Cells • Cells come in all shapes, sizes, and functions with life spans that vary • Most cells have a expiration date • What does that mean? • EX: • stomach cells ~3-5 days • Skin cells ~2-4 weeks • Red blood cells ~120 days • Cells that expire get replaced
Some cells do not expire • Once they are damaged they have very little repair/replacement • Muscle cells • Nerve cells • Brain cells
Cells are specialized • specialized cells are specially designed to perform the functions for which they are intended • (aka. cell differentiation) • Specialized cells cannot be moved to other parts of the body!
Cells • Somatic cells: body cells • Skin cells, liver cells, lung cells, etc. • Gamete cells: sex cells • Sperm and egg
Normal somatic cell activity • Cells function properly • Cells expire • Cells divide to replace expired cells Cell Cycle
Why divide? Why not grow larger? • The larger the cell… • Difficult more nutrients in and around • Difficult removing waste • More demands on DNA • Smaller cell is more efficient
Cellular Division • Cell cycle: series of events that cells go through as they grow and divide • Cell cycle consists of multiple phases: (pg 245) • Interphase- G1, S , G2 • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis MITOSIS
Cell cycle • driven by activation and inactivation of cyclin-dependent kinases (CDKs) • CDKs trigger phase transitions • CDKs are small serine/threonine protein kinases • Requires help from a cyclin • Cell cycle is NOT random!
Interphase • Longest phase • Involves G1(growth phase, prepares for DNA replication), S (synthesis of DNA, DNA replication), G2(checks DNA duplication, growth and prepares for division) • Centrioles form
Mitosis begins • Mitosis: the division of the nucleus • PMAT • Prophase, Metaphase, Anaphase, Telophase
Cell cycle and Mitosis • Start with one cell • End with two genetically identical cells • Each cell contains 46 chromosomes (diploid, 2N)
What happens when cell regulators aren’t working? Tumors and cancer can arise Benign vs malignant What does it mean if cancer metastasized? Factors that increase probability for cancer: inheritance, smoking, UV light, viruses, chemicals (drugs), etc
Cells Cells come in all shapes, sizes, and functions; with life spans that vary (they have an expiration date) These cells are constantly in the cell cycle Some cells do not expire Once they are damaged they have very little repair/replacement (i.e. muscle, nerve) These cells are in the G0 phase
G0 phase: cells are alive, metabolically active, but do not divide. • cells do not copy their DNA and do not prepare for cell division. • Includes: heart muscle, eyes, and brain
Cells are specialized specialized cells are specific to an area and function aka: differentiated cells Specialized, mature cells cannot be moved to other parts of the body!
Are all cells differentiated? No! Stem cells are non-differentiated cells What does that mean?
Stem cells Not all stem cells are the same- they have different abilities: Totipotent (omnipotent) Pluripotent Multipotent
Stem cells have the ability to help… • Heart disease • Alzheimer's • Spinal cord/nervous system complications • Diabetes • Organ failure • Cancer This list is only a fraction of what stem cells could potentially cure…