Chapter 4-Functional Anatomy of Prokaryotic and Eukaryotic Cells

A prokaryotic cell may possess each of the following cellular components EXCEPT: cell membrane ribosomes a nucleus flagella

*a nucleus

Spirochetes and spirilla are both spiral-shaped bacteria. However, they differ in that spirochetes have __________ and spirilla do not. *endoflagella peritrichous flagella N-acetylglucosamine fimbriae

*endoflagella

Features of prokaryotic cells

-usually single cell microorganisms (bacteria/archaea) and most of them multiply by binary fission. Some multiply by budding or fragmentation -bacterial species are differentiated by morphology, chemical composition, nutritional requirements, biochemical activities, and source of energy

Movement of bacteria

is often referred to as run and tumble. The movement of a bacterium toward or away from a stimulus is called taxis. Chemotaxis-movement to and away from chemicals Phototaxis-movemement to and away from light

Which of the following is NOT true of the gram-negative outer membrane? It contains lipids also known as endotoxins. It contains enzymes for energy synthesis. It contains lipopolysaccharide. It has polysaccharide antigens that are useful in bacterial identification. It is a part of the gram-negative cell wall.

*It contains enzymes for energy synthesis.

Gene Expression in Prokaryotes

In prokaryotes, gene expression happens in a different way. Both bacteria and archaea can have transcription and translation happen at the same time. This means that cells can make amino acids, which are the building blocks of proteins, at any time.

Endospores can only survive a few days. True False

False. Endospores are able to survive for thousands of years.

Consider a gram-positive cell in a hypertonic medium. If the peptidoglycan were damaged, the cell would _____.

shrink

Different ways bacterial cells can multiply

Budding happens when a cell makes a bud that looks like a bubble. The bud continues to grow while it is attached to the parent cell. Eventually, the bud breaks off from the parent cell. Binary fission happens when a cell splits into two identical daughter cells. Fragmentation happens when a cell breaks into small pieces or fragments, and each piece becomes a new cell.

Chemotaxis refers to what?

Chemotaxis is the movement of an organism in response to a chemical stimulus.

Phototaxis refers to the ability of microorganisms to __________.

Move toward a source of light

Functions of the glycocalyx include all of the following except increased virulence protection against dehydration biofilm formation binary fission

*binary fission

The term describing bacteria with flagella that are arranged as a tuft coming from one pole is __________.

*lophotrichous amphytrichous peritrichous monotrichous I DON'T KNOW YET (Explanation: The term describing bacteria with flagella that are arranged as a tuft coming from one pole is lophotrichous. Flagella may also be described as peritrichous (distributed over the entire cell); monotrichous (a single flagellum at one pole); or amphitrichous (flagella at both poles of the cell).

Which is not a component of a flagellum? filament basal body mycolic acid hook

*mycolic acid

Genetic information inside prokaryotic cells

Genetic information in prokaryotes exists inside the nucleoid. Unlike eukaryotes, prokaryotes do not have a membrane-bound nucleus. Instead, the circular DNA molecules live in a region of the cytoplasm. For instance, the circular bacterial chromosome is one large loop instead of individual chromosomes. DNA synthesis in bacteria starts with the initiation of replication at a specific nucleotide sequence. Then, elongation occurs to add new nucleotides. Next, termination happens after the new chromosome forms.

Archea basics:

Initially classified as ancient bacteria and called "archaeobacteria," archaea now have their own domain. Many species of archaea are extremophiles and live in extreme conditions, such as boiling hot springs or acidic water, which bacteria cannot tolerate. Some examples include hyperthermophiles that exist in temperatures above 176 degrees Fahrenheit (80 degrees Celsius) and halophiles that can live in salt solutions that range from 10 to 30 percent. The cell walls in archaea offer protection and allow them to live in extreme environments.

Organelles in Eukaryotic cells

Lysomsome-functions in digestion of food and recycling Mitchondria- transfer energy from food molecules to ATP. Vacuoles-stores oil, water, carbs and toxins The plasma membrane- made of phospholipids and protein and serves as the selective boundary of the cell. The nucleus-stores and protects the DNA/genetic information of the cell. Golgi apparatus-ships proteins where they need to go. Ribosome-functions in protein synthesis Chloroplasts -bacteria like element found in plants and site of photosynthesis. Transform energy from the sun and CO2 from atmosphere into food molecules (sugars). Cell Wall-provides protection, structural support

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Why is penicillin selectively toxic to bacterial cells but harmless to human cells?

Penicillin specifically weakens peptidoglycan, which is found only in bacterial cells.

Consider a gram-positive cell in a hypertonic medium. If the peptidoglycan were damaged, the cell would __________.

Shrink

Arrangement of cocci (round shaped) bacteria

When cocci divide to reproduce, the cells can remain attached to one another and arrange different shapes. Diplococci-bacteria that remain in pairs after dividing (look like two balls stuck together). Streptococco-bacteria that divide and remain attached in a chain(look like a bunch of balls stuck together in a chain) Tetrad-bacteria that divide into groups of four balls stuck together Sarcinae-those that divide and remain attached in groups of 8 Staphlococci-those that divide and form big grapelike clusters

Nutrient storage is important for prokaryotes

because some of them exist in environments that make it difficult to have consistent food supplies, prokaryotes have developed specific structures for nutrient storage. Vacuoles act as storage bubbles for food or nutrients. Bacteria can also have inclusions, which are structures for keeping reserves of glycogen or starches. Microcompartments in prokaryotes have protein shells and can hold enzymes or proteins. There are specialized types of microcompartments such as magnetosomes and carboxysomes.

Bacteria are one of the two domains that make up prokaryotic cells. They are diverse life forms and reproduce by binary fission. There are three basic bacterial cell shapes: cocci, bacilli and spirilla.

coccus (spherical shaped, oval), rod shaped bacillus (meaning little rods or walking sticks),and spiral shaped (twisted)

simple diffusion

diffusion occurs without the aid of an intermediary molecule such as channel proteins or carrier molecules

In a prokaryotic cell, all of the following are functions of either fimbriae or pili EXCEPT

formation of biofilms transfer of DNA *protection from phagocytosis attachment to a surface (Explanation: Fimbriae and pili do NOT function in protection from phagocytosis. That is the role of the capsule. Fimbriae help cells adhere to surfaces and are involved in forming biofilms. Pili are commonly involved in DNA transfer and twitching or gliding motility.)

Hypotonic solution

is one in which the concentration of solutes is greater inside the cell than outside of it

Hypertonic solution

is one where the concentration of solutes is greater outside the cell than inside it.

Gram-negative cells contain a periplasmic space that is __________.

rich in degradative enzymes

Spherical bacteria that divide and remain attached in chainlike patterns are called

streptococci

Faciliated diffusion

the movement of specific molecules across a cell membrane through protein channels

Isotonic Solution

the relative concentrations of solute and water are equal on both sides of the membrane.

Arrangement of spiral bacteria

three kinds: Vibrio-bacteria that looked like curved rods Spirillum-helical shape like a cork screw and rigid bodies (looks like a rigid squiggly line) Spirochete-helical shape but flexible unlike spirillum (looks like a loose squiggly line)

The motility of bacteria with flagella occurs through a series of "runs" and

tumbles. When a bacterium moves in one direction for a length of time, the movement is called a "run" or "swim." "Runs" are interrupted by periodic, abrupt, random changes in direction called "tumbles."

Glycocalyx

(meaning sugar coat) is the general term used for substances that surround cells. The bacterial glycocalyx (glycocalyx is also in eukaryotic cells too) is a sticky gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypedtide, or both. For the most part its made inside the cell and excreted to its surface. A glycocalyx is considered a slime layer when the glycoprotein molecules are loosely associated with the cell wall. Bacteria that are covered with this loose shield are protected from dehydration and loss of nutrients. ... The adhesive power of capsules is also a major factor in the initiation of some bacterial diseases.

Which of the following is NOT a structure of prokaryotic cells? Flagellum Capsule Chromosome Ribosome Chloroplast

*Chloroplast

Penicillin specifically interferes with peptidoglycan synthesis. Which of the following cells is most likely to be damaged by penicillin? Cells of archaea Human cells Gram-positive bacterial cells Yeast cells

*Gram-positive bacterial cells

You are observing a Gram stain of rod-shaped microorganisms that are linked in a chain and stain purple. How would you describe these bacteria using the correct terminology for the cell shape and arrangement?

*Gram-positive streptobacilli Gram-positive coccobacilli Gram-positive tetrads Gram-negative staphylococci

Which of the following statements about a gram-negative cell wall is FALSE? It includes a thin layer of peptidoglycan. It maintains the shape of the cell. It contains teichoic acid. It functions as an endotoxin.

*It contains teichoic acid.

With a light microscope, which of the following would allow discrimination between eukaryotes and prokaryotes? Observation of the plasma membrane Observation of flagella Observation of nuclei Observation of the ribosomes Observation of photosynthetic pigment I DON'T KNOW YET

*Observation of nuclei

All of the following are found in the cell walls of gram-positive bacteria EXCEPT lipoteichoic acid lipid A peptidoglycan N-acetylglucosamine teichoic acid

*lipid A

Which of the following pairs is matched correctly? protoplast—a genus of bacteria that typically do not have cell walls Mycoplasma spp.—bacteria that spontaneously, or in response to penicillin or lysozyme, partially lose their cell walls and swell into irregularly shaped bacteria that divide and metabolize and may regain their cell wall spheroplast—gram-negative bacteria that are exposed to lysozyme but retain some of the outer membrane L form—a wall-less bacterium created by the action of lysozyme; the plasma membrane remains intact, and the cell carries on metabolism

*spheroplast—gram-negative bacteria that are exposed to lysozyme but retain some of the outer membrane

Comparing Prokaryotic and Eukaryotic Cells

1.) both are similar in their chemical composition and chemical reactions 2.) prokaryotic lack membrane enclosed organelles, including a nucleus 3.) peptidoglycan is found in prokaryotic cell walls but not in eukaryotic cell walls. Archea is the exception to this. They do not have peptidoglycan. 4.) Eukaryotic cells have a membrane bound nucleus and other organelles Many antibiotics, including penicillin, work by attacking the cell wall of bacteria. Specifically, the drugs prevent the bacteria from synthesizing (make or producing) a molecule in the cell wall called peptidoglycan, which provides the wall with the strength it needs to survive in the human body. It is the back bone of the cell wall. This is discussed above. Prokaryotes and eukaryotes are not the same because the types of cells they have differ greatly. Prokaryotes do not have the membrane-bound organelles and nucleus you find in eukaryotes; their DNA floats inside the cytoplasm. In addition, prokaryotes have a smaller surface area compared to eukaryotes. Moreover, prokaryotes are single-celled despite some organisms being able to aggregate to form colonies. Prokaryotic cells are less organized than eukaryotic cells. There are also differences in the levels of regulation, such as cell growth, in prokaryotes. You can see this in the mutation rates of bacteria because fewer regulations allow for rapid mutations and multiplication. Since prokaryotes do not have organelles, their metabolism is different and less efficient. This prevents them from growing to a large size and sometimes limits their ability to reproduce. Nevertheless, prokaryotes are an important part of all ecosystems. From human health to scientific research, these small organisms matter and can affect you greatly.

Which of the following is NOT characteristic of the glycocalyx found in bacteria?

A structure that can be visualized by negative staining If firmly attached, contributes to bacterial virulence A viscous coating surrounding the cell made of polysaccharide, polypeptide, or both *Creates a slimy, slippery coating that prevents bacteria from attaching to surfaces I DON'T KNOW YET Explanation: The bacterial glycocalyx is a viscous (sticky), gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide, or both. Its chemical composition varies widely with the species. For the most part, it is made inside the cell and secreted to the cell surface.

acid fast bacteria

Bacteria that are considered acid fast have mycolic acid around cell wall (hydrophobic, waxy substance) around cell wall. Prevents uptake of dye. Stain with carbolfuchsin. Some archaea may lack cell wall. If they have wall they may have peptides or sugars, but no peptidoglycan

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

Capsule

What are Fimbriae and pili in prokaryotic cells?

Fimbriae and pili are interchangeable terms used to designate short, hair-like structures on the surfaces of procaryotic cells. Like flagella, they are composed of protein. Fimbriae are shorter and stiffer than flagella, and slightly smaller in diameter. Generally, fimbriae have nothing to do with bacterial movement (there are exceptions, e.g. twitching movement on Pseudomonas). Fimbriae are very common in Gram-negative bacteria, but occur in some archaea and Gram-positive bacteria as well. Fimbriae are most often involved in adherence of bacteria to surfaces, substrates and other cells or tissues in nature. In E. coli, a specialized type of pilus, the F or sex pilus, apparently stabilizes mating bacteria during the process of conjugation, but the function of the smaller, more numerous common pili is quite different. Common pili (almost always called fimbriae) are usually involved in specific adherence (attachment) of procaryotes to surfaces in nature. In medical situations, they are major determinants of bacterial virulence because they allow pathogens to attach to (colonize) tissues and/or to resist attack by phagocytic white blood cells. For example, pathogenic Neisseria gonorrhoeae adheres specifically to the human cervical or urethral epithelium by means of its fimbriae; enterotoxigenic strains of E. coli adhere to the mucosal epithelium of the intestine by means of specific fimbriae; the M-protein and associated fimbriae of Streptococcus pyogenes (See Figure 2) are involved in adherence and to resistance to engulfment by phagocytes.

Prokaryotic cell structure terms to know

Glycocalyx - in both proks. and euks Made inside cell; secreted to surface. Capsule - organized and attached Slime layer - disorganized, loosely attached No histones Plasmids - Molecules of extrachromosomal DNA in bacteria that is physically separated from chromosomal DNA and can replicate independently. Contain T genes for antibiotic resistance-produce toxins, enzymes.

Structure external to prokaryotic cell wall include

Glycocalyx- capsule, slime layer or extracellular polysaccharide is a gelatinous polysaccharide or polypeptide covering Flagella and Archaella-rotate to push the cell. Flagella are relatively long filamentous appendages consisting of a filament, hook, and basal body. Motile bacteria exhibit positive taxis-movement toward an attractant, and negative taxis-movement away from a repellent Axial Filaments-spiral cells that move by means of an axial filament Fimbriae and Pili- fibriae help cells adhere to surfaces pili are involved in twitching motility and DNA transer

What is gram negative/positive?

In bacteria, the cell wall consists of peptidoglycan or murein, which is made up of polysaccharide chains. However, the cell walls differ among gram-positive and gram-negative bacteria. Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, while gram-negative bacteria have a thin layer of peptidoglycan in their wall. Since the peptidoglycan layer is thinner in gram negative cell walls, they have an extra layer of lipopolysaccharides in their outer membrane. This is not found in gram positive bacteria. (see image on right) Gram negative bacteria are often associated with pathogens such as E. Coli or salmonella. Antibiotics and other drugs can target the cell walls in bacteria without harming humans because people do not have these types of walls in their cells. However, some bacteria develop antibiotic resistance, and the drugs stop being effective. Antibiotic resistance happens when bacteria evolve, and the ones with mutations that allow them to survive the medications are able to multiply.

Which of the following bacterial structures is necessary for chemotaxis?

Metachromatic granules Capsules *Flagella Plasmids (Explanation: Flagella are necessary for chemotaxis. Bacterial cells can alter the speed and direction of rotation of flagella and thus are capable of various patterns of motility, the ability of an organism to move by itself. One advantage of motility is that it enables a bacterium to move toward a favorable environment or away from an adverse one. The movement of a bacterium toward or away from a particular stimulus is called taxis, for example chemicals (chemotaxis).

Which of the following is a likely outcome, based on the unique cell structure of members of the genus Mycoplasma?

Mycoplasma species usually stain gram-positive. *Mycoplasma species have very flexible cells that can pass through bacteriologic filters. Mycoplasma species are susceptible to disruption by lysozymes. Mycoplasma species can release endotoxins when they lyse. Mycoplasma species are susceptible to penicillin. (Explanation: Members of the genus Mycoplasma and related organisms have no cell walls. They have very flexible cells that can pass through bacteriologic filters. Their plasma membranes are unique among bacteria in having lipids called sterols, which are thought to help protect them from lysis.)

Bacterial flagella. Flagella allow bacteria to move toward or away from stimuli (taxis)

Peritrichous-Flagella are present ALL around the bacteria Monotrichous and polar-FLAGELLUM (only one flagella) is at ONE end of the bacteria Lophotrichous and polar-Flagella are at ONE end of the bacteria Amphitrichous and polar-Flagella are found at BOTH ends of the bacteria (See illustration)

Prokaryote vs. Eukaryote

Prokaryote •One circular chromosome, not in a membrane •No histones •No organelles •Bacteria: peptidoglycan cell walls •Archaea: pseudomurein cell walls •Divides by binary fission Eukaryote •Paired chromosomes, in nuclear membrane •Histones •Organelles •Polysaccharide cell walls, when present •Divides by mitosis

What are Mycoplasmas?

Smallest free living organisms (bacteria) that can grow and reproduce outside living host cells. Because of their size and the fact that they have no cell walls, they are able to pass through most bacterial filters and were mistaken for viruses. Their plasma membrane is unique in that they have sterols in their plasma membrane (most bacteria do not have sterols in membrane). That help maintain their shape and give them flexibility and prevent them from rupture.

How do spirochetes and spirilla differ?

Spirilla have external flagella but spirochetes have axial filaments.

Structure internal to prokaryotic cell wall

The cell structure of prokaryotes can vary, but most organisms have several basic components. Prokaryotes have a cell membrane or plasma membrane that acts like a protective cover. They also have a rigid cell wall for added support and protection. Prokaryotic cells have ribosomes, which are molecules that make proteins. Prokaryotic cells differ from Eukaryotic in their RNA, which is necessary to make protein. Their genetic material is in the nucleoid, which is the region where DNA lives. This is not enclosed in a membrane like it is in a Eukaryotic cell. Also no histones in prokaryotic cells. Additional rings of DNA called plasmids float around the cytoplasm. A plasmid is a small, often circular DNA molecule found in bacteria and other cells. Plasmids are separate from the main bacterial chromosome and replicate independently of it. Plasmids contain genes for antibiotic resistance- almost always found on DNA in Plasmid. Prokaryotic cells also have cytoplasm. The ribosomes float in this. Prokaryotic bacteria contain endospores which can remain dormant for thousands of years. The vegetative cell is everything but the endospore. Endospores are often used in canned foods and can release toxins, which can be harmful, so its important to make sure they are treated properly.

What will occur if a bacterial cell with a weakened or damaged cell wall is placed in pure water?

The cell will form endospores. The cell will shrink. *The cell will swell and burst. The cell will remain the same size. The cell will form a new cell wall. (Explanation: If a bacterial cell with a weakened or damaged cell wall is place in pure water, the cell will swell and burst. This type of environment would be called a hypotonic solution. Outside the cell is a medium whose concentration of solutes is lower than that inside the cell (hypo means under or less). Cells with weak cell walls, such as gram-negative bacteria, may burst or undergo osmotic lysis as a result of excessive water intake)

A Gram stain of a wound reveals purple, spherical bacteria that divide and remain attached in grapelike clusters. These are referred to as __________.

gram-positive staphylococci

What are important functions of the cell wall?

helps keep it from rupturing and keeps the cell shape.

The shape of bacterium is determined by

heredity. Genetically, most bacteria are monomorphic, that is they maintain a single shape. But a number of environmental conditions can alter the shape. If the shape becomes altered than identification becomes difficult. Moreover some bacteria are genetically pleomorphic, meaning they can have many shapes, not just one. Some bacteria can be star shaped (stella in latin), others can be rectangular shaped.