Molecular model, Molecular model of a ribosome, Molecular model of a bacterial ribosome showing the RNA and protein components in the form of ribbon models. In the large (50S) subunit the 23S RNA is shown in cyan, the 5S RNA in green and the associated proteins in purple. In the small (30S) subunit the 16S RNA is shown in yellow and the proteins in orange.
The three solid elements in the centre of the ribosome, coloured green, red and reddish brown are the transfer RNAs (tRNAs) in the A, P and E sites respectively. The anticodon loops of the tRNAs are buried in a cleft in the small subunit where they interact with mRNA.
The other ends of the tRNA, which carry the peptide and amino acid, are buried in the peptidyl transferase centre of the large subunit, where peptide bond formation occurs.
Ribosomes (from ribonucleic acid and “Greek: soma meaning body) are complexes of RNA and protein that are found in all cells. Prokaryotic ribosomes from archaea and bacteria are smaller than most of the ribosomes from eukaryotes such as plants and animals.
However, the ribosomes in the mitochondrion of eukaryotic cells resemble those in bacteria, reflecting the evolutionary origin of this organelle.
The function of ribosomes is the assembly of proteins, in a process called translation. Ribosomes do this by catalysing the assembly of individual amino acids into polypeptide chains; this involves binding a messenger RNA and then using this as a template to join together the correct sequence of amino acids.
This reaction uses adapters called transfer RNA molecules, which read the sequence of the messenger RNA and are attached to the amino acids.
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Colon cancer cells, Cultured colon cancer cells showing the nuclei stained with DAPI in blue, the actin cytoskeleton in red and plectin (isoform 1k) in green. Confocal micrograph. Plectin interacts with cytoskeletal actin, affecting its behaviour. This subtype of plectin promotes the migration of cells and may affect metastasis.
Colorectal cancer, also called colon cancer or large bowel cancer, includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of cancer-related death in the Western world. Colorectal cancer causes 655,000 deaths worldwide per year, including about 16,000 in the UK, where it is the second most common site (after lung) to cause cancer death.
Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. The majority of the time, the diagnosis of localized colon cancer is through colonoscopy. Therapy is usually through surgery, which in many cases is followed by chemotherapy.
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Breast cancer cells, Scanning electron micrograph, Colour-enhanced image of a breast cancer cell.
Scanning electron micrograph. A cluster of breast cancer cells showing visual evidence of programmed cell death (apoptosis) in yellow. There are breast cancer cells photos.
Breast cancer is a cancer that starts in the cells of the breast. Worldwide, breast cancer is the second most common type of cancer after lung cancer (10.4% of all cancer incidence, both sexes counted) and the fifth most common cause of cancer death. Worldwide, breast cancer is by far the most common cancer amongst women, with an incidence rate more than twice that of colorectal cancer and cervical cancer and about three times that of lung cancer.
However breast cancer mortality worldwide is just 25% greater than that of lung cancer in women. In 2005, breast cancer caused 502,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths). The number of cases worldwide has significantly increased since the 1970s, a phenomenon partly blamed on modern lifestyles in the Western world.
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Scanning electron micrograph. Red blood cells clearly showing their biconcave disc shape.
Red blood cells are the most common type of blood cell and the vertebrate body’s principal means of delivering oxygen from the lungs or gills to body tissues via the blood.
Human red blood cells
Red blood cells are also known as RBCs, haematids or erythrocytes (from Greek erythros for “red” and kytos for “hollow”, with cyte nowadays translated as “cell”).
A schistocyte is a red blood cell undergoing cell fragmentation, or a fragmented part of a red blood cell.
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