Microbiology By Body System Chapter 3

Chloroplasts are organelles found in plant cells that contain chlorophyll, a pigment that captures light energy. This light energy is used in a process called photosynthesis to produce ATP, which is a form of chemical energy, and carbohydrates such as glucose. Therefore, it is true that chloroplasts use light energy to produce ATP and carbohydrates.

The formation of a biofilm can indeed contribute to bacteria's ability to cause disease. Biofilms are communities of bacteria that attach to surfaces and form a protective layer called an extracellular matrix. This matrix provides the bacteria with increased resistance to antibiotics and immune responses, making it easier for them to establish infections and evade the body's defenses. Additionally, biofilms can facilitate the exchange of genetic material between bacteria, leading to the spread of antibiotic resistance genes and making infections harder to treat. Therefore, the statement is true.

A bacterial cell moving toward light would exhibit positive phototaxis because it is being attracted to the light source. Phototaxis refers to the movement of an organism in response to light, and positive phototaxis specifically indicates movement towards the light.

The mitochondrion is responsible for producing most of the ATP in a eukaryotic cell. ATP, or adenosine triphosphate, is the main energy currency of cells. The mitochondrion is often referred to as the "powerhouse" of the cell because it carries out cellular respiration, a process that generates ATP through the breakdown of glucose and other molecules. The other organelles listed (lysosome, smooth ER, nucleus, and Golgi body) have important functions in the cell, but they do not play a direct role in ATP production.

Cilia are short, hairlike structures found on the surface of eukaryotic cells that are used for movement. They are typically present in large numbers and work together in a coordinated manner to create a wave-like motion, allowing the cell or surrounding fluid to move. Cilia are found in various organisms, including single-celled organisms like paramecia and multicellular organisms like humans. They play important roles in processes such as the movement of mucus in the respiratory tract, the propulsion of sperm, and the movement of fluid in the reproductive system.

The Golgi body, also known as the Golgi apparatus, is responsible for packaging and modifying cellular products, such as proteins and lipids, for export out of the cell. It receives these products from the endoplasmic reticulum and further processes them by adding sugars or other molecules to them. The Golgi body then packages these modified products into vesicles, which can be transported to the cell membrane for secretion. Therefore, the statement "The Golgi body prepares cellular products for export" is true.

The observation of an amoeba moving toward a food source indicates responsiveness. Responsiveness is the ability of an organism to detect and respond to changes in its environment. In this case, the amoeba is able to sense the presence of the food source and move towards it, demonstrating its responsiveness to the stimulus.

Bacterial protein synthesis can begin before the reading of the gene is complete because bacteria use a process called transcription-translation coupling. In this process, the ribosomes begin synthesizing proteins while the mRNA is still being transcribed. This allows for a more efficient and rapid production of proteins in bacteria.

Bacterial cell walls that are resistant to drying contain waxes. Waxes are hydrophobic substances that can form a protective barrier on the surface of the cell wall, preventing water loss and dehydration. This helps the bacteria to survive in dry environments. Carbohydrates, amino acids, lipopolysaccharide, and tubulin do not provide the same level of resistance to drying as waxes do.

Eukaryotic ribosomes are indeed composed of 60S and 40S subunits. This is a characteristic feature of eukaryotic cells, where the larger 60S subunit and the smaller 40S subunit come together to form a functional ribosome. These subunits play a crucial role in protein synthesis, with the 60S subunit being responsible for catalyzing the formation of peptide bonds and the 40S subunit aiding in the recognition and binding of mRNA molecules. Therefore, the statement "Eukaryotic ribosomes are composed of 60S and 40S subunits" is true.

Chromatin is a complex structure composed of DNA and proteins. While the question incorrectly refers to the packaging proteins as "hopanoids," the correct answer is still "True" because chromatin does indeed consist of DNA and specialized proteins that help in its organization and packaging.

Some members of archaea have hami. Archaea are a group of single-celled microorganisms that are similar to bacteria but have distinct genetic and biochemical characteristics. One of these characteristics is the presence of hami, which are hair-like structures on the surface of some archaea cells. These hami help archaea attach to surfaces and can also be involved in cell-cell interactions. Therefore, the correct answer is archaea.

Gram-negative bacteria have external structures containing a periplasmic space. The periplasmic space is located between the inner and outer membranes of Gram-negative bacteria and contains various proteins, enzymes, and transport systems. This space plays a crucial role in nutrient uptake, cell signaling, and protection against harmful substances. Gram-positive bacteria, archaea, and eukaryotes do not have this specific structure.

The glycocalyx of a eukaryotic cell performs several functions such as anchoring cells to each other, protection against dehydration, strengthening the cell surface, and cellular recognition and communication. However, it does not play a role in the transfer of genetic material between cells. This function is typically carried out by other structures such as the nucleus, mitochondria, or plasmids.

Reproduction is not defined as an increase in the size of an organism. Reproduction refers to the production of offspring or the creation of new individuals of the same species. It does not necessarily involve an increase in size.

Pili are not longer than fimbriae and flagella.

Tubulin is not a component of bacterial cell walls. Tubulin is a protein that forms microtubules, which are important for cell division and maintaining cell structure in eukaryotic cells. Bacterial cell walls are primarily composed of peptidoglycan, which provides structural support and protection to the cell. Lipoteichoic acids, tetrapeptide, and mycolic acid are all components that can be found in bacterial cell walls.

Both fimbrae and glycocalyces play an important role in the creation of biofilms. Fimbrae are short, hair-like structures on the surface of bacterial cells that help them adhere to surfaces and each other, promoting the formation of biofilms. Glycocalyces are gelatinous, sticky substances that surround bacterial cells, providing protection and aiding in attachment to surfaces. Together, fimbrae and glycocalyces enhance the ability of bacteria to form biofilms, which are communities of bacteria that adhere to surfaces and can be difficult to remove.

ATP is expended in both active transport and group translocation. Active transport is a process that requires energy to move substances against their concentration gradient, from an area of low concentration to an area of high concentration. This process is essential for maintaining ion gradients and transporting molecules across cell membranes. Group translocation is a type of active transport in which a molecule is chemically modified as it is transported across the membrane, requiring the use of ATP. Therefore, in both active transport and group translocation, ATP is used as a source of energy to drive the transport processes.

When cells are placed in a hypertonic solution, there is a higher concentration of solutes outside the cell compared to inside. As a result, water moves out of the cell through osmosis, causing the cell to lose water and shrink. This process is called crenation.

Tubulin is not a component of bacterial flagella. Tubulin is a protein that forms microtubules, which are structural components of eukaryotic cells, not bacterial cells. Bacterial flagella are composed of three main components: the filament, hook, and basal body. The filament is the long, helical structure that extends from the cell surface and is made up of flagellin protein. The hook connects the filament to the basal body, which anchors the flagellum to the cell membrane and acts as a motor to rotate the flagellum.

During osmosis, water actually crosses to the side of the membrane with a higher solute concentration, not a lower solute concentration.

Hami is a unique feature found only in archaea. It is a proteinaceous structure that resembles a grappling hook and is used by archaea to attach to surfaces or other cells. LPS, peptidoglycan, fimbriae, and pili are all features found in bacteria and not specific to archaea. Therefore, the presence of hami distinguishes archaea from bacteria.

Chloroplasts differ from mitochondria in that they have light-harvesting pigments. Chloroplasts are organelles found in plant cells that are responsible for photosynthesis. They contain pigments, such as chlorophyll, which absorb light energy and convert it into chemical energy. This process allows plants to produce glucose and oxygen. On the other hand, mitochondria are responsible for cellular respiration and do not contain light-harvesting pigments. They have their own DNA, two lipid bilayers, and 70S ribosomes, which are features that chloroplasts do not possess.

All three domains of life, Archaea, bacteria, and eukaryotes, have the potential to possess flagella. Flagella are whip-like appendages that some organisms use for movement. Archaea, bacteria, and eukaryotes can all have flagella, although the structure and composition of their flagella may vary. This means that organisms from each of these domains have the ability to propel themselves through their environment using flagella.

Prokaryotic flagella are not composed of tubulin. Tubulin is a protein that makes up the cytoskeleton in eukaryotic cells, not prokaryotic cells. Prokaryotic flagella are composed of a protein called flagellin.

Gram-negative bacteria contain an outer membrane. This outer membrane is an additional layer that surrounds the cell wall and provides extra protection. It helps to prevent the entry of harmful substances and contributes to the bacteria's ability to resist antibiotics. Gram-positive bacteria, on the other hand, do not have an outer membrane and only have a single cell membrane. Archaea and all prokaryotes do not necessarily have an outer membrane, so they are not the correct answer. Therefore, the correct answer is Gram-negative bacteria.

Lipid-soluble molecules are able to passively diffuse across the cytoplasmic membrane. Diffusion is the process by which molecules move from an area of high concentration to an area of low concentration, without the need for energy or a transport protein. Since lipid-soluble molecules can dissolve in the lipid bilayer of the membrane, they can easily diffuse through it. Facilitated diffusion requires the assistance of a transport protein, osmosis is the movement of water molecules, active transport requires energy, and group translocation involves the modification of molecules during transport.

Algae: glycocalyx present is paired incorrectly because glycocalyx is not present in algae. Glycocalyx is a layer of polysaccharides and proteins that surround the cell membrane in some bacteria and animal cells, but it is not found in algae. Algae have a cell wall composed of cellulose, not glycocalyx.

Mycolic acid is a waxy substance found in the cell walls of acid-fast bacteria, such as Mycobacterium tuberculosis. It contributes to the unique characteristics of these bacteria by making their cell walls impermeable to most stains and dyes. This property allows acid-fast bacteria to resist decolorization during the acid-fast staining procedure, which is used to identify them. Mycolic acid also helps protect acid-fast bacteria from the host immune system and contributes to their ability to survive in harsh environments.

Group translocation is a process in which a molecule is transported across a membrane while undergoing a chemical change. In this case, glucose 6-phosphate is phosphorylated inside the bacterial cell, which means a phosphate group is added to it. This modification allows the cell to accumulate glucose 6-phosphate against its concentration gradient, making it an example of group translocation. Facilitated diffusion, osmosis, plasmolysis, and simple diffusion do not involve a chemical change in the transported molecule.

Gram-positive bacteria may have cell walls containing teichoic acids. Teichoic acids are unique to Gram-positive bacteria and are an important component of their cell walls. They play a role in maintaining the structural integrity of the cell wall, regulating ion transport, and interacting with the host immune system. Teichoic acids are not found in Gram-negative bacteria or archaea. Therefore, the correct answer is Gram-positive bacteria.

Steroids are a class of lipids that are found in eukaryotes but not in prokaryotes. They play important roles in various biological processes, including cell signaling, membrane fluidity, and hormone regulation. Prokaryotes lack the enzymes necessary for steroid synthesis, which is why they do not contain steroids. Lipopolysaccharide, fatty acids, phospholipids, and hopanoids can be found in both eukaryotes and prokaryotes, making them incorrect options.

Both facilitated diffusion and active transport require a carrier protein. Facilitated diffusion is a passive process where molecules move across the cell membrane with the help of specific carrier proteins. Active transport, on the other hand, is an energy-dependent process that moves molecules against their concentration gradient. In active transport, carrier proteins are also involved to transport molecules across the cell membrane. Therefore, both facilitated diffusion and active transport require carrier proteins to facilitate the movement of molecules across the cell membrane.

Bacterial pili are specialized fimbriae. Fimbriae are thin, hair-like structures that extend from the surface of bacteria. They play a crucial role in attachment to surfaces, such as host tissues or other bacteria, and are involved in processes like biofilm formation and colonization. Unlike tubulin or peptidoglycan, which are components of the bacterial cytoskeleton and cell wall respectively, pili are not solid or rigid protein structures. While pili can aid in bacterial movement, they are primarily known for their adhesive properties and are considered specialized fimbriae.

Facilitated diffusion is a type of passive transport that does not require an input of energy. It involves the movement of molecules across a cell membrane with the help of specific carrier proteins. These carrier proteins facilitate the movement of molecules down their concentration gradient, from an area of higher concentration to an area of lower concentration. Since facilitated diffusion relies on the concentration gradient and the assistance of carrier proteins, it does not require energy input. Therefore, the correct answer is False.

The endoplasmic reticulum is classified as a membranous organelle of eukaryotic cells. It is a network of membranes that is involved in the synthesis, folding, and transport of proteins. It also plays a role in lipid metabolism and calcium storage. The endoplasmic reticulum is composed of both rough and smooth regions, with the rough endoplasmic reticulum having ribosomes attached to its surface. Therefore, the correct answer is endoplasmic reticulum.

The cell walls of both Gram-positive and Gram-negative bacteria contain tetrapeptides. Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which consists of a mesh-like structure of tetrapeptides. Gram-negative bacteria also have a peptidoglycan layer, but it is thinner and surrounded by an outer membrane. Both types of bacteria have tetrapeptides in their cell walls, making the statement true.

The cytoplasmic membranes of both bacteria and eukaryotes are composed of phospholipids. Phospholipids are a type of lipid molecule that have a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails. These phospholipids arrange themselves in a bilayer, with the hydrophilic heads facing the aqueous environment and the hydrophobic tails facing inward. This arrangement forms a barrier that separates the internal contents of the cell from the external environment. Both bacteria and eukaryotes have cytoplasmic membranes that perform similar functions, such as regulating the passage of molecules in and out of the cell and maintaining the integrity of the cell.

Lysosomes do not result from the endocytosis of food particles by eukaryotic cells. Lysosomes are membrane-bound organelles that contain enzymes responsible for breaking down waste materials and cellular debris. They are formed by the Golgi apparatus and are involved in various cellular processes such as digestion, recycling, and defense against pathogens. The endocytosis of food particles leads to the formation of food vacuoles, which then fuse with lysosomes for digestion. Therefore, the correct answer is false.

Centrioles are found in a region of the cell called the centrosome and are believed to play a role in cellular processes such as mitosis and cytokinesis. Centrioles are composed of microtubules and their structure is similar to that of eukaryotic flagella and cilia. However, centrioles are not found in prokaryotes, which are organisms that lack a nucleus and other membrane-bound organelles.

Cristae is not associated with the nucleus of a eukaryotic cell. Cristae are the folds found in the inner membrane of mitochondria, which are responsible for cellular respiration and energy production. The nucleus, on the other hand, contains chromatin (DNA and proteins), histones (proteins that help in DNA packaging), nucleolus (site of ribosome production), and nucleoplasm (the fluid inside the nucleus).

Lipid A is known as endotoxin because it is a component of the outer membrane of Gram-negative bacteria and is responsible for the toxic effects associated with bacterial infections. When released into the bloodstream, lipid A triggers an immune response, leading to inflammation and other symptoms of infection.

Mycoplasma bacteria are unique because they lack a cell wall. Most bacteria have a cell wall made of peptidoglycan, which provides structural support and protection. However, Mycoplasma bacteria have evolved to survive without a cell wall, making them more flexible and able to adopt various shapes. This absence of a cell wall also makes them resistant to certain antibiotics that target the cell wall. Instead, Mycoplasma bacteria have a plasma membrane that directly surrounds their cytoplasm, allowing them to still carry out essential cellular functions.

The endoplasmic reticulum (ER) is a network of membranes that extends throughout the cytoplasm of eukaryotic cells. It plays a crucial role in the transport of proteins and lipids within the cell. The ER is involved in the synthesis, folding, and modification of proteins, as well as the synthesis of lipids. The rough ER, which has ribosomes associated with it, is primarily responsible for protein synthesis, while the smooth ER is involved in lipid metabolism and detoxification. Therefore, the statement "The ER is a transport system within the cytoplasm" is correct because it accurately describes one of the main functions of the ER.

The eukaryotic cytoskeleton is a network of protein filaments that provides structural support to the cell and helps in various cellular processes. It anchors organelles, gives shape to the cell, aids in contraction of the cell, and performs endocytosis. However, it does not directly participate in the packaging of cellular secretions. This function is primarily carried out by the Golgi apparatus and secretory vesicles.

Endocytosis and exocytosis are means of transport used by eukaryotes. These processes involve the uptake of materials into the cell through the formation of vesicles (endocytosis) and the release of materials out of the cell through the fusion of vesicles with the plasma membrane (exocytosis). Bacteria and archaea, being prokaryotes, lack membrane-bound organelles and therefore do not possess the machinery required for these processes. Therefore, eukaryotes are the only cells that use both endocytosis and exocytosis.

Bacteria are prokaryotes, which means they lack a nucleus and membrane-bound organelles. One of the distinguishing features of bacterial cells is the presence of a cell wall, which provides structural support and protection. The cell wall of bacteria is composed of a substance called peptidoglycan, which is not found in eukaryotic cells. Therefore, the correct answer is bacteria.

Endospores are dormant, highly resistant structures formed by certain bacteria to survive unfavorable conditions. Dipicolinic acid is a major component found in the core of endospores and plays a crucial role in their resistance. It helps in stabilizing DNA and proteins, protecting them from damage caused by heat, radiation, and chemicals. Additionally, dipicolinic acid aids in the dehydration of the spore, preventing the growth of harmful microorganisms. Therefore, the presence of dipicolinic acid contributes to the ability of endospores to withstand harsh conditions and ensures their survival.

Peroxisomes are not involved in the digestion of nutrients brought into the cell through phagocytosis. Instead, they contain enzymes that are responsible for breaking down fatty acids and detoxifying harmful substances. Therefore, the statement is false.