week 1 - microorganisms as cells

Question 1

Metabolism

Answer 1

• Compartmentalisation
  o Cell membrane separates the cytoplasm from the environment
• Uptake of nutrients
• Energy storage and utilisation
• Elimination of waste
• Metabolic versatility (microbes)
  o Some pseudomonas bacteria can use antibiotics as a source of carbon and nitrogen
  o Microbes can live in very extreme environments
   E.g. high salt concs
  o All natural and most synthestic compounds can be broken down by one or more microorganisms
   E.g. plastics -> very slow

Question 2

Reproduction (growth)

Answer 2

• Prokaryotes (bacteria and archaea) – no nucleus
  o Single circular chromosome
  o Binary fission is the norm
   Getting bigger then dividing by two
   Repeating this
• Eukaryotes (fungi and protists)
  o Membrane bound nucleus
  o Several linear chromosomes
  o Meiosis
   4 cells with ½ of the genetic material
  o Budding (yeast)
   Can work out how old by looking at budding scars

Question 3

Differentiation

Answer 3

• Production of new substances or structures
• Common in multicellular organisms
• Fungi produce fruiting bodies
  o Mushrooms/toadstools
  o Spores both asexual and sexual

Question 4

Differentiation: bacteria

Answer 4

• Asymmetric division producing 2 different daughter cells
  o This is not sexual reproduction
  o Binary fission is more usual
   Very uncommon in bacteria
   Widely found in eukaryotes
• Endospores
  o Resistant to heat and desiccation
• Motile and sessile forms

Question 5

Communication: Quorum sensing

Answer 5

• Bacteria assess the population density
  o Ensures sufficient numbers before initiating a response
• Regulate gene expression
  o Toxin production in pathogenic bacteria
  o Luminescence in Vibrio fisherii
  o Biofilm formation in Pseudomonas
• Autoinducer molecule
  o E.g. Acyl homoserine lactone I Pseudomonas
   How organism senses other similar organisms in the surrounding area
  o Small and highly diffusible

Question 6

Movement

Answer 6

• Towards nutrients and away from toxic waste products
• Bacterial Fagella
  o Many bacteria
  o Flagella propel bacteria
   Spiral shaped protein structure that rotates
• Cytoplasmic streaming
  o Cytoplasm pushed to each of organism and moves in that direction
  o Amoeba
• Eukaryotic flagella
  o Made of microtubules
   Do not rotate
  o Dinoflagellates
• Cilia
  o Paramecium