference) across the membrane. For Na+ ions, diffusion through the Na+ channel is driven by both the concentration gradient and the electrical gradient. But for K+ ions, the electrical gradient opposes the concentration gradient. Therefore, the electrochemical gradient for Na+ is greater than the electrochemical gradient for K+.
Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability. Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply. 1. proteins 2. sucrose 3. lipids 4. carbon dioxide 5. water 6. ions 7. oxygen
3. lipids, 4. carbon dioxide, 5.water, 7. oxygen Some solutes pass readily through the lipid bilayer of a cell membrane, whereas others pass through much more slowly, or not at all. Small nonpolar (hydrophobic) molecules, such as dissolved gases (O2, CO2, N2) and small lipids, can pass directly through the membrane. They do so by interacting directly with the hydrophobic interior of the lipid bilayer. Very small polar molecules such as water and glycerol can pass directly through the membrane, but much more slowly than small nonpolar molecules. The mechanism that permits small polar molecules to cross the hydrophobic interior of the lipid bilayer is not completely understood, but it must involve the molecules squeezing between the hydrophobic tails of the lipids that make up the bilayer.Polar molecules such as glucose and sucrose have very limited permeability.Large molecules such as proteins cannot pass through the lipid bilayer.Ions and charged molecules of any size are essentially impermeable to the lipid bilayer because they are much more soluble in water than in the interior of the membrane. http://session.masteringbiology.com/problemAsset/1119629/22/1119629_006.jpg
Which of these does NOT contain a structural protein? 1.) ligaments 2.)spider silk 3.)ovalbumin 4.)muscles 5.)tendons
3.)
Define hypotonic
A hypotonic solution is any solution that has a lower osmotic pressure than another solution. In the biological fields, this generally refers to a solution that has less solute and more water than another solution
In many animal cells, the uptake of glucose into the cell occurs by a cotransport mechanism, in which glucose is cotransported with Na+ ions. -OUTSIDE CELL A). [Na+]high (Glucose [high] or [low]) -(BETWEEN) B). Glucose-sodium cotransporter (^[glucose]v[Na+]),(v[glucose]^[Na+]),(v[glucose]v[Na+]) -INSIDE CELL C). [Na+]low (Glucose [high] or [low]) D. 1. Na+ moves ([down] or [against]) its electrochemical gradient 2. Glucose moves ([down] or [against]) its concentration gradient
A). Glucose low B). v glucose v Na+ C). Glucose high D). 1.down 2.against In cotransport, the energy required to move one solute against its concentration or electrochemical gradient is provided by an ion moving into the cell down its electrochemical gradient. The ion that moves into the cell down its gradient is usually the same ion that is pumped out of the cell by an active transport pump: for example, Na+ in animal cells using the sodium-potassium pump, or H+ in plants and prokaryotes using the proton pump. In the case of the glucose-sodium cotransporter in animals, Na+ moves back into the cell down its electrochemical gradient, providing the energy for glucose to move into the cell against its concentration gradient. The energy for glucose transport into the cell is supplied indirectly by the sodium-potassium pump's hydrolysis of ATP, and directly by the Na+ electrochemical gradient created by the pump. http://session.masteringbiology.com/problemAsset/1125908/12/1125908_007.jpg
Covalent bonds are formed when A. Two atoms share electrons B. Two protons are shared between atoms. C. Electrons are transferred between atoms D. Ionic bonds are dissolved in water E. Functional groups are removed from monomers
A.
What is one characteristic that distinguishes the rough endoplasmic reticulum from the Golgi? A. Protein synthesis B. Processing of toxic materials C. Networks of interconnected membranes that can use vesicles to transport proteins. D. Protein trafficking E. Modification of proteins
A.
Examination of a short polypeptide reveals that all of the monomers contain carbon ring or methyl (-CH3) R groups. Therefore, the polypeptide is: A. Hydrophobic B. Acidic C. Soluble in water D. Charged E. Polar
A. Amino acid properties can be predicted by their R group and the R groups in these amino acid monomers are all hydrophobic.
The four major classes of macromolecules A. Are made from the same monomers B. Cannot be broken down into individual subunits C. Are soluble in water D. Are assembled by the process of condensation E. Are assembled because equilibrium favors synthesis
A. Incorrect. Different polymers are composed of different monomers. B. Incorrect. The process of building polymers can be reversed. It is called hydrolysis. C. Incorrect. Not all classes of macromolecules are soluble in water—for instance lipids. D. Correct. Condensation is another word for synthesis. E. Incorrect. Life is lived far from the natural equilibrium, which tends to break down large molecules.
What two things are necessary for simple diffusion? A. A concentration gradient and a channel or carrier protein B. A membrane-soluble molecule with a concentration gradient C. A carrier protein and a source of energy D. ATP and secondary active transport E. An hydrophilic macromolecule and a protein receptor
A. Incorrect. Simple diffusion requires no channel or carrier protein. B. All we need is a soluble molecule and a difference in concentration on one side of the membrane compared to the other. C. Incorrect. No carrier is needed for simple diffusion. D. Incorrect. Simple diffusion requires no type of transporter. E. Incorrect. Simple diffusion requires a soluble molecule and typically we think of molecules that are soluble in a membrane as being hydrophobic.
How many different nitrogenous bases are used in DNA and RNA nucleotides? A. 3 B. 4 C. 5 D. 10 E. 20
A. Incorrect. There are more than three. B. Incorrect. There are more than four. C. Correct. Adenine, guanine cytosine thymine and uracil. D. Incorrect. There are less than 10 nucleotides. E. Incorrect. There are 20 amino acids use to make proteins, but there are less than 20 nucleotides used to make DNA and RNA.
If you have a high concentration of K+ on one side of a membrane that has an open K+ channel in it, what will be likely to happen? A. Nothing will happen, K+ is an ion and cannot cross the membrane B. The K+ will flow through the channel until there are equal concentrations on each side C. The K+ will flow through the channel until it has all crossed the membrane D. No K+ will flow through the channel because it is charged E. If there is ATP available, then K+ will be moved across the membrane until it is all on the other side
A. Incorrect. True, a K+ ion probably will have a hard time going directly through the phospholipid bilayer, but there is an open channel there. B. Correct. This is facilitated diffusion. C. Incorrect. The K+ ion will flow through the channel, but the forces at work here will not allow all the ions to pass through. D. Incorrect. K+ will flow through the channel because a K+ channel can specifically transport charged potassium atoms. E. Incorrect. The concentration gradient will allow K+ to move without the need for ATP, and even if ATP were available, channels aren't designed to harness the power of ATP for transport.
Phospholipids of the cell membrane are commonly modified by the attachment of what type of molecules? A. Carbohydrates B. Cholesterol C. Proteins D. Nucleic acids E. Hormones
A. The addition of carbohydrates to phospholipids makes a glycolipid.
One of the reasons that cells usually remain small in size is that: A. As cells get larger the volume increases at a faster rate than the surface area B. As cells get larger the SER is unable to produce enough lipids to maintain the membrane C. As cells get smaller the ribosomes become more efficient D. The cytoskeleton is not strong enough to support a large cell E. Smaller cells have a smaller surface to volume ratio
A. The surface-area to volume ratio gets smaller and smaller as the cell gets larger and larger, making is hard for the cell to achieve it's metabolic needs through a relatively small membrane.
Placing a cell in a hypotonic solution will cause water to: A. Move into the cell by osmosis B. Move out of the cell by osmosis C. Have no net movement D. Move into the cell by active transport E. Move out of the cell by active transport
A. Water moves by osmosis and like diffusion it moves down its "concentration" gradient.
Negative R group equals?
Acidic
Consider the following statements about proteins: i. There are 20 unique monomers used to make proteins ii. Polymers of amino acids are called polypeptides iii. Proteins can be made of multiple polypeptides
All are true
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
Amphipathic nature, because detergents form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble.
A function of cholesterol that does not harm health is its role _____.
As a component of animal cell membranes
A functional group, already known to enable hydrogen bonding, is found on a new class of previously unknown macromolecules. Based on the presence of this functional group, what would you predict about these new macromolecules? A. They would be able to act like a weak acid B. They would be able to engage in hydrogen bonding C. They would be hydrophobic D. They would be nonpolar E. Very little—the properties of functional groups depends on other components of the macromolecule
B.
A certain cell's function is to synthesize and secrete a protein. In direct connection with its function, that cell will likely have A. An extensive smooth ER B. An extensive rough ER C. Many mitochondria D. Numerous cytoplasmic ribosomes E. Many lysosomes
B. Because the main function of the cell has to do with the function of the RER, it is very likely that the cell will devote more resources to building a large RER so it can do its job.
Cristae are a membrane structure found in which organelle? A. Chloroplasts B. Mitochondria C. Plastids D. Ribosomes E. The Golgi complex
B. Cristae are the name for the foldings of the inner membrane of the mitochondria.
. After a cold night, a single-celled paramecium living in a cattle pond moves to a warm, sunny spot to feed in. In response to this movement, the paramecium will most efficiently adjust its cell membranes by: A. Including longer and more unsaturated fatty acids in membrane phospholipids B. Include longer and more saturated fatty acids in membrane phospholipids C. Include shorter and more unsaturated fatty acids in membrane phospholipids D. Include shorter and more saturated fatty acids in membrane phospholipids E. Appling SPF 45 sunscreen
B. Having just moved from a cold spot to a warm spot, the membrane will have a lot of shorter and unsaturated fatty acid phospholipids to keep the membrane fluid in a cold environment. Now in the warm environment, this will be too fluid and we will need to restore the perfect fluidity by making the membrane a bit more solid. We can do this by adding longer and more phospholipids with saturated fatty acid chains.
If a molecule is produced from atoms that have an electronegativity difference of 0.1, what type of bonds are expected to form? A. Ionic bonds B. Nonpolar covalent bonds C. Polar covalent bonds D. Hydrogen bonds E. Hydrophobic interactions
B. Nonpolar covalent bonds generally form between atoms that have electronegativity differences of less than 0.5.
Carbon-nitrogen (CN) compounds are common in biochemistry and bonded through A. Ionic bonds, formed by nitrogen gaining the valence electrons from carbon B. Nonpolar covalent bonds C. Polar covalent bonds with carbon having a partial negative charge D. Polar covalent bonds with nitrogen having a partial negative charge E. Hydrophobic interactions because of the equal sharing of electrons
B. The difference in electronegativity is what would be expected for nonpolar covalent bonds.
The potential for hydrogen bonds in living systems may be found A. Only in water B. Whenever H is bound to O or N C. Only between different molecules D. Only within different parts of the same molecule E. Whenever C is bound to H
B. When H is bound to a much more electronegative element, like O or N, the covalent bond is highly polar, and this enables H bonding interactions.
All cells contain ion pumps that use the energy of ATP hydrolysis to pump ions across the plasma membrane. These pumps create an electrochemical gradient across the plasma membrane that is used to power other processes at the plasma membrane, including some transport processes. In animal cells, the main ion pump is the sodium-potassium pump. -OUTSIDE CELL B. ([Na+]low, [K+]high) or ([Na+]high,[K+]low) C. (excess + charge) or (excess - charge) -(BETWEEN) A. (3[Na+]v,2[K+]^)，（2[Na+]^,3[K+]v), (3[Na+]^,2[K+]v) -INSIDE CELL D. ([Na+]low,[K+]high) or ([Na+]high,[K+]low) E. (excess + charge) or (excess - charge)
B.[Na+]high [K+]low C. excess + charge A. 3 Na+ ^ 2 K+ v D. [Na+]low [K+]high E. excess - charge -Active transport by the sodium-potassium pump follows this cycle. 1. Three Na+ ions from the cytosol bind to the pump. 2. The binding of Na+ stimulates the phosphorylation of the pump protein by ATP. 3. Phosphorylation causes a conformational change in the pump that moves the three Na+ ions against their concentration gradient and releases them outside the cell. 4. The release of the Na+ ions permits two K+ ions from outside the cell to bind to the pump, and the phosphate group is released. 5. Release of the phosphate group causes another conformational change in the pump. 6. The conformational change in the pump moves the two K+ ions against their concentration gradient and releases them into the cytosol. http://session.masteringbiology.com/problemAsset/1119630/24/1119630_009.jpg The net result is that the concentration of Na+ is higher outside the cell and the concentration of K+ is higher inside the cell. In addition, one more positive charge has been transported out of the cell than into the cell, leaving the outside of the cell with an excess positive charge and the inside with an excess negative charge. Thus, the sodium-potassium pump creates both chemical gradients and charge differences across the plasma membrane. The function of the sodium-potassium pump in animal cells (and the proton pump in bacteria and plant cells) is essential to many cell functions. It prevents chemical and electrical gradients across the plasma membrane from reaching equilibrium (at which point the cell would be dead) and powers many types of active transport across the plasma membrane.
Positive R group equals?
Basic
Fats vary with respect to the number of ... (a) hydrocarbon tails. (b) C atoms in the tails. (c) double bonds in the tails. Both (b) and (c). All of the above.
Both (b) and (c) because, tail lengths of 16 to 22 are common. There may be from 0 to 6 double bonds.
The presence of many C-C and C-H bonds causes fats to be ... (a) rich in energy. (b) insoluble in water. (c) low in energy. Both (a) and (b). Both (b) and (c).
Both a.) and b.)
A nerve cell is required to build and maintain a high concentration of ions inside the cell. How will this likely be accomplished? A. Osmosis B. Simple diffusion C. Active transport D. Facilitated diffusion E. Using channel proteins
C. Active transport uses energy and can build a high concentration of ions.
The removal of the nucleolus will directly result in the deficiency of which organelle? A. SER B. Golgi C. Ribosomes D. Nucleus E. Lysosomes
C. In the nucleolus, the ribosomes are assembled.
A triglyceride that contains only saturated fatty acids would be A. Amphipathic B. Hydrophilic C. Solid at room temp D. Liquid at room temp E. Saturated with carbon-carbon double bonds
C. Saturated fatty acids pack well and are dense, making them solid at room temperature.
What sequence of events best describes the process of synthesis of a protein that is to be secreted from a cell? A. Synthesis on RER → transit in vesicle to cell membrane B. Synthesis on SER → vesicle transit to trans face of Golgi → packaging & sorting → vesicle transit from cis face of golgi to cell membrane C. Synthesis on RER → vesicle transit to cis face of Golgi → packaging & sorting → vesicle transit from trans face of Golgi to cell membrane D. Synthesis in the cytoplasm → vesicle transit to cis face of Golgi → packaging & sorting → vesicle transit from trans face of Golgi to cell membrane E. Synthesis on RER → vesicle transit to trans face of Golgi → packaging & sorting → vesicle transit from trans face of Golgi to cell membrane
C. This is the best representation of the many steps involved in synthesizing, modifying, sorting, and transporting proteins for secretion.
What does the smooth ER do?
Calcium ion storage, poison detoxification, lipid synthesis, synthesizes sex hormones
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell?
Cell wall
Which of these is a polysaccharide?
Cellulose, because Cellulose is a carbohydrate composed of many monomers.
_____ is the most abundant organic compound on Earth.
Cellulose, because Cellulose, a component of plant cell walls, is the most abundant organic compound found on earth.
What does the Golgi Apparatus do?
Cisternal maturation, protein modification and sorting
Palm oil and coconut oil are more like animal fats than are other plant oils. Because they _____ than other plant oils, they may contribute to cardiovascular disease.
Contain fewer double bonds
As a biochemist, you recently discover a new kind of carbohydrate polymer that is resistant to metabolic breakdown. From this information, what function would you expect for this molecule? A. It would be similar to starch and play a role in energy storage B. It would be similar to glycogen and play a role in cell structure C. It would be similar to cellulose and play a role in energy storage D. It would be similar to cellulose and play a role in cell structure E. It would be similar to starch and play a role in cell structure
D. Both cellulose and the new carbohydrate have beta linkages and probably a similar function, which is in cell structure.
A cell that is lacking the ability to synthesize cholesterol and membrane lipids probably has a problem with its: A. Mitochondria B. Golgi C. Rough ER D. Smooth ER E. Transport vesicles
D. The smooth ER functions to synthesize various types of lipids.
A new life form is discovered and is shown to have only one type of organelle: a ribosome. Based on this information, how should this organism be classified? A. Animal B. Plant C. Fungus D. Protist E. Prokaryote
E.
Glucose is used to make which two polymers in plants? A. Phospholipids and triglycerides B. Nucleic acids and starch C. Starch and glycogen D. Proteins and starch E. Cellulose and starch
E.
Polymers of glucose include: A. Starch, cellulose and glycogen, all used for energy storage B. Maltose, lactose and sucrose, the monomers of which are joined by beta glycosidic bonds C. Ribose, deoxyribose, and fructose, which can be used for energy storage or storage of genetic information D. Cellulose, starch, and glycogen, all of which are used in plants for energy storage or structure E. Glycogen, cellulose, and starch, the monomers of which are joined by condensation
E.
Which biological activity does NOT directly involve proteins? A) Changing the shape of a cell. B) Breaking food polymers into smaller molecules. C) Defending cells against viruses. D) Sensing light. E) None of the above; proteins are involved in all of them.
E.
Which of the following molecules are you likely to find as a component of cell membranes? A. Steroids B. Carbohydrates C. Phospholipids D. A & C only E. All of the above
E.
A sodium-potassium pump that moves sodium into a cell and potassium out of the cell is an example of what? A. Channel protein B. Peripheral protein C. Symporter D. Uniporter E. Antiporter
E. Antiporters move two different molecules in different directions.
A protein that needs modification prior to proper functioning will undergo those modifications in the: A. Mitochondria and/or Rough ER B. Transport vesicle and golgi C. Golgi and the transport vesicle D. Rough ER and lysosome E. Rough ER and golgi
E. Both the rough ER and Golgi are known to modify proteins.
What best describes the dominant property of a pure phospholipid membrane? A. Acidic B. Basic C. Saturated D. Hydrophilic E. Hydrophobic
E. Phospholipids (and membranes made of phospholipids) are dominated by the hyrdrophobic properties of the fatty acids.
In the synthesis of a membrane lipid, which of the following is not a good choice for a starting molecule: A. Glycerol B. Phosphate C. Saturated fatty acids D. Unsaturated fatty acids E. Glycogen
E. There is no glycogen in membrane lipids (but there is glycerol—don't get the two confused) so this would not be a good molecule to start with.
What do phosphoglycerides and fats have in common?
Ester linkages, because like fats, phosphoglycerides are made by coupling fatty acids to glycerol by means of ester linkages.
Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both. 1. transported substances never physically cross the plasma membrane 2. forms vesicles from inwards folding of the plasma membrane 3. requires fusion of vesicles with the plasma membrane 4. decreases the surface area of the plasma membrane 5. requires cellular energy 6. increases the surface area of the plasma membrane 7. secretes large molecules out of the cell
Exocytosis: 7. secretes large molecules out of the plasma membrane, 6. increases the surface area of the plasma membrane, 3. requires fusion of vesicles with the plasma membrane -Endocytosis: 4. decreases the surface area of the plasma membrane, 2. forms vesicles from inwards folding of the plasma membrane Both: 5. requires cellular energy, 1. transported substances never physically cross the plasma membrane -In exocytosis, substances are transported to the plasma membrane in vesicles derived from the endomembrane system. These vesicles fuse with the plasma membrane, releasing the enclosed substances outside the cell. In endocytosis, substances are taken into the cell by folding in of the plasma membrane and pinching off of the membrane to form a vesicle. Notice that in both exocytosis and endocytosis, the transported substances never actually cross the plasma membrane as they leave or enter the cell. http://session.masteringbiology.com/problemAsset/1125909/10/1125909_001.jpg
_____ are surface appendages that allow a bacterium to stick to a surface
Fimbriae
What does cholesterol have in common with sex hormones?
Four linked rings
The highlighted part of this molecule is derived from ... O (H) -- (HC)-(O) -C - - O v -- (HC)-(O) -C - - O v -- (HC)(O) -C (H)
Glycerol, because the other parts of the molecule are derived from fatty acids.
In fat synthesis,________and fatty acids combine to make fats plus________. phosphate; glycerol esters; phosphate glycerol; water esters; water glucose; phosphate
Glycerol; Water because, water is a by-product of the reaction that makes ester links between glycerol and fatty acids.
In the reaction that builds a fat,________ groups react with ________ groups.
Hydroxyl; Carboxyl, because fatty acids supply the carboxyl groups; the hydroxyls come from glycerol.
What does the hydrophilic head include?
Includes a glycerol molecule attached to a single phosphate group, which is then attached to another small molecule.
All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes? Select all that apply. (a)insulin (b)actin (c)lysosomal enzyme (d)ribosomal protein (e)ER protein (f)DNA polymerase
Insulin, ER protein, and lysosomal enzyme, because Most proteins that function in the cytosol (such as actin) or in the nucleus (such as DNA polymerase) are synthesized by free ribosomes. Proteins that function within the endomembrane system (such as lysosomal enzymes) or those that are destined for secretion from the cell (such as insulin) are synthesized by bound ribosomes. As a protein destined for the endomembrane system is being synthesized by a ribosome, the first amino acids in the growing polypeptide chain act as a signal sequence. That signal sequence ensures that the ribosome binds to the outer membrane of the ER and that the protein enters the ER lumen.
For good health, you don't want your body to run the LDL part of this diagram faster than the HDL part because
LDL cholesterol is stored; HDL cholesterol is destroyed.
How can a lipid be distinguished from a sugar? a) Lipids are mostly nonpolar. b) Lipids are mostly saturated. c) A lipid dissolves in water. d) A lipid is made up of only hydrocarbons. a) Lipids are mostly nonpolar.
Lipids are mostly nonpolar
What do fats, steroids, and waxes have in common?
Low solubility in water
What do lysosomes do?
Macromolecule digestion, autophagy
To find the best source of phospholipids, look at ...
Membranes, because the great majority of a cell's phospholipids occur in membranes.
Support and operate the much larger movement structures like cilia and flagella
Microtubules
Tiny projections of a cell, sort of looking like little fingers, that increase surface area without increasing volume. They're very important in your GI tract for absorbing nutrients.
Microvilli
Which of these is a source of lactose?
Milk (Lactose Intolerant)
The characteristic that all lipids have in common is that _____.
None of them dissolve in water
Where is a bacterial cell's DNA found?
Nucleoid region, because bacterium lack a nucleus.
Define Osmosis
Osmosis is the diffusion of water across a selectively permeable membrane.
Which lipid is most amphipathic? Triglyceride Phospholipid Fat Wax Cholesterol
Phospholipid
What does a phospholipid look like?
Phospholipids are composed of a phosphate group, a glycerol, and fatty acids.
What do phospholipids have?
Phospholipids have a hydrophilic head and hydrophobic tails.
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell.
Plasma Membrane, selectively permeable
It is difficult for molecules to pass through the phospholipid bilayer because ...
Polar molecules attract one another. Polar molecules have trouble escaping from the water to enter a membrane, and nonpolar molecules have trouble moving from the membrane into water. Thus, neither kind of molecule moves easily through membranes.
Phospholipids are most important for ...
Preventing leakage from cells
What is the function of a bacterium's capsule?
ProtectionPla
What does the rough ER do?
Protein synthesis
In a bacterium, where are proteins synthesized?
Ribosomes, Ribosomes are involved in the manufacture of polypeptides (proteins).
Polymers that contain sugars ...
Store hereditary information, store energy, and protect cells, because Polymers that contain sugars do all the named functions and more. For example, they also lubricate the path of roots through soil and they glue plant cells together.
In a membrane, the________of the phospholipids in one monolayer face the________of the phospholipids in the other monolayer.
Tails; Tails, because water on both sides of the membrane excludes the tails, forcing them into the interior where they face one another.
Saturated fats look like what?
The fatty acid tails lack double bonds.
What are the hydrophobic tails made up of?
The hydrophobic tails are two fatty acids attached to the glycerol molecule of the head.
The most unsaturated fats have ...
The most double bonds, because every double bond is a place where hydrogen could be added.
Either polar or charged...What am I?
The phosphate group and its attachments
Which of the following factors does not affect membrane permeability?
The polarity of membrane phospholipids, because phospholipids contain both a polar head and a nonpolar hydrocarbon tail, both of which are necessary for their ability to form membrane bilayers.
The permeability of a biological membrane to a specific polar solute may depend on which of the following?
The types of transport proteins in the membrane
What do DNA, proteins, and fats have in common?
They contain carbonyl groups
In facilitated diffusion, what is the role of the transport protein?
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
True, the hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail.
The picture represents a biological membrane. Which statement is true of the most abundant molecules in the membrane?
Water keeps them oriented in the membrane. They contain ionized phosphate groups. (They are phospholipids. Water orients them because they are amphipathic.)
Are water molecules attracted to the tails? Why or why not?
Water molecules are not attracted to the tails because C-H bonds are relatively nonpolar and therefore do not result in charged regions in the tail.
What are water molecules attracted to and why?
Water molecules are polar and therefore are attracted to the charged regions of the phospholipid head.
Which fact is most important in causing phospholipids to behave as they do in water?
Water molecules make hydrogen bonds, because the hydrogen bonds in water exclude the nonpolar tails of phospholipids, forcing the molecules into a bilayer.
Dr. Haxton told one of his students, "To move in the bloodstream, fats need the help of phospholipids." What would a good student say?
Yes. Nonpolar molecules aren't compatible with water.
Glycogen is___.
a polysaccharide found in animals
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? a) Hypotonic b) Hypertonic c) Osmotic d) Isotonic
a) Hypotonic (The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst.)
