lecture 1-2 (cells + cell cycle)

• Humans have 200 cell types at birth
• Organisms can be single-celled or multicellular
• All cells have these features structure, function, ability to reproduce, and cell cycle.
• The purpose of cell division is the growth of organisms and development, the repair of tissues, and reproduction to produce create more identical cells
• Mitosis results in the production of genetically identical daughter cells.
• Cytokinesis is the division of the cytoplasm
• Cells that divide frequently are skin cells, cheek cells, and intestinal cells
• Liver cells divide infrequently.
• Nerve cells never divide
• The cell division is regulated by the cell cycle to prevent the rise of cancer cells
• Label the phases of the cell cycle

  A) interphase

  B) mitotic

  C) g1

  D) s

  E) DNA synthesis

  F) g2

  
• G1 is the first gap phase of the cell cycle, where cell growth ocurs
• The S stage of the cell cycle is when the synthesis of DNA occurs.
• The G2 stage of the cell cycle is the second gap phase, where the cells prepare for cell division.
• Interphase is composed of the G1, S, and G2 phases.
• The cell cycle is regulated by signals found in the cytoplasm, such as mitosis-promoting factors (MPF) and cyclin, whose volumes are maximum once the cell enters mitosis.
• MPF is a protein kinase (signalling enzyme) which is activated once cyclin phosphorylates it. MPF is a cyclin-dependent kinase (CDK) and when combined with cyclin, forms MPF.
• The checkpoints in the cell cycle are points where the cycle can be stopped or started. The 3 checkpoints include G1, (the most important stage, where it can alternatively goes into the G0 phase), the G2 checkpoint, and M-phase checkpoint (which prevents the cells from dividing)
• If the cell cycle checkpoints fail or are absent, cancer can occur.
• Platelet derived growth factors (PDGF) are derived by platelets and stimulate the cell division to repair damaged tissue (fibroblasts). The fibroblast have a receptor to bind tyrosine kinases present in PDGF.
• The stages of mitosis are prophase (where the DNA condense into sister chromatids and the spindle apparatus appears), prometaphase (dissolving of the nuclear envelope and attachment of the microtubules to the chromosomes at the kinetochores), metaphase (migration of sister chromatids to the center of the cell and completion of the spindle apparatus), anaphase (chromatids are pulled apart by the spindle apparatus) and telophase (dissolution of the spindle apparatus, formation of the nuclear envelope, and decondensation of the chromosomes). Additionally, there's cytokinesis!
• Label the first few stages of mitosis

  A) interphase

  B) G2

  C) prophase

  D) prometaphase

  
• Label this diagram of the metaphase stage

  A) sister chromatids

  B) kinetochores

  C) kinetochore microtubules

  D) microtubules

  E) chromosomes

  
• Label the later stages of mitosis

  A) metaphase

  B) metaphase

  C) anaphase

  D) telophase

  E) cytokinesis

  
• Stem cells can be used to differentiate into specialised cells
• Stem cells are typically derived from embyronic tissues. It can also be from umbilical cord or amniotic fluid. Adult stem cells can be derived from blood cells or bone marrow cells.
• Stem cells have the potential to regenerate tissues that would normally never heal under regenerative medicine. This could help people who have a spinal cord injury or heart damage.
• Some problems with stem cells is that embryonic stem cells can grow irregularly or differentiate into an undesired cell type. It can also trigger the immune system and be rejected by the body, or just fail to function.