Cell Structure Flashcards
By looking inside a cell how could you tell if it was a prokaryote or a eukaryote?
Presence/absence of nucleus.
What important functions do the following play in cell: cytoplasmic membrane, ribosomes, cell wall?
Permeable barrier, translation of mRNA into protein and structural strength.
How are viruses like cells and in which major ways to they differ?
They both have genome but virus are not an open system, do not have metabolic capabilities, lack of chromosomes and cannot replicate unless it’s infecting a cell.
Differentiate between the nucleus and the nucleoid.
Nucleoid is only a mass within the prokaryotic cell due to chromosome aggregation. Nucleus is an specialized membrane that encloses eukaryotic genome.
What does it mean to say that a bacterial cell is haploid?
It has only one single copy of its genome.
How are the membrane lipids of Bacteria and Archaea similar and how do they differ?
They both have the same inner and outer construction but in Archaea the fatty acids are linked through ether bonds instead of ester bonds. Instead of real fatty acids they have a repetition of isoprene units and their membrane actually forms a monolayer.
List two reasons why cell cannot depend on diffusion as a means of acquiring nutrients.
It’s slow and by diffusion cell would never accumulate nutrients.
Why is physical damage to the cytoplasmic membrane such a critical issue for the cell?
Because cell membrane controls the uptake of solutes and water.
Contrast simple transported, phosphotransferase system and ABC transporters in terms of energy source, chemical alterations of the solute transported and number of proteins involved.
Simple transporters use proton motive force as energy source, do not alter the compound and involve one protein.
Phosphotransferase transporters use energy from PEP, phosphorylate their compounds and involve a group of enzymes.
ABC transporters hydrolysis ATP to get energy, do not alter the compound and it is bond to a periplasmic binding protein, which interacts with membrane transporter.
Which transport system is best suited for the transport of nutrients present at extremely low levels and why?
ABC system because periplasmic binding proteins have high affinity to their substrates.
Why is protein excretion important to cells?
Because they are involved in nutrient degradation, transport and uptake of substrates and pathogeny (toxins).
Why do bacterial cells need walls? Do all bacteria have cell walls?
Not all of them have cell walls. But it is a important for rigidity and also prevents osmotic lysis.
Why is peptidoglycan such a strong molecules?
Because it has many cross-links.
What does the enzyme lysozyme do?
It cleaves the beta-1,4-glycosidic bonds between N-acetyl-glucosamine and N-acetylmuranic acid.
What components constitute the outer membrane of gram-negative bacteria?
LPS, fatty acids and proteins.
