A Tour of the Cell
A.
B.
C.
D.
Definition of a “cell”
Types of cells based on membrane complexity
How cells are studied
Organelles of the eukaryotic cell
A. 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
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
B. Types of Cells
Eukaryotic cells
Have:
complex internal membrane system
compartmentalization
membrane-enclosed organelles
DNA is enclosed in a membrane-bound nucleus
Includes:
animal & plant cells, fungi, protozoa, algae
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
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 & archaea
the terms “prokaryotic cell” and “bacterial cell” often
are used interchangeably
C. How Cells Are Studied
Microscopic techniques
Differential centrifugation & chemical separation
D. Eukaryotic Organelles
Nucleus
– Location of the cell’s DNA
– Major processes:
• DNA replication
• DNA expression (transcription)
Ribosomes
– Thousands are located suspended in the cytoplasm
– Major process:
• Protein synthesis (translation)
D. Eukaryotic Organelles
Cytomembrane system
– Folded sacks of membranes within the cytoplasm
– Carry out processing and export of the cell’s proteins
– Major components:
• Endoplasmic reticulum (rough and smooth)
• Golgi apparatus
• Transport vesicles
• Lysosomes
D. Eukaryotic Organelles
Mitochondria
– Located in the cell’s 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
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
D. Eukaryotic Organelles
Cytoskeleton
– Microfilaments
– Microtubules
– Intermediate filaments
Vacuoles
Peroxisomes