A Tour of the Cell

1
A Tour of the Cell

1. Definition of a cell
2. Types of cells based on membrane complexity
3. How cells are studied
4. Organelles of the eukaryotic cell

2
Definition of a Cell

• Hierarchical structural organization
• Molecular organization
• Atoms, small molecules, polymers
• Subcellular organization
• Organelles
• Cells
• The simplest structure capable of having all of
  the properties of life
• Multicellular organization
• Tissues, organs, organ systems
• Ecosystem organization
• Populations, communities, biomes

3
B. Types of Cells Based on Membrane Complexity

• Features common to all cell types
• Bounded by a plasma membrane
• Contain cytoplasm
• Utilize energy and raw materials through
  metabolism
• Have both DNA and RNA
• Reproduce by cell division processes

4
B. Types of Cells

• Eukaryotic cells
• Have complex internal membrane
  system          compartmentalization         mem
  brane-enclosed organelles
• DNA is enclosed in a membrane-bound nucleus
• Includes         animal plant cells, fungi,
  protozoa, algae       

5
B. 2. Types of Cells

• Prokaryotic cells
• Have no (or few) internal membranes
• Many processes that are associated with
  organelles in eukaryotes (eg. Respiration,
  photosynthesis) are mediated by specialized
  regions of the plasma membrane in prokaryotes
         

6
B. 2. Types of Cells

• Prokaryotic cells (cont.)
• There is no membrane-bound nucleus in
  prokaryotes. Instead the DNA is located within a
  specialized region of the cytoplasm of the cell
  called the nucleoid region. There is no nuclear
  membrane surrounding the nucleoid.
• Includes the bacteria archaeathe terms
  prokaryotic cell and bacterial cell often are
  used interchangeably       

7
C. How Cells Are Studied

• Microscopic techniques
• Differential centrifugation chemical separation

8
D. Eukaryotic Organelles

• Nucleus
• Location of the cells DNA
• Major processes
• DNA replication
• DNA expression (transcription)
• Ribosomes
• Thousands are located suspended in the cytoplasm
• Major process
• Protein synthesis (translation)

9
D. Eukaryotic Organelles

• Cytomembrane system
• Folded sacks of membranes within the cytoplasm
• Carry out processing and export of the cells
  proteins
• Major components
• Endoplasmic reticulum (rough and smooth)
• Golgi apparatus
• Transport vesicles
• Lysosomes

10
D. Eukaryotic Organelles

• Mitochondria
• Located in the cells cytoplasm
• Major process cellular respiration
• The mitochondria oxidize nutrient molecules with
  the help of oxygen
• Some of the energy is conserved in the form of
  chemical energy (energy-containing chemical
  compounds) that can be used for biological
  processes
• Evolved from bacteria by a process called
  endosymbiosis

11
D. Eukaryotic Organelles

• Chloroplasts
• Located in the cytoplasm of plant cells, algae
  cells, and certain protozoan cells
• Major process photosynthesis
• Using the energy from light, CO2 is converted
  into carbohydrates such as glucose
• Evolved from bacteria by endosymbiosis

12
D. Eukaryotic Organelles

• Cytoskeleton
• Microfilaments
• Microtubules
• Intermediate filaments
• Vacuoles
• Peroxisomes