Microbiology 1: Introduction to Microbiology Flashcards Preview

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Flashcards in Microbiology 1: Introduction to Microbiology Deck (20):

What are some eukaryotic organisms?

• Animals, plants
• Algae (unicellular and multicellular, photosynthetic)
• Protozoa (unicellular, many free living others are intracellular parasites)
• Fungi (unicellular or multicellular, non-photosynthetic)


What are the general components of prokaryotes?

• No nuclear membrane
• No nucleolus
• No mitochondria
• No mitotic apparatus
• Single and circular chromosome


What are the general components of eukaryotes?

• True nucleus
• Nucleolus (site of ribosomal RNA synthesis)
• Multiple linear chromosomes
• Mitochondria
• Mitotic apparatus
• Membrane bound organelles


What are the characteristics of Gram positive (L) bacteria?

Have a cell wall characterized by a thick peptidoglycan layer. No outer membrane. Cell wall anchored to the cytoplasmic membrane by lipoteichoic acid.


What are the components and functions of bacteria?

Capsule: Allows bacteria to multiply and prevents them from being engulfed and broken down by phagocytes.

DNA: The genetic material of the cell – ONE chromosome!

Ribosomes: Needed for protein synthesis (the production of proteins)

Flagellum: Allows the bacteria to move through the environment (usually just rods)

Pili: Hairlike processes, used for adhesion to other cells.

Plasmid: An extra bit of genetic material found in some bacteria, carry genes that code for resistance or that code for the organism to cause disease (like a toxin).

Plasma membrane: Semipermeable; an osmotic barrier.

Cell wall: Prevents the bacteria from rupturing and provides shape. If this is damaged, the cell will lyse and die.


What is three domain system of classification of microorganisms?

1. Eubacteria – Prokaryotes
2. Archaea – Prokaryotes
3. Eukarya – Eukaryotes


What are Prokaryotes define by?

Prokaryotes are simpler than eukaryotes, predominantly unicellular and lack a cell nucleus, or any other membrane-bound organelles


What are 5 or 6 microorganism classifications?

Bacteria ƒ Viruses ƒ Fungi ƒ Protozoa ƒ Algae ƒ Prions (?)


What are prions?

Abnormal forms of the constituent protein (PrPc) of brain cells. They lack nucleic acid.
Prion protein (PrPC) is found in cell membranes. Transformation can occur, protein folds into a different form (PrPSc) now called a prion. Prions replicate by inducing more prion proteins to misfold. These prions then aggregate together. They are very hard to kill, do not elicit an immune response. They cause transmissible spongiform encephalopathy's like (bovine SE) mad cow disease, and kuru.


What are the staining steps?

crystal violet, iodine, alcohol, counter stain


What is a plasmid?

A circular, double stranded unit of DNA that replicates within a cell independently of chromosomal DNA. Plasmids can be very big or very small in terms of genetic material and can be passed between bacteria.


What are the living conditions of microorganisms?

Microorganisms can live at many different temperatures – with the ones in the body being optimal at 37°C.
However, some can also live at extreme temperatures (high and low), as they have been genetically changed to be able to survive in that environment.
Very few microorganisms can grow at a pH less than 2, which is why there are not as many present in the stomach (pH 1).


What are the characteristics of Gram negative (R) bacteria?

Have a cell wall characterized by a thin peptidoglycan layer. Both an outer and an inner membrane.


What are eukaryotes defined by?

The presence of a TRUE NUCLEUS.
There is a membrane-bound nucleus and membrane-bound organelles.
Here there is a nucleolus, which is the site of ribosome synthesis.
Eukaryotic cells are organised and structured, and contain multiple linear chromosomes.


Whata are some prokaryotic organisms?

• Bacteria
• Mycoplasma: free living, simplest form of life capable of independent growth. No cell wall – associated with primary atypical pneumonia
• Rickettsia: obligate intracellular parasites usually arthropod borne – associated with typhoid fever
• Chlamydia: obligate intracellular parasites which depend on host cell for energy – associated with trachoma and sexually transmitted disease


What colour do the gram stains change?

Gram positive stains purple/black as the thick peptidoglycan layer makes it harder the alcohol to wash out the stain.

Gram negative stains pink as the thinner peptidoglycan layer makes the cell easier to decolourize


What are viruses?

Unable to reproduce independently. Unable to carry out metabolic process. Not alive. Can replicate only after infecting a host cell. Obligate intracellular parasites.


What are the different shapes of bacteria?

Refer to notes


What is microbiology?

The study of microscopic living organisms


Why are gram stains important?

It allows the determination of a gram stain reaction and the visualisation of the bacterial shape (rod or cocci).
Following a gram stain, the bacteria will appear either purple-black or pink.