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Questions and Answers
What is a defining characteristic of bacteria compared to eukaryotic cells?
What is a defining characteristic of bacteria compared to eukaryotic cells?
- Complex system of organelles
- Larger size compared to eukaryotic cells
- Presence of a nuclear membrane
- Absence of mitochondria (correct)
Which of the following sizes is typical for clinically relevant bacterial species?
Which of the following sizes is typical for clinically relevant bacterial species?
- 0.1 to 0.25μm in length
- 1 to 5μm in width
- 0.25 to 1μm in width (correct)
- 5 to 10μm in length
What is the primary component of bacterial cell walls that leads to differences in Gram staining?
What is the primary component of bacterial cell walls that leads to differences in Gram staining?
- Glycocalyx presence
- Protein structure
- Chemical composition of the cell wall (correct)
- Cell membrane composition
What term describes the arrangement of bacteria based on their shapes and sizes?
What term describes the arrangement of bacteria based on their shapes and sizes?
Which of these bacterial structures is not typically found in animal cells?
Which of these bacterial structures is not typically found in animal cells?
What movement mechanism do spirochetes utilize compared to typical bacteria?
What movement mechanism do spirochetes utilize compared to typical bacteria?
How does the size of bacteria generally compare to that of viruses and eukaryotic cells?
How does the size of bacteria generally compare to that of viruses and eukaryotic cells?
What structure is primarily responsible for the organized capsule or slime layer in bacterial cells?
What structure is primarily responsible for the organized capsule or slime layer in bacterial cells?
Which bacterial shape is described as tapered with pointed ends?
Which bacterial shape is described as tapered with pointed ends?
What type of bacterial arrangement describes cells organized in chains?
What type of bacterial arrangement describes cells organized in chains?
Which statement about the gram-positive cell wall is correct?
Which statement about the gram-positive cell wall is correct?
Which of the following bacteria is characterized by having no defined shape?
Which of the following bacteria is characterized by having no defined shape?
What is the primary component that forms the cell wall of gram-negative bacteria?
What is the primary component that forms the cell wall of gram-negative bacteria?
What are the subunits that make up the peptidoglycan structure in gram-positive bacteria?
What are the subunits that make up the peptidoglycan structure in gram-positive bacteria?
Which of the following bacterial arrangements resembles grape-like clusters?
Which of the following bacterial arrangements resembles grape-like clusters?
Which bacterial morphology best describes a helical, corkscrew-like shape?
Which bacterial morphology best describes a helical, corkscrew-like shape?
Which of the following is a distinguishing feature of prokaryotic cells?
Which of the following is a distinguishing feature of prokaryotic cells?
What is the typical size range of prokaryotic cells?
What is the typical size range of prokaryotic cells?
Which component is generally absent in prokaryotic cells?
Which component is generally absent in prokaryotic cells?
Bacterial cells typically reproduce by which process?
Bacterial cells typically reproduce by which process?
Which of the following correctly describes bacterial cell wall composition?
Which of the following correctly describes bacterial cell wall composition?
What arrangement pattern can bacterial organisms exhibit?
What arrangement pattern can bacterial organisms exhibit?
Which statement is true about ribosomes in prokaryotic cells?
Which statement is true about ribosomes in prokaryotic cells?
Which of the following describes the nucleoid region in prokaryotic cells?
Which of the following describes the nucleoid region in prokaryotic cells?
How do bacterial cell walls differ from those of plants?
How do bacterial cell walls differ from those of plants?
What feature is unique to eukaryotic cells when compared to prokaryotic cells?
What feature is unique to eukaryotic cells when compared to prokaryotic cells?
Which of the following describes bacterial plasmids?
Which of the following describes bacterial plasmids?
In terms of metabolism, how do prokaryotes and eukaryotes primarily differ?
In terms of metabolism, how do prokaryotes and eukaryotes primarily differ?
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Study Notes
Prokaryotes
- Similarities: Contain nucleic acids, proteins, lipids, and carbohydrates
- Similarities: Use the same kinds of chemical reactions to metabolize food, build proteins, and store energy
- Differences: Structure of cell walls and membranes, and the absence of organelles (specialized cellular structures that have specific functions)
Chief Distinguishing Characteristics of Eukaryotes
- DNA is found in the cell's nucleus, which is separated from the cytoplasm by a nuclear membrane, and the DNA is found in multiple chromosomes
- DNA is consistently associated with chromosomal proteins called histones and with non-histone proteins
- Have a number of membrane-enclosed organelles
- Cell walls, when present, are chemically simple
- Cell division usually involves mitosis
Prokaryote vs. Eukaryote Cell Organization
- Prokaryote:
- Typical size: 0.4-2 µm in diameter, 0.5-5 µm in length
- Nucleus: No nuclear membrane; nucleoid region of the cytosol
- Genome location: In the nucleoid, at the mesosome
- Chromosomal DNA: Circular, complexed with RNA
- Genome: Plasmids, small circular molecule of DNA -containing accessory information; most commonly found in gram-negative bacteria; each carries genes for its own replication; can confer resistance to antibiotics
- Reproduction: Asexual (binary fission)
- Membrane-bound organelles: Absent
- Golgi bodies: Absent in all
- Lysosomes: Absent in all
- Endoplasmic reticulum: Absent in all
- Mitochondria: Absent in all
- Nucleus: Absent in all
- Chloroplasts: Absent in all
- Ribosomes: Present in all
- Ribosome size: 70 S in size, consisting of 50 S and 30 S subunits
- Electron transport: In the cell membrane if present; no mitochondria present
- Sterols in cytoplasmic membrane: Absent except in Mycoplasma spp
- Plasma membrane: Lacks carbohydrates
- Cell wall: Peptidoglycan in most bacteria
- Eukaryote:
- Typical size: 10-100 µm in diameter, >10 µm in length
- Nucleus: Classic membrane-bound nucleus
- Genome location: In the nucleus
- Chromosomal DNA: Linear, complexed with basic histones and other proteins
- Genome: In mitochondria and chloroplasts
- Reproduction: Sexual and asexual
- Membrane-bound organelles: Present in all
- Golgi bodies: Present in some
- Lysosomes: Present in some; contain hydrolytic enzymes
- Endoplasmic reticulum: Present in all; lipid synthesis, transport
- Mitochondria: Present in most
- Nucleus: Present in all
- Chloroplasts: Present in algae and plants
- Ribosomes: Present in all
- Ribosome size: 80 S in size, consisting of 60 S and 40 S subunits
- Electron transport: In the inner membrane of mitochondria and chloroplasts
- Sterols in cytoplasmic membrane: Present
- Plasma membrane: Contains glycolipids and glycoproteins
- Cell wall: Cellulose, phenolic polymers, lignin (plants)
Bacterial Morphology
- Bacteria can vary in size, morphology, and cell-to-cell arrangements
- Bacteria can vary in the chemical composition and structure of their cell walls
- Bacterial cell wall differences provide the basis for the Gram stain
- Common Bacterial Shapes:
- Cocci: Circular
- Coccobacilli: Ovoid
- Bacillus: Rod-shaped
- Fusiform: Tapered, pointed ends
- Curved
- Spiral: Helical, like corkscrew
- Spirochetes: Vary in length and in the number of helical turns (not all helical bacteria are called spirochetes)
- Pleomorphic: No defined shape
Bacterial Arrangement
- Pairs
- Chains
- Grape-like clusters
- Group of four
- Packets of eight
- Palisades
- Chinese characters
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