Bacteriology Flashcards
What are the differences between eukaryotic and prokaryotic cells?
Eukaryotic:
- Nuclei with linear chromosomes
- Organelles: mitochondria, Golgi apparatus, lysosomes and relatively large ribosomes
- Larger size: 0.1 – 100 μm
- Individual cells replicate by mitosis
Prokaryotic :
- Lack true membrane - bound nuclei
- Genetic information is contained in a single haploid circular chromosome
- Small size: 0.5-5 μm
- Bacteria: Unicellular organisms that replicate by binary fission - Bacteria: extrachromosomal DNA - plasmids
What are the similarities between eukaryotic and prokaryotic cells? (3)
- Cell membrane
- Cytoplasm
- DNA present in both (just different location)
- Ribosomes (but different structure)
What are the different structures of the bacterial ? (the ones they all have) (5)
- Cytoplasm
- Ribosomes
- Nucleoid
- Plasma membrane
- Complex and rigid cell wall
What are the structures the bacterial can sometimes have? (3-4)
- Capsule
- Flagella
- Pili/Fimbriae
(Endospores)
(OLD) What does the cytoplasm contains?
- MACROMOLECULES (proteins, mRNA, tRNA) + Nucleoid (DNA) and ribosomes (protein synthesis).
- SMALL MOLECULES : energy sources, precursors of macromolecules, metabolites or vitamins.
- INORGANIC IONS : for enzymatic activity.
(OLD) What is the functions of the cytoplasm?
- Facilitate chemical reactions
- Dissolve solutes (ex. carbohydrates and proteins)
What is the nucleoid in the prokaryotic cells?
It is the location in the prokaryotic cell where primary genetic material is found. Takes 1/3 of the cell.
What is the chromosomal DNA made of?
Single haploid circular chromosome containing double-stranded DNA. (Haploid meaning : no additional copies).
What are the ribosomes? Function?
- PROTEINS and RNA
Function: involved in protein synthesis!
What is the plasmid?
It is a circular molecule of DNA that replicates separately from the genome.
(several different types may be present in one cell)
Is the plasmid part of the nucleoid?
NO!
Is the plasmid genes essential under normal conditions?
No, it is not essential.
(Old) What is the functions of the plasmid? (2)
- SPECIAL GENES REPLICATION:
- Virulence factors: associated with disease
- Resistance genes: to survive in presence of antibiotics and other toxic compounds.
- CONJUGATIVE PLASMIDS: cell-to-cell transfer by conjugation (transfer DNA).
(Old) How can we relate ribosomes to medicine? How can they be used?
They can be the target for antibiotics.
(Old) What are the different components of the bacterial envelope?
- Cytoplasmic or plasma membrane.
- Cell wall (peptidoglycan layer)
- Periplasmic space
- Capsule (some bacteria)
(Old) Where the plasma membrane located?
Innermost membrane, next to cytoplasm.
(Old) What type of bacteria has a periplasmic space?
Gram negative
(Old) What are composed the components of the plasma membrane?
Phospholipid bilayer (head hydrophilic and tail hydrophobic).
(Old) What can pass by passive diffusion the plasma membrane?
Only hydrophobic coumpounds.
(Old) What the different proteins inside the plasma membrane?
- TRANSPORT PROTEINS : for specific transport of molecules into and out of the cell.
- ENERGY GENERATION COMPONENTS : used to generate ATP.
- Proteins to work as anchors or assembly of external structures.
What is the main functions of plasma membrane?
- Selective permeable membrane
What are the components of the cell wall? How are they arranged?
Peptidoglycan (unique to prokaryotic cells) : NAG + NAM.
Arranged in a mesh-like structure alternating NAG-NAM-NAG-NAM.
(Old) What is the link between each NAG and NAM?
Cross-linked with peptides by transpeptidase enzymes called: penicillin-binding proteins (PBPs).
What is the function of the cell wall?
- RIGIDITY
- PROTECTION against mechanical damage and osmotic lysis
What does contains the cell wall of gram +, gram - and mycobateria ?
Gram + : (Lipo)teichoic acid: strongly antigenic
–> High resistance to physical disruption and drying
Gram - : Lipopolysaccharides (LPS)
–> Low resistance to physical disruption and drying
Mycobacteria: mycolic acid as virulence factor
–> will not stain = need acid fast stain!
Is there an outer membrane in every bacteria?
No, usually common to Gram-negative bacteria.
What are the 2 part of LPS in Gram - ? What is the most important of the 2? What is its function?
- Lipid A : endotoxin that activates immune system and exert harmful effects
- Polysaccharide chain: antigenicity
What is the function of outer membrane?
- Selective permeability
- Resistance to large or hydrophobic toxic compounds
- Tolerance to detergents and bile salts