Cell Structure and Function

Cell Structure and Function
chapter 4 Cell Structure and Function 1

Chapter 4 At a Glance 4.1 What Is the Cell Theory?
4.2 What Are the Basic Attributes of Cells? 4.3 What Are the Major Features of Prokaryotic Cells? 4.4 What Are the Major Features of Eukaryotic Cells? © 2017 Pearson Education, Ltd.

4.1 What Is the Cell Theory? Cell theory
Every organism is made up of at least one cell The smallest organisms are unicellular, and cells are the functional units of multicellular organisms All cells arise from preexisting cells; this means that cells are the basic units of life © 2017 Pearson Education, Ltd.

4.2 What Are the Basic Attributes of Cells?
Most cells range in size from about 1 to 100 micrometers (millionths of a meter) in diameter © 2017 Pearson Education, Ltd.

human eye light microscope electron microscope Figure 4-1
1 cm 1 mm 100 m 10 m 1 m 100 nm 10 nm 1 nm 0.1 nm longest python house fly DNA apple most eukaryotic cells flu virus C most prokaryotic cells tallest redwood tree human crab hemoglobin carbon atom louse Figure 4-1 Relative sizes human eye light microscope electron microscope © 2017 Pearson Education, Ltd.

Cells are so small to ensure access to their environment Many nutrients and wastes move in and out of cells by diffusion Molecules dissolved in fluids disperse from regions where their concentration is higher to regions where their concentration is lower © 2017 Pearson Education, Ltd.

Plasma membrane Phospholipid bilayer interspersed with cholesterol Barrier between interior and exterior of cell Embedded proteins Communication portals Regulate passage of molecules and ions © 2017 Pearson Education, Ltd.

(interstitial fluid, outside) carbo- hydrate
Figure 4-2 (interstitial fluid, outside) carbo- hydrate glycoprotein A phospholipid bilayer helps to isolate the cell’s contents. Proteins help the cell communicate with its environment. cholesterol Figure 4-2 The plasma membrane channel protein membrane protein cytoskeleton (cytosol, fluid inside cell) © 2017 Pearson Education, Ltd.

Cytoplasm All the fluid and structures inside the plasma membrane but outside the nucleus Site of most biochemical reactions that support life Cytosol Fluid portion of cytoplasm Water, salts, organic molecules © 2017 Pearson Education, Ltd.

Figure 4-4 A generalized animal cell
microfilaments (cytoskeleton) cytosol cytoplasm Figure 4-4 A generalized animal cell © 2017 Pearson Education, Ltd.

Two basic types of cells Prokaryotic (“before nucleus”) cells form the bodies of bacteria and archaea, the simplest forms of life No nuclei Eukaryotic (“true nucleus”) cells form the bodies of animals, plants, fungi, and protists Far more complex Nuclei © 2017 Pearson Education, Ltd.

The plasma membrane performs all of the following functions except _____.
regulating flow of materials into and out of the cell facilitating protein synthesis providing a barrier facilitating communication with other cells Question: 4-4 Answer: b Diff: Easy Text Ref: Section 4.2 Skill: Factual Also relates to: Chapter 5 Notes: Use this question to establish the importance of concentration gradients, discussed in the next chapter. The process of diffusion will come up in various chapters throughout the book, such as the chapters on circulatory and endocrine systems, so it is important for students to understand concentration gradients. © 2017 Pearson Education, Ltd. 16

The plasma membrane performs all of the following functions except _____.
regulating flow of materials into and out of the cell facilitating protein synthesis providing a barrier facilitating communication with other cells Question: 4-4 Answer: b Diff: Easy Text Ref: Section 4.2 Skill: Factual Also relates to: Chapter 5 Notes: Use this question to establish the importance of concentration gradients, discussed in the next chapter. The process of diffusion will come up in various chapters throughout the book, such as the chapters on circulatory and endocrine systems, so it is important for students to understand concentration gradients. © 2017 Pearson Education, Ltd. 17

Where do most of the metabolic activities take place within the cell?
Cytoskeleton Cytoplasm Endoplasmic reticulum Golgi apparatus Question: 4-5 Answer: b Diff: Easy Text Ref: Section 4.2 Skill: Factual Also relates to: Chapter 5 Notes: This question links to the next three chapters, which cover energy and metabolic processes such as cell respiration and photosynthesis. © 2017 Pearson Education, Ltd. 18

Where do most of the metabolic activities take place within the cell?
Cytoskeleton Cytoplasm Endoplasmic reticulum Golgi apparatus Question: 4-5 Answer: b Diff: Easy Text Ref: Section 4.2 Skill: Factual Also relates to: Chapter 5 Notes: This question links to the next three chapters, which cover energy and metabolic processes such as cell respiration and photosynthesis. © 2017 Pearson Education, Ltd. 19

What would happen if a cell stopped making properly functioning RNA?
Nothing. The cell would function properly. The cell would not be able to translate the information in protein into DNA. The cell would not be able to translate the information in DNA into protein. The cell would not be able to translate the information in DNA into lipids. Question: 4-6 Answer: c Diff: Easy Text Ref: Section 4.2 Skill: Application Notes: By foreshadowing the chapter on transcription and translation, this question introduces students to the connection between DNA, RNA, and protein. © 2017 Pearson Education, Ltd. 20

What would happen if a cell stopped making properly functioning RNA?
Nothing. The cell would function properly. The cell would not be able to translate the information in protein into DNA. The cell would not be able to translate the information in DNA into protein. The cell would not be able to translate the information in DNA into lipids. Question: 4-6 Answer: c Diff: Easy Text Ref: Section 4.2 Skill: Application Notes: By foreshadowing the chapter on transcription and translation, this question introduces students to the connection between DNA, RNA, and protein. © 2017 Pearson Education, Ltd. 21

4.3 What Are the Major Features of Prokaryotic Cells?
Unicellular Relatively simple internal structure Not compartmentalized like eukaryotic cells On average, 100x smaller than eukaryotic cells © 2017 Pearson Education, Ltd.

Prokaryote shapes include rod-shaped bacilli, spiral-shaped spirilla, and spherical cocci Pili are surface proteins projecting from the cell wall; they may be short and numerous (attachment pili) or long and few (sex pili). A plasmid is a small ring of DNA. © 2017 Pearson Education, Ltd.

Figure 4-3a Prokaryotic cells
© 2017 Pearson Education, Ltd.

Figure 4-3b Prokaryotic cells

Figure 4-3c Prokaryotic cells

Prokaryotic cells have specialized surface features Nearly all have a cell wall Stiff protective coating Contains peptidoglycan in bacteria Some produce adhesive capsules, slime layers, and/or attachment pili Many form sex pili for transfer of plasmids Some feature flagella for propulsion Pili are surface proteins projecting from the cell wall; they may be short and numerous (attachment pili) or long and few (sex pili). A plasmid is a small ring of DNA. © 2017 Pearson Education, Ltd.

(a) Generalized prokaryotic cell (bacillus)
Figure 4-3a chromosome (within the nucleoid region) pili ribosomes plasmid (DNA) food granule Figure 4-3a Prokaryotic cells capsule or slime layer cytoplasm prokaryotic flagellum plasma membrane cell wall (a) Generalized prokaryotic cell (bacillus) © 2017 Pearson Education, Ltd.

Prokaryotic cells have specialized cytoplasmic structures Nucleoid A region that is not enclosed by a membrane Contains a single circular strand of DNA Most also feature plasmids outside the nucleoid Food granules Some have internal folds to harness light energy Plasmids are small rings of DNA. © 2017 Pearson Education, Ltd.

(e) Photosynthetic prokaryotic cell
Figure 4-3e photosynthetic membranes Figure 4-3e Prokaryotic cells (e) Photosynthetic prokaryotic cell © 2017 Pearson Education, Ltd.

If a cell had a nucleoid, it most likely would be a(n) _____.
animal cell plant cell fungal cell bacterial cell Question: 4-16 Answer: d Diff: Easy Text Ref: Section 4.4 Skill: Factual Notes: Only bacteria have their DNA free in the cell instead of being surrounded by a nuclear membrane. The free bacterial DNA is called a nucleoid. © 2017 Pearson Education, Ltd. 32

If a cell had a nucleoid, it most likely would be a(n) _____.
animal cell plant cell fungal cell bacterial cell Question: 4-16 Answer: d Diff: Easy Text Ref: Section 4.4 Skill: Factual Notes: Only bacteria have their DNA free in the cell instead of being surrounded by a nuclear membrane. The free bacterial DNA is called a nucleoid. © 2017 Pearson Education, Ltd. 33

4.4 What Are the Major Features of Eukaryotic Cells?
Unicellular and multicellular species Organelles within cells Specialized membrane-enclosed structures Domain Eukarya © 2017 Pearson Education, Ltd.

ribosomes nuclear envelope microfilaments (cytoskeleton) nuclear pore nucleus chromatin (DNA) nucleolus cytosol microtubule (cytoskeleton) flagellum (propels sperm cell) basal body rough endoplasmic reticulum vesicle intermediate filaments (cytoskeleton) cytoplasm centriole Golgi apparatus Figure 4-4 A generalized animal cell Distinct structures of animal cells include Centrioles Lysosomes Cilia ribosomes on rough ER polyribosome lysosome smooth endoplasmic reticulum vesicles releasing substances from the cell mitochondrion plasma membrane free ribosome © 2017 Pearson Education, Ltd.

Figure 4-5 A generalized plant cell
ribosomes nuclear envelope nuclear pore nucleus chromatin microfilaments (cytoskeleton) microtubule (cytoskeleton) nucleolus cell walls of adjoining plant cells chloroplast cytoplasm rough endoplasmic reticulum intermediate filaments vesicles Figure 4-5 A generalized plant cell Distinct structures of plant cells include Cell walls Central vacuoles Plastids smooth endoplasmic reticulum Golgi apparatus central vacuole mitochondrion vesicle cell wall plasma membrane plasmodesmata cytosol plastid free ribosome © 2017 Pearson Education, Ltd.

Extracellular matrix (ECM) Reinforces plasma membrane Sits just outside the plasma membrane In animals, includes supporting and adhesive proteins as well as chemical signals in a polysaccharide gel The ECM may differ from one tissue to another and from one species to another. © 2017 Pearson Education, Ltd.

Figure 4-6 The extracellular matrix
(interstitial fluid, outside) support protein extracellular matrix adhesion protein gel-forming substance cartilage cell Figure 4-6 The extracellular matrix (a) The extracellular matrix (b) Extracellular matrix of a cartilage cell © 2017 Pearson Education, Ltd.

Cytoskeleton proteins Within the cytoplasm Three major types Thin microfilaments of actin protein Medium-sized intermediate filaments of various proteins Thick microtubules of tubulin protein © 2017 Pearson Education, Ltd.

Figure 4-7 The eukaryotic cytoskeleton
subunit ribosomes rough endoplasmic reticulum 25 nm microfilaments (red) Microtubules: Composed of pairs of different polypeptides in a helical arrangement subunit 10 nm Intermediate filaments: Composed of ropelike bundles of various proteins subunits Figure 4-7 The eukaryotic cytoskeleton DNA in nucleus (blue) cell membrane 7 nm mitochondrion microtubules (green) Microfilaments: Composed of actin proteins that resemble twisted double strands of beads (a) Cytoskeleton (b) Light micrograph showing the cytoskeleton © 2017 Pearson Education, Ltd.

Cytoskeleton proteins Can alter cell shape By shortening, lengthening, or sliding past each other Requires energy (ATP) In animal cells, a scaffolding of intermediate filaments supports the cell, helps determine its shape, and links cells to one another and to the ECM. An array of microfilaments concentrated just inside the plasma membrane provides additional support and also connects with the surrounding ECM. © 2017 Pearson Education, Ltd.

Cytoskeleton proteins (continued) Can elicit movement May lengthen one end while shortening the other May act as railroad tracks for motor proteins moving molecules or organelles within the cell May be pulled by motor proteins (as in muscle cells) © 2017 Pearson Education, Ltd.

Cilia and eukaryotic flagella (continued) Each contains a ring of nine fused pairs of microtubules surrounding an unfused pair Basal body = uncoated portion extending into cytoplasm Composed of nine fused triplets and no central pair Produced by centrioles The structure of prokarytotic and eukaryotic flagella differs greatly. © 2017 Pearson Education, Ltd.

Figure 4-8 Cilia and flagella
cilia lining trachea protein sidearms fused microtubule pair (b) Cilia central pair of microtubules TEM showing cross- section Figure 4-8 Cilia and flagella flagellum of human sperm plasma membrane basal body (extends into cytoplasm) (a) Internal structure of cilia and flagella (c) Flagellum © 2017 Pearson Education, Ltd.

Cilia Beat in unison, like oars Shorter and more numerous than flagella Flagellum Rotate in a corkscrew motion, like a propeller When present, there are usually one or two © 2017 Pearson Education, Ltd.

Protists use cilia or flagella to swim through water In animals, cilia usually move fluids past a surface Gills of oysters Female reproductive tract of vertebrates Respiratory tract of most terrestrial vertebrates Most animal sperm cells are propelled by flagella © 2017 Pearson Education, Ltd.

Nuclear envelope Isolates nucleus from rest of the cell Double membrane Perforated by nuclear pores Passage of large molecules is regulated by the nuclear pore complex (gatekeeper proteins lining each pore) Studded on outer surface by ribosomes Continuous with membranes of endoplasmic reticulum © 2017 Pearson Education, Ltd.

Figure 4-9 Figure 4-9 The nucleus nuclear envelope nuclear pores
ribosomes Figure 4-9 The nucleus nuclear pores with nuclear pore complex © 2017 Pearson Education, Ltd.

Chromatin Nuclear material within nucleus Composed of chromosomes DNA molecules and their associated proteins Extremely long, indistinguishable strands when a cell is not dividing (most of the time) Condensed, distinct during cell division © 2017 Pearson Education, Ltd.

chromatin Figure 4-9a Figure 4-9a The nucleus

chromatin chromosome Figure 4-10 Figure 4-10 Chromosomes

Genes Specific sequences of nucleotides Molecular blueprint for synthesis of proteins and ribosomes Some proteins provide structure Some regulate movement of materials through membranes Some act as enzymes © 2017 Pearson Education, Ltd.

Protein synthesis occurs in the cytoplasm, but DNA is confined to the nucleus Copies of genes must be ferried from nucleus to cytoplasm Genes are copied from DNA to messenger RNA (mRNA) mRNA moves through nuclear pores into cytosol mRNA is translated into protein on ribosomes © 2017 Pearson Education, Ltd.

nucleolus Figure 4-9a Figure 4-9a The nucleus

Ribosomes Small particles of rRNA and proteins Workbench for protein synthesis Some appear as singletons in cytoplasm Some (polyribosomes) are strung together in cytoplasm Some stud the membranes of the nuclear envelope and rough endoplasmic reticulum © 2017 Pearson Education, Ltd.

ribosome mRNA polyribosome growing protein amino acid Figure 4-11
Figure A polyribosome growing protein amino acid © 2017 Pearson Education, Ltd.

Endomembrane system Internal membranes loosely connecting compartments Segregates molecules and orders biochemical processes Includes the nuclear envelope, vesicles, endoplasmic reticulum, Golgi apparatus, and lysosomes © 2017 Pearson Education, Ltd.

Vesicles Temporary sacs, tagged with “mailing label” amino acids by rough endoplasmic reticulum, that ferry molecules with the help of motor proteins Bud from and fuse with the endomembrane system and plasma membrane Exocytosis = fusion with plasma membrane to export the vesicle’s contents outside the cell Endocytosis = in-pocketing of plasma membrane to surround material with a vesicle and import it © 2017 Pearson Education, Ltd.

Endoplasmic reticulum (ER) Labyrinth of narrow channels forming interconnected sacs and tubules Typically makes up at least 50% of the total cellular membrane Important in the synthesis, modification, and transport of molecules Has both rough and smooth membranes, continuous with each other © 2017 Pearson Education, Ltd.

Rough ER Continuous with nuclear envelope; both are ribosome-studded As proteins are synthesized on ribosomes, some are extruded into the ER Some proteins remain within Many proteins are modified, properly folded, and sent to the Golgi apparatus (via vesicles) Others, on the outside of the rough ER, function in synthesis of new phospholipid membrane © 2017 Pearson Education, Ltd.

ribosomes rough ER Figure 4-12a Figure 4-12a Endoplasmic reticulum

Smooth ER Lacks ribosomes Also involved in synthesis of new membrane In some cells, produces other lipids, converts glycogen, stores ions, or breaks down harmful molecules © 2017 Pearson Education, Ltd.

smooth ER Figure 4-12a Figure 4-12a Endoplasmic reticulum

Golgi apparatus (or simply Golgi) Flattened, interconnected sacs Gives final touches to synthates Sorting Mailing labels Placement into vesicles Vesicles from the rough ER fuse with “receiving” face; vesicles carrying final product bud off “shipping” face © 2017 Pearson Education, Ltd.

modified protein leave the Golgi apparatus.
Figure 4-13 Protein-carrying vesicles from the ER merge with the Golgi apparatus. Figure The Golgi apparatus Golgi apparatus Vesicles carrying modified protein leave the Golgi apparatus. © 2017 Pearson Education, Ltd.

Overview of endomembrane pathway, using antibodies as an example.
Figure 4-14 (interstitial fluid) Vesicles merge with the plasma membrane and release antibodies into the interstitial fluid by exocytosis. (cytosol) Completed glycoprotein antibodies are packaged into vesicles on the opposite side of the Golgi apparatus. vesicles Golgi apparatus Vesicles fuse with the Golgi apparatus, and carbohydrates are added as the protein passes through the compartments. Figure A protein is manufactured and exported through the endomembrane system Overview of endomembrane pathway, using antibodies as an example. The protein is packaged into vesicles and travels to the Golgi apparatus. forming vesicle Antibody protein is synthesized on ribosomes and is transported into channels of the rough ER. © 2017 Pearson Education, Ltd.

Lysosomes Membrane-bound sacs Hydrolyze various biological molecules when fused with a food vacuole Food vacuoles are relatively large sacs formed during endocytosis of nutrients Also digest old or defective organelles © 2017 Pearson Education, Ltd.

Figure 4-15 (interstitial fluid) food Food particles are taken into the cell by endocytosis. (cytosol) food vacuole A lysosome fuses with a food vacuole, and the enzymes digest the food. The enzymes are delivered to the lysosome in vesicles. lysosome The Golgi apparatus modifies the enzymes for export to the lysosomes. Golgi apparatus The enzymes are packaged into vesicles and travel to the Golgi apparatus. Figure Lysosomes and food vacuoles are formed by the endomembrane system digestive enzymes Digestive enzymes are synthesized on ribosomes and travel through the rough ER. © 2017 Pearson Education, Ltd.

Vacuoles Some are temporary Others persist for the life of the cell Contractile vacuoles in freshwater protists prevent lysis Central vacuoles in plant cells Large Involved in osmoregulation, storage, concentration of pigments, turgor pressure © 2017 Pearson Education, Ltd.

Figure 4-16 A contractile vacuole
Water enters the collecting ducts and fills the central reservoir. (a) Paramecium collecting ducts central reservoir Figure A contractile vacuole pore The reservoir contracts, expelling water through the pore. (b) Contractile vacuole © 2017 Pearson Education, Ltd.

Endosymbiont hypothesis Mitochondria and chloroplasts evolved from prokaryotic bacteria roughly 1.7 billion years ago Prokaryotes gained entry into other prokaryotes without being digested and, over time, became interdependent and inseparable Evidence Both organelles are surrounded by a double membrane, the inner membrane more akin to modern-day prokaryote plasma membrane and the outer membrane more akin to modern-day eukaryotic plasma membrane. Mitochondria, chloroplasts, and average prokaryotic cells fall into the same size range. Both feature their own circular DNA, void of introns and histones, like prokaryotes. Both feature small ribosomes, like prokaryotes. Mitochondria, chloroplasts, and prokaryotes all reproduce via binary fission. © 2017 Pearson Education, Ltd.

Figure 4-17 A mitochondrion
outer membrane inner membrane intermembrane space matrix Figure A mitochondrion The outer membrane is smooth, whereas the inner membrane forms deep folds called cristae. The mitochondrial membranes enclose two fluid-filled spaces: the intermembrane compartment lies between the two membranes, and the matrix fills the space within the inner membrane. Some of the reactions that break down high-energy molecules occur in the fluid of the matrix; the rest are conducted by a series of enzymes attached to the membranes of the cristae. cristae © 2017 Pearson Education, Ltd.

Figure 4-18 The chloroplast is a complex plastid
outer membrane inner membrane stroma thylakoid channel interconnecting thylakoids Figure The chloroplast is a complex plastid Chloroplasts are surrounded by a double membrane. The inner membrane of the chloroplast encloses a fluid called the stroma. Within the stroma are interconnected stacks of hollow, membranous sacs. An individual sac is called a thylakoid, and a stack of thylakoids is a granum. The thylakoid membranes contain chlorophyll. During photosynthesis, chlorophyll captures the energy of sunlight and transfers it to other molecules in the thylakoid membranes. These molecules transfer the energy to ATP and other energy carriers. The energy carriers diffuse into the stroma, where their energy is used to drive the synthesis of sugar from carbon dioxide and water. granum (stack of thylakoids) © 2017 Pearson Education, Ltd.

Plastids Synthesize and/or store pigments or food molecules Fruit color Flower color Starch Lipids Only found in plants and photosynthetic protists Chloroplasts, elaioplasts (lipid-storing), and amyloplasts (starch-storing) are types of plastids. © 2017 Pearson Education, Ltd.

Animation: Tour of an Animal Cell Animation

Animation: Tour of a Plant Cell Animation

Which is NOT an organelle of animal cells?
Plastid Mitochondrion Endoplasmic reticulum Golgi apparatus Question: 4-1 Answer: a Diff: Easy Text Ref: Section 4.3 Skill: Factual Notes: All eukaryotic cells possess mitochondria, endoplasmic reticulum, and Golgi apparatus. Only plant cells have plastids, chloroplasts, and cell walls. © 2017 Pearson Education, Ltd. 91

Which is NOT an organelle of animal cells?
Plastid Mitochondrion Endoplasmic reticulum Golgi apparatus Question: 4-1 Answer: a Diff: Easy Text Ref: Section 4.3 Skill: Factual Notes: All eukaryotic cells possess mitochondria, endoplasmic reticulum, and Golgi apparatus. Only plant cells have plastids, chloroplasts, and cell walls. © 2017 Pearson Education, Ltd. 92

If an organism has cilia, most likely it is _____.
a plant an animal living in a dry environment living in a watery environment Question: 4-9 Answer: d Diff: Easy Text Ref: Section 4.3 Skill: Application Notes: This question will get students thinking about what cilia are, and then they can relate structure to function. Bring up the diversity of organisms and structures that have cilia (Paramecium, small aquatic invertebrates, oyster gills, mammalian oviducts, respiratory tracts). Discuss how fluids are associated with the use of cilia. © 2017 Pearson Education, Ltd. 93

If an organism has cilia, most likely it is _____.
a plant an animal living in a dry environment living in a watery environment Question: 4-9 Answer: d Diff: Easy Text Ref: Section 4.3 Skill: Application Notes: This question will get students thinking about what cilia are, and then they can relate structure to function. Bring up the diversity of organisms and structures that have cilia (Paramecium, small aquatic invertebrates, oyster gills, mammalian oviducts, respiratory tracts). Discuss how fluids are associated with the use of cilia. © 2017 Pearson Education, Ltd. 94

A cell’s membrane is not formed properly—it is not able to act as a barrier to its environment. What may be causing this problem? The ER is malfunctioning and cannot produce the proteins for the membrane. The ER is malfunctioning and cannot produce the phospholipids and cholesterol for the membrane. The mitochondria are malfunctioning and cannot produce the phospholipids and cholesterol for the membrane. The chloroplasts are malfunctioning and cannot produce the energy needed to move molecules across the membrane. Question: 4-12 Answer: b Diff: Moderate Text Ref: Section 4.3 Skill: Application Also relates to: Chapter 5 Notes: The next chapter covers the structure and function of the cell membrane. This question is a great way to show how the structure and function of the cell membrane rely on these other organelles. Emphasize how the organelles do not exist as individual entities, but rely on one another and work together for the greater good of the cell and, ultimately, the organism. © 2017 Pearson Education, Ltd. 95

A cell’s membrane is not formed properly—it is not able to act as a barrier to its environment. What may be causing this problem? The ER is malfunctioning and cannot produce the proteins for the membrane. The ER is malfunctioning and cannot produce the phospholipids and cholesterol for the membrane. The mitochondria are malfunctioning and cannot produce the phospholipids and cholesterol for the membrane. The chloroplasts are malfunctioning and cannot produce the energy needed to move molecules across the membrane. Question: 4-12 Answer: b Diff: Moderate Text Ref: Section 4.3 Skill: Application Also relates to: Chapter 5 Notes: The next chapter covers the structure and function of the cell membrane. This question is a great way to show how the structure and function of the cell membrane rely on these other organelles. Emphasize how the organelles do not exist as individual entities, but rely on one another and work together for the greater good of the cell and, ultimately, the organism. © 2017 Pearson Education, Ltd. 96

Why would a cell have a prominent ER and Golgi apparatus?
It is a muscle cell and needs to have an excess amount of processed lipid. It is a bacterial cell and secretes large amounts of protein antibodies to attack plant and animal cells. It is a leukocyte (white blood cell) and secretes large amounts of protein antibodies into the bloodstream. It is a plant cell and undergoes the process of photosynthesis, producing large amounts of protein. Question: 4-13 Answer: c Diff: Moderate Text Ref: Section 4.3 Skill: Application Notes: A preview of antibody production will foreshadow discussion of the function of the immune system and connect the function of the organelles to a larger system. © 2017 Pearson Education, Ltd. 97

Why would a cell have a prominent ER and Golgi apparatus?
It is a muscle cell and needs to have an excess amount of processed lipid. It is a bacterial cell and secretes large amounts of protein antibodies to attack plant and animal cells. It is a leukocyte (white blood cell) and secretes large amounts of protein antibodies into the bloodstream. It is a plant cell and undergoes the process of photosynthesis, producing large amounts of protein. Question: 4-13 Answer: c Diff: Moderate Text Ref: Section 4.3 Skill: Application Notes: A preview of antibody production will foreshadow discussion of the function of the immune system and connect the function of the organelles to a larger system. © 2017 Pearson Education, Ltd. 98

How are chloroplasts and mitochondria similar to prokaryotic cells?
Both are large in size. Both can undergo the process of photosynthesis. Both can undergo the process of cell respiration. Both have their own DNA and ribosomes. Question: 4-14 Answer: d Diff: Easy Text Ref: Sections 4.3 and 4.4 Skill: Factual Notes: Based on the endosymbiont hypothesis, this question shows the evolutionary significance of chloroplasts and mitochondria to the advancement of the eukaryotic cell. © 2017 Pearson Education, Ltd. 99

How are chloroplasts and mitochondria similar to prokaryotic cells?
Both are large in size. Both can undergo the process of photosynthesis. Both can undergo the process of cell respiration. Both have their own DNA and ribosomes. Question: 4-14 Answer: d Diff: Easy Text Ref: Sections 4.3 and 4.4 Skill: Factual Notes: Based on the endosymbiont hypothesis, this question shows the evolutionary significance of chloroplasts and mitochondria to the advancement of the eukaryotic cell. © 2017 Pearson Education, Ltd. 100

What is the purpose of the central vacuole in this cell?
Storage of digestive enzymes Protein synthesis Energy production Water storage Question: 4-17 Answer: d Diff: Easy Text Ref: Chapter 4.2 Skill: Factual Notes: In plant cells, the central vacuole stores water for times of water shortage and waste products that are not excreted directly from the cell. © 2017 Pearson Education, Ltd. 101

What is the purpose of the central vacuole in this cell?
Storage of digestive enzymes Protein synthesis Energy production Water storage Question: 4-17 Answer: d Diff: Easy Text Ref: Chapter 4.2 Skill: Factual Notes: In plant cells, the central vacuole stores water for times of water shortage and waste products that are not excreted directly from the cell. © 2017 Pearson Education, Ltd. 102

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