Unit 1: Chapter 5 Cell Biology of Bacteria and Eukaryotes (Bacteria ONLY) Flashcards
Prokaryote: Cell Traits
- Small cell size
- DNA organized in nucleotide throughout the cytoplasm
- Small gemome
- Circular chromosomes (usually), although may have multiple circualr and linear chromosomes
- Few intraceullar membranes
- No intraceullar endosymbiosis organelles
- Cell wall composed of peptidoglycan
- Rotray flagella for mortality, driven by proton motive force
Prokaryotes are cells of
Bacteria and archaea
Eukartoytes: Cell Traits
- Wide range of cell size, from very small to very large
- DNA contained in nucleus, enclosed by nuclear membrane
- Wide range of genome size, including very large
- Linear chromosomes (in nucleus); mitochondria (derived from bacteria) have one circular chromosome
- Chromosomes segregate by mitosis and meiosis, after replications during interphase
- Many types of intraceullar membranous organelles (such as endoplasmic reticulum, golgi, and lysosomes)
- Mitochondria and chloroplasets are organelles that evolved from endosymbitoic barteria
- Cell walls of plants and fungi composed of various carbohydrates (such as cellulose or chitin), but NEVER peptidoglycan
- Whipelike flagella for mortality, with microtubule contraction driven by ATP
Eukaryotes are cells of
Plants, animals, fungi, and protozoa
What are most bacterial cell walls composed of?
Peptidoglycan
What is monophonic bacteria?
Bacteria that does not change shape
The presence of a cell wall helps maintain shape of the cell
Most bacteria are __________
Monomorphic
What is pleomorphic bacteria?
Bacteria that can alter their shape
Very few bacteria that can do this, and they tend to be those without a cell wall.
Coccus Bacteria
Round in shape
Arrangements of Cocci
- Diplococci (two)
- Streptococci (chain)
- Staphylococci (grape-like cluster)
Baccillus
Rod shape bacteria
Arrangement of Bacillus
- Single bacillus
- Diplobacilli (two)
- Streptobscilli (chain-like)
Spirilla
Spiral-like bacteria
Arrangements of Spirilla
- Vibrio (comma shaped)
- Spirillum (more rigid)
- Spirochete (flexible)
What structures are found in ALL bacteria?
Plasma membrane, cytoplasm, ribosomes, and nucleoid
Structures of a bacteria and their function: Cell Membrane/ Plasma Membrane
Essential.
- Separates cytoplasm from external environment, and mediates the transport between the two
- Keeps cytoplasmic proteins from leaking
- Allows nutrients to enter
- Maintains concentration gradients of ions and nutrients
- Oxidative phosphorylation also takes place here
Structures of a bacteria and their function: Cytoplasm
Essential.
- Gel-like and contains cell structures such as ribosomes, chromosomes, and plasmids
- Cell growth
- Metabolism
- Replication
Structures of a bacteria and their function: Ribosomes
Essential.
- In the cytoplasm
- Translates mRNA to make proteins
Structures of a bacteria and their function: Nucleoid
Essential.
- Region that contains the genetic material
- DNA is not enclosed so the coils of DNA extend throughout the cytoplasm
- Contains one chromosome and is circular in shape; attached to the membrane
What is a plasmid?
This is an extrachromosomal DNA that is not essential to the bacteria
They contain genes that are advantageous (such as help make toxins, pili, fimbrae, etc)
This can make cell more pathogenic or live in an environment that it normally not survive in
Structures of a bacteria and their function: Glycocalyx
Not essential.
- Located outside the cell wall
- Compassion of sugars, glycoproteins, or both
- Helps prevent phagocytosis, protect cell from desiccation (drying), biofilm formation, and act as a source of nutrient
- Bacteria becomes more vulnerable if stripped of this.
What are the two types of glycocalyx?
- Capsule
- Slime Layer
Glycocalyx: Capsule
Thicker and tightly attached
Highly organized and attached tightly to cells
Can help with attachment as it sticky; does not need specific receptors to be able to attach
Glycocalyx: Slime Layer
Not attached tight
Unorganized and can easily be washed off
Structures of a bacteria and their function: Pilus
Not essential.
- Fewer in number and are at the poles of the cell; long
- Made out of protein monomer called pilin
- Can have a role in movement (Type IV)
- More often involved in adherence to surfaces
- F-pilus allow for transfer of DNA
Structures of a bacteria and their function: Fimbriae
Not essential.
- Located at the surface of bacterial cells; short hair-like structure around the cell
- They enable bacteria to bind to a specific receptor
- Made up of protein monomer called pilin
What are all the layers a cell might have called?
Cell envelope
What is the cell membrane made up of?
- Phospholipid bilayer
- Proteins
- Integral/ transmembrane (embedded in the whole bilayer)
- Peripheral (located on the inner or outer surface of the bilayer)
T or F: The cell membrane has selective permeability
True
What are the functions of the bacterial membrane proteins?
- Structural support
- Detecting environmental signals
- Secreting virulence factors and communication signals
- Transport across the cell membrane
Label the hydrophobic and hydrophilic tail in the phospholipid bilayer
What is the phospholipid bilayer made up of?
- Glycerol
- Phosphorus
- Two fatty acid tails
Membrane Permeability
Factors that determine liquid bilayer permeability
- Size of solute/ molecule; larger molecules are harder to pass through
- Charge of solute/ molecule; Nonpolar/ charged/ hydrophobic
Passive Transport
Movement along a concentration gradient
No energy required
Simple Diffusion
Movement of a solute from an area of high concentration to an area of low concentration
Facilitated Diffusion
Solute moves with a transporter protein
If they are charged, then they need to a protein channel to travel from high concentration to low concentration
Still NO energy required
Osmosis
The movement of water across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration
Water follows the solute, so wherever the solute is high the water follows
Isotonic Solution
There is the same concentration of water and solutes inside and outside the cell; there is no change in the cell
This is he most desirable state
Hypertonic Solution
A solution that contains more solute outside the cell
This causes water to move out the cell
The cell shrinks
No cell likes this
Hypotonic Solution
A solution that contains more solutes inside the cell
This causes water to move inside the cell
The cell expands and can lyse (burst)
Plants and bacteria like this
Active Transport
Movement of solute against a concentration gradient
Move from an area of low concentration to high
Energy and transporter proteins are required
When do cells use active transport?
When the nutrient concentration is low in the environment
What are some substances that are actively transported?
Sugars, ions, and amino acids
What is indirect active transport?
The use of energy from one gradient to drive transport up another gradient
Also known as coupled transport
2 Types of Indirect Active Transport
(Coupled Transport)
- Symport
- Antiport
Indirect Active Transport (Coupled Transport): Symport
When the two substances travel in the same direction across the membrane
Protons act as potential energy to pry open the gate
Indirect Active Transport (Coupled Transport): Antiport
When two different substances are moved in opposite directions
A cell uses the movement of an ion across a membrane and down (from high to low) its concentration gradient to power the transporter of a second substance up against its gradient (from low to high)
What is direct active transport?
Uses chemical energy such as ATP to transport solutes across a membrane against their concentration gradient (low to high)
Direct Active Transport: ATP-Binding Cassette (ABC Transporters)
The substrate binding protein binds to a solute (which has a high affinity for it). The substrate binding protein then directs the solute to the channel protein.
Hydrolysis of ATP ADP+P yields the energy needed to open the channel allowing the solute to move up the concentration gradient and up the cell.
The transporter then returns to its resting state
Influx ABC Transporters
Bring sugars, nutrients, and amino acids into the cell
Efflux ABC Transporters
Expels waste products from the cell
Siderophores
Tightly bind available iron (Fe3+) in the environment and bring the siderophore-iron complex to ABC transporters for movement across the membrane
Requires direct utilization of ATP
Iron is used for nutrients for bacteria
What causes iron to be released into its usable form?
PH differences
Structures of a bacteria and their function: Cell Wall
Not essential.
- Semi-rigid structure present outside the plasma membrane; Surrounds the cell like a cage
- Made of peptidoglycan
- Responsible for the shape of the cell
- Prevents the cell from bursting in a hypotonic environment (osmotic lysis)
What is peptidoglycan made of?
Made up of sugars and amino acids
Glycan chains cross-linked with peptides of 4 amino acids
Long chains consist of repairing units of NAG and NAM (glycan-backbone)
4 amino acids cross linked off of NAM (peptides)
NAG and NAM are modifications of _________
Glucose
Gram-Positive Cell Envelope
Thick cell wall, multiple layers of peptidoglycan
Think: an open sandwich with a think layer of meat
What is teichoic acids made of?
Alcohol and phosphate
What is the function of teichoic acids?
Rope like structure that holds all the layers of the gram positive (thick) cell wall together and anchors the inner membrane
Helps further stabilized the cell wall
Gram-Negative Cell Envelope
Thin cell wall, single layer of peptidoglycan, enclosed by an outer membrane
Think a closed sandwich with a thin slice of cheese in between the bread
What is the inner membrane made of?
Phospholipid Bilayer
2 fatty acids
1 phosphorus
Hydrophilic head
Hydrophobic tail
What is the outer membrane made of in a gram-negative cell wall?
LPS (Lipopolysaccharide); outer part of membrane
Phospholipids; inner part of the membrane
What is the structure of LPS?
- 2 sugars; 6 lipid tails
- Lipid A/ Endotoxin
- Chain of sugars off a sugar called Core Polysaccharide
- 10-40 sugars
- O-Polysaccharide/ O-Antigen off the chain of sugars
- Highly variable (up to 200 sugars)
What is the function of lipoproteins in gram negative cell walls?
It anchors the outer member to the cell wall
What method of transport does the outer membrane of a gram negative cell wall use?
Passive transport
It helps the transport of protein
What is a porin?
This is the outer membrane transporter which helps bring in sugars and peptides through passive transport
Our bodies make antibodies against _________
O-Antigens
What is an endotoxin?
A component of LPS that is extremely toxic to the host
Mycoplasmas
Lack a cell wall; no peptidoglycan
Changes shape a lot due to the lack of a cell wall
Sterols (cholesterol) in plasam membrane
Acid- Fast Cell Walls
Like gram-positive cell walls, but their envelopes are exceptionally thick and complex
Thick peptidoglycan
Sugar layer
Mycolic acid is waxy and very thick (not permeable, so tend to me slow growing since nutrients can’t get in); bound to peptidoglycan
Antibiotics are also hard to penetrate through them bc of this thick mycolic acid layer
How do antibiotics such as pencillinan and vancomycin work?
They work by preventing cross linking of peptides
Breaks down the peptidoglycan (cell wall)
Why does the cell need enzymes?
- make special sugars
- build peptides
- seal crosssbridges
What does the enzyme lysozyme do?
This is produced in almost every secretion in us and helps break down glycan chains
What does widespread use of antibiotics cause?
Evolution of antibiotic resistant strains
Flagella
Not essential, but advantage to have
- Rotary flagella enable motility and chemotaxis
- Made up of chains of flagellin protein
What does flagella help enhance?
The virulence aka the severity of the disease
Structure of the flagella
3 parts
- Filament
- Protein Hook
- Basel Body
- Rings
- Rod
Function of the filament in flagella
This is the part that we see
Function of the protein hook in flagella
Helps anchor filament to the cell
Function of the ring in the basal body
This helps rotate the cell
Function of the rod in flagella
This also acts as an anchor
How does the flagella move?
The flagella SPINS the whole cell
Gram Positive Flagellum Structure
1 single rod
2 rings
Gram Negative Flagellum Structure
1 single rod
4 rings
How are the flagella rings powered?
By a proton (ion) gradient
Endoflagella
Wraps around the cell body when surround by sheath
Flagella is present beneath an outer sheath and spiral around the cell
Flagella is anchored at one end of a cell
Moves in a twitchy fashion
Where is endoflagella present?
In a group of bacteria called Spirochetes
Motile Cells
Move toward or away from stimuli (taxis)
What is chemotaxis?
directed motion of an organism toward attractive environment or away from repellent surroundings
Attractants is what type of chemotaxis?
(positive or negative)
Positive
Repellents is what type of chemotaxis?
(positive or negative)
Negative
Anti/counter clockwise rotation of flagella causes it to move __________
Forward (swim)
Clockwise rotation of flagella causes it to ____________
Turn and change direction
Tumble
Thylakoids
Photosynthetic bacteria capture light with extensively folded intracellular membranes
Absorb the light and convert it to chemical energy as needed
Folds ensure that you have the energy needed to carry out photosynthesis
Gas Vesicles
Aquatic phototrophs use gas vesicles to increase buoyancy
Makes bacteria cell buoyant so its on the surface, near sunlight.
Trap and collect carbon dioxide and hydrogen produced by the cell’s metabolism
Storage Granules
Store energy such as glycogen or PHA
Variable depending on the type of bacteria
Sulfer Granules
Deposits of solid sulfur within the cytoplasm
Bacteria basically eats the rocks and the sulfur found in them is stored in the cytoplasm
Sulfer helps the cells avoid predation
Magnetosomes
Microscopic membrane-enclosed crystals of magnetite
Magnetite helps orient the cell based on the magnetic field of the environment
Multidrug resistance is most often found in bacteria that contain_______
Efflux Transporters
It helps microbes expel antibiotics which makes it multi drug resistant
Which cell walls (gram positive or gram negative) are more susceptible to penicillin and why?
Gram positive cell walls are more susceptible because antibiotic target the peptidoglycan in cell walls, and that is vital for the function of a gram positive cell. A gram negative cell wall has an outer membrane to help protect it.
What happens if you give an antibiotic treatment to a LPS-containing treatment?
It does kill the cells, but it can also cause a reaction that kills the patient
T or F: Bacterial cells grow and divide as a continuous process
True
Order of cellular components that make up a bacterial cell’s total weight from most to least
Water
Proteins
Lipids
DNA
Inorganic ions
Oxygen passes through the membrane by
simple diffusion
passive transport
Endospores
Heat and chemical resistant dormant structures
Is E. coli gram positive or gram negative?
Gram negative
Is streptococcus gram positive or gram negative?
Gram positive
Is staphylococcus gram positive or gram negative?
Gram positive