Flashcards in Lectures 7-15, Jasna's part Deck (22):
What are the components cytoplasmic membrane and cell wall of bacteria?
The bacteria cytoplasmic membrane is made up of phospholipid bilayers and can form bilayers.
The bacteria cell wall is made of murein and most bacteria contain a cell wall
What are the components cytoplasmic membrane and cell wall of archaea?
The archaea cytoplasmic membrane is made up of alkylglycerinethers and can form monolayers.
The archaea cell wall is made of pseudomurein, polysaccharides and proteins
Explain the simple transport system
The simple transport system is driven by the energy in the proton motive force, it is a symport transport as the transported substance enters the cell with the proton
Explain the group translocation system
Group translocation is the chemical modification of a substance because the transported substance becomes phosphorylated as it enters the cell. It is driven by phosphoenolpyruvate
Explain the ABC transporter
Transported substance binds to a periplasmic binding protein and enters the cell with the help of ATP
Explain the major differences between gram positive and gram negative bacteria
In gram positive bacteria there is no outer membrane, it has a thick peptidoglycan wall, technoic acid is present and it has a low lipid content. Gram staining binds and turns positive bacteria purple
In gram negative bacteria there is an outer membrane rich with lipids, there is a thin peptidoglycan wall and no technoic acid is present. Gram staining doesnt bind to negative bacteria and turns it pink
Name two surface appendages of bacterial cells and their functions
Flagella are surface appendages that assist in swimming motility of bacteria, allowing them to move
Pili are surface appendages that attach a bacterial cell to specific surfaces or to other cells. It can also attach two bacterial cells
Describe two different modes of bacteria motility
Swimming - Flagella (helical filaments) have a rotary motor which can turn clockwise and anti-clockwise. The motor is powered by the proton motive force
Gliding - Is a flagella independent motility, it is slower than swimming. It occurs along the long axis of cell and requires surface contact. Gliding specific proteins assist this movement.
What are the characteristics of endospores? Which bacteria can differentiate intoendospores?
Endospores are highly differentiated cells resistant to harsh environments like heat, chemicals and radiation. Endospores are in the dormant stage of the bacterial cycle and are present only in some gram positive bacteria. Bacteria differentiate into endospores to ensure survival of bacterium through environmental stress
What is the difference between chemoorganotrophy and chemolithotrophy?
Chemoorganotrophy is when cells use organic chemicals in its metabolic pathway to make ATP. Fermetation only uses chemoorganotrophy to use organic electron donors.
Chemolithotrophy is when cells use inorganic chemicals in its metabolic pathway to make ATP
What is chemolithoautotrophy?
When an organism obtains energy from the oxidation of inorganic compounds (like ATP) and uses CO2 as its sole source of carbon for growth.
Explain the principle transcriptional regulation by attenuation
Attenuation is transcriptional regulation by premature termination of mRNA synthesis. Exerted after initiation of transcription but before its completion. A hairpin (mRNA stem-loop) is made which terminates transcription. The leader peptide is also a determining factor of attenuation
What is a silent, missense and nonsense mutation
Silent mutation is where the mutation does not affect the amino acid sequence and a normal protein is made.
Missense mutation is where the mutation changes the amino acid made, therefore the polypeptide is changed and the protein is faulty.
Nonsense mutation is where the codon becomes a stop codon and the polypeptide is incomplete.
Would you be able to identify a periplasmic protein based on its amino acid sequence?
Yes, perisplasmic proteins contain a signal sequence, which can be easily identified in the primary amino acid sequence. Perisplasmic proteins can differ from integral membrane proteins like lipoproteins because lipoproteins have membrane anchors and perisplasmic dont.
Explain the role of phosphorylation in the two-component signal transduction system in bacteria
The sensor kinase detects the environmental signal and autophosphorylates which activates the sensor kinase. The SK then phosphorylates the response regulator. The phosphorylated response regulater binds to the operator and blocks/stimulates transcription.
Explain the difference between anaerobic and aerobic respiration
Aerobic respiration performed by eukaryotes uses oxygen as electron acceptor and the amount of energy released is high. Aerobic respiration produces water and CO2 as by-products and glucose is completely oxidised.
Anaerobic respiration is respiration without oxygen, using NO3, SO4 and organic electron acceptors in the ETC. Amount of energy yield is low and produces lactic acid as by product. Performed by eukaryotes and prokaryotes and glucose isn't completely oxidised.
What is a bacteriorodopsin?
Bacteriodopsin is a light powered protein pump in halophillic archaea. They absorb light energy in the bacteriodopsin to make ATP. The bacteriodopsin uses the light energy to pump protons against the gradient across the membrane.
What is the role of fermentation from pyruvate to lactate in anaerobic bacteria?
Fermentation from pyruvate to lactate is stage III of the Embden-Meyerhof pathway. In the absence of respiration, NADH that came from stage II is oxidised in stage III to NAD+ to be used in stage II
Genome sequencing has revolutionized discovery of vaccine targets in bacteria. Explain this statement
Genome sequencing allows identification of surface proteins using computer analysis (bioinformatics) These proteins can be purified and can be analysed to identify which proteins reacted strongly and have a strong immune response. These proteins are conserved for clinical trials.
Difference between fermentation and respiration
Fermentation occurs without oxygen and partially degrades sugars to release energy. It is a catabolic process that makes limited ATP without ETC and produces byproducts like ethanol.
Anaerobic respiration is the use of any molecule apart from oxygen in ETC.
Describe the amino acid sequences that mediate correct periplasmic proteins
The signal sequence is hydrophobic. The protein contains a N-terminal called the signal sequence. The signal sequence prompts the protein where to go. In periplasmic proteins, a protease called signal peptidase cuts the signal sequence away from rest of protein and the protein is released into periplasm.