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Ageing - Coggle Diagram

- - - - metastases - derivatives (descendants) of tumor around the body
- - - - Hayflick limit
        
        40-70 times
      - Telomeres and telomerase
        
        end replication problem in linear chromosomes - 1 - DNA strands are antiparallel, 2 - there are 2 options: 5' / 3' end. 3. for each of them replication is a little different (!!!!) - in one of them replication can't be complited fully because of the requirements of enzymes
        
        contain repetitive DNA sequences + do not contain genes
        
        telomerase - enzyme in cells which is reverse transcriptase, it has RNA sequence which is complimentary to telomere's repetitive sequences, thus allowing it to build up the telomere DNA by using this sequence as a template
        
        protect DNA genes when replication occurs, protect chromosomes from merging, acts as a molecular clock (the entire length of telomere determines cell's lifespan, shortening equally with each division and thus acting as a clock which counts the number of divisions left until the telomere fully degrades and cell undergoes apoptosis)
      - Apoptosis
        
        programmed cell death when a cell is damaged beyond repair (DNA mutations, chromosomes mutations, cell cycle aberrations, organells mulfunctioning, etc.)
        
        shaping certain body parts during embryogenesis
    - - Mitosis
        
        G0
        
        why?
        
        hasn't passed G1 checkpoint
        
        differentiate terminally (get the phenotype of a specific morphology (shape)) to operate according to their function (produce hormones / proteins / enzymes / propagate electric signal / contract)
        
        in oocytosis for arrest oocyte division until the reproductive age
      - Checkpoints
        
        G1
        
        Check that environment is favourable for undergoing division
        
        G2
        
        check that DNA was replicated correctly
        
        M
        
        spindle check - microtubules and chromosomes' allignment
      - factors
        
        external
        
        anchorage is necessary for division
        
        density-dependance (cells stop division if there's no room)
        
        nutrients
        
        hormons
        
        cell-cell communication
        
        internal
        
        growth factors
        
        organells, checkpoints passed
      - cytogenetics
        
        chromosomes - highly condensed chromatin visible during cell division
        
        DNA (double helix), nucleosomes beads, loops, chromosome
        
        each chromosome has a distinctive territory
        
        chromosomes can be anchored at lamin - protein layer underlying nuclear membrane (disrupted in Progeria disease - makes a faulty lamin, thus the shape of nucleus changes, thus chromosomes attachement and territory are affected, and this changes the pattern of gene regulation
        
        chromatin = DNA + proteins (histones)
        
        chromatid - one strand of DNA occured after replication and coupled with second strand making up a chromosome
  - - - totipotent
      - pluripotent
      - multipotent
      - unipotent
    - - produce one or more organisms that are genetically identical to the parent that donated the single cell.
      - remove the nucleus of an egg (enucleated egg).
      - take out a nucleus from a differentiated cell of another organism
      - put the nucleus from step 2 to an egg from step 1
      - transplant an egg to a surrogate mother (reproductive cloning)
      - Gurdon experiment with frog - if we transfer a nucleus from a differentiated cell, the embryo development will not be full, it will stop at some stage, without developing to an organism, while if we take a nucleus from an embryonic cell, we get the viable clone (tappole) = sth in a differentiated nucleus is blocking / preventing = this nucleus is not the same as embryonic cell nucleus (sth changed)
      - reproductive cloning - cloning results in birth of a new identical to a nucleus donor organism
        
        Dolly - problems - premature disease-driven death (arthritis + lung infection) - because of incomplete reprogramming (epigenetics? or telomeres were too short?)
        
        sometimes cloned animals aren't identical 100% (fur colour pattern was different) - explanation - X-chromosome inactivation (mosaicism) - dosage compensation
        
        epigenetical changes - restructuring in chromatin - acetylation of histones or DNA methylation - it interferes with pattern of gene expression necessary for normal development
      - therapeutic cloning - form stem cells for patients' treatment