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The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
In the first stage of sexual reproduction, meiosis, the number of chromosomes is reduced from a diploid number (2n) to a haploid number (n). During fertilisation, haploid gametes come together to form a diploid zygote, and the original number of chromosomes is restored.
Meaning: a prefix used to make words with a sense opposite to that of the root word; in this case, meaning "without" or "-less". This is usually used to describe organisms without a certain characteristic, as well as organisms in which that characteristic may not be immediately obvious.
It is helpful to be able to understand the source of scientific names. Although the Latin names do not always correspond to the current English common names, they are often related, and if their meanings are understood, they are easier to recall. The binomial name often reflects limited knowledge or hearsay about a species at the time it was named.
They tend to be unstable and to lose further chromosomes during subsequent mitotic divisions, until the 2n+1 and 2n-1 nuclei progressively revert to n. Consistent with this, in E. nidulans (where normally, n=8) nuclei have been found with 17 (2n+1), 16 (2n), 15 (2n–1), 12, 11, 10, and 9 chromosomes.
3' untranslated region (3'-UTR). Also three-prime untranslated region, 3' non-translated region (3'-NTR), and trailer sequence.. 3'-end. Also three-prime end.. One of two ends of a single linear strand of DNA or RNA, specifically the end at which the chain of nucleotides terminates at the third carbon atom in the furanose ring of deoxyribose or ribose (i.e. the terminus at which the 3' carbon ...