Bacteria Flashcards
Bacteria are what type of cell?
prokaryotic
Humans are what type of cell?
Eukaryotic
What is the size of bacteria cells?
Most bacteria range in size from less than 1μm
they are 10-100 times smaller than our cells
What allows bacteria cells to reproduce quickly?
Because of their high surface to volume area
What are the parts of a bacteria cell?
Envelope (outside surface of the cell)
Structures outside the envelope
Cytoplasm
What does the envelope contain?
the bacterial cell can have as many as three layers in its envelope
plasma membrane: found in Gram –negative and Gram-positive bacteria always made of phospholipids
cell wall: found in Gram-negative and Gram-positive bacteria always made up of peptidoglycan
outer membrane: found in Gram-negative bacteria only
What does the cell wall do?
all bacteria except mycoplasmas have a rigid, strong cell wall which functions to:
- give the cell its shape
- withstand turgor pressure (water pressure) (cell does not burst due to influx of water from hypotonic environment)
What is the cell wall made of?
peptidoglycan
glycan: carbohydrate
peptido: peptide
How do the cell walls of gram + and gram - bacteria differ?
Gram-negative bacteria have only a single layer of peptidoglycan. *Gram - negative has a much thinner cell wall (peptidoglycan layer).
E-coli is gram negative
the cell wall of Gram-positive bacteria consists of many layers of peptidoglycan
*Has a much thicker cell wall
Outer membrane is found where?
only in gram - bacteria
has 2 layers of phospholipids: inner is hydrophobic and outer is hydrophilic
What does porin in the outer membrane do?
allows important nutrients, 02 and H20 to pass through
lipid A a component of lipoprotein acts as a endotoxin to humans how?
produce symptoms: chills, fever, aches, weakness
in extreme cases septic shock
When do endotoxins take effect?
When the gram - bacteria die and the cell undergoes lysis (ruptures)
What is periplasm?
lies beneath the outer membrane of Gram-negative bacteria; filled with a gelatinous material containing proteins that are involved in facilitating the movement of nutrients into the cell
What is the plasma membrane?
- phospholipid layer in direct contact with cell wall
- only part of the envelope surrounding mycoplasmas
- produce ATP in bacteria cells.
What is a mycoplasma?
bacteria without a cell wall
What structures are outside the envelope?
capsule, flagella, Axial Filaments, pilus, cytoplasm, nucleoid region, ribosomes, plasmids, endospores
What does the capsule do?
- is a viscous, sticky, gelatinous substance outside the envelope of certain species of bacteria
- the capsule contributes to the bacterial virulence b/c it can protect the pathogenic bacteria from phagocytosis by the host’s cells.
- aids in the attachment of the bacteria to the host’s cells
What does the flagella do?
movement of cell
What does the axial filament do?
axial filaments cause the cell to move in a characteristic corkscrew fashion
What does the pilus do?
hair like structures
allow bacteria to stick to host cell
sex pilus: join two bacteria transfer DNA from one cell to another
What does the cytoplasm do?
prokaryotic cells is less complex than that of eukaryotic cells b/c of the absence of the various membrane-bound o organelles
What does the nucleoid region do?
- contains DNA of bacteria (not surrounded by nuclear envelope)
A bacterium contains a single molecule of double-stranded DNA, known as the bacterial chromosome.
The bacterial chromosome is attached to the plasma membrane.
What do ribosomes do?
protein synthesis
