Lecture #3 Flashcards
What is different for DNA in Prokaryotes vs Eukaryotes
Pro- DNA is not enclosed within a membrane
Euk- DNA is contained within a membrane bound nucleus
Prokaryotes’ chromosome look like?
Single and circular
Where is the chromosome located within the prokaryote?
The nucleoid
Why do prokaryotes not have membrane bound organelles?
Because it minimizes building costs and energy
Are bacteria eukaryotes or prokaryotes?
Prokaryotes
How many chromosomes do eukaryotes have?
Many
Can eukaryotes be single celled?
yes that or multicellular
What are 4 types of eukaryotes?
Protist, Plants,Animals and fungi
What are the 3 names of shapes bacteria come in? What shape are each?
- Coccus- Spherical
- Bacillus- Rods
- Spirillum- Spiral
What is an example of coccus bacteria
Streptococcus pyogenes, causes strep throat
What is an example of Bacillus bacteria
Escherichia coli (E. Coli)
What is an example of Spirillum Bacteria
Treponema Pallidum
What is Gycocalyx
A sticky gelatinous polymer on the outside of bacteria
What can gycocalyx be composed of
Either polysaccharide, protein or both
When gycocalyx is made of only sugar it is called…?
Extracellular polysaccharide
When is gycocalyx called a capsule? When is it called a slime layer?
Capsule- When the substance of gycocalyx is firmly attached to cell wall and organized (lululemon sweats)
Slime layer- When the substance is disorganized and loosely attached (baggy sweats)
What contributes to an organisms ability to cause disease
Capsules
How does a capsule allow a cell to be more able to cause disease?
By protecting the organism from phagocytosis (makes the cell slippery)
What is an example of a bacteria that can ONLY cause disease when encapsulated
Bacillus anthracis
What 3 things does a capsule do for bacteria?
- Allows organism to cause disease better
- Adhere and colonize host cells
- Protects bacterial wall against dehydration and holds nutrients inside cell`
What does extracellular polysaccharide do for bacteria?
Allows it to survive by attaching to different surfaces within the microbe environment (other bacteria, impacts, etc)
What bacteria attaches to the teeth and causes cavities
Streptococcus mutans
What can some organisms do to the capsule when energy sources are low
Break down the sugars and use it as an energy source
What are flagella
Long, filamentous and used for motility
What are the 3 parts that flagella is composed of?
- Filament
- Hook
- Basal Body
What is the filament of the flagella composed of and what does it form?
Made of circular flagellin protein and forms a helix around a hollow core and is not covered by a sheath
What is the hook made of in the flagella?
A different protein than the flagella
What does the basal body of the flagella do?
Anchors the flagellum to the plasma membrane and cell wall
What are the 4 possible flagellar arrangements?
Pertrichous
Monotrichous
Lophotrichous
Amphitrichous
What does the pertrichous arrangement look like?
Flagella distributed all over the cell
What does the monotrichous arrangement look like?
Single polar flagella
Which arrangement has two or more flagella at one or both ends of the cell
Lophotrichous
Which arrangement has a tuft of flagella at each end of the cell?
Amphitrichous
What is used to differentiate between different strains of bacteria
Flagellar proteins (H7)
Which way can flagella rotate?
Clockwise or counterclockwise
What does flagellar movement depend on?
Energy production
What is movement of a flagella in one direction for a continuous period of time called?
Run or swim
What are abrupt changes in direction of flagella called?What is it a result of?
Tumbles, result of flagella changing direction
Being motile allows the bacterium to do what?
Move away from dangerous environments and toward favourable environments
What is taxis
The movement of bacterium toward favourable environments
What is chemotaxis?
Movement toward a chemical stimulus
What is phototaxis?
Movement toward light stimulus
Bacteria move toward a____ and move away from a ______
attractant, repellent
What are pili and fimbrae?
Hair like appendages that are shorter, thinner and straighter than flagella and are not used for motility
What are pili and fimbrae made of?
Pilin protein
Where can fimbriae be located?
All over the cell or only at the pole
What do fimbriae enable the bacterial cell to do?
To adhere to surfaces and other bacterial cells and colonize
What does pili look like?
Longer than fimbriae
How many pili are on a cell?
Only one or two per cell
What do pili do?
Join two bacterial cells in order to transfer DNA in between them?
What is conjunction?
The transfer of DNA between two cells instead of colonizing and reproducing
Why do humans not need a cell wall?
Because we are multicellular and can repair our cells
What provides a bacterial cell with its characteristic shape
Bacterial Cell Wall
How does the bacterial cell wall protect the cell
Protects it from environmental changes and prevents cell rupture (osmotic rupture)
What is the bacterial cell wall made of?
Polysaccharide peptidoglycan
What is peptidoglycan made of and how does it look?
Composed of repeating disaccharides layered on top of one another creating chains which are combined to form a wall
What are the disaccharide chains linked together by in a cell wall
Short peptides
What two things of the disaccharide unit of a bacterial cell wall made of?
- N-acetyl glucosamine (NAG)
2. N-acetyl muramic acid (NAM)
What thickness of peptidoglycan is found outside a gram positive cell? Gram negative?
\+= Thick layer of peptidoglycan -= Thin layer of peptidoglycan
What type of acid is only found in gram positive organisms?
Teichoic Acids
What are two forms of teichoic acid? What do they do?
- Wall teichoic acids- extend out from peptidoglycan
2. Lipoteichoic acids- Connect the plasma membrane to the peptidoglycan
How many membranes do gram positive bacteria have?
only one- plasma membrane
How many membranes do gram negative bacteria have?
2- plasma membrane and outer membrane
What 3 things is the outer membrane of a gram negative bacteria made up of?
- Lipids
- Proteins
- Lipopolysaccharides
What is the lipid portion of a lipopolysaccharide do? What is it referred to as?
It is toxic and is referred to as endotoxin
What is the polysaccharide portion of a lipopolysaccharide made up of and what does it do?
Made up of O sugars and is used to distinguish gram negative organisms
Which type of cell (gram negative or positive) hold the crystal violet stain and why?
Gram + because the thick peptidoglycan where as the gram - has an outer membrane which stays intact and is not penetrated with dye
What are the 4 steps to a gram stain?
- Crystal violet (purple), then rinse–> both are purple
- Add iodine (mordant)–> intensifies, both purple
- Add alcohol (destain)–> breaks cell wall +=purple, -= no colour
- Add safranin (pink)–> += purple, -= pink
Where else can peptidoglycan be found other than bacterial cells?
No where, there is no similar compounds in eukaryotes
What is a host enzyme produced in tears, mucous, etc? What does it do to peptidoglycan ?
Lysozymes, degrades peptidoglycan
What does penicillin do to peptidoglycan?
Targets peptidoglycan synthesis
What state does the plasma membrane exist in?
Semi fluid
What does alcohol do to a plasma membrane?
Disrupts plasma membrane
What percentage of the cytoplasm is water? What is another name for it?
60-80%, cytozol
What are some material found in the cytoplasm?
Amino acids, carbs, nucleotide, enzymes and inorganic ions
Where are some endospores found in a cell?
Cytoplasm
What is the nucleoid?
The area that contains the bacterial chromosome
What are plasmids? Can bacteria have it?
Small, circular double stranded DNA molecules. Some bacteria have plasmids
What do plasmids do for a bacterial cell?
House nonessential genes which can help the bacterium survive adverse conditions such as high antibiotic concentrations
What occurs at ribosomes
Protein synthesis
What is ribosomes made of?
Protein and ribosomal RNA
What are the large and small subunits called on ribosomes? Together they are called?
Large: 50s
Small: 30s
Together= 70s ribosome
What is the difference between eukaryotic ribosomes and prokaryotic ribosomes?
Eukaryotes subunits are heavier= larger subunit is 60s, smaller is 40s which together are 80s
Why do certain antibiotics only target bacterial ribosomes?
Because bacterial ribosomes are different than eukaryotic ribosomes therefore they are able to get rid of a bacteria without killing all cells
What is selective toxicity?
When an antibiotic targets certain cells without harming all cells
What are inclusion bodies? Do all bacteria have them?
Deposits of nutrient granules which are stored for later use, no
What are 4 examples of inclusion bodies?
sulfur granules, polysaccharide granules, lipid inclusions, and enzymes
Do both gram positive and negative have endospore?
No, only gram positive
What do endospores do?
Allow bacterium to resist heat, desiccation, chemicals and radiation
What are endospores?
Similar to an apple seed, they dry up and hold only DNA so that later on when nutrients become available again, the cell is able to grow and reproduce once again
What are two examples of spore forming bacteria?
Bacillus Anthracis
Clostridium Botulinum
What is Clostridium Botulinum?
Botox
What occurs in sporulation?
- Bacterial cell replicates its DNA
- A septum forms dividing cell
- The larger compartment engulfs the smaller forming a forespore within mother cell
- Peptidoglycan and other protective material form around forespore
- Spore is freed from mother cell
What are 3 examples of simple eukaryotes?
- Protozoa- unicellular
- Algae- some uni, some multicellular
- Fungi- multicellular except yeast
What are 2 examples of higher eukaryotes (more complex)
Plants and animals
What is the 2 differences between eukaryotic and prokaryotic flagella and cilia
Eukaryotes- contain protein and cytoplasm, and move in whiplike fashion
Prokaryotes- are hollow and move in corkscrew motion
Is the eukaryotic cell wall more or less complex than prokaryotic ?
Simpler structurally
What is the cell wall in eukaryotes composed of?
Cellulose ( algae and plants)
Chitin (fungi)
What makes the cell wall of a eukaryotic cell rigid?
Sterols
What is endocytosis and are eukaryotic cells able to perform it?
Engulfing particles outside of the cell and brings it inside. Yes some cells are
What is in the eukaryotic cytoplasm that is unique to it?
Cytoskeleton
What does the cytoskeleton do?
- Provides support and shape
- Transports substances through the cell
What is the cytoskeleton made of?
Protein filaments on inside of plasma membrane
Are membrane bound organelles present in bacteria?
NO
