Biology 1107 Chapter 6
A newly discovered unicellular organism isolated from acidic mine drainage is found to contain a cell wall, a plasma membrane, two flagella, and peroxisomes. Based just on this information, the organism is most likely...
A eukaryotic plant cell
Animals cells have unique organelles called _____ that are composed of structures called _____.
Centrosomes; centrioles
Which structure is NOT part of the endomembrane system?
Chloroplast
What is true about chloroplasts and mitochondria?
Chloroplasts and mitochondria synthesize some of their own proteins.
The network of fibers that organizes structures and activities in a cell....
Cytoskeleton
Microtubules and microfilaments commonly work with which of the following to perform many of their functions? A) lysosomes B) RNA C) ribosomes D) Golgi Apparatus E) None of these are correct
D) Golgi Apparatus
Compare the structure and functions of a plant cell wall and the extracellular matrix of an animal cell.
A plant cell wall is primarily composed of microfibrils of cellulose embedded in other polysaccharides and proteins. The ECM of animal cells is primarily composed of collagen and other protein fibers, such as fibronectin and other glycoproteins. A plant cell wall provides structural support for the cell and collectively for the plant body. In addition to giving support, the ECM of an animal cell allows for communication of environmental changes into the cell.
Briefly describe the structure and function of: a)nucleus b)mitochondrion c)chloroplast d)endoplasmic reticulum
A) contains nuclear envelope, nucleolus, and chromatin. Contains most of the genes in eukaryotic cell B)organelle where cellular respiration occurs and most ATP is generated. C)photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules. D)network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough and smooth regions.
Which of the following organelles is UNLIKELY to show enhanced abundance in pancreatic cells that secrete large amounts of digestive enzymes? A) free cytoplasmic ribosomes B) rough ER C) Golgi Apparatus D) transport vesicles E) all of the listed organelles will show an increase in pancreatic cells secreting digestive enzymes.
A) free cytoplasmic ribosomes
Which of the following categories best describes the function of the rough ER? A) manufacturing B) breakdown of complex foods C) structural support of cells D) energy processing E) information storage
A) manufacturing
Which of the following sequences represents the order in which a protein made in the rough ER might move through the endomembrane system? A) nuclear envelope —> lysosome B) Golgi Apparatus—> lysosome C) lysosome—> plasma membrane D) Golgi Apparatus—> mitochondria E) plasma membrane—> nuclear envelope
B) Golgi Apparatus—> lysosome
Consider two cells with the same volume but with very different surface areas due to differences in their shapes. The cell with the larger surface area is likely to.... A) be a prokaryotic cell B) be involved in the rapid uptake of compounds from the cells environment C) be buried deep in the interior of an organism D) have a very high metabolic rate E) be nearly spherical in shape
B) be involved in the rapid uptake of compounds from the cells environment
Which of the following 5 membranes is most likely to have a lipid composition that is distinct from those of the other 4? A) plasma membrane B) mitochondrial outer membrane C) lysosome membrane D) ER E) Golgi Apparatus
B) mitochondrial outer membrane
Which of the following is present in a prokaryotic cell? A) mitochondrion B) ribosome C) nuclear envelope D) chloroplast
B) ribosome
Which of the following groups is involved in synthesizing molecules needed by the cell? A) smooth ER, ribosome, vacuole B) ribosome, rough ER, smooth ER C) lysosome, vacuole, ribosome D) rough ER, lysosome, vacuole E) vacuole, rough ER, smooth ER
B) ribosome, rough ER, smooth ER
Describe 2 characteristics shared by chloroplasts and mitochondria.
Both organelles are involved in energy transformation, mitochondria in cellular respiration and chloroplasts in photosynthesis. They both have multiple membranes that separate their interiors into compartments. In both organelles, the innermost membranes have large surface areas with embedded emzymes that carry out their main functions.
Which of the following is FALSE? A) the folds of the inner mitochondrial membrane are called cristae. B) mitochondria have more than one membrane. C) mitochondria contain ribosomes in the intermembrane space D) mitochondria are involved in energy metabolism E) mitochondria possess their own DNA.
C) mitochondria contain ribosomes in the intermembrane space
Which types of cells do you think could have a huge Golgi Apparatus?
Cells that secrete hormones.
Which of the following is FALSE in respect to eukaryotic chromosomes?
Chromosomes appear only as a cell is about to divide.
Basal bodies are most closely associated with what cell components?
Cilia
What is true about the cytoskeleton?
Components of the cytoskeleton often mediate the movement of organelles within the cytoplasm.
Which of the following is/are likely to limit the maximum size of a cell? A) the cells surface-to-volume ratio B) the shape of the cell C) the time it takes a molecule to diffuse across a cell D) all of the choices are correct E) none of the choices is correct
D) all of the choices are correct
Which of the following organelles might be found inside other organelles? A) mitochondria B) the nucleolus C) transport vesicles D) ribosomes E) no organelles are found inside of other organelles
D) ribosomes
Describe how cilia and flagella bend.
Dynein arms, move neighboring doublets of microtibules relative to each other. Because they are anchored within the flagellum or cillium, the doublets bend instead of sliding past each other. Synchronized bending of the 9 microtubules doublets brings about bending of both cilia and flagella.
As a cell begins the process of dividing, it's chromosomes become shorter, thicker, and individually visible in an LM. Explain what is happening at the molecular level.
Each chromosome consists of one long DNA molecule attached to numerous protein molecules, combo called chromatin. As a cell begins division, each chromosome becomes condensed, as it's diffuse mass of chromatin coils up.
Consider a protein that is made in the rough ER. You observe that when the synthesis of the protein is completed, the protein is located in the ER membrane. Where else in the cell might this protein be found?
Embedded in the plasma membrane, functioning in the transport of molecules into the cell.
In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells?
Eukaryotic cells are compartmentalized, which allows for specialization.
In plant cells, the middle lamella...
Glues adjacent cells together.
Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a....
Human skin cell
Chloroplasts and mitochondria are thought to be of prokaryotic origin. One piece of evidence that supports this hypothesis is that these organelles contain prokaryotic-like ribosomes. These ribosomes are probably most similar to ribosomes found....
In bacterial cells that
The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized....
In the rough ER and in the Golgi Apparatus
Describe the role of motor proteins inside the eukaryotic cell and in whole cell movement.
Inside the cell, motor proteins interact with components of the cytoskeleton to move cellular parts. Motor proteins "walk" vesicles along microtubules. The movement of cytoplasm within a cell invoked interactions of the motor protein myosin and microfilaments (actin filaments). Whole cells can be moved by the rapid bending of flagella and cilia, which is caused by the motor-protein-powered sliding of microtubules within these structures.
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle is most likely defective in this condition?
Lysosome
Membrane phospholipids....
May have "kinks" in their tails, each caused by the presence of a double bond between carbons.
Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within what?
Mitochondria
What does the endosymbiont theory propose as the origin for mitochondria and chloroplasts? Explain.
Mitochondria originated from an oxygen-using prokaryotic cell that was engulfed by an ancestral eukaryotic cell. Over time, the host and endosymbiont evolved into a singular unicellular organism. Chloroplasts originated when at least one of these eukaryotic cells containing mitochondria engulfed and then retained a photosynthetic prokaryote.
Which structure is common to plant AND animal cells?
Mitochondrion
Cilia and flagella move due to the interaction of the cytoskeleton with what?
Motor proteins
Colpidium colpoda is a unicellular eukaryotes that live in freshwater, eats bacteria, and moves by cilia. Describe how the parts of the cell work together in the functioning of C. Colpoda, including as many organelles and other cell structures as you can.
Moves around by using cilia. The interactions between motor proteins and microtubules cause the cilia to bend synchronously, propelling the cell through water. This is powered by ATP, obtained via breaking down sugars in the mitochondria. It obtains bacteria as a food source. This process uses actin filaments and other elements of the cytoskeleton to ingest the bacteria. Once ingested, the bacteria are broken down by enzymes in lysosomes. The proteins involved in all of these processes are encoded by genesis in DNA in the nucleus.
Which type of cell is most likely to have the largest number of mitochondria?
Muscle cells in the legs of a marathon runner
Microfilaments function in cell motility including...
Muscle contraction, amoeboid movement, and cytoplasmic streaming in plants
What would happen if the nuclear lamina proteins were denatured?
Nucleus looses its shape.
Cells are small because...
Of the geometric relationship between surface and volume.
What molecule is transported to the mitochondria and which molecule is produced?
Oxygen and ATP.
The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and, therefore, abundant in liver cells?
Peroxisomes
_____ are membrane bound metabolic compartments that specialize in the production of hydrogen peroxide and it's conversion to water.
Peroxisomes
Which cell would be best for studying lysosomes?
Phagocytic white blood cell
Describe the structural and functional distinctions between rough and smooth ER.
Primary distinction: presence of bound ribosomes on rough ER. Both make phospholipids, but membrane proteins and secretory proteins are all produced by ribosomes on rough ER. Smooth ER functions in detox, carb metabolism, and storage of calcium ions.
Where are the proteins that form the ECM produced an modified?
Produced at the ER and modified at the Golgi.
Examination of a cell by transmission electron microscopy reveals a high density of ribosomes in the cytoplasm. This observation suggests that this cell is actively producing large amounts of which molecules?
Proteins
What molecule do you think will go through the nuclear pores?
Proteins and mRNA
What role do ribosomes play in carrying out genetic instructions?
Ribosomes in the cytoplasm translate the genetic message, carried from the DNA in the nucleus by the mRNA , into a polypeptide chain.
You would expect a cell with an extensive Golgi Apparatus to...
Secrete large amounts of protein
What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane?
Subunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores.
A cell with a predominance of smooth ER is likely specialized to...
Synthesize lipids and detoxify
Chromosomes contain the genetic material and reside in the nucleus; how does the rest of the cell get access to the information they carry?
The DNA in a chromosome dictates synthesis of a messenger RNA (mRNA) molecule, which then moves out to the cytoplasm. There, the information is used for the production, on ribosomes, of proteins that carry out cellular function.
If the plant cell wall or the animal extracellular matrix were impermeable, what effect would this have on cell function?
The cell would not be able to function properly and would probably soon die, as the cell wall or ECM must be permeable to allow the exchange of matter between the cell and its external environment. Molecules invoked in energy production must also be able to enter as well as those that provide info about the cells environment. Other molecules, such as products synthesized by the cell for export and the by products of cellular respiration, must be allowed to exit.
In what way are the cells of plants and animals structurally different from single-celled eukaryotes?
The most obvious difference is the presence of direct cytoplasmic connections between cell of plants (plasmodesmata) and animals (gap junctions). These connections result in the cytoplasm being continuous between adjacent cells.
Describe the molecular composition of nucleoli and explain their function.
The nucleoli are nonmembranous structures involved in production of ribosomes. Consist of DNA and rRNA. Together, the rRNAs and proteins are assembled into large and small ribosomal subunits.
A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure or structures would you predict the majority of the radioactive phosphorous to accumulate?
The nucleus
Describe the relationship between the nucleus and ribosomes.
The nucleus contains the genetic material of the cell in the form of DNA, which codes for messenger RNA, which in turn provides instructions for the synthesis of proteins. (Including the proteins that make up part of the ribosomes.) DNA also code for ribosomal RNAs, which are combined with proteins in the nucleolus into the subunits of ribosomes. Within the cytoplasm, ribosomes join with mRNA to build polypeptides, using the genetic information in the mRNA.
When a cell ingests a bacterium, what role does the nucleus play?
The nucleus houses the chromosomes; each is made up of proteins and a single DNA molecule. The genes that exist along the DNA carry the genetic info necessary to make the proteins involved in investing a bacterial cell, such as the actin of microfilaments that from pseudopodia(filopodia), the proteins in the mitochondria responsible for providing the necessary ATP, and the enzymes present in the lysosomes that will digest the bacterial cell.
Explain how the compartmental organization of a eukaryotic cell contributes to its biochemical functioning.
The separation of different functions in different organelles has several advantages. Reactants and enzymes can be concentrated in one area instead of spread throughout the cell. Reactions that require specific conditions, such as a lower pH, can be compartmentalized. And enzymes for specific reactions are often embedded in the membranes that enclose or partition an organelle.
Describe how transport vesicles integrate the endomembrane system.
Transport vesicles move membranes and the substances they enclose between other components of the endomembrane system.
Describe the key role played by transport vesicles in the endomembrane system.
Transport vesicles move proteins and membranes synthesized by the rough ER to the Golgi for further processing and then to the plasma membrane, lysosomes, and other location in the cell, including back to the ER.
Do plant cells have mitochondria? Explain.
Yes. Plant cells are able to make their own sugar by photosynthesis, but mitochondria are organelles that are able to generate ATP molecules to be used for energy generation from sugars, a function requires on all cells.
Describe proteins path through the cell, starting with the mRNA molecule that specifies the protein.
mRNA is synthesized in nucleus, passes through nuclear lore, into cytoplasm, translated on bound ribosome(attached to the ER). Protein synthesized into lumen of ER and perhaps modified there. Transport vesicles carries protein to Golgi. After further modification in Golgi, another transport vesicle carries it back to ER where it performs cellular function.
