Cell Structure & Function Cell Structure & Function Introduction to Cells Eukaryotic Cells Prokarytoic Cells
Dec 23, 2015
Cell Structure & Function Cell Structure & Function
Introduction to CellsEukaryotic CellsProkarytoic Cells
Introduction to CellsIntroduction to Cells
History – Robert Hooke (1600’s) first described
cells in thin sections of cork that he examined under microscope
– Robert Brown (1820) first to describe that a nucleus seemed to be associated with all cells (at least eukaryotic cells)
Introduction to CellsIntroduction to Cells
History (continued)– Theodore Schwann & Matthias
Schleiden (1839) advanced cell theory»All organisms are composed of cells»The cell is the basic unit of life»All cells arise from preexisting cells
Introduction to CellsIntroduction to Cells
Cell Types– Prokaryotic– Eukaryotic
Sizes– Prokaryotic 0.2 to 2.0
microns– Eukaryotic 10 to 100
microns
Introduction to CellsIntroduction to Cells
Size Determinants– Cell surface to volume relationships
govern cell size– The smaller the cell the more
efficiently materials can be transported into and within the cell
– Cell must also be large enough to deal with information and metabolic requirements
Introduction to CellsIntroduction to Cells
Introduction to CellsIntroduction to Cells Common Components to All
– Plasma membrane – phospholipid bilayer that controls movement of substances into and out of cells
– Ribosomes – site of protein synthesis – note ribosomes have both RNA & protein
– Cytoplasm –matrix on interior of cell consisting of water soluble proteins and other materials
– Nuclear material – DNA/Protein complex that stores information
» Prokaryotic – circular» Eukaryotic – linear and in chromosomes
Eukaryotic CellsEukaryotic Cells
Eukaryotic Cells– Larger than prokaryotic– More complex than prokaryotic– All multicellular organisms composed
of eukaryotic cells– Eukaryotic cells composed of many
internal structures called organelles
Eukaryotic CellsEukaryotic Cells Endosymbiotic theory (Lynn Margullis – 1967) Evidence:
– Mitochondria & chloroplasts replicate via binary fision
– Mitochondria & chloroplasts have circular DNA– Mitochondria & chloroplasts have 70S (bacterial
ribosomes)– Mitochondria & chloroplasts start protein
synthesis in the same way as prokaryotic cells– Mitochondria & chloroplasts DNA sequences of
similar genes show greater relationships to prokaryotic genes
Eukaryotic CellsEukaryotic Cells
Nucleus Mitochondria Chloroplast Endoplasmic
reticulum (R & S) Golgi body
Lysosome Peroxisome Centrioles Vacuoles Flagella & cilia
Eukaryotic CellsEukaryotic Cells
Eukaryotic CellsEukaryotic Cells
Eukaryotic CellsEukaryotic Cells
Nucleus– Regulates growth
and reproduction of cell
– Contains DNA and chromosomes
Nucleolus – Ribosomal RNA
synthesis
Eukaryotic CellsEukaryotic Cells
Mitochondria – Energy production
in cell– Contains its own
DNA (circular)
Eukaryotic CellsEukaryotic Cells
Endoplasmic reticulum (rough and smooth)– Site of protein
synthesis in cells– Start of protein
export process– Connected to
nuclear pores and Golgi body
Eukaryotic CellsEukaryotic Cells
Golgi body– Sorting center for
proteins in cell– Produces vesicles
which fuse with plasma membrane
Eukaryotic CellsEukaryotic Cells
Lysosome– Only in animal
cells– Production of
intracellular digestive enzymes
– Involved with phagocytosis
Eukaryotic CellsEukaryotic Cells
Peroxisomes– Peroxisomes are small rounded
organelles found free floating in the cell cytoplasm.
– Contain at least 50 enzymes and are separated from the cytoplasm by a lipid bilayer single membrane barrier.
– Produce hydrogen peroxide which is toxic but is rapidly degraded by catalase
Eukaryotic CellsEukaryotic Cells
Flagella & cilia– Involved with
motility of cells– Composed of
microtubules
Eukaryotic CellsEukaryotic Cells
Vacuoles– Found only in plants– Large central organelle in plant cells– Regulates water in plant cells
Eukaryotic CellsEukaryotic Cells
Chloroplast– Site of
photosynthesis in plant cells
– Has own DNA (circular)
– Found only in plants
Eukaryotic CellsEukaryotic Cells Endosymbiotic theory (Lynn Margullis – 1967) Evidence:
– Mitochondria & chloroplasts replicate via binary fision
– Mitochondria & chloroplasts have circular DNA– Mitochondria & chloroplasts have 70S (bacterial
ribosomes)– Mitochondria & chloroplasts start protein
synthesis in the same way as prokaryotic cells– Mitochondria & chloroplasts DNA sequences of
similar genes show greater relationships to prokaryotic genes