Prokaryotes - Cell Structure and Function Flashcards
What are the 2 big domains of prokaryotes?
Bacteria and Archaea (extremophiles)
What are euryarchaeota?
Different groups of organisms within Archaea domain
What are methanogens?
Live in anoxic environments
What are Halophiles?
Na lovers
What are thermoacidophiles?
Grow at high temps with low pH
What are Crenarchaeota?
A subgroup of archaea that grow in hot acidic environments
What is an easy way to distinguish bacterias?
From their Shape and arrangements
What shape is bacillus cells?
Rod shape
-groups or chain arrangement
What is coccus cell?
Spherical shape
-group or chain arrangement
What are the 3 ways in which spiral shaped cells present?
- Vibrio (comma-shaped)
- Spirillum (flagella squigle)
- Spirochete (oscillation)
What are the traits that cell structure organizes cell function in bacteria and archaea cells?
- Snesing/responding to the surrounding environment
- Compartmentation of metabolism
- Growth and reproduction
What are pili?
Protein fibres extending from the surface of many bacteria and are used for attachment
What is a conjugation pili?
Used to transfer genetic material between cells
What are fimbriae?
Short cytoplasmic extensions that function in recognition, adherence etc and sex pili that are much longer and hallow and function in gene transfer between bacteria
What are plasmids?
Small circular short DNA
- these are genes that give an advantage but are not necessary for survival.
- When plasmids are removed the cell can continue living
What keeps flagella turning?
Motor composed of a helical filament, hook and basal body to keep it moving
What causes ulcers?
Helicobacter pylori
What is chemotaxis?
Moving up the [] gradient of a chemical attract
-start swimming towards it
Who uses chemotaxis?
Bacteria with and without flagella
What are endoflagella?
Flagella within the prokaryotic cell and move the cell through torsion exerted on the cell by the endoflagellar rotation
What is Glycocakyx?
Outer layter external to the cell wall
-adhering layer of polysaccharides
What is a capsule?
A thick layer on the outside of the cell wall
-thicker than glycocalyx
What is a slime layer made up of and why do prokaryotes have them?
A diffuse layer of polysaccharides
Protect the cell from the environment and allow them to attach to surfaces
How do you identify bacteria cultures with slime vs with no slime outter later?
On a petrie dish the bacteria with slime will look gooey and watery
What its the purpose of the cell wall?
Maintain cell shape, water balance and protects from injury
-some bacteria do not have this
How do we classify bacteria on the basis of cell wall structure?
Gram positive or gram negative
-using gram dye stain
What does it mean when a cell is gram positive?
- Purple stain
- Bacteria have thick walls with a dense layer of peptidoglycan
- teichoic acid
What do gram+ bacteria produce?
Endospores: spores produced within the bacterial cell
What does it mean when a cell is gram negative?
- Pink Stain
- Thin walls, less peptidoglycan
- EXTRA outer membrane containing lipopolysaccharide (v toxic)
What are characteristics of bacterial cells than dont gram stain negative very well?
- Acid fast bacteria (like those that cause TB)
- They have a lot of lipids in their cell walls
What is the difference between prokaryotic cell walls and archaic cell walls?
Archaea don’t have peptidoglycan in cell walls, some have pseudopeptidoglycan, polysaccharides, proteins or both
What is the most common archaea cell wall?
S-layer
-consisting of proteins or glycoprotein in a crystal lattice
What is an example of a bacteria that does not have a cell wall?
Mycoplasma species that infect animal cells
- look like fried egg
- stick to cilia
- grow on red blood cells
What controls what enters in and out of the cell?
The proteins will determine what goes in and out of the cell, no the cell wall
can proteins move within the cell membrane?
Yes, because the cell membrane is fluid
What do cells rely on to move things between the cell membrane?
Diffusion, osmosis and transport proteins
What is diffusion?
Movement of substances across the membrane in response to their [gradient], only from an area of high [] to low []
What is Osmosis?
Movement of water across a semi-permeable membrane in response to its [gradient} from high to low
Why does osmosis concern cells?
To make sure the movement of water is equal so the cell doesn’t shrink (hypertonic) or doesn’t swell (hypotonic) and explode
What is the difference between ends and exocytosis?
Endo when the cell membrane captures material and pinches off to form a sphere and enters the cell
Exo when small vacuoles merge with the cell membrane and release amterial to the cell exterior
Which cells can do end and exocytosis?
Eukaryotes can only do this but not all of them do
What disrupts/dissolves the bilayer?
Antimicrobial substances
How are archaea cells different from both pro and eukaryote cells?
- hydrophobic lipid tails are attached to glycerol differently
- Fatty acids and absent
- adjacent lipid tails are bound together to form a lipid monolayer instead of a bilayer
What is the structure of DNA in the nucleoid?
Closed looped DNA and protein
-most are haploid
What are inclusion bodies?
They store nutrient or building blocks for cellular structures
What are gas vesicles=?
Aquatic bacteria can use these to float on the waters surface
What are magnetosomes?
Contain crystals of magnetite or reignite, allowing cells fro response to magnetic fields
What is the role of cytoskeletal proteins?
Regulate cell division and help determine cell shape
-homologs of eukaryote tubulin
What limits the size of a cell?
The surfaced area to volume ratio
- as cells increase in size the surface area can’t keep up with the volume of the cell
- this is why bacteria are so small
How do eukaryotes avoid the surface area to volume ratio in terms of size?
They aggregate together to avoid the problem,
What is the biggest prokaryotic organism?
Sulfur pearl of Namibia
- visible to the naked eye
- sulfide oxidizing bacteria
