Biol 2401 A&P1 Ch3 Lecture

Which of the following conditions would cause (net) glucose to be transported into a cell via facilitated diffusion? Assume ATP is present inside the cell. A) 0.5 mM glucose in cytoplasm; 5 mM glucose in extracellular fluid B) 5 mM glucose in cytoplasm; 0.5 mM glucose in extracellular fluid C) 5.5 mM glucose in cytoplasm; 5.5 mM glucose in extracellular fluid D) 5 mM glucose in cytoplasm; 5 mM glucose in extracellular fluid

A) 0.5 mM glucose in cytoplasm; 5 mM glucose in extracellular fluid In this case, the concentration gradient is inward, because the glucose concentration is greater outside compared to inside. Because facilitated diffusion transports solutes with their concentration gradient, this condition would cause glucose to be transported into the cell. Cells constantly metabolize glucose to generate ATP and other products. This usually keeps the glucose concentration lower in the cytoplasm than the extracellular fluid. This means that facilitated diffusion usually satisfies a cell's glucose transport needs.

Which one of the following does not play a role in translation? A) DNA B) Anticodon C) Amino acids D) tRNA E) Ribosomes

A) DNA DNA contains the instructions for making proteins, but these instructions are transcribed to RNA before translation occurs.

________ are compartments within the cell whose contents are isolated from the cytosol. A) Membranous organelles B) Ribosomes C) Nonmembranous organelles D) Cytoskeleton E)Microvilli

A) Membranous organelles

Which of the following occurs during a single cycle of the sodium-potassium exchange pump? A) Three Na+ ions are transported out of the cell. B) Two K+ ions are transported out of the cell. C) Three K+ ions are transported into the cell. D)Three Na+ ions are transported into the cell.

A) Three Na+ ions are transported out of the cell. Three sodium ions are moved out of the cell for every ATP hydrolyzed by the pump. At the same time, two potassium ions are moved into the cell.

A process that requires cellular energy to move a substance against its concentration gradient is called ______ A) active transport. B) passive transport. C) diffusion. D) osmosis. E) facilitated transport.

A) active transport.

Passive movement of a solute by a carrier protein is called __________. A) facilitated diffusion B) simple diffusion C) active transport D) sodium-potassium exchange

A) facilitated diffusion Facilitated diffusion is carrier-mediated transport that is passive in nature. Passive means that the solutes move with their concentration gradient and no energy is required. This is like simple diffusion, except that in simple diffusion the solute crosses the membrane directly (is lipid soluble) and does not require a carrier.

Water and small hydrophilic solutes A) may pass through channels in the plasma membrane. B) do not mix with each other. C) cannot pass through a plasma membrane. D) may pass through the phospholipid bilayer of the plasma membrane. E)can dissolve holes in the plasma membrane.

A) may pass through channels in the plasma membrane.

The only kind of cell in the body that is not produced by the division of preexisting cells is A) none, because every cell is produced by the division of another cell. B) a liver cell. C) a neuron (nerve cell). D) a gamete (sperm or egg cell). E)an osteocyte (bone cell).

A) none, because every cell is produced by the division of another cell.

Which of the following is the main component of the cell membrane? A) phospholipids B) carbohydrates C) water D) cholesterol

A) phospholipids Although phospholipids have a polar head, the long fatty acid tails are nonpolar, making the membrane mostly nonpolar.

Identify the role of cholesterol in the plasma membrane. A) reduces membrane fluidity and permeability B) forms enzymes C) enables ions to pass D) provides energy E)anchors the phospholipids

A) reduces membrane fluidity and permeability

How is DNA organized in the nucleus when the cell is prepared for division? How is DNA organized in the nucleus when the cell is not dividing? A) tightly coiled as chromosomes; loosely coiled as chromatin B) loosely coiled as chromatin; tightly coiled as chromosomes C) tightly coiled as chromatin; loosely coiled as chromosomes D) loosely coiled as chromosomes; tightly coiled as chromatin E)loosely coiled as chromosomes; loosely coiled as chromatin

A) tightly coiled as chromosomes; loosely coiled as chromatin

If the concentration of sodium chloride in the interstitial fluid surrounding cells decreases and the concentration of other solutes remains constant, A)the cells will swell. B) the fluid outside of the cells will become hypertonic. C) the cells will shrink. D) the fluid outside of the cells will become isotonic. E) the cells will not change.

A)the cells will swell.

Which are active and passive transport? Primary Active Transport Osmosis Exocytosis Facilitated Diffusion Endocytosis Secondary Active Transport Simple Diffusion

Active: Primary Active Transport Secondary Active Transport Endocytodid exocytosis Passive: Osmosis Facilitated Diffusion Simple Diffusion

Imagine a beaker divided down the center by a rigid membrane that is freely permeable to water but impermeable to glucose. Side 1 contains a 10 percent glucose solution and side 2 contains the same volume of pure water. At equilibrium, what will be the situation? A) The volume of liquid will be greater in side 2. B) The volume of liquid will be greater in side 1. C) Water will continue to move from side 1 to side 2. D) The volume of liquid remain equal on both sides. D) Water will continue to move from side 2 to side 1.

B) The volume of liquid will be greater in side 1.

Same Scenario as above Sickle cell disease distorts the shape of red blood cells. This distortion renders the red blood cells incapable of carrying out their main function, which is transporting oxygen. What causes this distortion? A) a deletion in the nucleotide sequence B) a point mutation in the nucleotide sequence C) a reversal of the entire nucleotide sequence D) an insertion in the nucleotide sequence

B) a point mutation in the nucleotide sequence

The process by which cells become specialized is called _____ A) mutation. B) differentiation. C) cytokinesis. D) distinction. E) determination.

B) differentiation.

If an animal cell lacked centrioles, it would not be able to A) move. B) divide. C) produce DNA. D) synthesize proteins. E) metabolize sugars.

B) divide.

What concentration gradients are established and maintained by the sodium-potassium exchange pump? A) high Na+ concentration in the cytoplasm; high K+ concentration in the extracellular fluid B) high Na+ concentration in the extracellular fluid; high K+ concentration in the cytoplasm C) high Na+ and K+ concentrations in the extracellular fluid D)high Na+ and K+ concentrations in the cytoplasm

B) high Na+ concentration in the extracellular fluid; high K+ concentration in the cytoplasm The concentration of sodium is high outside the cell (extracellular fluid) and the concentration of potassium is high inside the cell (cytoplasm). The sodium-potassium exchange pump establishes these concentration gradients. The energy stored in these concentration gradients is used for a number of important processes throughout the body including nerve impulses and muscle contraction.

A not very well-studied A&P student heard about a phenomenon called water intoxication and thought it sounded fun so she decided to try it. She consumed a large amount of water in a short time (Don't try this—water intoxication is often fatal.). Instead of feeling drunk, she felt nauseated, developed a severe headache, began to get confused, and then became unconscious. Her much more prepared A&P student roommate quickly realized the problem and called an ambulance. When the roommate told the Emergency Department doctor what had happened, the doctor quickly began administering IV (intravenous) fluids.Based on this information and your understanding of osmosis and tonicity, what type of IV fluid is the doctor likely administering to try to save the life of the student suffering from water intoxication? A) isotonic IV fluid B) hypertonic IV fluid C) hypotonic IV fluid

B) hypertonic IV fluid Excellent! Her blood is very hypotonic, causing water to move from her blood into her cells, which caused her brain to swell. Raising the blood tonicity with hypertonic IV fluid should hopefully draw the excess water back out of the cells.If a person goes to the hospital for surgery and requires IV (intravenous) fluids, which of the following should you expect?

Which of the following does not occur during RNA processing? A) A modified guanine nucleotide is added to the beginning of the RNA strand as a cap. B) mRNA attaches to the small subunit of a ribosome. C) Segments of RNA that do code for the protein are reconnected. D) Segments of the RNA strand that do not actually code for the protein are removed. E) Adenine nucleotides are added to the end of the RNA strand, forming a tail.

B) mRNA attaches to the small subunit of a ribosome. mRNA attaches to the small subunit of a ribosome at the beginning of translation.

Cell membranes are said to be ________ because they allow some substances to pass but not others. A) hydrophilic B) selectively permeable C) doubly amphipathic D) hydrophobic E) impermeable

B) selectively permeable

Special cells called ________ cells maintain tissues by unending cycles of cell division. A) root B) stem C) mother D) omnipotent E) cytogenic

B) stem

Same Scenario as prior question The cessation of telomerase activity as we age limits the number of times a cell can replicate. Current research on telomerases is particularly useful in the fight against cancer. Why is this so? A) Cancer cells have telomerases that trigger the loss of stem cell populations. B) Cancer cells have telomerases that suppress the occurrence of cellular mutations. C) Cancer cells employ a mechanism that activates telomerases, which leads to uncontrolled cellular division. D) Telomerase activation may help reduce the amount of mechanical damage incurred by DNA in cancer cells.

C) Cancer cells employ a mechanism that activates telomerases, which leads to uncontrolled cellular division.

The hormone epinephrine (adrenaline) increases the pumping rate of the sodium-potassium exchange pump in skeletal muscles. How would you expect this to affect the concentration of Na+ and K+ in the muscle cytoplasm? A) The Na+ and K+ concentrations would both decrease. B) The Na+ concentration would increase and the K+ concentration would decrease. C) The Na+ concentration would decrease and the K+ concentration would increase. D)The Na+ and K+ concentrations would both increase.

C) The Na+ concentration would decrease and the K+ concentration would increase. Each cycle of the sodium-potassium exchange pump moves three Na+ ions out of the cell and two K+ into the cell. This tends to decrease the concentration of Na+ in the cytoplasm while increasing the concentration of K+. Because epinephrine increases the pumping rate of the exchange pump, these changes in ion concentrations would become more pronounced. These effects on skeletal muscle by epinephrine are part of the "fight-or-flight" response that enhances muscle performance.

Which of the following events occurs during transcription? A) Those segments of the RNA strand that do not actually code for the protein are removed. B) The message in mRNA is translated into a protein. C) A cap is added to the RNA molecule. D) mRNA binds to a ribosome in the cytoplasm. E) A molecule of RNA is formed based on the sequence of nucleotides in DNA.

E) A molecule of RNA is formed based on the sequence of nucleotides in DNA. During transcription, RNA nucleotides line up with their complementary DNA partners, transcribing the information in DNA into RNA.

If a hole is torn in a cell's plasma membrane, the cell will die because A) germs are attracted toward cytoplasm leaking from a cell. B) it will not be able to undergo cell division. C) its chromosomes will not be held in place. D) cells can only make more plasma membrane during cell division. E) it will not be able to maintain differences between the cytoplasm and extracellular fluid.

E) it will not be able to maintain differences between the cytoplasm and extracellular fluid.

Which of the following is a correct statement about mRNA? A) mRNA is transcribed from DNA in the cytoplasm. B) mRNA binds directly to amino acids during translation. C) Segments of mRNA that code for protein are removed before translation. D) mRNA includes a cap that consists of extra adenine nucleotides. E) mRNA moves from the nucleus to the cytoplasm following RNA processing.

E) mRNA moves from the nucleus to the cytoplasm following RNA processing. mRNA undergoes RNA processing in the nucleus and then moves to the cytoplasm for translation.

Most of the ATP required to power cellular operations is produced in the ______ A) cilia. B) cytoplasm. C) nucleus. D) endoplasmic reticulum. E) mitochondria.

E) mitochondria.

The site of translation is A) ribosomes in the cell nucleus. B) the plasma membrane. C) the Golgi apparatus. D) the cell nucleus. E) ribosomes in the cell cytoplasm.

E) ribosomes in the cell cytoplasm. Translation occurs at ribosomes in the cell cytoplasm.

Synthesis of lipids and glycogen takes place at the___________ A) mitochondria. B) rough ER. C) Golgi apparatus. D) ribosomes. E) smooth ER.

E) smooth ER.

Diffusion of a substance across the cell membrane may be influenced by all of the following except A) its concentration gradient. B) its lipid solubility. C) its charge of the substance. D) the presence of membrane channels for the substance. E) the availability of ATP.

E) the availability of ATP.

The extracellular fluid in most tissues is called ________ fluid. A)cytosolic B) cytoplasmic C)outside D)peripheral E)interstitial

E)interstitial

Primary Active Transport Osmosis Exocytosis Facilitated Diffusion Endocytosis Secondary Active Transport Simple Diffusion

TOP: Simple Diffusion Facilitated Diffusion Osmosis MIDDLE: Secondary Active Transport Primary Active Transport BOTTOM: Endocytosis Exocytosis

Mutations are permanent changes in a cell's DNA that affect the nucleotide sequence of one or more genes. The simplest is a point mutation, a change in a single nucleotide that affects one codon. The triplet code has some flexibility because several different codons can specify the same amino acid. But a point mutation that produces a codon that specifies a different amino acid will usually change the structure of the completed protein. A single change in the amino acid sequence of a structural protein or enzyme can prove fatal. Certain cancers and two potentially lethal blood disorders, thalassemia and sickle cell anemia, result from changes in a single nucleotide. Several hundred inherited disorders have been traced to abnormalities in enzyme or protein structure that reflect single changes in nucleotide sequence. More extensive mutations, such as additions or deletions of nucleotides, can affect multiple codons in one gene or in several adjacent genes. They can also affect the structure of one or more chromosomes. Most mutations occur during DNA replication, when cells are duplicating their DNA in preparation for cell division. A single cell, a group of cells, or an entire individual may be affected. This last prospect occurs when the changes are made early in development. QUESTION: While some mutations in the coding sequence of DNA may prove to be positive, most mutations negatively impact the lives of individuals. However, some mutations have no effect at all. How is this possible? A) Ribosomes require only two of the three nucleotides in a codon to stay constant B) .Nucleotides in the short tandem repeats are immune to mutations. C) There is redundancy in the genetic code to where more than one triplet codes for the same amino acid. D) Mutations are never passed on genetically.

C) There is redundancy in the genetic code to where more than one triplet codes for the same amino acid.

Each triplet of bases in a gene corresponds to _______ A) one mRNA. B) one protein. C) one amino acid in a protein. D) one chromosome. E) one DNA nucleotide.

C) one amino acid in a protein.Mutations are permanent changes in a cell's DNA that affect the nucleotide sequence of one or more genes. The simplest is a point mutation, a change in a single nucleotide that affects one codon. The triplet code has some flexibility because several different codons can specify the same amino acid. But a point mutation that produces a codon that specifies a different amino acid will usually change the structure of the completed protein. A single change in the amino acid sequence of a structural protein or enzyme can prove fatal. Certain cancers and two potentially lethal blood disorders, thalassemia and sickle cell anemia, result from changes in a single nucleotide. Several hundred inherited disorders have been traced to abnormalities in enzyme or protein structure that reflect single changes in nucleotide sequence. More extensive mutations, such as additions or deletions of nucleotides, can affect multiple codons in one gene or in several adjacent genes. They can also affect the structure of one or more chromosomes. Most mutations occur during DNA replication, when cells are duplicating their DNA in preparation for cell division. A single cell, a group of cells, or an entire individual may be affected. This last prospect occurs when the changes are made early in development.

What is the normal direction of calcium transport via the calcium pump? A) into the cell, against the calcium concentration gradient B) out of the cell, with the calcium concentration gradient C) out of the cell, against its concentration gradient D) into the cell, with the calcium concentration gradient

C) out of the cell, against its concentration gradient The calcium pump moves calcium ions out of the cell - from the cytoplasm to the extracellular fluid. Because the calcium concentration is much higher outside the cell compared to the inside, this transport is against the calcium concentration gradient. Inside calcium concentrations often increase in response to hormones and nerve input. Calcium pumps are important in terminating these responses by returning calcium concentrations to resting levels.

What part of a cell membrane is usually in contact with the interstitial fluid? A) hydrophobic molecules B) fatty acid tails C) phosphate heads of phospholipids D) cholesterol

C) phosphate heads of phospholipids The phosphate heads of the phospholipids are polar, so they are attracted to the polar water molecules.

Which of the following is a characteristic of the cell membrane? A) not permeable B) impermeable C) semipermeable D) fully permeable

C) semipermeable The cell membrane is semipermeable, or selectively permeable, because some things can easily pass through it while others cannot.

Telomerase, Aging, and Cancer Each telomere contains a sequence of about 8000 nitrogenous bases, but they are multiple copies of the same six-base sequence, TTAGGG, repeated over and over again. Telomeres are not formed by DNA polymerase. Instead, they are created by an enzyme called telomerase. Telomerase is functional early in life, but by adulthood it has become inactive. As a result, the telomere segments lost during each mitotic division are not replaced. Eventually, shortening of the telomere reaches a point at which the cell no longer divides. This mechanism is a factor in the aging process, since many of the signs of age result from the gradual loss of functional stem cell populations. Experiments are in progress to determine whether activating telomerase (or a suspected alternative repair enzyme) can forestall or reverse the effects of aging. This would seem to be a very promising area of research. Activate telomerase and halt aging--sounds good, doesn't it? Unfortunately, there's a catch: In adults, telomerase activation is a key step in the development of cancer. If for some reason a cell with short telomeres does not respond normally to repressor genes, it will continue to divide. The result is mechanical damage to the DNA strands, chromosomal abnormalities, and mutations. Interestingly, one of the first consequences of such damage is the abnormal activation of telomerase. Once this occurs, the abnormal cells can continue dividing indefinitely. Telomerase is active in at least 90 percent of all cancer cells. Research is underway to find out how to turn off telomerase that has been improperly activated. Choose the correct statement about telomerases. A) Telomerases are functionally identical to DNA polymerases. B) Telomerases are enzymes that are active throughout one's lifetime. C) Telomerases consist of specific groupings of nitrogenous bases that are repeated. D) Telomerases are enzymes that form telomeres.

D) Telomerases are enzymes that form telomeres.

If a person goes to the hospital for surgery and requires IV (intravenous) fluids, which of the following should you expect? A) The IV fluid should be hypotonic to the patient's blood. B) The tonicity of the IV fluid doesn't matter—the patient won't be in the operating room that long so any tonicity would be OK for a couple of hours. C) The IV fluid should be hypertonic to the patient's blood. D) The IV fluid should be isotonic to the patient's blood.

D) The IV fluid should be isotonic to the patient's blood.

Carriers transport solutes across the plasma membrane by __________. A) forming a pore in the membrane, which allows solutes to pass through B) making solutes more soluble in the plasma membrane C) opening channel gates that allow solutes to pass D) changing shape as the solutes bind, causing the solutes to move across the membrane

D) changing shape as the solutes bind, causing the solutes to move across the membrane After the solute(s) have bound to the carrier, the transporter changes shape. This conformational change is what moves the solute(s) into or out of the cell. If the transport direction is against the solutes' concentration gradient, then an energy source must be used.

What is the energy source used by the calcium pump during its normal operation? A) the ATP concentration gradient B) the calcium concentration gradient C) the calcium pump D) the hydrolysis of ATP

D) the hydrolysis of ATP The calcium pump hydrolyzes ATP, and the energy released from this chemical reaction is used to actively transport Ca2+ ions against their concentration gradient - from the cytoplasm to the extracellular fluid. In a resting cell, the calcium concentration in the extracellular fluid is about 20,000-fold greater than the concentration in the cytoplasm. This means that the calcium pump moves ions up a very large gradient.

The electric potential difference across the cell membrane is known as ______ A) the plasmalemma potential. B) the membrane difference. C) the cellular potential. D) the membrane potential. E) the cellular difference.

D) the membrane potential.

Which of the following best describes the difference between active and passive transport mechanisms? A) Active mechanisms use energy to move solutes with their concentration gradients. Passive mechanisms move solutes against their concentration gradients. B) Active mechanisms use the energy stored in a solute's concentration gradient. Passive mechanisms do not use energy. C)Active mechanisms use energy to move solutes out of the cell. Passive mechanisms move solutes into the cell. D)Active mechanisms use energy to move solutes against their concentration gradients. Passive mechanism move solutes with their concentration gradients.

D)Active mechanisms use energy to move solutes against their concentration gradients. Passive mechanism move solutes with their concentration gradients. Active transport is defined by its use of energy to transport solutes against their concentration gradient. In contrast, passive transport, such as facilitated diffusion does not use energy. In passive transport, solutes are transported with their concentration gradient. In general, this means that active transport moves solutes from a region of low concentration to a region of high. Passive transport does the opposite - moving solutes from a region of high concentration to a region of low.

Which of the following is not a major function of proteins in the cell membrane? A) anchoring cells to other structures B) acting as receptors C) forming channels D)forming the entire glycocalyx

D)forming the entire glycocalyx The glycocalyx is composed mostly of carbohydrates.