1.01 Cell Structure and Classification of Bacteria Flashcards
The study of microscopic organisms including a large and diverse group/classes of: ▪ Bacteria ▪ Viruses ▪ Archaea ▪ Fungi ▪ Protozoa
Microbiology
Microorganisms are responsible for cycling which of the chemical elements that are essential for life?
▪ Carbon ▪ Nitrogen ▪ Sulfur ▪ Hydrogen ▪ Oxygen
These microorganisms lack many attributes of cells including the ability to replicate.
Viruses
How does a virus reproduce?
When it infects a cell
These are viruses that infect other viruses
Virophage
Viral particles are generally small and consist of a ____ ____ molecule either ___ or ___
Viral particles are generally small and consist of a nucleic acid molecule either DNA or RNA
A DNA virus infecting Acanthamoeba (a free-living soil amoeba)
Mimivirus
A larger marine virus that resembles bacteria because of their size when observed
Megavirus
Small, single-stranded, covalently closed circular RNA molecules existing as highly base-paired rodlike structures
Viroids
True or False. Viroids are totally dependent on host functions for its replication
True
True or False. Viroid RNA is replicated by the RNA-dependent RNA polymerase of the host
False. Viroid RNA is replicated by the “DNA- dependent” RNA polymerase of the host
Prions are a type of protein that can trigger normal proteins in the brain to ____ _______?
Fold abnormally
Prion diseases of importance?
- Kuru, Creutzfeldt-Jakob disease (CJD) - Most common
- Gerstmann-Straussler-Scheinker Disease
- Fatal Familial Insomnia
- Bovine Spongiform Encephalopathy
What are the four major groups of protists?
- Algae - produce O2 as a product of photosynthesis
- Protozoa - Unicellular non photosynthetic protists
- Fungi - Unicellular non-photosynthetic protist
- Slime molds - characterized by the presence of an ameboid multinucleated mass of cytoplasm called Plasmodium
One of the distinguishing features of protists.
True nucleus
Agents of motility of protists.
Flagella or cilia
Contains the cell’s genome
Nucleus
A structure often visible within the nucleus, it is rich in RNA that is the site of ribosomal RNA synthesis
Nucleolus
Major producer of glycoproteins.
Rough ER
Participates in synthesis of lipids.
Smooth ER
Site of ATP production
Mitochondria
converts sunlight energy into chemical energy through photosynthesis
Chloroplasts
Membrane-enclosed sacs that contain various digestive enzymes to digest macromolecules.
Lysosomes
Membrane-enclosed structure that produce H2O2 from the reduction of O2
Peroxisome
Cytoskeleton fills the cytoplasm and is composed of? (3)
- Microfilaments
- Intermediate filaments
- Microtubules
True or False. Most plant cells have no other surface layers. However, animal cells have an outer cell wall
False. Most animal cells have no other surface layers however plant cells have an outer cell wall composed of cellulose
Organelle that move with a wavelike motion to propel the cell through water
Motility organelles
Motility organelle that emanate from the polar region of the cell
Flagella
Shorter than flagella, surrounds the cell
Cilia
Average bacteria cell size
0.5-2.0 um diameter
Surface area
12 um ^2
Volume
4 um
Surface Area to volume
3:1
Typical eukaryotic cell surface area/Volume
0: 3:1
* Eukaryotic cell is jam- packed with more elements that is why it has a smaller SA compared to bacteria
Essential bacterial cell components.
(NCCRGP)
- Nucleoid
- Cytoplasm
- Cell wall
- Ribosomes
- Granule Vesicles and Vacuoles
- Periplasmic Space
Non-essential bacterial cell components. (PCFPE)
*not seen in all bacteria
- Plasmids
- Capsule and Glycocalyx
- Flagella
- Pili
- Endospores
- Gel-like matrix of water, enzymes, nutrients, wastes, and gases & contains cell structures like numerous ribosomes and polysomes
- Location of growth, metabolism, and replication
Cytoplasm
Internal mobilities? (3)
- Cytoplasmic streaming
- Amoeboid movement and formation
- Disappearance of vacuoles
Bacteria’s way of storing nutrients
Granules or inclusions
Example of bacteria staining that aids in identification?
Metachromatic Granules of Corynebacterium diphtheriae
− Small electron dense particles
− Involved in protein synthesis
Ribosomes
Size of ribosome
70S (with subunits of 30s +50 s)
3 types of RNA
- rRNA
- tRNA
- mRNA
Functions of the plasma membrane. (5)
- Semipermeable membrane
- Housing enzymes
- Generation of ATP
- Cell motility
- Mediation of chromosomal segregation
With the exception of _______, bacterial
cytoplasmic membrane lacks sterol.
Mycoplasma
The cell wall is composed of?
Peptidoglycan polymer (amino acids + sugars)
*Provides rigid support while freely permeable to solutes
Backbone of peptidoglycan molecule is composed of which 2 derivatives of glucose?
- N-acetylglucosamine (NAG)
2. N-acetylmuramic acid (NAM)
NAG/NAM strands are are connected by?
Inter-peptide bridges
True or False. D form of amino acids are used because it is harder to breakdown compared to the L form.
True
The two major classes of bacteria.
- Gram Positive
2. Gram negative
Why are these differences in cell wall structure so important?
Because there are some antibiotics that specifically target the cell wall thus making it permeable to the effects of the antibiotics, facilitating the killing of the organism (I.e. Penicillin)
a) A major component of the cell wall of a Gram (+) bacterium only.
b) Functions?
a. Teichoic acids
b. 1. attachment for phages
2. Important role in Antigenic determination
What are its compositions?
- Glycerol
- Phosphates
- Ribitol
a. Only seen in Gram (-) bacteria
b. Functions?
c. Structures?
a. Lipopolysaccharides
b. Functions as an Endotoxin or Pyrogen – responsible for causing fever
c. 1. Lipid
2. Polysaccharide - corresponds to the antigen O of E. coli and Salmonella
Forms a slime layer causes bacteria to adhere to solid surfaces and helps prevent the cell from drying out.
Glycoproteins loosely associated w/
the cell wall
The slime layer of Gram (+) _______ _____ allows it to accumulate on tooth enamel (one of the causes of cavities). This causes the other bacteria in the mouth become trapped in the slime and form a biofilm and eventually a buildup of plaque.
Streptococcus mutans
Capsules adheres to solid surfaces and to nutrients in the environment.
Polysaccharides firmly attached to the cell wall
Which bacteria have the type of capsule that protects bacteria from being phagocytized by cells of the hosts immune system?
Streptococcus pneumoniae
Flagella arrangement which consist of 1 flagellum
Monotrichous
Flagella forms a TUFT at 1 end
Lophotrichous
Flagella at BOTH ENDS
Amphitrichous
Flagella is all AROUND bacteria
Peritrichous
Wind around bacteria causing movement in waves
Endoflagella
Short protein appendages (smaller than flagella) that adhere bacteria to surfaces
Pili
E. coli types of pili. (3)
K88
K99
F41
Used in conjugation and exchange of genetic information
F-pilus
It allows bacteria to survive in extreme temperature/environment
Endospores
Location of the spores
- Central
- Subterminal
- Terminal
Spores used for quality control of heat sterilization equipment
Bacillus stearothermophilus spores
Used for biological warfare
Bacillus anthracis spores
One of the most important bacteriologic techniques within the microbiology laboratory because it is used in microscopic examination
Gram Stain
Who discovered the Gram Stain in 19th century?
Hans Christian Gram
Purpose of gram staining that: - Distinguishes between the two most common chemical cellular structures of bacteria - Easy visualization of the morphology and cellular arrangement of the organism
Differential Stain
Enumerate the Gram Stain Procedures. (5)
- Fixation
- Primary Stain
- Mordant
- Decolorization
- Counterstain/Secondary Stain
Methods of Fixation
- Heating
2. Use of methanol
What is the Stain used in primary staining?
Crystal violet
The mordant applied after the crystal violet to chemically bond the alkaline dye to the bacterial cell wall
Gram’s Iodine
They retain crystal violet after decolorization.
Gram positive (+)
Addition of the counterstain SAFRANIN will stain the clear gram-negative bacteria ____ or ____.
pink, red
Highly CROSS-LINKED thick layer of peptidoglycan of Gram ____ bacteria will retain the primary dye, crystal violet.
Positive
Spherical, and resemble tiny balls. Give an example
Coccus/Cocci
Streptococcus
Rod shaped, and resemble a pill, some bacilli have rounded ends while others have squared ends.
Bacillus/Bacilli
Bacillus anthracis - anthrax
a. Twisted or helical morphology that resembles little cork screws.
b. They appear as curved rods
a. Spiral
b. Vibrios
They have pliant bodies
Spirilla or spirochetes
What causes gastritis and what is the shape of this bacterium?
Helicobacter pylori, spiral
Arrangement that are found in pairs attached to each other
Diplococci
or
Diplobacilli
These bacteria form long chains and remain attached to each other
Streptococcus
or
Streptobacilli
These coccus bacteria are arranged irregularly in clusters like grapes
Staphylococcus