Ch. 04 Group 1 - Chapter 04: Section 4.1-4.4

Which of the following processes occurs in bacterial plasma membranes but NOT in eukaryotic plasma membranes? Active transport RNA synthesis Facilitated diffusion ATP synthesis Protein synthesis

ATP synthesis ATP synthesis would NOT occur in eukaryotic plasma membranes. Instead, ATP would be produced in mitochondria, which are also known as the "powerhouses of the cell."

You have isolated a cell with a peptidoglycan cell wall. What other structure can you safely assume the cell has? A mitochondrion A nucleus A chloroplast A plasma membrane

A plasma membrane You can safely assume that the cell has a plasma membrane. The plasma (cytoplasmic) membrane encloses the cytoplasm of a cell. The plasma membrane of prokaryotes consists primarily of phospholipids and proteins, eukaryotic plasma membranes also contain carbohydrates and sterols, such as cholesterol.

A population of bacterial cells has been placed in a very nutrient-poor environment with extremely low concentrations of sugars and amino acids. Which kind of membrane transport becomes crucial in this environment? Simple diffusion Facilitated diffusion Osmosis Pinocytosis Active transport

Active transport Active transport would be crucial in this environment. In performing active transport, the cell uses energy in the form of ATP to move substances across the plasma membrane. Among the substances actively transported are ions (for example sodium, potassium, calcium), amino acids, and simple sugars. Movement by active processes will allow these substances to move against the concentration gradient, allowing a cell to accumulate needed materials. The movement of a substance in active transport is usually from outside to inside, even though the concentration might be much higher inside the cell.

Which of the following processes requires cellular energy in the form of ATP? Facilitated diffusion Active transport Osmosis Simple diffusion

Active transport In performing active transport, the cell uses energy in the form of ATP to move substances across the plasma membrane. Among the substances actively transported are ions, amino acids, and simple sugars. Although these substances can also be moved into cells by passive processes, their movement by active processes can go against the concentration gradient.

Which of the following organisms have eukaryotic cells that do NOT contain a cell wall? Fungi Animals Plants Algae

Animals Some eukaryotic cells, including animal cells, do NOT contain a cell wall. Their plasma membrane is covered by a glycocalyx, a layer of material containing substantial amounts of sticky carbohydrates.

Many pathogenic (disease-producing) bacteria produce a(n) __________ that protects them from phagocytosis by host cells.

Capsule

Which of the following membrane transport mechanisms takes place in eukaryotic cells but NOT in prokaryotic cells? Osmosis Endocytosis Facilitated diffusion Active transport

Endocytosis Substances can cross eukaryotic and prokaryotic plasma membranes by simple diffusion, facilitated diffusion, osmosis, or active transport. Group translocation does not occur in eukaryotic cells. However, eukaryotic cells can use a mechanism called endocytosis. This occurs when a segment of the plasma membrane surrounds a particle or large molecule, encloses it, and brings it into the cell. The three types of endocytosis are phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Which of the following processes uses membrane proteins that act as channels or carriers allowing ions or large molecules to move across the plasma membrane without using energy? Facilitated diffusion Simple diffusion Osmosis Active transport

Facilitated diffusion In facilitated diffusion, integral membrane proteins function as channels or carriers that facilitate the movement of ions or large molecules across the plasma membrane. Such integral proteins are called transporters or permeases. Facilitated diffusion is similar to simple diffusion in that the cell does not expend energy, because the substance moves from a high to a low concentration. The process differs from simple diffusion in its use of transporters. Some transporters permit the passage of mostly small, inorganic ions that are too hydrophilic to penetrate the nonpolar interior of the lipid bilayer.

Which of the following processes uses membrane proteins that act as channels or carriers allowing ions or large molecules to move across the plasma membrane without using energy? Osmosis Simple diffusion Facilitated diffusion Active transport

Facilitated diffusion In facilitated diffusion, integral membrane proteins function as channels or carriers that facilitate the movement of ions or large molecules across the plasma membrane. Such integral proteins are called transporters or permeases. Facilitated diffusion is similar to simple diffusion in that the cell does not expend energy, because the substance moves from a high to a low concentration. The process differs from simple diffusion in its use of transporters. Some transporters permit the passage of mostly small, inorganic ions that are too hydrophilic to penetrate the nonpolar interior of the lipid bilayer.

Which of the following bacterial structures is necessary for chemotaxis? Flagella Metachromatic granules Plasmids Capsules

Flagella

Which of the following statements is true? a) Endospores are extremely durable structures that can survive high temperatures. b) endospores allow a cell to attach to solid surfaces and to surfaces within the host. c) One bacterial cell produces many endospores. d) Endospores are reproductive structures.

a) Endospores are extremely durable structures that can survive high temperatures. Endospores are extremely durable structures that can survive high temperatures. They do not carry out metabolic reactions. The endospore contains a large amount of an organic acid called dipicolinic acid (DPA), which is accompanied by a large number of calcium ions. Evidence indicates that DPA protects the endospore DNA against damage. The highly dehydrated endospore core contains only DNA, small amounts of RNA, ribosomes, enzymes, and a few important small molecules. These cellular components are essential for resuming metabolism late

Which of the following statements about ribosomes is FALSE? a) Antibiotics that interfere with protein synthesis harm both prokaryotic and eukaryotic ribosomes. b) Antibiotics that interfere with protein synthesis harm prokaryotic ribosomes, but not eukaryotic ribosomes. c) Eukaryotic ribosomes are larger (80S) than prokaryotic ribosomes (70S). d) Cells with a high rate of protein synthesis have large numbers of ribosomes.

a) The statement that antibiotics, which interfere with protein synthesis, would harm both prokaryotic and eukaryotic ribosomes, is FALSE. Ribosomes are composed of two subunits, each of which consists of protein and a type of RNA called ribosomal RNA (rRNA). Prokaryotic ribosomes differ from eukaryotic ribosomes in the number of proteins and rRNA molecules they contain; they are also somewhat smaller and less dense than ribosomes of eukaryotic cells.

The nucleoid of the bacterial cell __________. a) contains the bacterial chromosome b) contains many linear chromosomes c) is connected to the endoplasmic reticulum d) has abundant histone proteins e) is enclosed in a nuclear membrane

a) contains the bacterial chromosome The nucleoid of the bacterial cell contains the bacterial chromosome. The nucleoid contains a single long, continuous, and frequently circularly arranged thread of double-stranded DNA called the bacterial chromosome.

The plasma membrane is considered a barrier to the environment because __________. a) it controls the passage of molecules into the cell b) no molecules may pass through it c) it is located outside of the cell wall d) it contains rigid cellulose and steroid molecules e) only water and small molecules may penetrate the membrane

a) it controls the passage of molecules into the cell The plasma membrane is considered a barrier to the environment because it controls the passage of molecules into the cell. The most important function of the plasma membrane is to serve as a selective barrier through which materials enter and exit the cell. In this function, plasma membranes have selective permeability, sometimes called semipermeability, which indicates that certain molecules and ions are allowed to pass through the membrane but others are stopped.

Which of the following is NOT a functionally analogous pair? a) 70s ribosomes; 80S ribosomes b) Pili; centrioles c) Circular bacterial chromosome; linear eukaryotic chromosomes d) Peptidoglycan; cellulose e) Bacterial flagella; 9 + 2 flagella

b) Pili; centrioles Pili and centrioles are NOT functionally analogous. Pili are involved in motility and DNA transfer. Centrioles are part of the centrosome, an area that is the organizing center for the mitotic spindle, which plays a critical role in cell division, and for microtubule formation in non-dividing cells.

The nucleus of a eukaryotic cell differs from the nucleoid of a prokaryotic cell in all of the following ways EXCEPT which one? a) The eukaryotic nucleus is surrounded by a nuclear envelope. There is no envelope surrounding the prokaryotic nucleoid. b) The prokaryotic nucleoid usually contains a single circular chromosome, whereas the eukaryotic nucleus contains multiple linear chromosomes. c) The prokaryotic nucleoid contains DNA combined with histones. Histones are lacking in the eukaryotic nucleus. d) The eukaryotic nucleus contains nucleoli. There are no nucleoli in the prokaryotic nucleoid.

c) The prokaryotic nucleoid contains DNA combined with histones. Histones are lacking in the eukaryotic nucleus. Prokaryotic DNA does NOT contain histones. The DNA found in the eukaryotic nucleus is combined with several proteins, including some basic proteins called histones and non-histones. When the cell is not reproducing, the DNA and its associated proteins appear as a threadlike mass called chromatin. During nuclear division, the chromatin coils into shorter and thicker rod-like bodies called chromosomes. Prokaryotic chromosomes do not undergo this process, do not contain histones, and are not enclosed in a nuclear envelope.

The __________ is a fluid structure that allows membrane proteins to move freely. cell wall glycocalyx ribosome cell membrane

cell membrane The cell membrane must be about as viscous as olive oil, which allows membrane proteins to move freely enough to perform their functions without destroying the structure of the membrane. This dynamic arrangement of phospholipids and proteins is referred to as the fluid mosaic model.

Which of the following statements is true? a) Endospores allow a cell to attach to solid surfaces and to surfaces within the host. b) One bacterial cell produces many endospores. c) Endospores are reproductive structures. d) Endospores are extremely durable structures that can survive high temperatures.

d) Endospores are extremely durable structures that can survive high temperatures. Endospores are extremely durable structures that can survive high temperatures. They do not carry out metabolic reactions. The endospore contains a large amount of an organic acid called dipicolinic acid (DPA), which is accompanied by a large number of calcium ions. Evidence indicates that DPA protects the endospore DNA against damage. The highly dehydrated endospore core contains only DNA, small amounts of RNA, ribosomes, enzymes, and a few important small molecules. These cellular components are essential for resuming metabolism later.

Which of the following statements does "NOT" provide evidence for the endosymbiotic theory? a) The same antibiotics that inhibit protein synthesis in prokaryotes also inhibit protein synthesis within mitochondria and chloroplasts. b) Mitochondria and chloroplasts contain circular DNA, similar to the DNA in prokaryotes. c) The ribosomes contained within mitochondria and chloroplasts are very similar to prokaryotic ribosomes. d) Prokaryotes contain peptidoglycan in their cell walls.

d) Prokaryotes contain peptidoglycan in their cell walls. Prokaryotes contain peptidoglycan in their cell walls does NOT provide evidence for the endosymbiotic theory. According to one part of this theory, the ancestral eukaryote developed a rudimentary nucleus when the plasma membrane folded around the chromosome. This cell may then have ingested aerobic bacteria evolving into a symbiotic relationship in which the host nucleoplasm supplied nutrients and the endosymbiotic bacterium produced energy that could be used by the nucleoplasm. Peptidoglycan found in prokaryotes does not provide evidence for the endosymbiotic theory.

Which of the following pairs is MISMATCHED? a) Golgi complex; secretion b) Endoplasmic reticulum; internal transport c) Lysosome; digestive enzymes d) Ribosomes; storage e) Mitochondria; ATP production

d) Ribosomes; storage Ribosomes; storage are MISTMATCHED. Ribosomes are NOT used for storage. All eukaryotic and prokaryotic cells contain ribosomes, the location in which protein synthesis takes place.

Bacillus anthraciscauses the deadly disease anthrax. Organisms of the genus Bacillus may form endospores. This bacterium would be suitable for biological warfare because endospores __________. a) are centrally located within the bacterial cells b) contain a high concentration of toxic enzymes c) are multilayered structures d) are difficult to stain e) are resistant to high temperatures, UV light, and desiccation

e) are resistant to high temperatures, UV light, and desiccation When essential nutrients are depleted, certain gram-positive bacteria, such as those of the genera Clostridium and Bacillus, form specialized "resting" cells called endospores. Unique to bacteria, endospores are highly durable dehydrated cells with thick walls and additional layers. They are formed internal to the bacterial cell membrane. When released into the environment, they can survive extreme heat, lack of water, and exposure to many toxic chemicals and radiation.

Polyphosphate (volutin), carboxysomes, and magnetosomes are examples of __________. mesosomes fimbriae chloroplasts capsules inclusion bodies

inclusion bodies Polyphosphate (volutin), carboxysomes, and magnetosomes are examples of inclusion bodies. Inclusions are reserve deposits found in prokaryotic and eukaryotic cells. Volutin represents a reserve of inorganic phosphate (polyphosphate) that can be used in the synthesis of ATP; carboxysomes are inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase; and magnetosomes are inclusions of iron oxide (Fe3O4) surrounded by invaginations of the plasma membrane.

Within the cytoplasm of bacterial cells are reserve deposits where certain nutrients accumulate. These are called __________. lysosomes ribosomes inclusions vacuoles

inclusions Within the cytoplasm of prokaryotic cells are several kinds of reserve deposits, known as inclusions. Cells may accumulate certain nutrients when they are plentiful and use them when the environment is deficient.

A __________ solution is a medium in which the overall concentration of solutes equals that found inside the cell. Water enters and leaves the cell at the same rate. hypotonic ionic isotonic hypertonic

isotonic An isotonic solution is a medium in which the overall concentration of solutes equals that found inside a cell. Water leaves and enters the cell at the same rate (no net change); the cell's contents are in equilibrium with the solution outside the cytoplasmic membrane.

The antibiotic polymyxin B combines with phospholipids. This will cause __________. stoppage of protein synthesis leakage of intracellular contents binary fission loss of motility sporulation

leakage of intracellular contents By disrupting the membrane's phospholipids, a group of antibiotics known as the polymyxins causes leakage of intracellular contents and subsequent cell death.

A eukaryotic cell can ingest a prokaryotic cell by __________. active transport pinocytosis osmosis phagocytosis digestive vacuolization

phagocytosis A eukaryotic cell can ingest a prokaryotic cell by phagocytosis. During phagocytosis, cellular projections called pseudopods engulf particles and bring them into the cell. Phagocytosis is used by white blood cells to destroy bacteria and foreign substances.

The endoplasmic reticulum that has ribosomes attached to its outer surface is referred to as __________. Golgi rough ER wavy ER smooth ER

rough ER The endoplasmic reticulum that has ribosomes attached to its outer surface is referred to as rough ER. The membrane of rough ER is continuous with the nuclear membrane and usually unfolds into a series of flattened sacs. The outer surface of rough ER is studded with ribosomes, the sites of protein synthesis. Proteins synthesized by ribosomes that are attached to rough ER enter cisternae within the ER for processing and sorting.

Assume you are growing a bacterial culture in a glucose medium. Your lab partner adds more glucose in hopes of speeding up the experiment. The bacteria suddenly die. The best explanation for this result is that __________. the cells underwent sporulation the cells plasmolyzed the bacteria could not use glucose osmotic lysis occurred glucose is toxic to bacteria

the cells plasmolyzed The best explanation for this result is that the cells plasmolyzed. Your lab partner created a hypertonic solution by adding more glucose. A hypertonic solution is a medium having a higher concentration of solutes than that inside the cell (hyper means above or more). Most bacterial cells placed in a hypertonic solution shrink and collapse or plasmolyze because water leaves the cells by osmosis.