CYTOLOGY

1
CYTOLOGY
2
Cytology

• Living organisms are made up of cells.
• Either PROKARYOTIC or EUKARYOTIC cells.
• A. two major cell types
• B. distinguished by structural organization
• See table on handout for differences.
• Plant, Animal and Bacteria Cell Models at
  http//www.cellsalive.com/

3
Prokaryotic Cells

• Kingdoms
• 1. Monera (Eubacteria)
• 2. Archaea (Archaebacteria)
• Characteristics
• 1. lack a nuclear membrane
• 2. have no membrane-bound organelles

4
Prokaryotic Cell - Bacteria
5
Eukaryotic Cells

• Kingdoms
• 1. Protista
• 2. Fungi
• 3. Plantae
• 4. Animalia
• Characteristics
• 1. have a nuclear membrane
• 2. have membrane-bound organelles

6
Eukaryotic - Animal Cell
7
Eukaryotic - Plant Cell
8
Cellular Evolution

• Current evidence indicates that eukaryotes
  evolved from prokaryotes between 1 and 1.5
  billion years ago.
• Two theories
• 1. Infolding theory
• 2. Endosymbiotic theory

9
1. Infolding Theory

• The infolding of the prokaryotic plasma membrane
  gave rise to eukaryotic organelles.

10
2. Endosymbiotic theory

• Endosymbiosis refers to one species living within
  another - the host.
• Theory - the movement of smaller photosynthetic
  (chloroplast) and heterotrophic (mitochondria)
  prokaryotes into larger prokaryotic host cells.

11
Cytoplasm

• Entire region between the nuclear membrane and
  the cell (plasma) membrane.
• This includes all organelles!

12
Cytosol

• The semi-fluid medium found in the cytoplasm.
• This does not include the organelles.

13
Nucleus

• Conspicuous membrane-bound cellular organelle in
  eukaryotes.
• Contains the genes (DNA).

14
Nucleolus

• Spherical region in nucleus.
• Found in non-dividing cells.
• Has nuclear organizers and ribosomes.
• Sometimes more than one nucleolus present.

15
Ribosomes

• Nuclear and cytoplasmic organelle.
• Composed of 60 protein and 40 ribosomal-RNA
  (rRNA).
• Site of protein synthesis.

16
Endomembrane System

• Eukaryotic organelles that are formed of
  interrelated membranes.
• 1. nuclear envelope (membrane)
• 2. endoplasmic reticulum
• 3. transport vesicles
• 4. golgi apparatus (complex)
• 5. lysosomes
• 6. vacuoles
• 7. plasma (cell) membrane

17
1. Nuclear Membrane

• Encloses the nucleus.
• A double membrane perforated with pores through
  which materials enter and leave the nucleus.

18
2. Endoplasmic Reticulum

• Extensive membranous network of tubules and sacs
  called cisternae.
• Two distinct regions
• A. Rough endoplasmic reticulum (RER).
• B. Smooth endoplasmic reticulum (SER).

19
2. Endoplasmic Reticulum

• A. Rough endoplasmic reticulum (RER).
• 1. Studded with ribosomes.
• 2. Site of protein synthesis
• B. Smooth endoplasmic reticulum (SER).
• 1. Synthesizes lipids, phosolipids and
  steroids.
• 2. Detoxifies drugs, alcohol and poisons.

20
3. Transport Vesicles

• A membrane organelle that transits materials from
  one part of the cell to another.
• ER ? Golgi apparatus
• Golgi apparatus ? plasma membrane

21
4. Golgi Apparatus (Complex)

• A stacked, flattened membranous organelle with
  sacs called cisternae.
• Modifies, stores and routes products from the ER
  to the plasma membrane.

22
5. Lysosomes

• Membrane-enclosed bag of hydrolytic enzymes
  (digestive enzymes).
• Functions
• 1. intracellular digestion - phagocytosis.
• 2. Autophagy - engulfs other cellular organelles.

23
6. Vacuoles

• Large membrane-closed sac for cellular storage.
• Three types
• 1. Food vacuole (lysosomes attach)
• 2. Contractile vacuole (Protozoans)
• 3. Central Vacuole (mature plant cells)

24
7. Plasma (Cell) Membrane

• The boundary of every cell.
• Approximately 8 nm thick.
• Separates the living cell from its nonliving
  surroundings.
• Acts as a selective barrier.

25
Mitochondria

• A doubled membrane cellular organelle with its
  own circular DNA found in both plants and
  animals.
• It is the site of cellular respiration, a
  catabolic, exergonic, oxygen requiring process
  that uses energy extracted from organic
  macromolecules (like glucose) to produce ATP.

26
Mitochondria
27
Chloroplast

• A doubled membrane cellular organelle with its
  own circular DNA found in photosynthetic plants.
• The site of photosynthesis, an anabolic,
  endergonic, carbon dioxide requiring process the
  uses light energy (sun) and water to produce
  organic macromolecules (glucose).

28
Chloroplast
29
Cytoskeleton

• Network of fibers through out the cytoplasm.
• Aids in cellular support and movement.
• Composed of three components
• 1. Microfilaments - globular protein (actin)
• - support and cellular contraction
• 2. Intermediate filaments - fibrous protein
• - support
• 3. Microtubles - globular protein (tubulin)
• - support and cell motility

30
Centriole

• Composed of microtubules.
• Remember Animal cells only!
• Helps organize microtuble assembly during cell
  division (mitosis and meiosis).

31
Cilia and Flagella

• Extensions of the plasma membrane.
• Microtubular core (9 2 pattern).
• Attached by a basal body (identical to centriole).

32
Cell Wall

• Strong cellulose fibers surrounding plant cells
  and some bacteria only!
• Composed of polysaccharides and proteins.