Summary
Microbes and Land Plants COMPLETE SUMMARY
- Institution
- University Of Cape Town (UCT)
Notes covering the microbes, land plants and fungi section of the BIO1004S course.
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Module 2: Microbes, Algae, Fungi and landPlants
CHAPTER 18, 26-31
INTRODUCTORY LECTURE
NUTRITIONAL MODE ENERGY SOURCE CARBON SOURCE EXAMPLES
AUTOTROPH
PHOTOAUTOTROPH light CO2 Photosynthetic
prokaryotes, plants,
certain protists
CHEMOAUTOTROPH Inorganic chemicals CO2 Certain prokaryotes (eg.
Sulfolobus)
HETEROTROPH
PHOTOHETEROTROPH Light Organic compounds Certain prokaryotes (eg.
Rhodobacter)
CHEMOHETEROTROPH Organic chemicals Organic compounds Many prokaryotes, some
protists, fungi, animals,
some plants
Phylogeny =genealogical/evolutionary relationships
Whittaker’s 5 Kingdom view
1. Plantae
2. Fungi
3. Animalia
4. Protista
5. Monera
NOW.. use 3 kingdom view
1. Eukarya
2. Archaea
3. Bacteria
, CHAPTER 26 - INTRODUCTION TO VIRUSES
• Viruses = infectious particle made up of genes within a protein coat
• Intracellular parasites
• CANNOT reproduce w/out a host cell + lack metabolic machinery of their own —> not living
CONCETP 26.1
• Viruses discovered via observance of tobacco mosaic disease that stunts the growth of tobacco
plants
• Gives leaves a mottled colouration
• Adolf Mayer observed that the disease could be transferred from plant to plant by rubbing
sap from infected plants onto healthy plants
• First thought to be bacterial
• Ivanowsky passed the sap through a lter designed to remove bacteria
• Sap still produced disease —> not!! Bacterial disease!
• E ect of disease was undiluted when passed from plant to plant —> therefore
pathogen replicates within infected plant (NOT BACTERIA)
• Disease could not be cultivated int test tubes or on petri dishes
• Viruses have a host range —> can infect cells of only a limited number of host species
• Result of the evolution of recognition systems by a virus (lock and key mechanism between
viral surface proteins and receptor molecules on the outside of a cell)
VIRUSES STRUCTURE
• Can have double or single stranded DNA or RNA depending on virus type
• DNA or RNA virus based on the kind of nucleic acid that makes up the genome
• Genome is usually organised as a single linear or circular molecule of nucleic acid
• Smallest virus = 3 genes
• Capsid = proteins hell enclosing the viral genome
• Rod, polyhedral or complex in shape
• Made up of protein subunits (capsomeres)
• Rod shaped viruses = helical
• Adenoviruses - a ect respiratory tract of animals = polyhedral capsid w/ triangular facets
(icosahedral virus)
• Viral envelope = derived from the membrane of the host cell, contains host cell phospholipids
and membrane proteins —> membranous envelope that acts as an accessory structure to aid in
infection
• Bacteriophages = viruses that infect bacteria
CONCEPT 26.2 VIRUSES REPLICATE ONLY IN HOST CELLS
• Viruses lack metabolic enzymes and equipment for metabolism (eg. Protein synthesis)
• = obligate intracellular parasites (can only replicate inside a host cell)
1) virus enters the cell and is uncoated —> released viral DNA and capsid proteins
2) Host enzymes replicate the viral genome
3) Host enzymes transcribe the viral genome into viral mRNA which host ribosome use to make
more capsid proteins
4) Viral genome and capsid proteins self-assemble into new virus particles that exit the cell
• Virus makes use of hot cell enzymes, ribosomes. tRNAs, amino acids and ATP.
• DNA viruses use DNA polymerases of the host to synthesise new genomes along pre-existing
templates provided by viral DNA
ff ff fi
, • RNA viruses are virally encoded RNA polymerases that can use RNA as a template
• Uninfected cells make no enzymes for carrying out this process
• Symptoms of infection caused by:
• Cellular damage
• Cell death
• Body’s response to destruction
• Vaccines = harmless derivatives of pathogenic microbes that stimulate the immune system to
mount defences against the actual pathogen
• Viroids = circular RNA that infects plants
• Prions = infectious proteins (eg. Mad cow disease)
Classes of animal viruses
CLASS/FAMILY ENVELOPE? EXAMPLES
DOUBLE STRANDED DNA
adeonovirus No Respiratory diseases, tumour causing diseases
papillomavirus No Warts, cervical cancer
Polyomavirus No Tumours
herpesvirus Yes Herpes simplex 1 and 2 (cold sores, genital sores),
varicella zoster (shingles, chicken pox), Epstein-barr
virus (mononucleosis, burrito’s lymphoma)
Poxvirus Yes Smallpox, cowpox
SINGLE STRANDED DNA
Parvovirus No B19 parvovirus
DOUBLE STRANDED RNA
reovirus No Rotavirus (diarrhoea) colarado tick fever
SINGLE STRANDED RNA
picornavirus No Rhinovirus (common cold), poliovirus, hepatitis A
Coronavirus Yes SARS
Flavivirus Yes Yellow fever virus, west nile virus, hepatitis C
togavirus Yes Rubella, equine encephalitis
SERVES AS A TEMPLATE FOR
MRNA SYNTHESIS
Filovirus Yes Ebola
Orthomyxovirus Yes In uenza
paramyxovirus Yes Measles, mumps
rhabdovirus Yes rabies
SERVES AS A TEMPLATE FOR
DNA SYNTHESIS
Retrovirus Yes HIV/AIDS, RNA tumour virus (leukaemia)
fl
, CHAPTER 27 — PROKARYOTES
MICROBES = collective term for all unicellular (microscopic) organisms
CHARACTERISTIC DOMAIN
Bacteria Archaea Eukarya
Nuclear envelope No No Yes
Membrane bound No No Yes
organelles
Peptidoglycan in cell Yes No No
wall
Membrane lipids Unbranched Some branched Unbranched
hydrocarbons hydrocarbons hydrocarbons
RNA polymerase One kind Several kinds Several kinds
Response to Growth inhibited Not inhibited Not inhibited
antibiotics
Circular chromosomes Yes Yes No
Ability to grow above No Some species No
100°C
• Peptidoglycan = network of sugar polymers cross-linked by polypeptides
• Archaeal cell walls contain polysaccharides and proteins but lack peptidoglycan
• Non-monophyletic (two lineages)
• Important role in decomposition and nutrient cycling + mutualists!
CONCEPT 27.1 STRUCTURAL AND FUNCTIONAL ADAPTATIONS CONTRIBUTE TO
PROKARYOTIC SUCCESS
• Most prokaryotes = unicellular but some aggregate after cell division
• Most are smaller than eukaryotes
BACTERIA AND ARCHAEA
Microscopic, unicellular (may be colonial)
Enclosed by a lipid membrane and cell wall
Cell wall protects the cell and prevents bursting in a hypotonic environment (cell would shrink +
plasmolyze —> water loss can prevent cell reproduction)
Often agellate
Lack interior membranes + membrane bound organlles
Genome is circular, not in chromosomes and no nucleus
Reproduce via binary ssion
Some ability to transfer genetic material - across di erent species!! Allows for gene development and
variation
fl fi ff
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