Notes in 1- Chromosomes

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Published	02/10/2024	Linear chromosomesFeatures: • {{c1::Telomere}} - ends of the chromosome  • {{c1::Centromere}} - DNA that links two sister chromatids • {{c1::Hete…
Published	02/10/2024	DNA synthesis is carried out by {{c1::DNA Polymerases}}Can't initiate DNA synthesis de novo, must use an existing {{c2::RNA primer}}Leading strand:Syn…
Published	02/10/2024	{{c1::DNA Polymerases}} can't initiate DNA synthesis de novo, must use an existing {{c2::RNA primer}}
Published	02/10/2024	On one strand:Synthesizes DNA in a 5' to 3' brine direction in one goOn the other strand:Synthesizes DNA in 5' to 3' brine direction using a seri…
Published	02/10/2024	Why are the two strands of DNA anti-parallel?
Published	02/10/2024	{{c1::End-replication problem}} is when the ends of linear DNA cannot be replicated completely during lagging strand DNA synt…
Published	02/10/2024	Why do Telomeres get shorter as metazoan organisms age?
Published	02/10/2024	{{c1::Telomerase}} is an enzyme that adds repeats and resynthesizes to fill in the ends of DNA during DNA replication.It helps solve the End-replicati…
Published	02/10/2024	{{c1::Telomeres}} are located at the ends of the chromosomes, made up of hundreds of copies of DNA sequence 5'-TTAGGG-3' They are gradually lost …
Published	02/10/2024	Cell Cycle:[1] {{c1::Interphase}}G1 - Cell growth (10-12 hrs)S - DNA replication (6-8 hrs)G2 - Division preparation (2-4 hrs)[2] {{c1::Mitosis}} …
Published	02/10/2024	Mitosis (cell division in somatic cells - PMAT){{c1::P - Prophase}}Chromosomes condense Nuclear membrane disappears Spindle fibres form from…
Published	02/10/2024	{{c1::P - Prophase}}Phase of Mitosis that features: Chromosomes condenseNuclear membrane disappearsSpindle fibres form from the centriole
Published	02/10/2024	{{c1::M - Metaphase}}Phase of Mitosis that features:Chromosomes aligned at the equator of the cellAttached by fibre to each centrioleMaximum cond…
Published	02/10/2024	{{c1::A - Anaphase}}Phase of Mitosis that features:Sister chromatids separate at centromereSeparate longitudinallyMove to opposite ends of cell
Published	02/10/2024	{{c1::T - Telophase}}Phase of Mitosis that features:New nuclear membranes formationEach cell contains 46 chromosomes (diploid)
Published	02/10/2024	{{c1::Cytokinesis}} is when the cytoplasm separates to fully form the two new daughter cells.
Published	02/10/2024	The {{c1::Centromere}} is a constricted region joining sister chromatids in the middle.Content:• Repetitive DNA sequences known as {{c2::Satellite DNA…
Published	02/10/2024	{{c1::Euchromatin}} is an open form of chromatin that comprises active or potentially active genes{{c1::Heterochromatin}} is a condensed form of …
Published	02/10/2024	Human genomes is made up of:{{c1::3 billion}} bp{{c1::20-30k}} genesabout {{c1::2%}} protein-coding DNA
Published	02/10/2024	Extragenic sequences:[1] {{c1::Tandemly}} repeated DNA sequences – {{c2::Satellite DNA}} (14-500 bp repeats in of 20-100 kb arrays, at centr…
Published	02/10/2024	beads around a string form {{c1::nucleosomes}}– 146 bp DNA wrapped (1.8 turns) around core of 8 histone proteinsFormation of a solenoid structure…
Published	02/10/2024	Nucleosomes pack into a coil that twists into another larger coil, and so forth, producing condensed, supercoiled chromatin fibers.This structure…
Published	02/10/2024	Describe the structure of DNAfrom uncondensed (DNA double helix) to condensed (Chromosome)
Published	02/10/2024	At metaphase DNA is condensed by a factor of {{c1::10,000}}
Published	02/10/2024	Purpose of packaging DNA• Negatively charged DNA neutralised by positively charged histone proteins • DNA takes up less space • Inactive heterochromat…
Published	02/10/2024	What's the purpose of packaging DNA?
Published	02/10/2024	{{c1::Metacentric}}centromere medially situated so that the two chromosomal arms are of roughly equal length{{c1::Submetacentric}}centromere situated …
Published	02/10/2024	Chromosome analysis
Published	02/10/2024	{{c1::G-banding}} is a technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes.about 550 bands per cell
Published	02/10/2024	{{c1::Fluorescent in situ hybridisation (FISH)}} is a laboratory technique for detecting and locating a specific DNA sequence on a chromosome.The…
Published	02/10/2024	Types of Fluorescent in situ hybridisation (FISH) probes:• {{c1::Unique sequence}} probes • {{c1::Centromeric}} probes – Useful for determining chromo…
Published	02/10/2024	Why is it better to look at chromosomes of a person in metaphase spread rather than interphase spread?
Published	02/10/2024	{{c1::Meiosis}} is cell division in germ cells.• Diploid cells (in ovaries and testes) divide to form haploid cells• Chromosomes are passed on as re-a…
Published	02/10/2024	MeiosisFeatures:• Homologous chromosome pairing - tetrads• Genetic recombination (crossing over)• Two PMATs I & II→ no centromere separation in 1s…
Published	02/10/2024	Gametogenesis [1] {{c1::Oogenesis}} = process of egg formation[2] {{c1::Spermatogenesis}} = process of sperm formation• Both go though several st…
Published	02/10/2024	Describe some differences in gametogenesis between Males and Females
Published	02/10/2024	{{c1::Fertilisation}} occurs when two haploid cells (egg, sperm) form 1 diploid cell (zygote) – develops into embryo.Whether the {{c1::sperm}} co…
Published	02/10/2024	{{c1::X-inactivation}} is the random inactivation of one X chromosome during early embryo in female mammals → prevents them from having…
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