CYTOGENETICS LEC SUMMATIVE 2

• WEEK 3


  DNA, CHROMOSOMES, AND CELL DIVISION
• The Cell


  the basic, living, structural, and functional units of the organs.
• the scientific study of cells

  Cytology
• This cell is found in MULTICELLULAR organisms like animals, plants, and fungi.

  Eukaryotic Cell
• This cell is found in UNICELLULAR organisms like Bacteria

  Prokaryotic Cell
• Eukaryotic Nucleus


  True Nucleus
• Prokaryotic Nucleus


  No true nucleus
• Eukaryotic Cell Wall


  Present in fungi and plants
• Prokaryotic Cell Wall


  Present
• Organelles 


  Eukaryotic - present

  Prokaryotic - absent
• NUCLEUS AND CYTOPLASM

  • organelles
  • cytosol


  Cell Structure (2) main parts
• Protective outer covering:


  Plasma membrane
• The Plasma Membrane


  Functions and Properties:

  • Thin, pliable, elastic
  • Outermost layer that protects and separates the cell’s internal from the external environment
  • Selective barrier that facilitates passage of materials into and out of the cell
• • Resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins
  • Some proteins float freely while others seem anchored at specific locations

  Fluid Mosaic Model
• Cell Structure: Plasma membrane Composition:

  1.Phospholipid bilayer (P-B)

  2.Cholesterol (C)

  3.Carbohydrates (Ca)

  4.Proteins (P)

  • Integral proteins
  • Peripheral proteins

  Approximately:

  • 55% proteins
  • 42% lipids
  • 3% carbohydrates

  Of the membrane lipids...

  • 75% are phospholipids
  • 20% are cholesterol
  • 5% are glycolipids
• 1. Phospholipid bilayer 


  basic structural framework; amphiphatic
• 2.Cholesterol

  • Inserted among closely packed phospholipids, restricting their movements

  • modulates fluidity and movement of membrane components
• 3.Carbohydrates


  Form the Glycocalyx

  ○ “molecular signature’’ that enables

  cells to recognize one another

  ○ Cell attachment to one another ○ Hydrophilic

  ● makes RBCs “slippery” as they flow through narrow blood vessels

  ● Protects cells lining the airways and digestive canal from drying out
• 4.Proteins


  Function as:

  ● Ion channel ● Carrier

  ● Receptor

  ● Enzyme

  ● Linker

  ● Cell identity marker
• Integral Proteins

  • Transmembrane proteins
  • Directly embedded in the lipid bilayer
  • Many are Glycoproteins
  • Can only be extracted upon

  destruction of lipid bilayer
• • Peripheral proteins


  Attached to either of the polar sides or to integral proteins.
• What makes the cell membrane selectively permeable?

  Due to its structure.
• • Houses all the cellular contents between the plasma membrane and the nucleus.

  Has 2 components:

  CYTOPLASM

  1.Cytosol

  • fluid portion (aka intracellular fluid)
  • 55% of total cell volume
  • 70-90% water
  • Site of many chemical reactions

  2.Organelles

  • little organs
  • specialized structures with characteristic shapes and have specific function.
• 3 parts of Cytoskeleton

  • Microfilament
  • Intermediate filaments
  • Microtubules
• 1. Microfilaments


  • Thinnest

  • Actin and myosin

  • Generate movement,

  mechanical support,

  cell’s shape and strength

  • Microvilli
• 2.Intermediate filaments


  • Thicker

  • Stabilize position of

  organelles
• 3. Microtubules


  • Thickest among the three

  • Long, unbranched, hollow

  tubes

  • Tubulin

  • Assembly begins from the

  centrosome toward the

  periphery of the cell

  • Cilia and flagella
• CENTROSOME

  • Microtubule organizing center


  Two components:

  • centrioles - cylindrical; nine clusters of microtubular triplets arranged in a circular pattern
  • pericentriolar matrix - surrounds centrioles, forms mitotic spindle during cell division
• Mitochondrion

  • Powerhouse of the cell
  • Active cells that use ATP at higher rate

  have larger number of mitochondria

  -Liver, Kidneys, Muscles

  • Inner and Outer membrane
• infoldings of inner membrane

  Cristae
• has quantities of enzymes

  used to extract energy from nutrients.

  Matrix
• • Self-replicating
  • Contain DNA similar to that of found in the Nucleus
  • Plays a role in Apoptosis (normal/programmed cell death)

  Mitochondrion
• • network of flat tubular structures (cisternae) and flat vesicular structures
  • Extends from nuclear envelope, projects throughout the cytoplasm.
  • Process molecules made by nucleus and transport them

  Endoplasmic Reticulum

  • Lipid bilayer with proteins
• Rough Endoplasmic Reticulum

  • With Ribosomes attached
  • Mixture of RNA and Proteins
  • Protein synthesis
  • glycoprotein and phospholipid synthesis
• Smooth Endoplasmic Reticulum

  • With Enzymes
  • Functionally diverse
  • Fatty acids and Steroid synthesis
  • in liver cells: releases glucose, detoxify lipid-soluble drugs
  • in muscle fibers: release Calcium

  (Sarcoplasmic Reticulum)
• Endoplasmic Reticulum RIBOSOMES


  are the sites of Protein Synthesis
• Golgi Complex

  • 3-20 flattened saccules.
  • Prominent in secretory cells.
  • Functions in association with the endoplasmic reticulum.

  ER vesicles continually pinch off

  from the ER and shortly fuse with the Golgi apparatus.

  • Modifies, sorts, packages, and transports proteins from ER.
• Golgi Complex

  • Cis face = entry

  (Faces the Rough ER)

  • Trans face = exit

  (Faces the Plasma Membrane)

  • Intermediate saccules
• Golgi Complex


  All proteins exported from the cell are processed in the Golgi Complex.
• Lysosome

  • Forms by breaking off from the Golgi apparatus
  • Dispersed throughout the cytoplasm