Prokaryotic and eukaryotic cells

Without consulting chapter figures, sketch the characteristic prokaryotic and eukaryotic cell types and label their pertinent organelle and membrane systems. 

Table 1.1 The main features distinguishing prokaryotic and eukaryotic cells... 

The dihydrofolate reductase enzyme (DHFR) is involved in one-carbon metabolism and is required for the survival of prokaryotic and eukaryotic cells. The enzyme catalyzes the reduction of dihydrofolate to tetrahydrofolate, which is required for the biosynthesis of serine, methionine, purines, and thymidylate. The mouse dihydrofolate reductase (mDHFR) is a small (21 kD), monomeric enzyme that is highly homologous to the E. coli enzyme (29% identify) (Pelletier et al., 1998). The three-dimensional structure of DHFR indicates that it is comprised of three structural fragments F[l], F[2] andF[3] (Gegg etal., 1997). 

Fig. 7.1. (a) A schematic diagram of a eukaryote, (b) Typical prokaryotic and eukaryotic cells,... 

Merten, O.-W., Mattanovich, D., Lang, C., Larsson, G., Neubauer, P., Porro, D., Postma, P., Teixeirade Mattos, J., and Cole, J. A. Recombinant Protein Production with Prokaryotic and Eukaryotic Cells A Comparative View on Host Physiology Kluwer. 

Technically, in vitro transcription is achieved from standard expression plasmids typically carrying SP6 or T7 promoters using marketed kits. Translation into the polypeptide may be either coupled directly to the transcription (in vitro TnT) or require isolation of the RNA. Again, a large number of suitable prokaryotic and eukaryotic cell extracts as well as complementation factors are freely available. 

Bacterial protein biosynthesis is a cascade of events which manufacture chains of amino acids before they are folded into specific structures to carry out various biological functions. Protein biosynthesis is absolutely essential for the survival of prokaryotic and eukaryotic cells. Ribosomes, macromolecular complexes made up of proteins and RNA, participate in decoding the genetic message to synthesize both essential and nonessential proteins to carry out cellular functions. 

In this chapter, we review the current knowledge of the structure, assembly and function of the 20S proteasome and its regulators in prokaryotic and eukaryotic cells. 

Blackmore CG, McNaughton PA, and van Veen HW. Multidrug transporters in prokaryotic and eukaryotic cells physiological functions and transport mechanisms. Mol Membr Biol 2001 18 97-103. 

The topoisomerases enzymes are essential in prokaryotic and eukaryotic cell visibility. Most quinolones have a characteristic core planar heterocyclic nucleus. 

Membranes play essential roies in the functions of both prokaryotic and eukaryotic cells. There is no unicellular or multicellular form of life that does not depend on one or more functional membranes. A number of viruses, the enveloped viruses, also have membranes. Cellular membranes are either known or suspected to be involved in numerous cellular functions, including the maintenance of permeability barriers, transmembrane potentials, active as well as specific passive transport across the membranes, hornione-receptor and transmitter-receptor responses, mitogenesis, and cell-cell recognition. The amount of descriptive material that might be included under the title of biological membranes is encyclopedic. The amount of material that relates or seeks to relate structure and function is less, but still large. For introductory references see Refs. 53, 38, 12, 47, 34, 13. Any survey of this field in the space and time available here is clearly out of the question. For the purposes of the present paper we have selected a rather narrow, specific topic, namely, the lateral diffusion of molecules in the plane of biological mem-branes.38,12,43,34 We consider this topic from the points of view of physical chemistry and immunochemistry. 

Posttranscriptional processing is not limited to mRNA. Ribosomal RNAs of both prokaryotic and eukaryotic cells are made from longer precursors called preribosomal RNAs, or pre-rRNAs, synthesized by Pol I. In bacteria, 16S, 23S, and 5S rRNAs (and some tRNAs, although most tRNAs are encoded elsewhere) arise from a single 30S RNA precursor of about 6,500 nucleotides. RNA at both ends of the 30S precursor and segments between the rRNAs are removed during processing (Fig. 26-21). 

Ribosomal RNAs of both prokaryotic and eukaryotic cells are synthesized from long precursor molecules called preribosomal RNAs. The 23S, 16S, and 5S ribosomal RNAs of prokaryotes are produced from a single RNA precursor molecule, as are the 28S, 18S, and 5.8S rRNAs of eukaryotes (Figure 30.15). [Note Eukaryotic 5S rRNA is synthesized by RNA polymerase III and modified sepa-j rately.] The preribosomal RNAs are cleaved by ribonucleases to yield intermediate-sized pieces of rRNA, which are further "trimmed"... 

Describe the principal structural or organizational differences between prokaryotic and eukaryotic cells. 

Table 5.4. Features Distinguishing Prokaryotic and Eukaryotic Cells...

Transfer RNAs are processed from larger precursors in both prokaryotic and eukaryotic cells. This processing involves two types of nucleases Endoribonucleases, that cleave at internal sites in the RNA, and exonucleases, that remove nucleotides from the ends of the chains. 

On the basis of what you know about genes in prokaryotic and eukaryotic cells, define a gene. Make sure that your definition is brief and concise. Does your definition have any limitations or problems ... 

Potentized homeopathic drugs are capable of producing effects on both prokaryotic and eukaryotic cells. Prokaryotic cells are usually smaller in size (1 - 10 pm) than eukaryotic ones (5 - 100 pm). Membrane-bound organelles like mitochondria, endoplasmic reticulum, Golgi complexes etc. are present in eukaryotic cells but absent in prokaryotic ones. While eukaryotic cells have nucleus containing DNA with histone and non-histone proteins in chromosoms, prokaryotic cells have no nucleus and their DNA with non-histone proteins lies in nucleoid without any membranous envelope. However, both types of cells are covered by plasma membrane with some common features. 

Most differences in elongation result from the fact that the eukaryotic cell has different compartments, which are separated by membranes. Both prokaryotic and eukaryotic cells, of course, have an inside and outside however, eukaryotic proteins can be targeted to, for example, the mitochondrion. 

Vellai T, Vida G (1999) The origin of eukaryotes the difference between prokaryotic and eukaryotic cells. Proc R Soc Lond B Biol Sci 266 1571-1577 Vellai T, Takacs K, Vida G (1998) A new aspect to the origin and evolution of eukaryotes. J Mol... 

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