Biology II Chapter 27 - 1

Card Set Information

Author:
Yasham
ID:
84460
Filename:
Biology II Chapter 27 - 1
Updated:
2011-10-06 18:30:39
Tags:
Biology Bacteria Archaea Campbell
Folders:

Description:
Chapter 27 of Campbell's Biology Textbook 8th - Bacteria and Archaea
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user Yasham on FreezingBlue Flashcards. What would you like to do?


  1. (T/F) The first organisms to thought to inhabit Earth are prokaryotes. Throughout their long evolutionary history, prokarytotic populations have been (and contiued to be) subjected to natural selection under many different environmental conditions.
    True.
  2. A key feature of nearly all prokaryotic cells is the ________, which maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment.
    cell wall.
  3. (T/F) A key feature of nearly all prokaryotic cells is the cell wall, which maintains cell shape, provides physical protection, and prevents the cell from bursting in a hypotonic environment.
    True
  4. What is a hypertonic environment?
    In comparing two solutions, referring to the one with a greater solute concentration, which when surrounding a cell, will cause the cell to lose water.

    In this environment, prokaryotes will lose water and shrink away from their wall. Severe water loss inhibits cell reproduction, which explains why salt can be used to preserve foods such as pork and fish.
  5. Eukaryotic cell walls are usually made of cellulose or chitin. In contrast, most bacterial cell walls contain ____________.
    peptidoglycan.

    Peptidoglycan is a network of modified-sugar polymers cross-linked by short polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from this surface. Archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan.
  6. What are the differences between bacterium walls and archaeal walls?
    Most bacterial cell walls contain peptidoglycan, a network of modified-sugar polymers cross-linked by short polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface.

    Archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan.
  7. (T/F) Most bacterial cell walls contain peptidoglycan while archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan.
    True.
  8. What is the Gram stain technique used for?
    To classify many bacterial species into two groups based on differences in cell wall composition.

    gram-postive (bacteria with simpler walls and a relatively large amount of peptidoglycan) and gram-negative (bacteria with less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids)).
  9. What is a Gram-positive bacteria?
    Gram-positive bacteria have simpler walls with a relatively large amount of peptidoglycan.

  10. What is a Gram-negative bacteria?
    Gram-negative bacteria have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids).

  11. What are the differences between Gram-positive and Gram-negative bacteria?
    • Gram-positive bacteria:
    • Simple walls with a relatively large amount of peptidoglycan

    • Gram-negative bacteria:
    • Less peptidoglycan
    • Structurally more complex
    • Outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids)

  12. What is 1 in the figure below? Is this bacteria Gram-positive or Gram-negative? Is this present in the other type of bacteria?
    Carbohydrate portion of lipopolysaccharide.

    This is a Gram-negative bacteria. It is not present in Gram-positive bacteria.
  13. The lipid portions of the lipopolysaccharides in the walls of many gram-______ bacteria are toxic, causing fever or shock.

    Furthermore, the outer membrane of a gram-_____ bacterium help protect it from the body's defenses.
    gram-negative in both cases. Gram-negative bacteria also tend to be more resistant than gram-positive species to antibiotics because the outer membrane impedes entry of the drugs.
  14. (T/F) Gram-negative bacteria also tend to be more resistant than gram-positivespecies to antibiotics because the outer membrane impedes entry of the drugs.
    True.
  15. (T/F) Human cells, similar to gram-positive bacteria, contain peptidoglycan.
    False.

    The effectiveness of certain antibiotics, such as penicillin, derives from their inhibition of the peptidoglycan cross-linking. These drugs destroy many species of pathogenic bacteria without adversely affecting human cells, which do not contain peptidoglycan.
  16. The cell wall of many prokaryotes is covered by a ________, a sticky layer of polysaccharide or protein.

    This enables prokaryotes to adhere to their substrate or to other individuals in a colony. In some cases, it protects the prokaryote against dehydration, and some shield pathogenic prokaryotes from attacks by their host's immune system.
    capsule
  17. The effectiveness of certain antibiotics, such as penicillin, derives from their inhibition of the ________________. The resulting cell wall may not be functional, particularly in gram-positive bacteria.

    Such drugs destroy many species of pathogenic bacteria without adversely affecting human cells, which do not contain peptidoglycan.
    peptidoglycan cross-linking
  18. What is a capsule in a prokaryote and what is the function in some cells?
    The capsule is a sticky layer of polysaccharides or protein.

    This enables prokaryotes to adhere to their substrate or to other individuals in a colony. In some cases, it protects the prokaryote against dehydration, and some shield pathogenic prokaryotes from attacks by their host's immune system.
  19. Some prokaryotes stick to their substrate or to one another by means of hair-like protein appendages called ________, rather than with the use of a capsule.
    fimbriae

    They are also known as attachment pili.
  20. (T/F) Fimbriae are typically longer and less numerous than sex pili.
    False.

    Fimbriae are typically shorter and more numerous than sex pili.
  21. What are sex pili in a prokaryote? What determines the formation of the sex pili and what process is this used for?
    Appendages that pull two cells together prior to DNA transfer from one cell to another.

    The F factor (F for fertility) must be present for the development of the sex pili so that the mating bridge may be formed and DNA may be donated from conjugation.

    It should also be noted that many R plasmids have genes that encode sex pili and enable plasmid transfer from one bacterial cell to another by conjugation.
  22. (T/F) Fimbriae and flagellum in prokaryotes serve the same function of mobility.
    False.

    Fimbriae have the function of adhering a prokaryote to their substrate or to another prokaryote by the protein appendages called fimbriae.

    Flagellum serve for the function of mobility.
  23. (T/F) All prokaryotes are capable of directional movement.
    False.

    About half of all prokaryotes are capable of directional movement.
  24. (T/F) Flagella (singular - flagellum) may be scattered over the entire surface of the cell or concentrated at one or both ends.
    True.
  25. (T/F) Prokaryotic flagella are one-tenth the width of eukaryotic flagella and are also covered by an extension of the plasma membrane.
    False.

    Prokaryotic flagella are one-tenth the width of eukaryotic flagella and are not covered by an extension of the plasma membrane.
  26. In a heterogenous environment, many prokaryotes exhibit ________, movement toward or away from a stimulus.
    taxis
  27. What is positive chemotaxis?
    Movement toward nutrients or oxygen.

    This is in contrast to negative chemotaxis, the movement away from a toxic substance.
  28. What is negative chemotaxis?
    Movement away from a toxic substance.

    This is in contrast to positive chemotaxis, the movement towards nutrients or oxygen.
  29. All cells have several basic features in common:

    They are bounded by a selective barrier, called the plasma membrane.

    Enclosed by the membrane is a semifluid, jellylike substance called cytosol, in which organelles and other components are found

    All cells contain chromosomes, which carry genes in the form of DNA

    All cells have ribosomes, tiny complexes that make proteins according to instructions from the genes.
    True.

    Know this.
  30. The cells of prokaryotes are simpler than those of eukaryotes, in both their internal structure and their genomic organization.

    (T/F) Prokaryotic cells lack the complex compartmentalization found in eukaryotic cells. However, some prokaryotic cells do have specialized membranes that perform metabolic functions.
    True.

    These membranes are usually infoldings of the plasma membrane.
  31. What is the nucleoid region?
    The region in a prokaryotic cell consisting of a conentrated mass of DNA.

    Prokaryotes lack a membrane-bounded nucleous like those found in eukaryotes.
  32. In addtition to its single chromosome, a typical prokaryotic cell also has much smaller rings of separately replicating DNA called _______, most carrying only a few genes.
    plasmids.
  33. (T/F) DNA replication, transcription and translation are fundamentally similar processes in prokaryotes and eukaryotes. However, some differences include that prokaryotic ribosomes are samaler than eukaryotic ribosomes and difffer in their protein and RNA content.
    True.

    These differences allow for certain antibiotics to bind to ribosomes and block protein synthesis in prokaryotes but not in eukaryotes. This allows for killing of bacteria without harming ourselves.
  34. What are three key features about the biology of prokaryotes?
    • They are small
    • They reproduce by binary fission
    • They have short generation times

    As a result, prokaryotic populations can consist of many trillions of individuals - far more than populations of multicellular eukaryotes, such as plants and animals.
  35. What is binary fission? In prokaryotes, does this involve mitosis? In eukaryotes, does this involve mitosis?
    A method of asexual reproduction by "division in half". In prokaryotes, binary fission does not involved mitosis; but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process.

    A single prokaryote cell divides into 2, which then divide to 4, 8, 16....
  36. What are some of the factors that limit the reproduction of prokaryotes?
    The cells eventually exhaust their nutrient supply, poison themselves with metabolic wastes, face competition from other microorganisms, or are consumed by other organisms.
  37. What is an endospore? Why is this an important cell to learn about?
    A thick-coated, resistant cell produced by a bacterial cell exposed to harsh conditions.

    When an essential nutrient is lacking, the original cell produces a copy of its chromosome and surrounds it with a tough wall, forming the endospore. Water is removed from the endospore, and its metabolism halts. The rest of the original cell then disintegrates, leaving the endospore behind.

    In some environments, endospores can remain dormant byt viable for centuries, able to rehydrate and resume metabolism when their environment improves.
  38. Why is the short generation time of prokaryotic populations very benefitial? Does this imply that even though the structure is considered "simple" that they are primitive" or "inferior" in an evolutionary sense?
    Due to the short generation times, prokaryotic populations can evolve substantially in short periods of times. The ability of prokaryotes to adapt rapidly to new conditions highlights the fact that although the structure of their cells is simpler than that of eukaryotic cells, prokaryotes are not "primitive" or "inferior" in an evolutionary sense. They are highly evolved.
  39. What is 1 in a prokaryote shown below?
    Fimbriae: Hairlike appendages that help cells adhere to other cells or a substrate.
  40. What is 2 in a prokaryote shown below?
    Cell wall: Found in nearly all prokaryotes, structure differes in gram-positive and gram-negative prokaryotes.
  41. What is 3 in a prokaryote shown below?
    Capsule: sticky layer of polysaccharide or protein that can help cell adherence and/or evation of a host's immune system.
  42. What is 4 in a prokaryote shown below?
    Circular chromosome: Often accompanied by smaller rings of DNA called plasmids.
  43. What is 5 in a prokaryote shown below?
    Sex pilus: appendage that facilitates conjugation
  44. What is 6 in a prokaryote shown below?
    Internal organization: No nucleus or other membrane-bounded organelles; usually no complex compartmentalization
  45. What is 7 in a prokaryote shown below?
    Flagella: Organs used by most motile bacteria for propulsion; many species can move toward or away from certain stimuli
  46. Identify and explain at least two adaptations that enable prokaryotes to survive in environments too harsh for other organisms.
    Adaptations include the capsule (shields prokaryotes from the host's immune system) and endospores (enable cells to survive harsh conditions and to revive when the environment becomes favorable).
  47. Contrast the cellular and genomic organization of prokaryotes and eukaryotes.
    Prokaryotic cells generally lack the internal compartmentalization or eukaryotic cells. Prokaryotic genomes have much less DNA than eukaryotic genomes, and most of this DNA is contain in a single ring-shaped chromosome located in a nucleoid region rather than within a true membrane-bounded nucleous

    In addition, many prokaryotes also have plasmids, small ring-shaped DNA molecules containing a few genes.
  48. What are three factors that give rise to high levels of genetic diversity in prokaryotes?
    • Rapid production
    • Mutation
    • Genetic recombination.
  49. (T/F) Prokaryotes reproduce sexually, which leads to the large amount of genetic variation.
    False.

    Prokarotes reproduce asexually, it is due to the result of rapid reproduction and mutation that leads to the large amount of genetic variation.
  50. (T/F) Genetic mutations have a high probability of occuring in prokaryotes that reproduce by binary fusion.
    False.

    Binary fusion leads to offspring cells that are genetically identical to the original parent cell. However, it is due to insertions, delections, and base-pair substitutions in the DNA that lead to some offspring cells that differ genetically.

    It should also be noted that the probability of a spontaneous mutation occuring in E. coli occur about one in 10 million per cell division (1 x 10^-7). However, due to the rapid rate of reproduction (also known as short generation times) and the large population sizes, leads to rapid evolution.

    Individuals that are genetically better equipped for their local environment tend to survive and reproduce more prolifically than less fit individuals.
  51. What is genetic recombination? How does this occur in prokaryotes?
    General term for the production of offspring with combinations of traits that differ from those found in either parent.

    • While meiosis and fertilization does not occur in prokaryotes, this may occur through three other processes:
    • transformation
    • transduction
    • conjugation
  52. An important point is that new __________, though individually rare, can greatly increase genetic diversity in species like E. coli that have short generation times and large population sizes.

    This diversity can lead to rapid evolution: Individuals that are genetically better equipped for their local environment tend to survive and reproduce more prolifically than less fit individuals.
    mutations.

    Mutations are rare but with such short generation times and large population sizes, the mutations have a large impact on prokaryotes.
  53. What is transformation? What is the cell after it has gone through transformation? How might this transform a nonpathogenic cell to a pathogenic cell?
    In a prokaryotic cell, the genotype and possible phenotype is altered by the uptake of a foreign DNA from its surroundings.

    After transformation, the cell is a recombinant: Its chromosome contains DNA derived from two different cells.

    The transformation occurs when a live nonpathogenic cell takes up a piece of DNA carrying the allele for pathogenicity. The foreign allele is then incorporated into the cell's chromosome, replacing the existing nonpathogenic allel - an exchange of of homologous DNA segments.
  54. What is transduction? What does this involve in terms of other cells? What type of gene transfer does this involve?
    In transduction, bacteriophages (viruses that infect bacteria) carry bacterial gene from one host cell to another.

    Transduction is a type of horizontal gene transfer where the genome of one is transfered to another through mechanisms such as transposable elements, plasmid exchange, viral activity and perhaps fusions of different organisms.

    For most phages, transduction results from accidents that occur during the phage reproductive cycle. A virus that carries bacterial DNA may not be able to reproduce because it lacks it own genetic material. However, the virus may be able to attach to another bacterium (a recipient) and inject the piece of bacterial DNA acquired from the first cell (the donor). Some of this DNA may subsequently replace the homologous region of the recipient cell's chromosomes by DNA recombination.
  55. Should you look over this card and go through the steps that occur? What type of genetic recombination is this?
    Yes. This is transduction. It involved bacteriophages or phages and a mistake during the packing step of the phage assembly.
  56. What is the process of conjugation? What type of cells does this process involve? Is it a one way or two way transfer? Does the donor cell die due to the process?
    Conjugation is the transfer of genetic material between two bacterial cells (of the same or different species) when they are joined over a "temporary" mating bridge.

    The DNA transfer is one-way: One cell donates the DNA, the other receives it. The donor uses sex pili to attach to the recipient, which is then retracted like a graplling hook.

    The ability to form sex pili and donate DNA during conjugation results from the presence of a particular piece of DNA called the F factor (F for fertility).

    The donor cell does not die due to the process.
  57. What is the F factor? What does the F designate? What type of process is the F factor important for? What form does the F factor exist as?
    The F factor (F for fertility) is about 25 genes, most required for the production of the sex pili and the donation of DNA during conjugation for gene recombination.

    The F factor can exist either as a plasmid or as a segment of DNA within the bacterial chromosome.
  58. What does a F- cell designate? What does a F+ cell designate? What process of genetic recombination are these used in? Is the condition transferable?
    F+ cell designates that it contains a F plasmid or the F factor integrated in the cell. This cell functions as the DNA donor during conjugation.

    F- cell designates that it lacks the F factor and functions as the DNA recipient during conjugation.

    The F+ condition is transferable in the sense that an F+ cell converts and F- cell to F+ if a copy of the entire F+ plasmid is transfered or the F+ chromosome aligns followed by the DNA exchange.
  59. What is a F plasmid? What process is it used in?

    At the end of the process, does the cell turn into an F+ cell?
    • The plasmid form of the F factor used during the conjugation process of gene recombination. Only a single strand of the F plasmid is transferred and so that DNA replication may occur in both the donor and the recipient cells - turning both the cells into F+ cells.
  60. What is a cell with the F factor in built in the chromosome known as? What does the cell function as? What process of genetic recombination are these present in?

    At the end of the process, does the cell turn into an F+ cell?
    • Hfr cell (high frequency of recombination)
    • These are similar to F+ cells that contain the F factor in the plasmid and function as a donor during conjugation with an F- cell.

    • When the chromosomal DNA from an Hfr cell enters an F- cell, homologous regions of the Hfr and F- chromosomes align and allow for segments of their DNA to be exchanged.
    • DNA recombination occurs and a fragment is integrated into the recipient cell's chromosome. The piece outside of the bacterial chromosome will eventuall be degraded by the cell's enzymes.

    The recipient cell now contains a new combination of genes but no F factor. it is a recombinant F- cell.

  61. What is an R plasmid?
    A bacterial plasmid carrying genes that confer resistant to certain antibiotics. These "resistance genes" code of enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics.

    Under the theory of natural selection, the fraction of the bacterial population carrying genes for antibiotic resistance will increase as attempts to kill them off via antibiotics are made.
  62. What features of prokaryotes make it likely that considerable genetic variation will be added to their populations in each generation?
    Prokaryotes have extremely large population sizes, in part because they have short generation times.

    The large number of individuals in prokaryotic populations make it likely that in each generation, there will be thousands of individuals that have new mutations at any particular gene, thereby adding considerable genetic diversity to the population.
  63. Distinguish between the three mechanisms of transferring DNA from one bacterial cell to another.
    Transformation - naked, foreign DNA from the environment is taken up by a bacterial cell.

    Transduction - phages carry bacterial genes from one bacterial cell to another.

    Conjugation - A bacterial cell directly transfers plasmid or chromosomal DNA to another cell via a mating bridge that temporarily connects the two cells.

What would you like to do?

Home > Flashcards > Print Preview