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Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders typically inherited. [2] The most common type is known as sickle cell anemia. [2] It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. [2] This leads to a rigid, sickle -like shape under ...
Sickle cell trait causes a change in the haemoglobin molecule in the blood. Normally, red blood cells have a very flexible, biconcave shape that allows them to move through narrow capillaries ; however, when the modified haemoglobin S molecules are exposed to low amounts of oxygen, or crowd together due to dehydration, they can stick together ...
Genetics is the study of genes, genetic variation, and heredity in organisms. [1][2][3] It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically.
Anatomical terminology. [ edit on Wikidata] Gap junctions are membrane channels between adjacent cells that allow the direct exchange of cytoplasmic substances. [ 1 ] Substances exchanged include small molecules, substrates, and metabolites. [ 1 ] Gap junctions were first described as close appositions as other tight junctions, but following ...
A strict but broad definition is an absolute decrease in red blood cell mass, [59] however, a broader definition is a lowered ability of the blood to carry oxygen. [60] An operational definition is a decrease in whole-blood hemoglobin concentration of more than 2 standard deviations below the mean of an age- and sex-matched reference range. [61]
Immune system. The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinters, distinguishing them from the organism's own healthy tissue.
For other uses, see Mutation (disambiguation). Three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3). In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. [ 1 ] Viral genomes contain either DNA or RNA.
Apoptosis (from Ancient Greek: ἀπόπτωσις, romanized: apóptōsis, lit. 'falling off') is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. [1] Biochemical events lead to characteristic cell changes (morphology) and death. [2]