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Life Science 142 > Lecture 3 > Flashcards

Lecture 3 Flashcards

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Biology 101 flashcards
1
Q

What are characteristics of viruses

A
  • Non-cellular and non-living
  • Able to mutate – evolve
  • Infectious and able to infect specific cells
    -They are Obligate parasites – unable to metabolize outside host cell
    -They are able to remain dormant until next invasion(enter a host cell)
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2
Q

Explain virus classification

A
  • Virus possess either DNA or RNA
  • Nucleic acid either single or double –stranded
  • Classification depends on size and shape
  • Classified on whether an outer envelope is present or absent
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3
Q

What cells are viruses able to infect

A
  • HIV infects blood cells
  • Polio infects nerve cells
  • Hepatitis infects liver cells
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4
Q

What is the outer covering made of

A
  1. Capsid ( protein )
  2. Envelope ( absent in some )
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5
Q

What is the inner core made of

A
  1. Nucleic Acid ( DNA / RNA )
  2. Proteins ( enzymes )
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6
Q

Explain viruses compared to prokaryote

A

Viruses :

  • No cellular structure
  • No metabolism
  • Unable to respond to stimuli
  • Multiplies inside host cell
  • Able to evolve

Prokaryote :

  • Consists of cell
  • Able to metabolize
  • Able to respond to stimuli
  • Multiplies independently
  • Able to evolve
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7
Q

Explain the bacteriophage cycle

A

1) Lytic cycle:
During the lytic cycle, the host cell breaks open (lysis); releases viral component – host cell dies

2) Lysogenic cycle:
There is no destruction of host DNA; The virus becomes part of host DNA – it forms prophage

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8
Q

Explain the lytic cycle fully

A
  1. Attachment - capsid combines with receptor
  2. Penetration - viral DNA enter host
  3. Biosynthesis - viral components are synthesised
  4. Maturation - assembly of viral components
  5. Release - new viruses leave host cell
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9
Q

Explain the Lysogenic cycle fully

A
  1. Integration - viral DNA is integrated into bacterial DNA andd then is passed on when bacteria reproduce
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10
Q

Explain animal viral reproduction - HIV in detail

A
  1. Attachment and penetration :
    • Virus binds receptors on cell membrane and enters cell. Viral protein coat is removed
    • Reverse transcriptase transcribes viral DNA to double stranded DNA
    • Double stranded DNA is incorporated into host cell genome
  2. Synthesis :
  • Viral genes are transcribed to RNA
  • Some RNA is packed into new viruses
  • Other RNA is translated into HIV proteins at ribosomes in cytoplasm.
  1. Assembly:
  • Protein coats surround viral RNA and enzymes . Envelope proteins migrate to cell membrane
  1. Release:
  • New viruses bud from host cell
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11
Q

What are the parts of the HIV lifecycle

A
  1. Attachment
  2. Fusion
  3. Uncoating
  4. Reverse transcription
  5. Replication
  6. Integration
  7. Biosynthesis
  8. Maturation
  9. Release
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12
Q

Explain Avian Influenza fully

A
  • Wild birds are normally carriers
  • Contagious when transmitted to domestic poultry

There are two forms:

  1. Low pathogenic form –birds display ruffled feathers; reduced egg production
  2. High pathogenic form – causes multiple internal organ failure – mortality 90-100% in 2 days
  • Human infections since 1997 –is caused by contact with diseased birds or contaminated surfaces
  • Normally single infections
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13
Q

Explain viriods and prions

A
  1. Are naked RNA strands that cause crop diseases
  2. Misshaped protein molecules and it causes BSE (mad cow disease), Creutzfeldt-Jakob disease
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14
Q

List the virus and what it causes

A
  • Herpes, hepatitis, adenovirus (HVP in cervical cancer; others cause colds & sore throats)
  • Varicella zoster –causes small pox
  • Paramyxovirus – cause measles and mumps
  • Orthomyxovirus – influenza
  • N1H1 – swine flu
  • Monkey pox-infectious disease caused by the monkeypox virus. Symptoms: painful rash, enlarged lymph nodes and fever
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15
Q

Explain congo fever

A

Congo Crimean haemorrhagic fever – caused by a RNA based Nairovirus complex

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16
Q

Explain Marburg haemorrhagic fever

A

One of the most virulent pathogens of humans - > 80% mortality in Angola in 2004

17
Q

Explain Bunyaviridae

A

Isolated from cattle, sheep, goats, hares and hedgehogs

18
Q

Explain Ebola virus

A
  • African haemorrhagic fever)
  • 4 distinct subtypes , 3 affect humans
    causing fatalities 50-90% of cases – mostly in central Africa since 1976 in Congo
  • In 2014: June/July > 759 cases with > 460 fatalities. Where? Guinea, Liberia & Sierra Leone,
19
Q

What domain do prokaryota consist of

A

Bacteria
Archea

20
Q

What are the phylums of prokaryota

A
  • Proteobacteria
  • Cyanobacteria
  • Spirochaetes
  • Firmicutes
  • Actinobacteria
  • Chlamydiae
21
Q

Explain bacteria fully

A
  • Characteristics of Bacteria :
  1. They are Prokaryotic
  2. Reproduce asexually
  • They are Metabolically diverse :
  1. Heterotrophic: Ingests biomass as energy source
  2. Autotrophic: Produces its own energy
    • Chemosynthesis (Chemical) or photosynthesis (Light)
  • The motile forms move by flagella (eg tail)
  • Various shapes identified:
  1. Bacillus - rod
  2. Spirillum - spiral or helical
  3. Cocci - round or spherical - own diversity

Clusters – staphylococci
Chains – streptococci
Short rods – coccobacillus
Long filament - fusiform

22
Q

Similarities between bacteria and archea

A
  • Both are Prokaryotic cells-no nucleus or membrane bound organelles
  • They have circular chromosomes
  • Predominantly unicellular
  • Some can fix nitrogen and grow at temperatures above 80 degrees
23
Q

What are the 3 types of archea

A
  1. Phylum: Crenarchaeota
  2. Phylum: Euryarchaeota
  3. Phylum: Korarchaeota
24
Q

Expalin phylum : crenarchaeota of archea

A

Ability to withstand extremes in temperature and acidity
Phylum: Euryarchaeota – methane-producers and high saline-tolerant taxa- they are referred to as methanogens are methane producers and halophiles live in high salt concentrations
Phylum: Korarchaeota – lesser known archaea, found in hot springs or deep ocean floors
Main types divided into sub-types- thermoacidophiles

25
Q

Expalin phylum : Euryarchaeota of archea

A

Methane-producers and high saline-tolerant taxa- they are referred to as methanogens are methane producers and halophiles live in high salt concentrations

26
Q

Expalin phylum : Korarchaeota of archea

A

Lesser known archaea, found in hot springs or deep ocean floors

Main types divided into sub-types- thermoacidophiles

27
Q

Explain domain Archae fully

A
  • Able to withstand extreme conditions
  • They possess unique lipids in plasma membrane
  • Lipids: glycerol + hydrocarbons
  • They have no peptidoglycan – they have polysaccharides and proteins instead.
  • No photosynthesis
  • No parasites – some mutualists, commensalists
  • Archaea are biochemically different from Bacteria and Eukaryadifferent
  • Archaea rRNA is from Bacteria rRNA
  • Archaea ribosomal proteins & transcription is similar to Eukarya
28
Q

Explain cynobacteria fully

A
  • They are Gram negative
  • They are able to Photosynthesize
  • Large organisms: They are unicellular/colonial/ filamentous
  • Non-motile
  • Thick-walled cell – with no nucleus
  • They are nitrogen fixing organisms
  • Cyanobacterium + fungus = lichen
  • Cyanobacteria form symbiotic relationships with liverworts, ferns, corals
  • They may cause eutrophication
29
Q

Explain bacteria fully

A
  • Cell wall contains peptidoglycans
  • Gram-stain procedures distinguishes bacteria on the basis of cell wall structure
  • Gram-positive: thick peptidoglycan cell wall surrounded by outer membrane. After staining procedure cells appear purple.
  • Gram-negative: thin layer of peptidoglycan cell wall surrounded by outer membrane. Cells appear pink after staining procedure
30
Q

Explain the reproduction and nutrition of bacteria

A
  1. Reproduction :
  • Asexual by binary fission
  • Transformation – acquisition of free strands of DNA (E.g. Plasmids)
  • Conjugation-transfer of genetic material
  • Endospore formation (survival strategy) –seen bacteria such as botulism, anthrax
  1. Nutrition
  • Obligate anaerobes (bound by one mode) - O2 absent
  • Facultative anaerobes (more than one mode: can live in the presence or absence of oxygen)
  • Photoautotrophs – produces O2 or S2
  • Chemoautotrophs: CO2 + 2H2S (CH2O)n + 2S
    or CO2 + H2O (CH2O)n + O2 or nitrate and nitrite formation
  • Heterotrophs: get organic material from the environment.

Life Science 142 (24 decks)

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