Plant Cell PDF

CELL Prepared by: Prof. Aimee V. Manoto  The Cell Theory  All organisms are composed of cells  Cell is the smallest functional unit of life  Cells arise from pre-existing cells Mod...

CELL Prepared by: Prof. Aimee V. Manoto  The Cell Theory  All organisms are composed of cells  Cell is the smallest functional unit of life  Cells arise from pre-existing cells Modern Cell Theory  The characteristics of an organism depend on each individual cells  Continuity of characteristics is maintained through the genetic material  Energy flow occurs within cells Note: click the slide title and it will link you to a Youtube video on History of the Cell “false” nucleus “true” nucleus Naked DNA Membrane-bound nucleus No organelles Membrane-bound organelless Internal structure of cells. (a) Diagram of a prokaryote. (b) Diagram of a eukaryote.  Comparison between Prokaryotic & Eukaryotic Cells Prokaryotic Eukaryotic  Ave 1-2 um in dia.  >10-100 um  No nucleus  With nucleus  Without membrane bound  With membrane bound organelles organelles  DNA packed in chromosomes  Circular, Naked DNA (nucleiod)  Unicellular/multicellular  unicellular  Divides by mitosis & meiosis  Divides by fission  w/ cytoskeleton  Cytoskeletons absent  Capable of endocytosis &  Not capable of endocytosis & exocytosis exocytosis  70S ribosomes  80S ribosomes  Eg. bacteria, cyanobacteria  Eg. plants, animals, fungi, algae, (BGA), mycoplasmas protozoans CELL WALL Functions: - Provides rigidity to the plant - Protects the plant cell from bursting under hypotonic condition Chemical components of cell wall: CELLULOSE PECTIN LIGNIN PLASMA MEMBRANE Also called cell/cytoplasmic membrane Fluid (as described by the Fluid Mosaic Model) Functions: 1) Regulate the transport of molecules in & out of the cell 2) Site of enzyme specific activity  PLASMODESMA/TA  small channels that directly connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells CYTOPLASM  Thick fluid  80% water — containing amino acids, lipids, carbohydrates, ions, and enzymes  Site of many chemical reactions  Suspends organelles & other substances NUCLEUS  “control center” bec. it coordinates all the cell's activities, which include growth, intermediary metabolism, protein synthesis, and reproduction (cell division).  it stores the cell's hereditary material, or DNA  Nucleolus – where ribosomes are produced  Chromosomes – threadlike structures inside the nucleus that carries the genetic material (where DNA is packed) ENDOPLASMIC RETICULUM  processes, and transports a wide variety of biochemical compounds for use inside and outside of the cell  Rough ER - contains ribosomes - site of protein synthesis  Smooth ER - w/o ribosomes - for production of lipids & hormones RIBOSOMES  On the cytoplasm as free ribosomes and in rough ER  Synthesize proteins  Produced in the nucleolus GOLGI APPARATUS  also called Golgi body or Golgi complex  found in both plant and animal cells  composed of membrane- covered sacs called cisternae  the packaging and shipping/distribution department for the cell's chemical products. MITOCHONDRION  double-membraned  site of ATP synthesis via Cellular Respiration  power generator of the cell, converting oxygen and nutrients into adenosine triphosphate (ATP)  CYTOSKELETON MICROTUBULES  gives shape to the cell; protoplasmic streaming & bldg blocks of cilia, centriole (direct the cell during cell division), basal bodies & flagella (locomotory structure) MICROFILAMENTS  for strength when exposed to mechanical stress; muscle contraction INTERMEDIATE FILAMENTS  maintain cell shape; suspend & organize organelles; interconnect cytoskeletal elements & organize enzymes attached to them LYSOSOMES & MICROBODIES  Lysosomes - “garbage system”of the cell - Contain hydrolytic enzymes for digestion of biomolecules; protect cell from foreign materials; digest subcellular parts as immediate fuel during cell starvation (“suicidal bag”)  Microbodies Peroxisomes - contain enzymes for oxidation of substances Glyoxisomes –contain enzymes for conversion of fats to carbohydrates CHLOROPLAST –- plastids that have photosynthetic function - contain pigment chlorophyll. VACUOLES  Membrane bound sac filled with liquid that contains a variety of materials (sugars, organic acids, minerals, etc.) in addition to water  Helps the cell maintain its shape; for space filling as cell grows  VAULTS  A newly discovered organelle ( 1990’s)  Cytoplasmic ribonucleoproteins shaped like octagonal barrels (as the shape of nuclear pore)  Thousands in a cell  Cellular “trucks” – dock at nuclear pores, pick up molecules synthesized in the nucleus & deliver to various places in the cell (eg. mRNA to ribosomes for protein synthesis)