Unit A 死记烂背 Flashcards
A1.1
7 Properties of Water which support life
Cohesion
Adhesion
High Specific Heat Capacity
Polar Solvent Medium
Viscosity
Buoyancy
Thermal Conductivity
A1.2
Evidence of Complementary Base Pairing in DNA
Erwin Chargaff (1949)
* Chromatography
* No. Adenine = Thymine, No. Cytosine = Guanine
A1.2
Evidence of DNA as a Double Helix
Watson and Crick (1953)
- Modelling after Roselyn Franklin’s findings
A1.2
Evidence that DNA is the genetic material
Hershey and Chase (1953)
- 144 bacteriophages, 35-S capsid or 32-P DNA
- infection and centrifugation
- 32-P and bacteria in pellet, 35-S and viruses in supernatant
A2.1
Evidence of Spontaneous Generation of Carbon Compounds
Miller and Urey (1953)
- ammonia, methane, hydrogen, water vapour
- electrodes
- produces pink/red mixture in 7 days
A2.1
4 Properties of Early Earth
- Low oxygen due to reaction with iron
- High radiation due to low ozone
- High methane and carbon dioxide due to tectonic activity
- Electrical storms
A2.1
4 Requirements for Cell Formation
- Metabolism and catalysis
- Self-assembly of essential molecules
- Compartmentalization in membranes
- Self-replication
A2.2
3 Principles of Cell Theory
- Living organisms are made up of cells.
- Cells are the basic structural/organizational unit of all organisms.
- All cells come from pre-existing cells.
A2.2
4 Exceptions to Cell Theory
- Skeletal Muscle - multinucleate
- Aseptate Fungal Hyphae - absence of septa creates coenocyte
- Phloem Sieve Tube Elements - sieve like septa
- Erythrocytes - anucleate
A2.2
3 Properties of Optical Microscopes
- 200 nm resolution
- natural or stained colour
- examine living or dead specimens
A2.2
3 Properties of Transmission Electron Microscopes
- 1 nm resolution
- monochromatic
- examine dead specimens only
A2.2
4 Pieces of Evidence for Endosymbiosis
- Double membrane
- Own genetic information, DNA transcription and protein synthesis
- 70S ribosomes
- Reproduces/replicates independent of host cells
A2.2
3 Advantages of Multicellularity
- more efficient metabolism
- more complex functions possible (emergent properties)
- death of one cell does not significantly interrupt organism survival
A2.3
4 Examples of Viruses
Parvovirus - single-strand adenovirus
COVID-19 - single-strand retrovirus
bacteriophage lambda - double-strand adenovirus
rotaviruses - doubel-strand retrovirus
A2.3
5 Steps of Lytic Cycle
- Attachment of bacteriophage
- Injection of phage proteins and DNA
- Biosynthesis of phage proteins and DNA to form virus DNA and capsids
- Maturation proteins cause cell lysis
- 100 viral copies released
A2.3
5 Steps of Lysogenic Cycle
- Attachment of bacteriophage
- Injection of phage proteins and DNA
- Integration of viral DNA into host DNA
- Cell replication replicates viral and host DNA
- Daughter cells contain viral genome
A2.3
2 Ways Viruses enter Cells
- Receptor Mediated Fusion - Fusion at cell membrane at neutral pH
- Endosome - Endocytosis and fusion at low pH
A2.3
Size of Viruses, Bacteria, and Eukaryotic Cells
- Viruses - 20 - 500 nm
- Bacteria - 1 - 10 μm
- Eukaryotic Cells - 10 - 100 μm
A2.3
2 Explanations for Origin of Viruses
- Progressive Hypothesis - viruses form from modified cell components
- Regressive Hypothesis - viruses form from loss of cell components
A2.3
4 Reasons for Rapid Influenza Mutation Rate
- RNA replicase has no proofread mechanism
- High recombination rate with 8 RNA
- Zoonotic infection produces new strains
- Haemaglutinin and neuraminidase bind and release from host cells, and are prone to recombination
A2.3
2 Reasons for Rapid HIV Mutation Rate
- Reverse transcriptase has no proofread mechanism
- Recombination
A3
5 Steps of DNA Hybridisation for Differentiating Species
- Extract: cut genes using restrictive endonucleases
- Label using a radioactive or a fluorescent tag
- Heating: break hydrogen bonds between bases
- Cooling: reform double helixes, some helixes are hybrids
- Repetition: measure the degree to which the helixes attach, proportional to similarity of genes
A3
3 Types of Natural Selection
- Directional
- Stabilizing
- Disruptive
A4.2
4 Measures of Biodiversity
- Genetic Diversity
- Species Richness
- Species Evenness
- Ecosystem Diversity
A4.2
7 Methods to Identify Members of the Same Species
- Fertility of offspring
- Phylogeny
- DNA barcoding
- Proteome bank
- Immunological Comparisons
- Fossil records
- Gause’s Law
A4.2
4 Challenges to Identifying Species
- Poorly explored habitats (eg. deep sea, tropical forest soil)
- Mutualistic relationships
- Microorganisms
- Extinction rate
A4.2
5 Methods of Preserving Biodiversity
- In-Situ - conservation in natural habitat
- Ex-Situ - conservation outside natural habitat
- Captive Breeding - breeding and reintroduction
- Rewilding - restoring biotic conditions
- Reclamation - restoring abiotic conditions
A4.2
3 Categories of Ecologically Significant Species
Flagship Species - ambassador for conservation efforts
Keystone Species - important to ecosystem stability
Umbrella Species - protection of umbrella species habitats protects many other species
