Tài liệu, ebook Khoa Học Tự Nhiên

Ubiquitination – covalent attachment of ubiquitin to other proteins targets those proteins for degradation by the proteosome Cascades of phosphorylation and dephosphorylation Transmission of signals across the cell membrane to the nucleus (discussed more in Chapter 17) Sensitization – tissues exposed to hormones for long periods of time lose abi...

65 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 926 | Lượt tải: 0

Initiation – core RNA polymerase plus sigma (σ) factor Core has four subunits: two alpha (α), one beta (β), one beta prime (β') DNA is unwound and polymerization begins Elongation – core RNA polymerase without σ factor Continues until RNA polymerase recognizes termination signal Termination – two kinds in bacteria Rho-dependent – Rho (ρ) pro...

61 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 904 | Lượt tải: 0

Oxidative phosphorylation system in the mitochondria generates free radicals, which can damage DNA Accumulation of mtDNA mutations over time may result in age-related decline in oxidative phosphorylation Evidence in support of role of mtDNA and aging: Percentage of heart tissue with a mitochondrial deletion increases with age Brain cells of peo...

69 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 883 | Lượt tải: 0

Incidence of abnormal phenotypes caused by aberrant chromosome organization or number is 0.004% Half of spontaneously aborted fetuses have chromosome abnormalities Incidence of abnormal phenotypes caused by single-gene mutations is 0.010%

89 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 960 | Lượt tải: 0

Specialized chromatin in central core of centromere marks this region for attachment of kinetochore proteins Central core of each centromere: Composed of unique chromatin that does not recombine and is not transcribed Surrounded by regions of heterochromatin interspersed with euchromatin Histone variant CENP-A is present in central core of all...

40 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 847 | Lượt tải: 0

All published research with SNPs uses standardized nomenclature All newly-obtained information is deposited in freely- available, public databases maintained by the NIH 29 interlinked databases at NCBI Examples dbSNP – comprehensive catalog of all human SNPs dbGap – database of results obtained in various GWASs OMIM – online compendium of ann...

41 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 887 | Lượt tải: 0

Pressing issues raised by individual genome sequences Privacy of genetic information Limitations on the use of genetic testing Patenting of DNA sequences Societal views on aging Training physicians Impact of increased longevity produced by improved medicine Somatic gene therapy vs germ-line gene therapy For further descriptions, see the var...

55 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 897 | Lượt tải: 0

Two general classes of human disorders are caused by mutations in hemoglobin genes Hemolytic anemias (e.g. sickle-cell anemia) Mutations affect amino acid sequence and the three dimensional structure of a- or b-globin chain Results in destruction of red blood cells Thallasemias Mutations result in reduction or elimination of one of the two glo...

66 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 838 | Lượt tải: 0

Mutations in genes encoding gene products for transcription, RNA processing, translation, and protein processing are often lethal Some mutations in tRNA genes can suppress mutations in protein-coding genes

70 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 867 | Lượt tải: 0

20 different amino acids R group is the side chain that is unique to each amino acid Four groups of amino acids based on R group properties (Fig 7.24b) –COOH group and –NH2 group of adjacent amino acids are joined in covalent peptide bond Polypeptides have "N terminus" and "C terminus"

72 trang | Chia sẻ: nguyenlam99 | Ngày: 11/01/2019 | Lượt xem: 915 | Lượt tải: 0