BMS1062: Molecular Biology: Higher order genetics + Transcription and RNA processing

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Department
Biomedical Sciences
Course
BMS1062
Professor
Peter Boag
Semester
Spring

Description
HIGHER ORDER GENETICSChromosome structure and functionEach chromosome consists of a single linear DNA moleculeEukaryoticdiploid two copies of each chromosomeProkaryoteshaploid one copy per cellDNA must be highly compacted to fit into the cell see chromatin aboveChromatin can be divided into two types o Euchromatin less densely packed can be transcribed takes up most of the nucleus o Heterochromatin very densely packed not transcribed often found at centromeresDuring mitosis and meiosis becomes 510 times more densely packedless tightly packed between mitotic cyclesNucleosomesbasic structure of chromatincomposed ofo equal mass of DNA and histone proteins o core region comprising two copies of the histone proteins H2A H2B H3 H4 o histones are small basic proteins o One associated histone H1 proteinChromatin remodelling is an important regulator of gene expression o Transcription is repressed when gene promoter and activator regions wound in nucleosome o Section of DNA in nucleosome controlled by o Histone protein tail acetylation oSWISNF protein complex Histone proteins have amino acid tails sticking out of the nucleosome o Histone tails bind the next nucleosome stabilising the condensed structure o Acetylation CHCO of histone tails stops interaction with neighbouring 3nucleosome o Acetylated stops condensationfavours transcription o Deacetylated favours condensationrepresses transcriptionMitosisProcess where replicated chromosomes partition equally into the two daughter cellsOccurs after the chromosome has been replicated to give sister chromatids S phaseMitosis maintains chromosome number Prophase o Nuclear membrane breaks downMetaphase o Chromosomes align along equator of cellAnaphase o Chromatids separate and move towards the polesTelophase o Nuclear membranes reform cell splits in twoCentromeresOne centromere per chromosomeDirects chromosome segregation during mitosis and meiosisSection that pulls chromosomes to either poleContains satellite DNA short repetitive sequencesTelomeresthe structures at the end of the linear DNA moleculesRequired for stability of the linear moleculeTelomeric repeats synthesised onto the end of the chromosome from an RNA template by telomerase o In humans repeat unit is TTAGGG
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