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Questions and Answers
What type of cells are bacterias?
What type of cells are bacterias?
What type of cells are organisms other than bacteria?
What type of cells are organisms other than bacteria?
What are the 3 most common shapes of bacterias?
What are the 3 most common shapes of bacterias?
bacillus, coccus, spirillum
What is a bacillus?
What is a bacillus?
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What is a coccus?
What is a coccus?
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What is a spirillum?
What is a spirillum?
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What are the major parts of a bacterial cell?
What are the major parts of a bacterial cell?
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What are the three layers that can be found within the envelope of a bacterial cell?
What are the three layers that can be found within the envelope of a bacterial cell?
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The plasma membrane in bacteria is similar to that in eukaryotic cells, as both consist of a bilayer of __________.
The plasma membrane in bacteria is similar to that in eukaryotic cells, as both consist of a bilayer of __________.
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What function does the cell wall serve in bacterial cells?
What function does the cell wall serve in bacterial cells?
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What is the main component of all bacterial cell walls?
What is the main component of all bacterial cell walls?
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What is the role of transpeptidases in bacterial cell walls?
What is the role of transpeptidases in bacterial cell walls?
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The cell wall of Gram-negative bacteria consists of many layers of peptidoglycan.
The cell wall of Gram-negative bacteria consists of many layers of peptidoglycan.
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What is lipid A and where is it found?
What is lipid A and where is it found?
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What is the periplasm in bacteria?
What is the periplasm in bacteria?
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What are the components found in the cytoplasm of bacterial cells?
What are the components found in the cytoplasm of bacterial cells?
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What is a nucleoid?
What is a nucleoid?
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What are ribosomes involved in?
What are ribosomes involved in?
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Study Notes
Structure of Bacterial Cells
- Bacteria are classified as prokaryotic cells, distinguished from eukaryotic organisms which possess membrane-bound organelles.
- Common bacterial shapes include bacillus (rod-shaped), coccus (spherical), and spirillum (spiral).
Bacterial Shapes
-
Bacillus: Typically exhibits rod-like morphology, can form arrangements such as:
- Single bacillus
- Streptobacillus (chains)
- Coccobacillus (intermediate shape)
-
Coccus: Spherical shape, may appear in:
- Diplococci (pairs)
- Streptococci (chains)
- Staphylococci (clusters)
- Spirillum: Characterized by spiral forms.
Major Parts of a Bacterial Cell
- Composed of three major components:
- Envelope
- Cytoplasm
- Structures external to the envelope.
Envelope Composition
-
Plasma Membrane:
- Present in both Gram-negative and Gram-positive bacteria, and mycoplasmas.
- Composed of a phospholipid bilayer enriched with proteins involved in ATP metabolism.
-
Cell Wall:
- Absent in mycoplasmas; provides rigidity and shape to bacteria.
- Functions to withstand turgor pressure from a hypotonic environment.
- Composed of peptidoglycan, consisting of:
- Glycan portion with alternating monosaccharides.
- Peptido portion containing a peptide of four amino acids linking the chains.
-
Outer Membrane:
- Unique to Gram-negative bacteria; consists of:
- Inner layer of phospholipids.
- Outer layer mainly of lipopolysaccharides (LPS).
- Unique to Gram-negative bacteria; consists of:
Enzymes and Antibiotics
- Transpeptidases help enlarge the cell wall during bacterial growth; penicillin inhibits these enzymes, affecting cell wall integrity.
Gram Staining Differences
- Gram-negative bacteria: Have a single layer of peptidoglycan.
- Gram-positive bacteria: Possess multiple layers of peptidoglycan, contributing to structural strength.
Porins and Permeability
- The outer membrane is selectively permeable; substances must pass through porins (membrane proteins) for entry.
- Examples of permeable substances include water and some gases (e.g., O2).
Endotoxins
- Lipid A, derived from LPS, acts as an endotoxin in humans.
- Symptoms from endotoxins manifest only when Gram-negative bacteria die, leading to their release during lysis.
- Initial worsening of symptoms may occur post-antibiotic treatment due to endotoxin release.
Periplasm
- A region within Gram-negative bacteria, located between the outer membrane and plasma membrane.
- Filled with gelatinous material and proteins that aid the transport of nutrients into the cell.
Cytoplasm Characteristics
- Less complex than eukaryotic cytoplasm due to the absence of membrane-bound organelles.
- Contains essential components such as:
- Nucleoid (region housing bacterial DNA).
- Ribosomes (for protein synthesis).
- Plasmids (circular DNA molecules that can confer additional traits).
Nucleoid and Ribosomes
-
Nucleoid:
- Contains a single, circular double-stranded DNA molecule known as the bacterial chromosome.
- DNA is not enclosed by a membrane, differing from eukaryotic cells.
-
Ribosomes:
- Present in both prokaryotic and eukaryotic cells for protein synthesis; essential for cellular function and growth.
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Description
Test your knowledge on the structure of bacterial cells with these flashcards. This quiz covers important definitions and concepts regarding prokaryotic and eukaryotic cells, as well as the shapes of bacteria. Perfect for students studying microbiology or related fields.
