Cell Structure Function Introduction to Cells Eukaryotic Cells

Cell Structure & Function Introduction to Cells Eukaryotic Cells Prokarytoic Cells

Introduction to Cells l 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 Cells l 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 Cells l Cell Types – Prokaryotic – Eukaryotic l Sizes – Prokaryotic – Eukaryotic 0. 2 to 2. 0 microns 10 to 100 microns

Introduction to Cells l 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 Cells

Introduction to Cells l 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 Cells l 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 Cells l l Endosymbiotic theory (Lynn Margullis – 1967) Evidence: – – Mitochondria & chloroplasts replicate via binary fision Mitochondria & chloroplasts have circular DNA Mitochondria & chloroplasts have 70 S (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 Cells l l l Nucleus Mitochondria Chloroplast Endoplasmic reticulum (R & S) Golgi body l l l Lysosome Peroxisome Centrioles Vacuoles Flagella & cilia

Eukaryotic Cells

Eukaryotic Cells

Eukaryotic Cells l Nucleus – Regulates growth and reproduction of cell – Contains DNA and chromosomes l Nucleolus – Ribosomal RNA synthesis

Eukaryotic Cells l Mitochondria – Energy production in cell – Contains its own DNA (circular)

Eukaryotic Cells l Endoplasmic reticulum (rough and smooth) – Site of protein synthesis in cells – Start of protein export process – Connected to nuclear pores and Golgi body

Eukaryotic Cells l Golgi body – Sorting center for proteins in cell – Produces vesicles which fuse with plasma membrane

Eukaryotic Cells l Lysosome – Only in animal cells – Production of intracellular digestive enzymes – Involved with phagocytosis

Eukaryotic Cells l 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 Cells l Flagella & cilia – Involved with motility of cells – Composed of microtubules

Eukaryotic Cells l Vacuoles – Found only in plants – Large central organelle in plant cells – Regulates water in plant cells

Eukaryotic Cells l Chloroplast – Site of photosynthesis in plant cells – Has own DNA (circular) – Found only in plants

Eukaryotic Cells l l Endosymbiotic theory (Lynn Margullis – 1967) Evidence: – – Mitochondria & chloroplasts replicate via binary fision Mitochondria & chloroplasts have circular DNA Mitochondria & chloroplasts have 70 S (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