Human Anatomy & Physiology, 9e (Marieb/Hoehn)Chapter 3 Cells: The Living Units

3.1 Matching Questions

Figure 3.1

Using Figure 3.1, match the following:

1) Produces ATP aerobically.Answer: BDiff: 1 Page Ref: 94; Tbl. 3.3

2) Site of enzymatic breakdown of phagocytized material.Answer: CDiff: 1 Page Ref: 94; Tbl. 3.3

3) Packages proteins for insertion in the cell membrane or for exocytosis.Answer: EDiff: 1 Page Ref: 94; Tbl. 3.3

4) Site of synthesis of lipid and steroid molecules.Answer: ADiff: 1 Page Ref: 94; Tbl. 3.3

1Copyright © 2013 Pearson Education, Inc.

5) Forms the mitotic spindle.Answer: DDiff: 1 Page Ref: 94; Tbl. 3.3

6) Replicate for cell division.Answer: DDiff: 1 Page Ref: 94; Tbl. 3.3

7) Source of cell autolysis.Answer: CDiff: 2 Page Ref: 94; Tbl. 3.3

2Copyright © 2013 Pearson Education, Inc.

Figure 3.2

Using Figure 3.2, match the following:

8) Nonpolar region of phospholipid.Answer: CDiff: 1 Page Ref: 64; Fig. 3.3

9) Glycocalyx.Answer: ADiff: 1 Page Ref: 64; Fig. 3.3

10) Polar region of phospholipid.Answer: BDiff: 1 Page Ref: 64; Fig. 3.3

11) Peripheral protein.Answer: EDiff: 1 Page Ref: 64; Fig. 3.312) Integral protein.Answer: DDiff: 1 Page Ref: 64; Fig. 3.3

13) Identification "tags" for the cell.Answer: ADiff: 2 Page Ref: 64-65; Fig. 3.3

14) Hydrophilic portion of phospholipid.Answer: BDiff: 2 Page Ref: 64; Fig. 3.3

3Copyright © 2013 Pearson Education, Inc.

Match the following:

A) Transfer RNAB) Synthetase enzymesC) Ribosomal RNAD) ATPE) Messenger RNA

15) Forms part of the protein synthesis site in the cytoplasm.Diff: 1 Page Ref: 102

16) Act as "interpreter" molecules that recognize specific amino acids and nucleotide base sequences.Diff: 1 Page Ref: 102

17) Attaches the correct amino acid to its transfer RNA.Diff: 1 Page Ref: 104

18) Provides the energy needed for synthesis reactions.Diff: 1 Page Ref: 104

19) Produced in the nucleus, this molecule specifies the exact sequence of amino acids of the protein to be made.Diff: 1 Page Ref: 102

20) May be attached to the ER or scattered in the cytoplasm.Diff: 1 Page Ref: 102

Answers: 15) C 16) A 17) B 18) D 19) E 20) C

4Copyright © 2013 Pearson Education, Inc.

Match the following:

A) Late prophaseB) Early prophaseC) AnaphaseD) MetaphaseE) Telophase

21) Chromosomes uncoil to form chromatin.Diff: 1 Page Ref: 101; Fig. 3.33

22) Chromosomal centromeres split and chromosomes migrate to opposite ends of the cell.Diff: 1 Page Ref: 101; Fig. 3.33

23) Nuclear membrane and nucleolus disintegrate.Diff: 1 Page Ref: 100; Fig. 3.33

24) Chromosomes align on the spindle equator.Diff: 1 Page Ref: 101; Fig. 3.33

25) Centrioles move to opposite ends of the cell.Diff: 1 Page Ref: 101; Fig. 3.33

Answers: 21) E 22) C 23) A 24) D 25) B

5Copyright © 2013 Pearson Education, Inc.

Match the following:

A) NucleusB) MicrotubulesC) Endoplasmic reticulumD) RibosomesE) Nucleoli

26) Plays a role in the synthesis of steroid-based hormones and proteins.Diff: 2 Page Ref: 94; Table 3.3

27) The actual site of protein synthesis.Diff: 1 Page Ref: 94; Table 3.3

28) Hollow cytoskeletal elements that act as organizers for the cytoskeleton.Diff: 2 Page Ref: 95; Table 3.3

29) Dense spherical bodies in the nucleus that are the synthesis site for ribosomal RNA.Diff: 1 Page Ref: 96; Table 3.3

30) Houses DNA and RNA.Diff: 1 Page Ref: 95; Table 3.3

Answers: 26) C 27) D 28) B 29) E 30) A

Match the following:

A) Gap junctionsB) DesmosomesC) Tight junctions

31) Help prevent molecules from passing through the extracellular space between adjacent cells.Diff: 1 Page Ref: 66

32) Type of anchoring junction.Diff: 1 Page Ref: 66-67

33) Communicating junction.Diff: 1 Page Ref: 67

34) Present in electrically excitable tissues.Diff: 1 Page Ref: 67

35) Abundant in tissues subjected to great mechanical stress.Diff: 2 Page Ref: 66-67

Answers: 31) C 32) B 33) A 34) A 35) B

6Copyright © 2013 Pearson Education, Inc.

3.2 True/False Questions

1) Each daughter cell resulting from mitotic cell division has exactly as many chromosomes as the parent cell.Answer: TRUEDiff: 1 Page Ref: 98

2) Apoptosis is programmed cell suicide; cancer cells do not undergo this process.Answer: TRUEDiff: 1 Page Ref: 110

3) Introns represent a genome scrap yard that provides DNA segments for genome evolution and a variety of small RNA molecules.Answer: TRUEDiff: 2 Page Ref: 102

4) Final preparation for cell division is made during the cell life cycle subphase called G2.Answer: TRUEDiff: 2 Page Ref: 97

5) Lipid rafts, found in the cell outer membrane surface, are concentrating platforms for certain receptor molecules or for protein molecules needed for cell signaling..Answer: TRUEDiff: 3 Page Ref: 65

6) In osmosis, movement of water occurs toward the solution with the lower solute concentration.Answer: FALSEDiff: 2 Page Ref: 69-70

7) The genetic information is coded in DNA by the regular alternation of sugar and phosphate molecules.Answer: FALSEDiff: 1 Page Ref: 99

8) A process by which large particles may be taken into the protection of the body by invaders like bacteria, or for disposing of old or dead cells is called phagocytosis.Answer: TRUEDiff: 1 Page Ref: 75

9) The orderly sequence of the phases of mitosis is prophase, metaphase, anaphase, and telophase.Answer: TRUEDiff: 1 Page Ref: 100-1; Fig. 3.33

7Copyright © 2013 Pearson Education, Inc.

10) Diffusion movement always occurs from areas of greater to areas of lesser concentration.Answer: FALSEDiff: 1 Page Ref: 68

11) Facilitated diffusion always requires a carrier protein.Answer: FALSEDiff: 1 Page Ref: 69

12) DNA transcription is another word for DNA replication.Answer: FALSEDiff: 1 Page Ref: 102-103

13) The glycocalyx is often referred to as the "cell coat," which is somewhat fuzzy and sticky with numerous cholesterol chains sticking out from the surface of the cell membrane.Answer: FALSEDiff: 2 Page Ref: 65

14) In their resting state, all body cells exhibit a resting membrane potential ranging from -50 to about +50 millivolts.Answer: FALSEDiff: 1 Page Ref: 79

15) Microfilaments are thin strands of the contractile protein myosin.Answer: FALSEDiff: 2 Page Ref: 87-88

16) Interstitial fluid represents one type of extracellular material.Answer: TRUEDiff: 1 Page Ref: 110

17) Cholesterol helps to stabilize the cell membrane while decreasing the mobility of the phospholipids.Answer: TRUEDiff: 1 Page Ref: 65

18) Aquaporins are believed to be present in red blood cells and kidney tubules, but not in any other cells in the body.Answer: FALSEDiff: 1 Page Ref: 70

19) Most organelles are bounded by a membrane that is quite different in structure from the lipid bilayer of the plasma membrane.Answer: FALSEDiff: 2 Page Ref: 83

8Copyright © 2013 Pearson Education, Inc.

20) There is only one cell type in the human body that has a flagellum.Answer: TRUEDiff: 1 Page Ref: 90

21) Microtubules are hollow tubes made of subunits of the protein tubulin.Answer: TRUEDiff: 1 Page Ref: 88

22) Telomeres are the regions of chromosomes that code for the protein ubiquitin.Answer: FALSEDiff: 2 Page Ref: 111

23) Nitric oxide is known to be the first gas to act as a biological messenger.Answer: TRUEDiff: 1 Page Ref: 81

24) The speed of individual particle diffusion is influenced by temperature and particle size, not by concentration.Answer: TRUEDiff: 2 Page Ref: 68

25) Concentration differences cause ionic imbalances that polarize the cell membrane, and active transport processes.Answer: TRUEDiff: 2 Page Ref: 78-79

3.3 Multiple-Choice Questions

1) Which of the following is FALSE regarding the membrane potential?A) In their resting state, all body cells exhibit a resting membrane potential.B) The resting membrane potential occurs due to active transport of ions across the membrane due to the sodium-potassium pump.C) The resting membrane potential is determined mainly by the concentration gradients and differential permeability of the plasma membrane to K+ and Na+ions.D) The resting membrane potential is maintained by solely by passive transport processes.Answer: DDiff: 2 Page Ref: 79-80

2) Which vesicular transport process occurs primarily in some white blood cells and macrophages?A) exocytosisB) phagocytosisC) pinocytosisD) intracellular vesicular traffickingAnswer: BDiff: 3 Page Ref: 78; Tbl. 3.2

9Copyright © 2013 Pearson Education, Inc.

3) In certain kinds of muscle cells, calcium ions are stored in ________.A) the smooth ERB) the rough ERC) both smooth and rough ERD) the cytoplasmAnswer: ADiff: 1 Page Ref: 85

4) The RNA responsible for bringing the amino acids to the ribosome for protein formation is ________.A) rRNAB) mRNAC) tRNAD) ssRNAAnswer: CDiff: 1 Page Ref: 102

5) A red blood cell placed in pure water would ________.A) shrinkB) swell initially, then shrink as equilibrium is reachedC) neither shrink nor swellD) swell and burstAnswer: DDiff: 1 Page Ref: 71; Fig. 3.9

6) Which of the following describes the plasma membrane?A) a single-layered membrane that surrounds the nucleus of the cellB) a double layer of protein enclosing the plasmaC) a phospholipid bilayer surrounding the cellD) a membrane composed of tiny shelves or cristaeAnswer: CDiff: 1 Page Ref: 63-64

7) Which of these is not a function of the plasma membrane?A) It is selectively permeable but permits water and gases to cross.B) It prevents potassium ions from leaking out and sodium ions from crossing into the cell.C) It acts as a site of cell-to-cell interaction and recognition.D) It encloses the cell contents in such a way that water I the body is divided into separate compartments.Answer: BDiff: 1 Page Ref: 68

10Copyright © 2013 Pearson Education, Inc.

8) Which structures are fingerlike projections that greatly increase the absorbing surface of cells?A) stereociliaB) microvilliC) primary ciliaD) flagellaAnswer: BDiff: 1 Page Ref: 90

9) Which of the following statements is correct regarding net diffusion?A) The rate is independent of temperature.B) The greater the concentration gradient, the faster the rate.C) Molecular weight of a substance does not affect the rate.D) The lower the temperature, the faster the rate.Answer: BDiff: 2 Page Ref: 68

10) Which type of cell junction acts as anchors and distributes tension through a cellular sheet and reduces the chance of tearing when it is subjected to great mechanical stress?A) gap junctionsB) desmosomesC) connexonsD) tight junctionsAnswer: BDiff: 3 Page Ref: 66

11) If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen?A) The cells will swell and ultimately burst.B) The cells will lose water and shrink.C) The cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition.D) The cells will show no change due to diffusion of both solute and solvent.Answer: BDiff: 2 Page Ref: 71-72

12) What moves cell organelles from one location to another inside a cell?A) Motor proteinsB) MicrotubulesC) MicrofilamentsD) Intermediate filamentsAnswer: ADiff: 2 Page Ref: 88-89

11Copyright © 2013 Pearson Education, Inc.

13) Once solid material is phagocytized and taken into a vacuole, which of the following statements best describes what happens?A) A ribosome enters the vacuole and uses the amino acids in the "invader" to form new protein.B) A lysosome combines with the vacuole and digests the enclosed solid material.C) The vacuole remains separated from the cytoplasm and the solid material persists unchanged.D) The phagocytized material is stored until further breakdown can occur..Answer: BDiff: 1 Page Ref: 86-87

14) Riboswitches are folded RNAs that act as switches to turn protein synthesis on or off in response to ________.A) changes in the environmentB) specific tRNAsC) specific codes from the DNAD) the presence or absence of ubiquitinsAnswer: ADiff: 1 Page Ref: 105

15) Which of the following is a function of a plasma membrane protein?A) circulating antibodyB) molecular transport through the membraneC) forms a lipid bilayerD) oxygen transportAnswer: BDiff: 1 Page Ref: 65-66; Fig. 3.4

16) Which of the following statements is correct regarding RNA?A) Messenger RNA, transfer RNA, and ribosomal RNA play a role in protein synthesis.B) If the base sequence of DNA is ATTGCA, the messenger RNA template will be UCCAGU.C) There is exactly one specific type of mRNA for each amino acid.D) rRNA is always attached to the rough ER.Answer: ADiff: 2 Page Ref: 102

17) Which of the following would not be a constituent of a plasma membrane?A) glycolipidsB) messenger RNAC) glycoproteinsD) phospholipidsAnswer: BDiff: 1 Page Ref: 63-65

12Copyright © 2013 Pearson Education, Inc.

18) Mitosis ________.A) is the formation of sex cellsB) is division of the nucleusC) creates diversity in genetic potentialD) is always a part of the cell cycleAnswer: BDiff: 1 Page Ref: 98

19) The electron microscope has revealed that one of the components within the cell consists of pinwheel array of 9 triplets of microtubules arranged to form a hollow tube. This structure is a ________.A) centrosomeB) centrioleC) chromosomeD) ribosomeAnswer: BDiff: 2 Page Ref: 89

20) Which of these is an inclusion, not an organelle?A) melaninB) lysosomeC) microtubuleD) ciliaAnswer: ADiff: 1 Page Ref: 81

21) Which of the following is not a factor that binds cells together?A) glycoproteins in the glycocalyxB) glycolipids in the glycocalyxC) wavy contours of the membranes of adjacent cellsD) special membrane junctionsAnswer: BDiff: 2 Page Ref: 65

22) If the nucleotide or base sequence of the DNA strand used as a template for messenger RNA synthesis is ACGTT, then what would be the sequence of bases in the corresponding mRNA?A) TGCAAB) ACGTTC) UGCAAD) GUACCAnswer: CDiff: 2 Page Ref: 99; Fig. 3.40

13Copyright © 2013 Pearson Education, Inc.

23) Which transport process is the main mechanism for the movement of most macromolecules by body cells?A) phagocytosisB) pinocytosisC) receptor-mediated endocytosisD) secondary active transportAnswer: CDiff: 3 Page Ref: 76-77

24) Caveolae are closely associated with all of the following except ________.A) lipid raftsB) receptors for hormonesC) enzymes involved in cell regulationD) enzymes involved in cell metabolismAnswer: DDiff: 3 Page Ref: 76

25) Passive membrane transport processes include ________.A) movement of a substance down its concentration gradientB) movement of water from an area of high solute concentration to an area of low concentrationC) consumption of ATPD) the use of transport proteins when moving substances from areas of low to high concentrationAnswer: ADiff: 1 Page Ref: 68-72

26) Which of the following is NOT a function of the smooth endoplasmic reticulum?A) lipid metabolism and cholesterol synthesisB) steroid-based hormone synthesisC) breakdown of stored glycogen to form free glucoseD) protein synthesis in conjunction with ribosomesAnswer: DDiff: 1 Page Ref: 84

27) Mitochondria ________.A) are always the same shapeB) are single-membrane structures involved in the breakdown of ATPC) contain some of the DNA and RNA code necessary for their own functionD) synthesize proteins for use outside the cellAnswer: CDiff: 1 Page Ref: 83

14Copyright © 2013 Pearson Education, Inc.

28) Ribosomes, endoplasmic reticulum, and the Golgi apparatus functionally act in sequence to synthesize and modify proteins for secretory use (export) only, never for use by the cell. This statement is ________.A) false; proteins thus manufactured are for use inside the cell onlyB) false; integral cell membrane proteins are also synthesized this wayC) false; lipids, not proteins, are synthesized this wayD) trueAnswer: BDiff: 2 Page Ref: 83-85

29) Peroxisomes ________.A) are also called microbodies, and contain acid hydrolasesB) are able to detoxify substances by enzymatic actionC) function to digest particles ingested by endocytosisD) sometimes function as secretory vesiclesAnswer: BDiff: 2 Page Ref: 85-86

30) Which of the following is NOT a function of lysosomes?A) digesting particles taken in by endocytosisB) degrading worn-out or nonfunctional organellesC) forming acid hydrolases which are necessary to help form cell membranesD) breaking down bone to release calcium ions into the bloodAnswer: CDiff: 1 Page Ref: 86-87

31) Which statement is the most correct regarding transcription/translation?A) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it.B) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.C) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it.D) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine.Answer: DDiff: 3 Page Ref: 102-105

32) In which stage of mitosis do the identical sets of chromosomes uncoil and resume their chromatin form?A) prophaseB) metaphaseC) anaphaseD) telophaseAnswer: DDiff: 1 Page Ref: 101; Fig. 3.32

15Copyright © 2013 Pearson Education, Inc.

33) Which of the following is NOT a role of cell adhesion molecules:A) anchor cells to molecules in the extracellular space and to each otherB) mechanical sensorsC) initiators of cell-to-cell signaling for muscle contractionD) transmitters of intracellular signals that direct cell migration, proliferation, and specializationAnswer: CDiff: 2 Page Ref: 80

34) Which of the following does not serve as a signal for cell division?A) repressor genesB) joining of cyclins and CdksC) loss of contact inhibitionD) shrinking surface-to-volume ratioAnswer: ADiff: 3 Page Ref: 99

35) Which of the following is a principle of the fluid mosaic model of cell membrane structure?A) Phospholipids form a bilayer that is largely impermeable to water-soluble molecules.B) Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains.C) The lipid bilayer is a solid at body temperature, thus protecting the cell.D) All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell.Answer: ADiff: 1 Page Ref: 63-64

36) Which of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"?A) Second messengers act through receptors called K-proteins.B) Second messengers usually inactivate protein kinase enzymes.C) Cyclic AMP and calcium may be second messengers.D) Second messengers usually act to remove nitric oxide (NO) from the cell.Answer: CDiff: 1 Page Ref: 81; Fig. 3.16

37) The main component of the cytosol is ________.A) proteinsB) sugarsC) saltsD) waterAnswer: DDiff: 1 Page Ref: 81

16Copyright © 2013 Pearson Education, Inc.

38) The functions of centrioles include ________.A) organizing the mitotic spindle in cell divisionB) providing a whiplike beating motion to move substances along cell surfacesC) serving as the site for ribosomal RNA synthesisD) producing ATPAnswer: ADiff: 1 Page Ref: 89

39) A gene can best be defined as ________.A) a three-base triplet that specifies a particular amino acidB) noncoding segments of DNA up to 100,000 nucleotides longC) a segment of DNA that carries the instructions for one polypeptide chainD) an RNA messenger that codes for a particular polypeptideAnswer: CDiff: 2 Page Ref: 99

40) Crenation (shrinking) is likely to occur in blood cells immersed in ________.A) an isotonic solutionB) a hypotonic solutionC) a hypertonic solutionD) blood plasmaAnswer: CDiff: 3 Page Ref: 71

41) Some hormones enter cells via ________.A) exocytosisB) primary active transportC) pinocytosisD) receptor-mediated endocytosisAnswer: DDiff: 1 Page Ref: 76

42) If a tRNA had an AGC anticodon, it could attach to a(n) ________ mRNA codon.A) AUGB) UCGC) TCGD) UGAAnswer: BDiff: 1 Page Ref: 99

3.4 Fill-in-the-Blank/Short Answer Questions

1) The RNA that has an anticodon and attaches to a specific amino acid is ________ RNA.Answer: transferDiff: 1 Page Ref: 102

17Copyright © 2013 Pearson Education, Inc.

2) Water may move through membrane pores constructed by transmembrane proteins called ________.Answer: aquaporinsDiff: 2 Page Ref: 70

3) ________ is the division of the cytoplasmic mass into two parts.Answer: CytokinesisDiff: 1 Page Ref: 98-99

4) The metabolic or growth phase of a cell life cycle is called ________.Answer: interphaseDiff: 1 Page Ref: 96

5) In order for the DNA molecule to get "short and fat" to become a chromosome, it must first wrap around small molecules called ________.Answer: histonesDiff: 1 Page Ref: 93; Fig. 3.30

6) ________ are hollow tubes made of spherical protein subunits called tubulins.Answer: MicrotubulesDiff: 1 Page Ref: 88

7) Aerobic cellular respiration occurs in the ________.Answer: mitochondriaDiff: 1 Page Ref: 83

8) What major chemical is responsible for apoptosis?Answer: caspasesDiff: 3 Page Ref: 110

9) The most common extracellular ion is ________.Answer: sodiumDiff: 1 Page Ref: 79-80

10) The process of discharging particles from inside a cell to the outside is called ________.Answer: exocytosisDiff: 1 Page Ref: 77-78

11) A red blood cell would swell if its surrounding solution were ________.Answer: hypotonicDiff: 1 Page Ref: 71; Fig. 3.9

12) Hollow cylinders that connect plasma membranes composed of transmembrane protein are called ________.Answer: connexonDiff: 1 Page Ref: 67; Fig. 3.5

18Copyright © 2013 Pearson Education, Inc.

13) Describe two important functions of the Golgi apparatus.Answer: To modify, sort, and package proteins.Diff: 3 Page Ref: 85

14) Why can we say that a cell without a nucleus will ultimately die?Answer: Without a nucleus, a cell cannot make proteins, nor can it replace any enzymes or other cell structures (which are continuously recycled). Additionally, such a cell could not replicate.Diff: 3 Page Ref: 91

15) Are Brownian motion, diffusion, and osmosis seen only in living tissue?Answer: No. Because they are passive processes that do not require energy, they can occur in the absence of any cellular processes.Diff: 3 Page Ref: 72

16) What processes maintain a steady state "resting" membrane potential?Answer: Both diffusion and active transport mechanisms operate within the cell membrane to maintain a resting membrane potential.Diff: 3 Page Ref: 79-80

17) Briefly describe the glycocalyx and its functions.Answer: The glycocalyx is the sticky, carbohydrate-rich area on the cell surface. It helps bind cells together and provides a highly specific biological marker by which cells can recognize each other.Diff: 3 Page Ref: 65

18) Explain the term genetic code. What does it code for? What are the letters of the code?Answer: The genetic code is the information encoded in the nucleotide base sequence of DNA. A sequence of three bases, called a triplet, specifies an amino acid in a protein. The letters of the code are the four nucleotide bases of DNA designated as A, T, C, and G.Diff: 3 Page Ref: 104; Fig. 3.36

19) Why are free radicals so dangerous to cells, and how are they dealt with by the body?Answer: Free radicals are highly reactive chemicals that cause havoc in any cellular environment by reacting with things they should not. Cells with peroxisomes have enzymes specific to reducing free radicals into less reactive chemicals.Diff: 3 Page Ref: 85-86

20) In all living cells hydrostatic and osmotic pressures exist. Define these pressures and explain how they are used in the concept of tonicity of the cell.Answer: Hydrostatic pressure is the pressure of water exerted on the cell membrane. Osmotic pressure is created by different concentrations of molecules in a solution separated by the cell membrane. Because these pressures are exerted on the membrane they can be used by the cell to change the shape of the cell, regulate substances entering and exiting the cell, and change the osmolarity of the cell.Diff: 3 Page Ref: 71

21) What is the common route of entry for flu viruses into a cell?

19Copyright © 2013 Pearson Education, Inc.

Answer: Flu viruses and diphtheria toxins use receptor-mediated endocytosis. The virus can attach to the receptors or to the substances the receptors accept to "hitch a ride" into the cell.Diff: 3 Page Ref: 76

22) Other than the nucleus, which organelle has its own DNA?Answer: Mitochondria.Diff: 2 Page Ref: 83

23) How are the products of free ribosomes different from membrane-bound ribosomes?Answer: Free ribosomes make soluble proteins that function in the cytosol. Membrane-bound ribosomes produce proteins that are to be used on the cell membrane or exported from the cell.Diff: 2 Page Ref: 83-84

24) How are peroxisomes different from lysosomes?Answer: Peroxisomes contain oxidases that use oxygen to detoxify harmful substances. They are very good at neutralizing free radicals. Peroxisomes directly bud from the ER. Lysosomes contain powerful hydrolytic enzymes that will pretty much destroy anything they come in contact with. They are manufactured by the Golgi apparatus.Diff: 2 Page Ref: 85-86

25) Briefly name the subphases of interphase and tell what they do.Answer: G1 - growth phase. The cell is metabolically active and the centriole begins to divide at the end of this phase.S - DNA replicates itself. New histones are made and assembled into chromatin.G2 - Enzymes and proteins are synthesized and centriole replication is completed. This is the final phase of interphase.Diff: 2 Page Ref: 96-97

26) What are nucleolar organizer regions?Answer: nuclear regions containing the DNA that issues genetic instructions for synthesizing ribosomal RNADiff: 2 Page Ref: 93

27) How is the resting potential formed? How is it maintained?Answer: It is formed by diffusion-limited concentration differences of ions resulting in ionic imbalances that polarize the membrane. It is maintained by active transport processes.Diff: 3 Page Ref: 79-80; Fig. 3.15

28) List possible causes of aging.Answer: 1. chemical insults and free radical formation (wear and tear theory)2. diminished energy production by free radical-damaged mitochondria3. progressive disorders in the immune system4. genetic programmingDiff: 3 Page Ref: 111

20Copyright © 2013 Pearson Education, Inc.

29) What factors contribute to the fragility of the lysosome and subsequent cell autolysis?Answer: cell injury, cell oxygen deprivation, presence of excessive amounts of vitamin A in the cellDiff: 3 Page Ref: 86-87

30) Why can we say that cells are protein factories?Answer: Most of the metabolic machinery of the cell is involved in protein synthesis since structural proteins constitute most of the dry cell material and functional proteins direct all cellular activities.Diff: 3 Page Ref: 99

31) What are cell exons and introns?Answer: Exons are amino acid-specifying informational sequences in genes. Introns are noncoding gene segments that provide a reservoir of ready-to-use DNA segments for genome evolution and a source of a large variety of RNA molecules.Diff: 3 Page Ref: 102

32) What are lipid rafts? What are their functions?Answer: They are assemblies of saturated phospholipids associated with sphingolipids and cholesterol. They are concentrating platforms for molecules needed for cell signaling.Diff: 3 Page Ref: 65

3.5 Clinical Questions

1) A patient was admitted to the hospital for severe dehydration. Explain what changes occur in extracellular and intracellular fluid compartments during dehydration.Answer: Fluid volume deficit occurs when the body loses both water and electrolytes from the extracellular fluid compartment. Fluid is initially lost from the intravascular compartment (blood). Then fluid is drawn from the interstitial compartment into the intravascular compartment, depleting the interstitial compartment. To compensate for the decreased volume, the body then draws intracellular fluid out of the cells. This could lead to collapse and death.Diff: 3 Page Ref: 69-72

2) Your patient has the flu and reports 5—6 loose stools a day. He has experienced an isotonic fluid volume loss. Explain what an isotonic fluid loss means.Answer: An isotonic fluid volume loss occurs when water and electrolytes are lost in equal proportion.Diff: 3 Page Ref: 71

3) At of age of 6 months, Caleb was diagnosed with Tay-Sachs disease. As his primary care physician, what would you tell his parents about this disease?Answer: It is an inherited condition where various chemicals are broken down in the brain by a cell organelle called the lysosome. Unfortunately, because of the buildup of undigested nerve cell lipids, the symptoms of listlessness and motor weakness will progress to mental retardation, seizures, blindness, and ultimately death.Diff: 3 Page Ref: 87

21Copyright © 2013 Pearson Education, Inc.

4) Your patient has a respiratory disease that has literally paralyzed the cilia. Explain why this patient would be at an increased risk for a respiratory infection.Answer: Ciliated cells that live in the respiratory tract propel mucus, laden with dust particles and bacteria, upward and away from the lungs. If the cilia are paralyzed, bacteria remain in the lungs and may cause infection.Diff: 3 Page Ref: 90-91

5) Describe the difference in cell division between normal cells and cancer cells.Answer: Normal cells divide in two distinct events–mitosis and cytokinesis which are well-controlled. Cancer cells divide wildly, with uncontrollable mechanisms and defective mitosis, sometimes ending in unequal chromosome sets, which makes them dangerous to their host.Diff: 3 Page Ref: 99

6) Research shows that neurofibrillary tangles associated with the disintegration of microtubules are the primary cause of Alzheimer's disease. If microtubules disintegrate, what then might happen to brain cells?Answer: Microtubules determine cell shape and intracellular movement. They are dynamic organelles constantly growing from the centrosome, dissembling, and then reassembling. Without microtubules, the elongated brain cell might either lose shape or lose its ability to move materials from end to end and keep its distant parts well-supplied and alive. Loss of signal followed by cell death result.Diff: 3 Page Ref: 88

22Copyright © 2013 Pearson Education, Inc.