1 / 15

ukm.my/choong

http://www.ukm.my/choong. Chro mosome Structure. What is c hromoso me?. i) A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries genes and functions in the transmission of hereditary information.

roman
Télécharger la présentation

ukm.my/choong

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. http://www.ukm.my/choong

  2. Chromosome Structure

  3. What is chromosome?

  4. i) A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries genes and functions in the transmission of hereditary information. ii) A circular strand of DNA in bacteria (prokaryotic cells) that contains the hereditary information necessary for cell life. What is chromosome?

  5. chromosomes were first observed in plant cells by a Swiss botanist Karl Wilhelm von Nageli in 1842. • also discovered in Acaris worms by Belgian scientist Edouard van Beneden (1846-1910). • the chromosome behaviour (e.g. mitosis) in salamander was described by Germen cytologist Walther Flemming in 1882. The word of mitosis was only invented by Germen anatomist Heinrich von Waldeyer later (in 1888). History

  6. found in the nucleus of a cell. • consists of DNA and protein (histone etc.). • in linear arrangement. • ready to absorb dyes (it’s named after; in Greek: chroma is colour, soma is body). Characteristics of eukaryotic chromosome

  7. Centromere Electron micrograph of one of the human chromosomes

  8. Secondary constriction or NOR (nucleolar organizing region) Telomere Structure of chromosome Primary constriction or centromere Chromosome arm Telomere

  9. telomeres are end caps of chromosomes. It is important for chromosomes that not form a ring (e.g. plasmid). • telomeres are made up of both protein and DNA. • the sequence motif of telomeres, (TTAGGG)n, is highly conserved across species. Structure of Chromosome - Telomere

  10. Telomeric repeat organism TTAGGG TTAGGG TTAGGG TTAGGG TTAGGG GGGGTT GGGGTT GGGGTTTT GGGGTTTT AGGGTT(TC) TTTAGGG TTTTAGGG Homo sapien (man) Physarium (slime mould) Didymium (slime mould) Neurospora (filamentous fungi) Trypanosoma (protozoan) Tetrahymena (protozoan) Glaucoma (protozoan) Stylonichia (protozoan) Euplotes (protozoan) Plasmodium (protozoan) Arabidopsis (plant) Chlamydomonas (alga) Structure of Chromosome - Telomere

  11. the ends of chromosomes must terminate in some sort of functional cap to prevent shortening of the chromosome at each round of cell division. • when a chromosome breaks (losing telomeres), the ends may fuse resulting translocations or ring chromosomes (if both telomeres are lost from the same chromosome). • the DNA at the extreme ends of telomeres is not in the form of double helix but a single strand to form the hairpin structure for the integrity of telomere. • the enzyme responsible for replication of telomeres is telomerase. • broken chromosomes somehow reform (chromosome healing) telomere using telomerase. • in humans, it has been known that telomeres in germline cells are longer than those in somatic cells. Structure of Chromosome - Telomere

  12. the primary constriction of chromosomes. • characterized by particular repeat DNA sequences (satellite DNA; repeat size ranges from 5bp to 170bp) and also associated by specific proteins (e.g. CENP-A, CENP-B, CENP-C, CENP-D). • this is also the last point of separation of sister chromatids during cell division. • structure kinetochore is located in centromeres. Kinetochore involves directly in cell division. Structure of Chromosome - Centromeres

  13. NORs – nucleolar organizing regions. • transcribed DNA. • form visible structure (neucleolus) in the nucleus. • the site of ribosome formation. • NORs are found associated with satellited chromosomes. In human the satellited chromosomes are chromosomes 13, 14, 15, 21 and 22. Structure of Chromosome - NORs

  14. Interphase nucleus of onion root tip through light microscope Structure of Chromosome - NORs nucleolus

  15. electron micrograph of interphase cell from bat pancreas Structure of Chromosome - NORs nucleolus

More Related