BIOL120 Study Guide - Midterm Guide: Scanning Electron Microscope, Matthias Jakob Schleiden, Symbiogenesis

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5 Aug 2016
Lecture 1
25% of plants are found in drugs
How do plants enhance the quality of life?
 medications
 ecosystem diversity
 biofuels
Challenges that plants have to face
1. Harvesting light energy
2. Getting out of the water
3. Locking in moisture when water is not available
4. Coping with gravity
5. Dividing
6. Using resources
Cells were first observed and discovered by Robert Hooke, cellula in latin means “small room”
Cells must stay small so that the surface area, which allows for exchange of oxygen, water and
nutrients, can supply the needs of the internal regions for a given volume
 if cells grow too big, its genetic material cannot supply information fast enough to meet the
needs of the cell. (page 27)
Light microscopes give images of the cell
Transmission electron microscope (TEM) reveals structures of a cell by passing through a thin
layer of tissue  this type of microscope achieves the highest resolution
Scanning electron microscope reveals the surface of a cell
German botanist Matthias Schleiden concluded that microscopic studies confirmed that plants
are composed of cells
 A year later, Theodor Schwann confirmed that animals are also composed of cells
Cell Theory: the cell is the basis of an organism’s structure and reproduction
1. Organisms are made up of one or more cells
2. The cell is the basic structural unit of all organisms
3. Cells can only arise from existing cells
Prokaryote means “before the nucleus”, and eukaryotes, meaning “true nucleus” evolved from
Kingdom Protista: single-celled and simple multicellular eukaryotes. Animals, fungi, and plants
evolved from ancient protists (page 362)
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Kingdom plantae (plants): multicellular photosynthetic eukaryotes adapted for life on land
(page 362)
Prokaryotic cells range between 0.2-10 micrometers
 do not have organelles
 surrounded by a cell membrane that controls movement of water, gases, and molecules
Eukaryotic cells range between 5-300 micrometers
 have organelles surrounded by one or two membranes
 some organelles have “chromosomal” DNA configured in a loop (like bacteria) – explained by
the endosymbiotic theory
Endosymbiotic theory: a theory that suggests that the ancestors of some organelles evolved
because of prokaryotic cells that ingested other prokaryotic cells. (Page 588)
 organelles such as the mitochondria and chloroplasts and nuclei probably originated as
prokaryotes that invaded another cell.
 in primary endosymbiosis, a photosynthetic prokaryote was engulfed by a heterotrophic cell,
and the resulting cell evolved into an alga
 in secondary endosymbiosis, an alga was engulfed by another heterotrophic cell  resulting
with a chloroplast with 3 membranes
Prokaryotes and Eukaryotes similarities:
1. Have similar metabolic processes
2. Produce macromolecules
 4 types of macromolecules
1. Protein (make up amino acids, structural and enzymatic)
2. Lipids (hydrophobic, stores energy, building blocks of membranes)
3. Carbohydrates (composed of carbon, hydrogen, and oxygen – stores energy)
4. Nucleic acids (DNA and RNA stores genetic information, and programs the biological
activities of the cell)
Plants cellular structure
 chloroplast and a large central vacuole
Protoplast: everything except the cell wall
cytoplasm: all the parts of the cell within the cell membrane
apoplast: the between the cell wall and the outside of the protoplast
symplast: the “cytoplasmic” bridge between cells
Plasmodesmata is the same thing as plasma membrane or cell membrane
Lecture 2
Importance of plants – actin based organelle movement, no centrioles
Photosynthesis sustains the life system – , energy, organic compounds
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