Schematic diagram of bacterial protein synthesis. …

Blood is an amazing and vitally important part of the body,because it contains many finely-tuned chemical systems that allowit to maintain the chemical environment needed for the body'smetabolism. One of the most important functions of blood isdelivering O₂ to all parts of the body by thehemoglobin protein. O₂ is carried in the hemoglobinprotein by the heme group. The heme group (a component of thehemoglobin protein) is a metal complex, with iron as the centralmetal atom, that can bind or release molecular oxygen. Both thehemoglobin protein and the heme group undergo conformationalchanges upon oxygenation and deoxygenation. When one heme groupbecomes oxygenated, the shape of hemoglobin changes in such a wayas to make it easier for the other three heme groups in theprotein to become oxygenated, as well. This feature helps theprotein to pick up oxygen more efficiently as the blood travelsthrough the lungs. Hemoglobin also enables the body to eliminateCO₂, which is generated as a waste product, via gasexchange in the blood (CO₂ exchanged for O₂in the lungs, and O₂ exchanged for CO₂ inthe muscles). The species generated as waste by theoxygen-consuming cells actually help to promote the release of O₂from hemoglobin when it is most needed by the cells. Hence,hemoglobin is a beautiful example of the finely tuned chemicalsystems that enable the blood to distribute necessary moleculesto cells throughout the body, and remove waste products fromthose cells.

Each subunit in Figure 2 contains regions with a coiled shape;many of the amino acids that make up the polypeptide chaininteract to form this particular structure, called an alphahelix. In an alpha helix (Figure 3), each amino acid is"hydrogen-bonded" to the amino acid that is fourresidues ahead of it in the chain. In hemoglobin, thehydrogen-bonding interaction occurs between the H of an -NH groupand the O of a -CO group of the polypeptide backbone chain; theamino-acid side chains extend outward from the backbone of thehelix. Approximately 75% of the amino-acid composition ofhemoglobin adopts an alpha-helical structure. Another commonstructural motif is the beta-pleated sheet, in which amino acidsline up in straight parallel rows.

The secretory pathway of protein synthesis and sorting

The construction of the proteins is carried out on the of the host . There are free floating ribosomes where proteins are built for functions in the cytoplasm. Those proteins which are to be used as part of the cell membrane or transported outside the cell are manufactured on ribosomes which are attached to the .

plays a huge role in protein synthesis and translation. Its job is to translate the message within the nucleotide sequence of mRNA to a specific sequence. These sequences are joined together to form a protein. Transfer RNA is shaped like a clover leaf with three loops. It contains an amino acid attachment site on one end and a special section in the middle loop called the anticodon site. The anticodon recognizes a specific area on a mRNA called a .

The following is a brief overview of protein synthesis

The words of the
genetic code are telling the cell which amino acid comes next in the sequence of particular amino acids
that make up a specific protein.

You will remember that messenger RNA contains a sequence of bases which, read three at a time, code for the amino acids used to make protein chains. Each of the sets of three bases is known as a . The table below repeats one from the previous page:

This diagram comes from Wikipedia

In the body, the iron in the heme is coordinated to the fournitrogen atoms of the porphyrin and also to a nitrogen atom froma histidine residue (one of the amino-acid residues inhemoglobin) of the hemoglobin protein (see Figure 4). The sixthposition (coordination site) around the iron of the heme isoccupied by O₂ when the hemoglobin protein isoxygenated.

questions on protein synthesis.

This is a molecular model of the alpha-helix structure in a subunit of hemoglobin. The blue strands are a ribbon representation to emphasize the helical structure. The green dotted lines show the hydrogen bonding between the -NH and -CO functional groups.

SparkNotes: SAT Subject Test: Biology: Protein Synthesis

To understand the oxygen-binding properties of hemoglobin, wewill focus briefly on the structure of the protein and the metalcomplexes embedded in it.

Protein biosynthesis - Wikipedia

Note: The coordinates for the hemoglobin protein (in this and subsequent molecular representations of all or part of the protein) were determined using x-ray crystallography, and the image was rendered using SwissPDB Viewer and POV-Ray (see ).

Translation or Protein Synthesis - HyperPhysics Concepts

On the right is a schematic diagram showing representations of electron-density clouds of the oxygenated heme group (pink), the attached histidine residue (light blue), and the attached oxygen molecule (gray). The oxygenated heme assumes a planar configuration, and the central iron atom occupies a space in the plane of the heme group (depicted by a straight red line).

09/01/2018 · Translation or Protein Synthesis

Eventually, the ribosome will come to a stop codon. The three stop codons don't code for any amino acids, and so the process comes to a halt. The protein chain produced up to that point is then released from the ribosome, and then folds itself up into its secondary and tertiary structures.