Ch. 4 Introduction to Eukaryotic Cells

Describe the structure and function of cilia

-"eyelashes" -Cilia provide an oar-like motion -They are similar to flagella but they are shorter and more numerous than flagella -Only eukaryotes have cilia -Example: the epithelial cells of our upper airway, which sweep mucus and pathogens up and away from the lungs

Give examples of eukaryotes with cell walls and discuss how cell walls differ among eukaryotic kingdoms

-Fungi, plants, and certain protists have cell walls, but animal cells don't -Eukaryotic cell walls do not contain peptidoglycan or pseudopeptidoglycan, making them chemically distinguishable from prokaryotic cell walls -Chitin is a core compound in many fungal cell walls, while cellulose is abundant in plant cell walls -Protists have diverse cell walls that can include cellulose, calcium carbonate, xylan, silica, and a variety of other protein- and carbohydrate-based compounds

Describe the structure of eukaryotic ribosomes and state where they are located

-Made up of protein and ribosomal RNA (rRNA). Eukaryotic cells have 80S ribosomes that are made up of a small subunit (the 40S subunit) and a large subunit (the 60S subunit) -Eukaryotic ribosomes can be found free in the cytoplasm, or bound to the membrane of an organelle called the endoplasmic reticulum (ER)

Describe the eukaryotic glycocalyx and list some of its roles

-Sticky extracellular layer called "Sugar husk" as their outermost layer -The glycocalyx contains a diverse collection of carbohydrates, glycoproteins, and glycolipids -Each of these sugary components can have a different role in protecting the cell from a variety of stresses, promoting or preventing cell adhesion where appropriate, and assisting with cellular communication

Discuss the basic structural and functional features of the endoplasmic reticulum

-The endoplasmic reticulum (ER) is a series of interconnected membranous sacs that originate from the outer membrane of the nuclear envelope -Rough ER has ribosomes on the outer surface; smooth ER is not associated with ribosomes -The ER assists with protein modifications -The rough and smooth ER coordinate with the Golgi apparatus to sort, package, and ship proteins and lipids around the cell and to the cell surface

Describe the general structure and function of the nucleus

-The nucleus is a large double-membrane structure that houses the cell genome -Nuclear pores regulate nuclear transport -A dense region of the nucleus, called the nucleolus, is enriched with RNA; it is the site where ribosomal subunits begin their development

Outline the types of vesicles and vacuoles that exist in eukaryotic cells and state their general functions

-Transport vesicles move substances around the cell -Secretory vesicles shuttle materials to the cell surface for discharge from the cell -Lysosomes contain a wide variety of hydrolytic enzymes that break down substances engulfed by the cell during phagocytosis and receptor-mediated endocytosis. They also act as garbage disposal tools for the cell, removing damaged organelles and other defunct cell components -Peroxisomes are found in most eukaryotic cells. They contain enzymes that break down certain fats and amino acids and protect the cell from hydrogen peroxide and other toxic oxygen intermediates -Vacuoles are a conglomerate of many vesicles that have merged to make a larger membranous sac. Vacuoles contain mainly water and various organic and inorganic substances such as nutrients, toxins, and even waste products. Vacuoles vary in size and shape. They are common in plants and fungi, but may also be found in certain animal cells, prokaryotes, and protists

Arrange the steps of the acid-fast procedure in the correct order

1) Place slide over heated beaker of water 2) Apply carbolfuchsin to smear 3) Remove slide from heat and rinse 4) Apply acid-alcohol to smear and rinse 5) Apply methylene-blue to smear and rinse 6) Blot slide and view under microscope

Use the micrograph of the Gram stain to draw conclusions and make predictions about the pictured bacterium Based on your observation of the Gram stained bacterial specimen, select ALL appropriate statements

1) The bacteria pictured are cocci 2) The pictured bacteria produce endotoxin (also known as lipopolysaccharide, LPS) 3) The indicated bacterium is Gram-negative

Use the micrograph of the Gram stain to draw conclusions and make predictions about the indicated bacterium Based on your observation of the indicated bacterium in this Gram stain, select ALL appropriate statements

1) The indicated bacterium is a bacillus 2) The indicated bacterium produces endotoxin (also known as lipopolysaccharide, LPS) 3) The indicated bacterium is Gram-negative

Observe the micrograph and draw conclusions about the indicated bacterium Based on your observation of the indicated bacterium in this micrograph, select ALL appropriate statements

1)The indicated bacterium is motile 2)The indicated bacterium has a peritrichous flagella arrangement

Eukaryotic ribosomes are made up of a small _________ subunit and large _________ subunit

40S; 60S

Explain how hyphae relate to fungal growth

A collection of tubular structures by which most fungi (aside from yeast) grow The movement of cytoplasm from one cell to another helps a fungus distribute nutrients from one part of its body to another. The hyphae of a single fungus typically branch as they grow, forming an interwoven mat called a mycelium (plural, mycelia). The mycelium functions as the feeding structure of a fungus

The bacilli are acid-fast. The acid-fast staining procedure stains the acid-fast bacteria red, because those bacteria retain the carbolfuchsin primary stain. The bacilli in the image are red, so they're acid-fast. In contrast, blue cocci are non-acid-fast.

A smear from a mixed culture of bacilli and cocci is stained with the acid-fast procedure. This is an image of the stained smear at 1000X total magnification. Which of the bacteria, if any, are acid-fast?

What is the role of acid-alcohol in the acid-fast staining technique?

Acid-alcohol is the decolorizing agent

While performing the acid-fast stain procedure, you heat your fixed bacteria with carbolfuchsin for 5 minutes, let the slide cool, and then rinse with water. What is your next step?

Add acid-alcohol Acid-alcohol is the decolorizing agent in the acid-fast staining procedure. Acid-alcohol removes carbolfuchsin from non-acid-fast cells

What is the purpose of heating the slide during the staining process?

Allows for further penetration of the stain through the lipoidal wall and into the cytoplasm

Nematodes, tapeworms, and flukes are members of the kingdom

Animalia

Name and describe the five main classes of fungal spores

Asexual fungal spores Conidiospores: chains of spores; not enclosed in a sac Ex: penicillium, and aspergillus species Sporangiospore: spores formed within a sac called a sporangium Ex: Absidia species (the cause of murcomycosis in humans) Sexual fungal spores Zygospores: Haploid gametes found at the tips of hyphae Ex: Phylum zygomycota; includes black bread molds (Rhizopus species) Ascospores: Haploid gametes form within a sac called an ascus Ex: Phylum Ascomycota; includes truffles, morels, many yeasts and cup fungi Basidiospores: Bud off of a pedestal structure called the basidium Ex: Phylum Basidiomycota; includes mushrooms

Which of the following types of cell division is found in prokaryotic cells?

Binary fission

While performing the acid-fast stain procedure, you add methylene blue to your smear for the appropriate amount of time and then rinse with water. What is your next step?

Blot slide dry Methylene blue is used as the counterstain in the acid-fast staining procedure. It's also the last reagent used in the procedure. So once you've rinsed off the excess methylene blue, you'll need to blot the slide dry. Once dry, the slide is ready for viewing under the microscope.

What color do you expect Escherichia coli to be after performing the acid-fast stain?

Blue

Name and describe the two main groups of parasitic helminths

Broad collection of organisms that spans roundworms and flatworms In general, such organisms act as parasites, meaning they live in or on a host They tend to have complex life cycles that can involve different host species Most helminthic parasites in humans spend at least some part of their life cycle in the gastrointestinal tract

________ is to fungal cell walls as _________ is to bacterial cell walls

Chitin; peptidoglycan

Which of the following correctly describes the cellular morphology and appearance of Staphylococcus aureus after performing an acid-fast stain?

Clusters of blue cocci

Which of the following describes the correct cellular morphology and Gram reaction for Staphylococcus aureus?

Clusters of gram-positive cocci

Which of the following type of fungal spores arise from mitosis and do not result in genetic variation?

Conidiospores

What substance is used as a decolorizing agent when performing a capsule stain?

Copper sulfate

Which of the following describes the cellular morphology and appearance of Mycobacterium smegmatis after performing an acid-fast stain?

Dark-red bacilli

Define the term mycosis and give examples of human mycoses

Disease caused by fungi Ex: Tinea unguium, or dermatophytic onychomycosis, causes nails to become brittle and discolored Vaginal yeast infections caused by candida species Tinea/ ringworm infections

Review the structure and function of mitochondria and state what features make them similar to bacteria

Double-membrane structure with their own 70S ribosomes and circular chromosome -Make most of a cell's adenosine triphosphate (ATP) -Nickname is the "powerhouse" of the cell Membranes — Mitochondria have their own cell membranes, just like a prokaryotic cell does. DNA — Each mitochondrion has its own circular DNA genome, like a bacteria's genome, but much smaller

Describe and compare the main transport mechanisms used by eukaryotic cells

Endocytosis: Import mechanism primarily used by E. cells Import things into the cell Requires ATP and is used as a generalized (bulk or mass) transport mechanism, as well as specialized transport regulated by receptors on the cell's surface Exocytosis: remove things from the cell Requires ATP A cellular exportation process that involves vesicles delivering their contents to the plasma membrane Used as generalized (bulk or mass) transport mechanism

Which of the following eukaryotic organelles plays an essential role in protein and lipid production in the cell?

Endoplasmic reticulum

Your patient has severe diarrhea and is passing mucus and blood. Stool samples that were obtained and checked under the microscope revealed cysts. His patient history also indicates that he recently traveled to southeast Asia. What is he likely infected with?

Entamoeba histolytica

Which of the following organisms is gram-negative?

Escherichia coli

Discuss the basic structure of eukaryotic flagella and compare eukaryotic and prokaryotic flagella

Eukaryotic flagella are used for motility Eukaryotic flagella are made of the protein tubulin and have what is called a nine-plus-two arrangement Eukaryotic flagella move in a back-and-forth, wave-like motion

Provide a basic description of a eukaryotic cell and state how eukaryotes differ from prokaryotes

Eukaryotic: Plants, animals, protists, and fungi Larger in size, structurally more complex, have larger genomes that are spread across multiple linear chromosomes Well defined nucleus, as well as a variety of other membrane-bound organelles, such as mitochondria and chloroplasts Sexual and/or asexual reproduction Take longer than binary fission does in prokaryotes Prokaryotes have a single, circular chromosome Do not conduct sexual reproduction

The spore is resistant to which of the following extreme environmental conditions?

Extreme temperatures, radiation, and desiccation.

Name and describe the four kingdoms of eukaryotes

Four kingdoms Animalia are multicellular, heterotrophic, nonphotosynthetic, and have no cell wall Plantae are multicellular, photosynthetic, autotrophic, and have a cell wall Fungi are unicellular or multicellular, heterotrophic, nonphotosynthetic, and have a cell wall Protista are unicellular or multicellular, some are heterotrophic and others are autotrophic, some have cell walls, and some are photosynthetic A. Most fungi rely on spores for reproduction. Sexual fungal spore types are used to group fungi into different phyla; they include zygospores, ascospores, and basidiospores. There are two classes of asexual spores made by fungi: conidiospores and sporangiospores B. Fungal diseases are called mycoses; most mycoses occur in people with compromised immune function or disrupted normal microbiota C. Animal-like protists are called protozoans. Protozoans are grouped by their means of motility into the following: amoeboid (Sarcodina); flagellated (Mastigophora), ciliated (Ciliophora), and spore forming (Apicomplexa)

You are observing an unknown, unicellular organism with a high-resolution and magnification microscope. You are noting the presence of various membrane-bound organelles. Which of the following types of cells are you likely working with?

Fungus

Which of the following is characterized as a Mastigophora, or "flagellated protozoan"?

Giardia intestinalis

Which of the following statements is INCORRECT regarding the Gram staining procedure?

Gram-negative cells carry a net negative charge in their cell walls; gram-positive cells carry a net positive charge

Which of the following describes the correct cellular morphology and Gram reaction for Bacillus cereus?

Gram-positive rods

What can you conclude about the pictured bacteria? Based on your observation of this stained specimen, select ALL appropriate statements.

If a Gram stain was performed on this bacterium within 24 hrs of a fresh culture, it would most likely be Gram-positive The pictured bacteria are bacilli The indicated structure is an endospore

Which of the following vesicles contain a wide variety of hydrolytic enzymes that break down substances engulfed by the cell during phagocytosis?

Lysosomes

You INCORRECTLY perform an acid-fast stain on a smear from a mixed culture of Mycobacterium smegmatis (acid-fast bacilli) and Staphylococcus aureus (non-acid-fast cocci). Your mistake is that you forget to use carbolfuchsin during the procedure. If you viewed this slide with a microscope, what would each cell type look like?

M. smegmatis (acid-fast) cells would be colorless. S. aureus (non-acid-fast) cells would be blue Normally, carbolfuchsin stains acid-fast cells red, but the question indicates that this step was omitted. Subsequent use of methylene blue will color only the non-acid-fast cells because methylene blue cannot penetrate the waxy cell wall of the acid-fast cells. This leaves the acid-fast cells colorless, and the non-acid-fast cells blue

You INCORRECTLY perform an acid-fast stain on a smear from a mixed culture of Mycobacterium smegmatis (acid-fast) cells and Staphylococcus aureus (non-acid-fast) cells. Your mistake is that you forget to use methylene blue during the procedure. If you viewed this slide with a microscope, what would each cell type look like?

M. smegmatis (acid-fast) cells would be red. S. aureus (non-acid-fast) cells would be colorless The correctly used acid-alcohol decolorizer would ensure that at least one cell type would not be red. Methylene blue is used as the counterstain in the acid-fast staining procedure. Forgetting to use methylene blue would leave the non-acid-fast cells colorless after the acid-alcohol decolorization step. In contrast, acid-fast cells are largely stained by the primary stain (carbolfuchsin), so the lack of methylene blue does not affect their appearance

You INCORRECTLY perform an acid-fast stain on a smear from a mixed culture of Mycobacterium smegmatis (acid-fast cells) and Staphylococcus aureus (non-acid-fast cells). Your mistake is that you forget to use acid-alcohol during the procedure. If you viewed this slide with a microscope, what would each cell type look like?

M. smegmatis cells would appear red. S. aureus cells would appear purple Acid-alcohol is the decolorizing agent. If you forgot to decolorize, both cell types would retain the red primary stain, carbolfuchsin. The water-soluble methylene blue counterstain would not penetrate the cell walls of the acid-fast M. smegmatis, so these cells would remain red. In contrast, methylene blue would penetrate the non-acid-fast S. aureus. With S. aureus retaining both carbolfuchsin and methylene blue, these bacteria would appear purple

In order for the stain to penetrate the impervious coat of the spore, which primary stain is steamed into the cell surface?

Malachite green

Define the term protozoan, list the four main groupings of protozoans, and state how they are classified

Means "first animal." The term protozoan is not an official taxonomic rank; It is a term of convenience to describe animal-like protists that are unicellular, lack a true cell wall, exhibit asexual and sexual reproduction, and typically live by heterotrophic means (which means most don't conduct photosynthesis, although some like Euglena do) Amoeboid Protozoans (Sarcodina): They are unicellular, jelly-like protozoa found in fresh or sea water and in moist soil. Body lacks a periplast. May be naked or covered by a calcareous shell. Usually lack flagella and have temporary protoplasmic outgrowths called pseudopodia for locomotion. These pseudopodia or false feet help in movement and capturing prey. They include free living forms such as Amoeba or parasitic forms such as Entamoeba Flagellated Protozoans (Mastigophora): They are free living, non-photosynthetic flagellates without a cell wall. Possess flagella for locomotion and capturing prey. Include parasitic forms such as Trypanosoma, which causes sleeping sickness in human beings and free living forms such as Noctiluca Ciliated Protozoans (Ciliophora): They are aquatic individuals that form a large group of protozoa. Characteristic features are the presence of numerous cilia on the entire body surface and the presence of two types of nuclei. All the cilia beat in the same direction to move the water laden food inside a cavity called gullet. Include organisms such as Paramaecium, Vorticella etc. Only ciliated protozoan known to cause human disease Spore-Forming Protozoans (Apicomplexa): They include disease causing endoparasites and other pathogens. They are uninucleate & their body is covered by a pellicle. They do not possess cilia, flagella or pseudopodia & instead move by gliding. They include the malaria causing parasite Plasmodium. Largest phyla. Go through 3 phases: merogony, gamogony, & sporogony

Why do acid-fast cells NOT appear blue following the addition of methylene blue?

Methylene blue does not penetrate acid-fast cell walls. The waxy mycolic acid layer of acid-fast cell walls is impervious to water-soluble dyes such as methylene blue and even to the intense acid-alcohol decolorizing agent. Acid-fast cells retain the carbolfuchsin primary stain and remain red at the end of the acid-fast staining procedure.

Which of the following fibers are found as part of the eukaryotic cytoskeleton?

Microtubules, intermediate filaments, and microfilaments

Which of the following provides supporting evidence that mitochondria and chloroplasts may have once been free-living prokaryotes?

Mitochondria and chloroplasts contain 70S ribosomes

Compare and contrast mitosis and meiosis

Mitosis: a form of asexual reproduction that is the most common way eukaryotic cells divide; generates two identically identical offspring from one parent cell The offspring cells maintain the same number of chromosomes as the parent cell All human cells, except for egg and sperm cells, divide using mitosis Meiosis: A from of cell division that generates specialized cells, called gametes, that combine in sexual reproduction to make a genetically unique zygote Fungal sexual spores are another example of gametes Consists of two cell division stages One parent cell produces 4 gametes(daughter cells) Gametes are haploid (means they have half the number of chromosomes of their diploid parent, which originally had its chromosomes arranged in pairs before meiosis started) Crossing over allows genetic recombination Occurs when producing sex cells

Eukaryotic cells are not found in which of the following kingdoms?

Monera

Members of which genus of bacteria are best stained using the acid-fast method?

Mycobacterium

A thick waxy layer of what substance in the cell wall constitutes the major portion of the mycobacterial cell wall, separating it from other microorganisms?

Mycolic acids (lipoidal)

Which of the following cell structures are only found in eukaryotic cells?

Nucleus

Why is it recommended that Gram staining be performed on young bacterial cultures (not older than 24 hours)?

Over time, gram-positive cells lose their ability to retain the crystal violet stain after decolorization.

Discuss the basic structural and functional features of eukaryotic plasma membranes and how they differ among kingdoms

Plasma Membrane: -Serves as a selective barrier between the cell and the environment Structure: -Phospholipid bilayer with hydrophilic heads and hydrophobic fatty acid tails -Crowded by a variety of receptors and channels that are scattered throughout Sterols: -Hydrophobic compounds that are scattered throughout Eukaryotic Cell Membranes, maintaining membrane fluidity and stability EX. Cholersterol rare for prokaryotes to contain sterols in their membranes, eukaryotic membranes contain many sterols, which have central roles in maintaining membrane stability and fluidity

Which of the following structures is found in all cells?

Plasma membrane

What is the purpose of carbolfuchsin in the acid-fast staining technique?

Primary stain Carbolfuchsin is a lipid-soluble dye that can penetrate the waxy cell walls of acid-fast bacteria. This red dye is used as the primary stain in the acid-fast procedure.

What color do you expect Mycobacterium smegmatis to be after performing the acid-fast stain?

Red

While performing the acid-fast stain procedure, you add acid-alcohol drop by drop until no more stain runs from the smear. What is your next step?

Rinse with distilled water Rinsing with water is necessary after each reagent is used in the acid-fast procedure. The acid-alcohol decolorizing agent, if not washed off, will interfere with the subsequent methylene blue counterstain

What stain is used as the counterstain when performing a spore stain?

Safranin

Which of the following processes is likely to occur when environmental conditions become unfavorable?

Sporogenesis

Which of the following represents a true statement regarding spororgenesis?

Sporogenesis results in the formation of an endospore, which is later released from the degenerating vegetative cell

Explain why Protista is sometimes described as a catchall kingdom

Taxonomists place eukaryotic organisms that do not fit in other kingdoms in this group A protist is any organism that is not animal, plant or fungus

Describe the general structural and functional features of the Golgi apparatus

The Golgi apparatus is a series of interconnected flattened sacs that modifies cellular proteins, builds lipids, and sorts and distributes the finished products -A variety of vesicles ship materials from the Golgi to their final destination -Resembles a series of disc-like flattened sacs called cisternae that stack upon one another

Which of the following represents a true statement regarding the structure of the capsule?

The capsule structure protects bacteria from the immune response of the host.

Why is it important that crystal violet be a contrasting color to safranin?

The contrast allows you to differentiate between gram-negative and gram-positive cells by observing the color of the organism

Explain the structure and function of the cytoskeleton and name the organelle that builds microtubules

The cytoskeleton is a network of protein fibers that maintain cell shape, facilitate cell movement, and coordinate the movement of vesicles, organelles, and other cellular cargo -It is made of microtubules, intermediate filaments, and actin microfilaments

What is the most critical step in the Gram staining procedure?

The decolorization step

Describe the endosymbiotic theory as it relates to the evolution of eukaryotes

The evolution of eukaryotes as a series of sequential, cell-merging events between an ancient eukaryotic ancestor and certain prokaryotes The prefix endo means inside, while symbiotic refers to collaboration between organisms Therefore, the word endosymbiotic reflects the idea that these cell-merging events came about through a mutually beneficial relationship among the participants

Why is acid-alcohol used as a decolorizing agent rather than ethyl alcohol?

The mycolic acids in the cell walls of acid-fast bacteria make them resistant to acid-alcohol

Which of the following is true regarding the capsule staining procedure?

The slide should not be heated, even to achieve heat fixation

Which of the following is not a feature of eukaryotic flagella?

They are built from flagellin proteins

What is the purpose of steaming the stain while applying malachite green?

To allow the malachite green to penetrate more deeply into the thick spore coat

Which of the following fungal species may cause infections in healthy individuals that have not suffered from interruption in the normal microbiota?

Trichophyton species

The acid-fast stain has diagnostic value in identifying bacteria that contribute to which of the following infectious diseases?

Tuberculosis and leprosy

Which of the following represents the correct association to describe the color of cells after the staining process is complete:

Vegetative cells = Red; Spores = Green

What compound is used as the decolorizing agent in the spore stain?

Water

While __________ bacteria retain carbol fuchsin after acid-alcohol treatment, __________ bacteria are decolorized by acid-alcohol

acid-fast; non-acid-fast

While vegetative cells are metabolically _____, cells in the spore form are metabolically _____.

active; inactive

Plants _________.

are multicellular organisms that carry out photosynthesis

Animals are not typically microscopic, yet we cover them in microbiology because _________

certain parasitic worms, or helminths, are usually spread in a microscopic form

If you stopped staining after applying only the malachite green stain and rinsing with water, vegetative cells would appear ___________ and spores would appear ____________

colorless; green

If you forgot to add the counterstain to the mixed culture sample at the end of the staining procedure, gram-negative cells would appear __________ and gram-positive cells would appear

colorless; purple

After methylene blue is applied as a counterstain, acid-fast bacteria will appear __________ while non-acid-fast bacteria will appear

dark red; blue

Just after the decolorizer (acid-alcohol) is applied, acid-fast bacteria will appear __________ and non-acid-fast bacteria will appear

dark red; colorless

The sticky outer layer that can be found in both prokaryotic and eukaryotic cells is known as the _________

glycocalyx

The endosymbiotic theory states that nonphotosynthetic prokaryotes merged with an ancestral cell and, over evolutionary time, became___________. Some of these new cells engaged in a second merging event with a photosynthetic prokaryote, possibly a cyanobacterium. The photosynthetic prokaryote eventually—over evolutionary time—became ___________.

mitochondria; chloroplasts

Whole cells or viruses are engulfed and imported into a eukaryotic cell via

phagocytosis

Most bacteria are easily stained by aqueous stains. The lipoidal material that comprises mycobacterial cell walls, however, does not bind to aqueous stains, instead requiring a stain such as carbol fuchsin, which is composed of 5%

phenol

The Golgi apparatus:

resembles a series of disc-like, flattened sacs called cisternae that stack upon one another

While the formation of the spore is called _____, the reversion to a vegetative cell is called _____.

sporogenesis; germination