Lecture 2 Flashcards
Give 3 common properties of all cells
Highly organised cytoplasmic membrane
Growth and reproduction
DNA is used as hereditary information except in RNA viruses
cellular metabolism
Redox reactions generate electrochemical gradients which are commonly used to make ATP
What are the 3 domains?
Archaea
Eukarya
Bacteria
In the 1920s Chatten made a key definition about intracellular structures what was it?
That bacteria do not have nuclei
Who discovered that eukaryotes = a true nucleus?
Stanier and van Niel in 1962
What were the 5 kingdoms?
Plants Fungi Animals Single cell eukaryotes Monera
Who devised the 5 kingdom system and when?
Whittaker in 1969
Who designed the 3 domain system?
Woese in 1985
How was the 3 domain system established?
Using gene sequencing on the 16S ribosomal RNA gene
What is the defining feature of a prokaryote?
They tend not to have membrane bounded organelles
What is the key definition of a eukaryote?
They have a true nucleus
What is endosymbiotic theory?
The theory that mitochondria and chloroplasts were originally bacteria in thier own right then were engulfed by phagocytosis, leading to their role in the eukaryotic cell.
How do prokaryotes and eukaryotes differ in the organisation of their DNA?
Eukaryotes have DNA-histone complexes
Prokaryotic DNA is tightly coiled with associated RNA and proteins to form a nucleiod
How does transcription and translation differ in prokaryotes and eukaryotes?
Prokaryotes have a sigma subunit of RNAP for recognition of promoters were as in eukaryotes the transcription factor and RNAP bind directly to the promoter sequences independently
In prokaryotes transcription and translation occur almost simultaneously
What is significant about Thiomargarita namibiensis?
It is 1 mm long
When was Gram staining invented?
1884
What is the process of Gram Staining?
- Heat fix to a glass slide
- Stain crystal violet
- Wash
- Potassium iodide added
- Ethanol rinse
- Countestain with safranin
What happens in the ethanol rinse step of Gram staining?
The Gram positive bacteria are unaffected however the Gram negative bacteria’s plasma membranes dissolve causing the purple stain to be washed away.
What is the purpose of safranin in Gram staining?
It is used so that the Gram negative bacteria is visible
What is peptidoglycan?
A linear polymer made of repeating saccharide units which are crosslinked by peptide bonds.
Which is more sensitive to penicillin Gram positive bacteria or Gram negative?
Gram positive as the penicillin works by preventing the peptide bonds forming across strand of peptidoglycan
