Nucleus of living cell

Yum K, Na S, Xiang Y, Wang N, Yu MF (2009) Mechanochemical delivery and dynamic tracking of fluorescent quantum dots in the cytoplasm and nucleus of living cells. Nano Lett 9 2193-2198... 

R351 W. J. Gehring, How Do Hox Transcription Factors Find Their Target Genes in the Nucleus of Living Cells , Biol. Atgourd hui, 2011, 205, 75. 

The prudent choice of appropriate side chain protecting groups for Lys and Arg did pose a particular problem in combination with the chemical stability of the metallocenes and available resins and linkers. In order to study cellular uptake and localization in the nucleus of living cells, derivatives of 36 and 37 with an additional fluorescent dye attached to the peptide were also prepared. Cellular uptake and localization of these conjugates was then followed in different cell lines by fluorescence microscopy. This is the first study of sub-cellular localization of organometaiiic peptide derivatives with non-radioactive metals (see also Section 5.5.3.2 below for an example ofa dual radiometal- and fluorescent-labeled peptide). 

Zhang H, Wang Q, Kajino K, Greene MI. (2000) VCP, a weak ATPase involved in multiple cellular events, interacts physically with BRCAl in the nucleus of living cells. DNA Cell Biol 19(5), 253-263. 

Biju, V, Muraleedharan, D., Nakayama, K, Shinohara, Y., Itoh, T., Baba, Y. and Ishikawa, M. (2007) Quantum dot-insect neuropeptide conjugates for fluorescence imaging, transfection, and nucleus targeting of living cells. Langmuir, 23, 10254-10261. 

FIGURE 1-3 The universal features of living cells. All cells have a nucleus or nucleoid, a plasma membrane, and cytoplasm. The cytosol is defined as that portion of the cytoplasm that remains in the supernatant after centrifugation of a cell extract at 150,000 g for 1 hour. 

The living world contains two fundamentally different type of cells the eukaryotes, in which a second membrane, different from the cell membrane, encloses the nucleus of the cell and the prokaryotes, which do not have this feature.1 Prokaryotic organisms are invariably unicellular and are, in many ways, much simpler than eukaryotes. 

In the nucleus of a cell, DNA comprises a code carrying all the instructions that the cell needs to live. In the nuclei of eukaryotic cells, the DNA molecules, coiled like microscopic spaghetti, form compact, bulky structures called chromosomes. Under the light microscope, chromosomes have the appearance of solid, flexible rods. Early microscopists applied the word chromosome, meaning colored body, to structures that took up basic red or purple dyes in the nucleus of a dividing cell. Humans have 23 chromosomes, but other organisms, like the fruit fly, have as few as four, and others, such as the dog, as many as 39. 

Some RNA aptamers that were isolated in vitro have also been expressed in vivo to study their biological function within the context of a living pro- or eucaryotic cell. Among them is an aptamer which binds to the reverse transcriptase (Rev) protein of the human immunodeficiency virus type 1 (HIV-1) [42,43,70],This anti-HIV-l-Rev aptamer was cloned into an expression cassette based on the U6 snRNA promoter, in which aptamer transcripts are protected against nuclease degradation to some extent. Transient expression in the nucleus of cultured cells led to 107-109 full-length aptamer transcripts per cell. When anti-HIV-l-Rev aptamer-expressing cells were co-transfected with the HIV-1 provirus, viral replication was efficiently inhibited in these cells, as shown by an assay in which the production of HIV-1 reverse transcriptase was measured [71],... 

Nucleic acids are found in all living cells, with the exception of the red blood cells of mammals. DNA occurs primarily in the nucleus of the cell, and RNA is found mainly in the cytoplasm, outside the nucleus. There are three major types of RNA, each with its own characteristic size, base composition, and function in protein synthesis (as described later in this section) messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). 

Viruses are much smaller than bacteria and have no metabolism of their own. They are composed of DNA or RNA, and they reproduce by entering the nucleus of a cell and causing the cell to manufacture more virus. This process eventually kills the cell. Viruses can infect plants, animals, humans, and even bacteria. Because viruses reproduce only inside living cells, they are difficult and expensive to culture. 

You have seen that proteins, as enzymes, control the chemical reactions in living systems, but what controls the synthesis of these proteins The DNA molecules in the nucleus of a cell contain plans for making protein molecules. Each segment of DNA that contains information to make a given protein is called a gene. When a cell needs to make a specific protein molecule, the appropriate DNA molecule makes a photocopy of the protein plan in the form of a complementary messenger RNA molecule. This process is called transcription. 

We have seen that the amino acid sequence in a protein determines that protein s structure and function. If the amino acid sequence is incorrect, the protein is unlikely to function properly. How do cells in living organisms synthesize the many thousands of different required proteins, each with the correct amino acid sequence The answer lies in nucleic acids, molecules that serve as blueprints for protein synthesis. Nucleic acids employ a chemical code to specify the correct amino acid sequences for proteins. Nucleic acids are broadly divided into two types deoxyribonucleic acid, or DNA, which exists primarily in the nucleus of the cell and ribonucleic acid, or RNA, which exists throughout the cell. 

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