Mitosis

• This DNA-protein complex is called chromatin. A mixture of DNA and proteins that form the chromosomes found in the cells of humans and other higher organisms
• Enumarate the parts in the picture.

  A) Heterochromatin

  B) euchromatin

  C) RNA polymerase ll

  
• •Nucleosomes (a section of DNA that is wrapped

  around a core of proteins) which is composed of

  globular structures known as histones where the

  DNA strands are attached, and coiled looking like

  beads attached on a string in a form of chromatin

  measuring up to 11 nm.
• •This solenoid level of packaging becomes

  supercoiled forming loops that are visible and are

  usually called chromatin loops which further

  leads to condensation of the chromosomes up to

  700 nm.
• •When the DNA molecules is replicated and

  undergoes also packaging and coiling, it would

  form the entire mitotic chromosome or

  metaphase chromosome which measures up to

  1,400 nm
• Enumerate the name

  A) histones

  B) nucleosome

  C) linkers

  D) solenoid

  E) supercoil

  
• Euchromatin


  Slightly packed or partially condensed form of chromatin that contains structural genes and is usually transcriptionally active

  
• Chromatids


  • During prophase of mitosis, each chromosome duplicates and forms two sister chromatids connected by a centromere
  • Sister chromatids are identical
  • Separate into individual chromosomes during anaphase

  
• Kinetochore


  Proteinaceous disc-shaped structure on the sides of the centromere that allows chromosomal mobility during anaphase

  
• Cell cycle


  1. Interphase (chromosomes long and extended)

  2. Mitotic phase (chromosomes condensed)

  
• Interphase stages


  1. G1 phase (cell growth, organelle duplication, molecular building blocks)

  2. S phase (DNA synthesis, centrosome duplication)

  3. G2 phase (rapid cell growth, preparation for mitosis)

  
• Mitotic (M) phase


  1. Cell divides its copied DNA and cytoplasm to make two new cells

  2. Mitosis (nuclear division)

  3. Cytokinesis (cytoplasmic division)

  
• Mitosis stages


  1. Prophase (chromosome condensation)

  2. Metaphase (chromosome alignment)

  3. Anaphase (chromosome separation)

  4. Telophase (nuclear division and cytokinesis)

  
• Different cells take different lengths of time to complete the cell cycle, from 9-10 hours for fast-cycling mammalian cells to 24 hours for a typical human cell