BRAINCAKEProkaryotic Cells
Revision notes for Prokaryotic Cells in Edexcel Biology B (8BI0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.
- Bacterial CellBacteria are prokaryotic cells.
- Pili and FlagellaMany bacteria have thin projections from their surface: pili and flagella.
- Cell Surface MembraneLike all cells, a bacterium has a cell surface membrane (plasma membrane).
- PlasmidsA plasmid is a small, circular loop of double-stranded DNA found in the cytoplasm of many bacteria, separate from the main bacterial chromosome in…
- NucleoidProkaryotic cells have no nucleus.
- 70S RibosomesRibosomes are the sites of protein synthesis (translation).
- Gram-StainingGram staining is a differential staining technique that divides bacteria into two groups according to the structure of their cell wall.
- AntibioticsAn antibiotic is a chemical that kills bacteria or stops them growing, without harming the cells of the host.
- Alternative Classification of BacteriaAs well as the Gram stain, bacteria can be classified by their shape and by their respiratory requirements.
- VirusesViruses are tiny infectious particles, usually between about 20 nm and 300 nm across, much smaller than bacteria.
- The Structure of VirusesAll viruses share the same basic plan: a core of nucleic acid protected by a protein coat.
- DNA VirusesViruses are classified mainly by the nucleic acid in their genome.
- RNA VirusesRNA viruses have a genome made of RNA rather than DNA.
- RNA RetrovirusesRetroviruses are a special group of RNA viruses.
- Viral ReproductionA virus has no ribosomes, no enzymes for respiration and no supply of ATP.
- Virus Life CycleAlthough viruses differ in detail, their replication inside a host cell follows the same general sequence of stages: 1.
- DNA Virus LatencyLatency is a state in which a virus is inside a host cell but is not replicating and is not making new virus particles.
- DNA Virus Lytic PathwayIn the lytic pathway, a virus replicates straight after infection and the host cell is destroyed.
- RNA Virus ReplicationRNA viruses face a problem that DNA viruses do not.
- Positive ssRNA VirusesIn positive-sense single-stranded RNA (+ssRNA) viruses, the genome has the same base sequence as mRNA.
- Negative ssRNA VirusesIn negative-sense single-stranded RNA (−ssRNA) viruses, the genome is complementary to mRNA.
- Retrovirus ReplicationRetroviruses such as HIV replicate by copying their RNA genome into DNA and inserting it into the host's DNA.
- Viruses and DiseaseViruses cause disease in several ways, and the symptoms of an infection come from a mix of damage done by the virus and the body's own response.
- The Spread of Viral DiseasesViral diseases spread when virus particles pass from an infected host to a new one.
- Treating Viral DiseasesViral diseases are much harder to treat than bacterial ones.
- Preventing Viral DiseasesBecause viral diseases are hard to treat, prevention is the most effective approach.
- VaccinationA vaccine contains antigens from a pathogen, given so that the body makes an immune response and memory cells without the person having the disease.
- Disease ControlDisease control means the measures a government or health service takes to reduce the spread of an infectious disease through a whole population…
- Drug DevelopmentDeveloping a new drug, such as an antiviral, takes 10 to 15 years and follows a strict series of stages designed to show that the drug is safe and…
- PandemicsDiseases are described by how widely they occur: • Endemic: always present at a steady level in a particular region, e.g. malaria in parts of…
- EthicsMany decisions about treating and controlling viral diseases raise ethical questions: questions about what is right, not just what works.
On the specification
- 2.1 Eukaryotic and prokaryotic cell structure and function
- 2.2 Viruses