18

Do all bacterial cells have a double membrane? No. There are a number of bacterial membrane and cell wall structures. Some of them have a double membrane, some of them don't. In microbiology, we often make the initial distinction between two groups of bacteria based on whether or not they take up an iodine based stain called a Gram stain. Gram negative ...


17

Strictly speaking, all nucleated (eukaryotic) cells contain linear DNA. In addition to the nucleus, the mitochondria (which break down food molecules and create chemical energy) and chloroplasts (which facilitate photosynthesis) also have small stores of their own DNA and this DNA is circular. This adds weight to the hypothesis that these organelles were ...


13

Yes there are prokaryotes with linear chromosomes (especially archaea). Eukayotic chromosomes are almost always linear but this, study reports that yeasts with a loss of function mutation in the ATM homolog genes TEL1 and rad3, form circular chromosomes as a consequence of lack of telomeres. Upon prolonged culture these yeasts were found to undergo mitosis ...


9

In (very) short: enzymes are necessary for life. Cytoplasm is necessary for enzymes to function. Water is necessary for cytoplasm to exist. Cells have osmotic membranes. Given a cell in a solution (even a goopy one, like jam) with a very high concentration of sugar, water will move along a gradient of low to high sugar concentration, in other words, water ...


4

In short our environment always tries to maintain an equilibrium, a stable state. When microbes encounter a surrounding like a high concentrated sugar state or solution (hypertonic), water diffuses out of the permeable cellular membrane of the microbe to its outer environment with high sugar concentration causing dehydration of the microbe and it leads to ...


2

Animal cells Generally all (animal) cells have different shapes because they do different things. Each cell type has a specific role which it has to play in order to assist the body in working efficiently and functionally. Thus their shape supports them to carry out these roles effectively. Look at (animal cells): Neurones Photoreceptors Immune Cells ...


2

Short answer Wikipedia has unnecessarily made an already confusing situation much worse. Sda is its own protein, it is regulated by DnaA, and it prevents sporulation. Full answer I don't think your misunderstanding is based on the meaning of 'domain' - the definition you give sounds quite reasonable - but rather the use of the term domain with respect to ...


2

Unless the poster can cite more recent papers to support the assertion regarding a difference in rates of prokaryotic and eukaryotic protein synthesis, I would say that this is incorrect. Lacroute and Stent (1968) reported a rate of 15 amino acids per sec for β-galactosidase in Escherichia coli, whereas Knopf and Lamfrom (1965) reported a rate of 7 amino ...


2

There are lots of ways to distinguish between eukaryotes and prokaryotes, as listed by microbiologynotes.com: Difference: Eukaryotes: Prokaryotes: ------------------------------------------------------------------------------- Size > 5µm 1-2µm by 1-4µm Nucleus Nucleus ...


1

This sounds like a difference in perspective of when exactly cells "die". If you consider that, in a cell division, a mother cell "gives birth" to two daughter cells, you could argue that the mother cell has "died". It makes sense to think about cell division in this way because it puts both daughter cells in the same level, without one being "special" due ...


1

If you mean "why do we have mitochondria instead of our cells doing the work themselves" Then I can think of several answers. First, oxidative phosphorylation must take place within an organelle, and requires specialized cellular machinery to occur. So either a prokaryote can wait a couple million years to evolve these structures, or it can ask its friend ...


1

Alicyclobacilli are strictly aerobic and thus take up oxygen and secrete carbon dioxide, as opposed to the (facultative) anaerobic yeasts and bacilli that usually cause spoilage. So yes, alicyclobacilli produce CO2. But why doesn't the packaging swell? Compare the number of gas molecules in the simplest reactions for aerobic and anaerobic metabolism: ...


1

As far as I understand your question, the "development" of eukaryotic cells can be linked to the endosymbiotic theory Symbiogenesis. This diagram only depicts a possible trajectory of evolution which is still unknown. A cell that respired anaerobically took in a bacterium that respired aerobically, supplying both itself and the larger cell with energy in ...


1

Prokayotic cells use anaerobic respiration. Glycolysis is the only stage of cellular respiration that does not occur in mitochondria. The glycolysis process does not need oxygen and uses anaerobic respiration. The other stages require oxygen and use aerobic respiration.


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