BISC 101 Lecture Notes - Lecture 3: Vacuole, Thylakoid, Exocytosis

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BISC 101 – Lecture 3 – A Tour of the Cell: Part I
Cells are the Fundamental Units of Life
Within the levels of biological organization, cells are the simplest collection of
matter that is alive
Cell theory
oAll organisms consist of cells
oAll cells are derived from pre – existing cells
Atom  Molecule  Organelle  Cell  Tissue  Organ  Organ System  Organism
oLevels of Organization
Bacterial and Achaea Cell Structures and Their Functions
According to Morphology species fall into two categories:
The basic structural and functional unit of every organism is one of two types of
cells:
oProkaryotes: Do not have a membrane – bound nucleus
Ex: Bacteria and Archaea
oEukaryotes: Contain a membrane – bound nucleus
Ex: Algae, fungi, plants, animals
Archaea (Prokaryotes) live in extreme environments
oThermophiles: Live in high temperatures
oPsychrophiles: Live in cold environments
oHalophiles: Live in very saline environments like the Dead Sea (High
levels of salt)
oAcidophiles: Live in low pH
oAlkaliphiles: Live in high pH
Archaea are NOT related to bacteria, they are instead more related to eukaryotes
oArchaea ribosomal RNA is very similar to eukaryotic rRNA
Differences Between Prokaryotic and Eukaryotic Cells
1. Eukaryotic chromosomes and DNA are found inside a membrane – bound
compartment called nuclear envelope where the nucleus is; plasmids are rare
Prokaryotes have chromosomes in a non – membrane bound nucleoid
since there is no nucleus; plasmids are very common
2. Eukaryotic cells are much larger than prokaryotic cells
3. Eukaryotic cells contain a lot of membrane – bound organelles
No membrane – bound organelles
4. Eukaryotic cells have a dynamic cytoskeleton found throughout the cell
Limited in extent for prokaryotes
5. DNA is packaged as multiple linear chromosomes
Prokaryotes have DNA packaged as a circularly arranged chromosome
6. Cytoplasm in the region between the plasma membrane and nucleus
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Cytoplasm only bound by the plasma membrane since there is no
nucleus
7. Eukaryotes divide by a process called mitosis
Prokaryotes divide by a process called binary fission
Basic Features of ALL Cells
Plasma or Cell Outer Membrane: Selective barrier allows sufficient passage of
oxygen, nutrients, and waste to service the volume of every cell
oSeparates interior environment of cell from outside
oGeneral structure of a biological membrane is a double layer or bilayer of
phospholipids
oBilayer contains carbohydrate markers for white blood cells to identify
substances as good or threatening cells
DNA: Genetic material is packaged into one or more chromosomes
Ribosomes: Small complexes where protein synthesis takes place
Cytosol: Semifluid substance within plasma membrane
Eukaryotic Cells
Eukaryotic cells are much larger than bacteria and archaea (prokaryotic cells)
oLarge size allows them to ingest bacteria and archaea whole
oHowever, ions and small molecules cannot diffuse across a large volume
fast
Eukaryotic cells are subdivided and have organelles that hold molecules required
for a specific chemical reaction
oIncompatible chemical reactions can be separated
New fatty acids can be made in one organelle while damaged fatty
acids can be recycled in a different organelles
Chemical reactions become more efficient
Eukaryotic Cell’s Genetic Instructions
Eukaryotic cell’s genetic instruction are housed in the nucleus and carried out by
ribosomes
Nucleus: Contains chromosomes and functions as an information storage and
processing center
oContains most of the DNA in a eukaryotic cell aka information central
oDoes not hold all – mitochondria and chloroplast also hold DNA
Nuclear Envelope: A complex double membrane that encloses the nucleus,
separating it from the cytoplasm
oThis envelope is a double membrane; each membrane consists of a lipid
bilayer
oStudded with pore – like openings that regulate entry and exist of
molecules from nucleus
oDNA and proteins form genetic material called chromatin
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