Overview of Cells Prokaryotes vs Eukaryotes The Cell

Overview of Cells • Prokaryotes vs Eukaryotes • The Cell Organelles • The Endosymbiotic Theory

Prokaryotic Cells • Archaea • Bacteria • Come in many different shapes and sizes ü. 5 µm – 2 µm, up to 60 µm long • Have large surface to volume ration – nutrients from outside can easily reach all parts of the cell

Eukaryotic Cells • • Protists Fungi Animal Cells Plant Cells • Like prokaryotic cells, eukaryotic cells come in many different shapes and sizes, but have the same basic set of organelles • Multicellular organisms (fungi, plants and animals) have specialized eukaryotic cells that each perform a particular job and all work together for the benefit of the organism

Eukaryotic Cells Common Organelles – Plasma membrane – Nucleus ü ü ü Chromatin (DNA) Nucleolus Nuclear Envelope – Ribosomes – Rough Endoplasmic Reticulum (rough ER) – Smooth Endoplasmic Reticulum (smooth ER) – Golgi Apparatus – Centrioles – Mitochondria – Cytoskeleton – Vesicles, Peroxisomes, Lysosomes, Small Vacuoles

Eukaryotic Cells Organelles only found in Plants – All those in animal cells except Centrioles – plus PCell Wall PChloroplasts PLarge Vacuoles – The cell wall and vacuoles help plant cells maintain a rigid shape (keep plant from drooping)

Organelles • Organelles are the parts within a cell that have specific functions • Prokaryotic cells (e. g. bacteria) are smaller and less complex (fewer organelles) than eukaryotic cells. Eukaryotic Cells Prokaryotic Cells Plant Cells – Plasma Membrane (eukaryotic) – Plasma Membrane – Cytoplasm – – Cytoplasm Cell Wall DNA (no nucleus) Ribosomes – Nucleus – – – – ü ü ü Chromatin (DNA) Nucleolus Nuclear Envelope – Cell Wall – Chloroplasts – Vacuole Ribosomes Vesicles, Peroxisomes, Lysosomes Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Golgi Apparatus Centrioles Mitochondria Cytoskeleton

Organelles Polysaccharides Organelles are made of: • Proteins – made of amino acids • Lipids – made of fatty acids • Carbohydrates - polysaccharides made of sacharides (sugars) • Nucleic Acids (DNA and RNA) – made of nucleotides Proteins (Polypeptides) Lipids Nucleic Acids

Components found in all cells Plasma Membrane • Made of a Phospholipid Bilayer • Various proteins, lipids, and sugars float in membrane • Semipermeable ü Small hydrophobic molecules pass easily through ü Contains pores that enable water and very small ions to pass through ü large molecules must pass through channel proteins

Components found in all cells Plasma Membrane ü Eukaryotic cells also membrane-bound internal organelles composed of lipid bilayer membranes • Nuclear Envelope • Golgi Apparatus • Endoplasmic Reticulum (rough and smooth) • Mitochondria • Chloroplasts (in plants) • Vesicles, Lysosomes, Peroxisomes & Vacuoles

Components found in all cells Cytoplasm • The fluid that fills cells and surrounds the organelles • Consists of: • Water (mostly) • Proteins (e. g. hormones and enzymes) • Small Molecules (e. g. ions)

Components found in all cells DNA • Prokaryotic Cells • May be linear or circular • Contained in the nuclear region (nucleoid) • May also include short, circular plasmids • Eukaryotic Cells • Longer (approx. 9 feet per cell in humans), coiled around histone proteins to help pack it into the cell • Always linear • Contained in the nucleus • Known as chromatin when relaxed and chromosomes when condensed (supercoiled)

Components found in all cells Ribosomes • Float freely in the cytoplasm of prokaryotic and eukaryotic cells • Also coat the rough ER of eukaryotic cells

Components found in all cells Ribosomes • Build proteins using instructions encoded in DNA

Components found in all cells Ribosomes • Build proteins using instructions encoded in DNA • Complex of protein and r. RNA forming two subunits Purple = Proteins Blue = r. RNA of small subunit Grey = r. RNA of large subunit

Components found only in Eukaryotic Cells Nucleus • Nuclear Envelope ü double membrane ü nuclear pores allow RNA to exit • Chromatin – “relaxed” DNA • Nucleolus – where ribosomes are assembled