Lesson 2: Bacterial Characteristic Flashcards
5 Shapes of Bacteria
Cocci
Bacilli
Vibrio
Spirilla
Spirochetes
Shape of the Bacteria
“Kokkos meaning berry; are spherical or oval cells; equal in diameter”
Cocci
Shape of the Bacteria
“Baculus meaning rod; are rod shaped cells; length is longer than its width; longer and slender; there are some short and plump that looks like oval and can be mistaken as cocci”
Bacilli
Shape of the Bacteria
“Are comma shaped curved rods and derive their name from their characteristics vibratory motility”
Vibrios
Shape of the Bacteria
“Are rigid spiral forms; coil or snake-like”
Spirilla
Shape of the Bacteria
“Speira meaning coil and chaite meaning hair; are flexuous spiral forms; flexible movement”
Spirochetes
These are branching filamentous bacteria and resembles fungi
Rays of the sun resemblance
Actinomycetes
These are cell wall deficient, and hence do not possess a stable morphology. They occur as round or oval bodies and as interlacing filaments
Mycoplasma
Cocci Arrangement
Pairs:
Chains:
Groups of 4:
Groups of 8:
Grape-like clusters:
Pairs: Diplococci
Chains: Streptococci
GO4: Tetrad
GO8: Sarcina
Grape-like: Staphylococci
Bacterial growth can be studied using cell counts like?
Total Count
Viable Count
PHASES OF GROWTH CURVE
- No increase in number
- Increase in cell size
- Flat/Horizontal line curve
Lag Phase
PHASES OF GROWTH CURVE
- Cells start dividing
- Steady increase in number
- More bacterial division, no cell death
- There is a limit where it will flatten
Log or Exponential Phase
PHASES OF GROWTH CURVE
- Cell division stops due to depletion of nutrients
- Accumulation of toxic products
- Viable count: stationary
- Equal number of dying cells and newly formed cells
Stationary Phase
PHASES OF GROWTH CURVE
- Population decreases due to cell death
- Culture medium is not suitable for growth
Phase of Decline (Death Phase)
Ideal phase to get sample
Log Phase
Phase where sporulation occurs
Stationary Phase
This phase is where involution forms are common
Phase of Decline (Death Phase)
Bacteria that grow only in the presence of oxygen
Ex. Cholera, Vibrio
Obligate aerobes
Bacteria that are ordinarily aerobic but can grow in the absence of oxygen
Facultative anaerobes
Bacteria that grow in the absence of oxygen
Ex. Clostridia
Anaerobic bacteria
Bacteria that may even die on exposure to oxygen
Ex. Bacteroides, Clostridium, Propionibacterium
Obligate anaerobes
Bacteria that grow best in the presence of low oxygen tension
Ex. Spirochetes
Microaerophilic bacteria
Uses carbon dioxide as their electron receptor
Capnophile
Grows best at temperature of 25-40C
Mesophiles
Grows best at temperature of below than 20C
Psychrophiles
Grows best at high temperature of 55-80C
Thermophiles
Lowest temperature that kills a bacterium under standard conditions in a given time
Thermal Death Point
It is a protein that increases in concentration as a cell grows and gets ready for cell division
DNA-A
Majority of pathogenic bacteria grow best at neutral or slightly alkaline pH of?
7.2 - 7.6
Bacteria solution should be isotonic for growth and sudden exposure to hypertonic solutions may cause osmotic withdrawal of water and shrinkage of protoplasm called ________
Plasmolysis
DNA replication begins at a single defined DNA sequence of 245 base pairs called?
Origin of Replication (oriC)
DNA helicase is also called?
DnaB
Cleaves the RNA ends of the Okazaki fragments DNase1 then fills in the cleaved gaps with DNA nucleotides
RNAse H
It transports the DNA Helicase
DNA Helicase Loader
DNA helicase loader is also called?
DnaC
An enzyme which synthesizes an RNA primer on the DNA template which is used by DNA Polymerase as a starting point
DNA Primase
DNA polymerase is ferried to the replication fork by proteins called?
Clamp Loaders
The main replication polymerase in E. coli is called?
DNA Polymerase 3
Short sequences synthesized in the lagging strand because DNA polymerase can synthesize only from 5’ to 3’
Okazaki Fragments
It closes the remaining gaps in the okazaki fragments
DNA ligase
Proofreads new molecules of DNA and removes mismatched bases before continuing DNA synthesis
DNA Polymerase
Process in which the information in the nucleotide base sequence of mRNA is used to dictate the amino acid sequence of a protein
Translation
3 steps of Protein Synthesis
Initiation
Elongation
Termination
3 initiation factors of E. coli in the Initiation Phase
IF1
IF2
IF3
Small ribosomal subunit contains __ subunits
30s subunits
Large ribosomal subunits contain __ subunits
50s subunits
Carries the genetic information copied from DNA
mRNA
A ribosomal binding site in bacteria and archaea located around 8 bases upstream of the start codon AUG, it binds the mRNA to the ribosome near the first AUG
Shine Dalgarno sequence
Readily binds to the small ribosomal subunit and its presence blocks the large and small subunits from prematurely associating
Facilitates the binding of the mRNA to the small subunit of the ribosome
IF3
Binds to the small subunit at a location called the A-site
IF1
It is where the incoming tRNA normally binds
A-site
It is bound to GTP and escorts the initiator tRNA to a different site, the P-site
IF2
It carries the anticodon
tRNA
An enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain
Peptidyl transferase
Has the general shape of a tRNA mimics a tRNA and enters the A site
RF 1 or RF 2 (Release Factor 1,2)
Along with EFG binds at the A site and undocks the two ribosomal subunits
Ribosome Recycling Factor or RRF
These are agents in the environment that cause permanent changes in DNA except for spontaneous mutation
Mutagens
Types of Mutations
One or a few base pairs are deleted or added to DNA
Frameshift mutation
Types of Mutations
Occur without the presence of any mutagen
Spontaneous mutations
Types of Mutations
Amino acid substitutions
Missense mutations
Types of Mutations
Creates a stop codon
Nonsense mutation
This occurs during reproduction when genes are passed from an “ORGANISM TO ITS OFFSPRING”
Vertical Gene Transfer
This occurs in bacteria and involves a portion of the cell’s DNA being transferred from “DONOR TO RECIPIENT”
Horizontal Gene Transfer
When some of the donor’s DNA has been integrated into the recipients DNA, the resultant cell is called a?
Recombinant
Genes are transferred from one bacterium to another as “naked” DNA in solution
Transformation
A type of transferring genetic material wherein it requires contact between living cells
Conjugation
DNA is passed from one bacterium to another in a bacteriophage and is then incorporated into the recipient’s DNA
Transduction
These are self-replicating circular molecules of DNA carrying genes that are not usually essential for the cell’s survival
Plasmids
These are small segments of DNA that can move from one region to another region of the same chromosome or to a different chromosome or plasmid
Transposons
