Structure and function of features within the cell wall (prokaryotes) Flashcards
What is the plasma membrane also known as?
Cytoplasmic membrane
The plasma membrane is a phospholipid bilayer that encloses the cytoplasm.
What is the primary function of the plasma membrane?
Contains proteins for selective permeability, cell signaling, secretion, movement, and ATP production.
What is the composition of the cytoplasm?
80% water, packed with ribosomes, proteins, carbohydrates, lipids, and ions.
What are ribosomes and their role in the cell?
Molecular machines that synthesize proteins by reading mRNA codons. They are made of 2 subunits that lock onto messenger RNA (mRNA) and read the codons to link amino acids together.
What is the nucleoid?
Region of the cytoplasm containing the genome and genome-related proteins.
What type of chromosome do bacteria have?
Circular chromosome of supercoiled double-stranded DNA in the nucleoid
What are plasmids?
Small, usually circular, double-stranded DNA molecules separate from the chromosome. A single cell can contain many different plasmids and can contain multiple copies of the same plasmid.
Do plasmids contain essential genes for survival?
Generally do not contain essential genes but may have specialized genes for virulence or drug resistance. They can be passed horizontally between bacteria regardless of species through conjugation.
How can plasmids be transferred between bacteria?
Through conjugation, regardless of species.
What are spores, specifically endospores?
Small, dehydrated, metabolically inactive forms of bacteria produced in response to harsh conditions.
What happens to endospores when conditions improve?
They germinate into normal, vegetative cells.
What distinguishes an endospore from other types of spores?
Endospores are a survival mechanism, not a means of reproduction. While “spore” is often used generally to refer to a resistant structure produced by certain microorganisms, an “endospore” specifically refers to a dormant, highly resistant structure formed inside a bacterial cell as a survival mechanism under harsh conditions, essentially a protective casing containing the bacteria’s essential genetic material, whereas a “spore” can encompass reproductive spores produced by fungi or other organisms which are used to propagate new individuals; the key difference is that endospores are not a means of reproduction for bacteria, but a way to survive unfavorable environments, while many other types of spores are used for reproduction.
Which structures are found in ALL bacteria?
Cell membrane, cytoplasm, ribosomes.
What is the inner layer of the Gram-negative bacterial cell wall made of?
Peptidoglycans.
What connects the peptidoglycan layer to the outer cell membrane in Gram-negative bacteria?
Strands of lipoproteins.
What component of the Gram-negative bacteria cell wall is released during systemic infections?
Lipid A
What is the structure created by bacteria in response to nutrient limitations or harsh environments?
Endospores
What type of spores do fungi form?
Spores (not endospores) for reproduction.
What is the role of the plasma membrane in bacteria?
Encloses the bacterial cytoplasm.
Where are plasmids located within the bacterial cell?
Within the cytoplasm
What is the primary function of the prokaryotic cell wall?
To provide structural support and protection to the cell.
True or False: Prokaryotic cell walls are made of cellulose.
False: Prokaryotic cell walls are primarily made of peptidoglycan. Cellulose is a complex carbohydrate that’s the main component of plant cell walls.
Fill in the blank: The main component of the prokaryotic cell wall is ______.
peptidoglycan.
What are the two main types of prokaryotic cell walls?
Gram-positive and Gram-negative.
Multiple Choice: Which type of prokaryotic cell wall contains a thick layer of peptidoglycan?
A) Gram-positive
What is the role of teichoic acids in Gram-positive bacteria?
To provide structural support and regulate cell wall synthesis.
True or False: Gram-negative bacteria have a periplasmic space.
True.
Fill in the blank: The outer membrane of Gram-negative bacteria contains ______.
lipopolysaccharides.
What is the function of lipopolysaccharides in Gram-negative bacteria?
To act as an endotoxin and contribute to the structural integrity of the outer membrane.
True or False: The cell wall is permeable to all substances.
False: The cell wall is selectively permeable.
Fill in the blank: Antibiotics like penicillin target the synthesis of ______.
peptidoglycan.
What is the function of the capsule in some prokaryotes?
To enhance protection against phagocytosis and desiccation.
Multiple Choice: Which structure is involved in the attachment of bacteria to surfaces?
C) Fimbriae
What distinguishes the cell wall of archaea from that of bacteria?
Archaea may have cell walls made of pseudopeptidoglycan or other polymers.
Fill in the blank: The process by which bacteria can change their cell wall structure in response to environmental conditions is known as ______.
adaptation.
What is a major characteristic of a Gram-negative cell wall?
It has a thin peptidoglycan layer and an outer membrane.
Multiple Choice: Which enzyme breaks down peptidoglycan?
A) Lysozyme
What is the primary role of the cell wall in prokaryotes?
To maintain cell shape and prevent osmotic lysis.
Fill in the blank: The main structural unit of peptidoglycan is a repeating disaccharide composed of ______ and ______.
N-acetylglucosamine and N-acetylmuramic acid.
What structure provides rigidity to the bacterial cell wall?
Peptidoglycan.
What is the role of the periplasmic space in Gram-negative bacteria?
It contains enzymes and proteins involved in nutrient acquisition and processing.
True or False: The outer membrane of Gram-negative bacteria is similar to the plasma membrane.
True.
What is the function of porins in the outer membrane of Gram-negative bacteria?
To allow the passage of small molecules and ions.
Multiple Choice: Which type of bacteria is more resistant to antibiotics due to their cell wall structure?
B) Gram-negative
What is the role of the S-layer in some prokaryotes?
To provide additional protection and structural support. An S-layer is a protein layer that coats the outside of some bacteria and archaea. It’s a key part of the cell envelope and can perform many biological functions.
True or False: The cell wall contributes to the pathogenicity of some bacteria.
True.
Fill in the blank: The structure that helps bacteria adhere to host tissues is known as ______.
fimbriae.
What type of bacteria typically has a higher resistance to physical disruption?
Gram-positive bacteria due to their thicker cell wall.
Multiple Choice: Which component is responsible for the negative charge on the surface of Gram-positive bacteria?
C) Teichoic acids
True or False: Bacterial capsules are always present in all bacterial species.
False.
What is the primary structural difference between the cell walls of Gram-positive and Gram-negative bacteria?
Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin layer and an outer membrane.
What type of bond links the sugar and peptide components in peptidoglycan?
Beta-1,4-glycosidic bonds.
