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Cell Biology
- (^) Cell biology is the study of cells
- (^) Cells are the fundamental unit of life
- (^) The smallest unit of an organism considered living; “the building block of life” Biosphere Ecosystem Florida coast Community All organisms on the Florida coast Population Group of brown pelicans Nucleus Nerve Spinal cord Cell Nerve cell Tissue Nervous tissue Organ Brain Organelle Nucleus Molecule DNA Atom Organism Brown pelican Organ system Nervous system Brain
Cell Biology
- (^) In 1665, Robert Hooke (“the father of microscopy”) used a crude microscope to examine a piece of cork and saw “little rooms” or cells
- (^) In the late 1600’s, Antoni van Leeuwenhoek described “very little animacules” using a refined lens he crafted; what he saw were bacteria!
Cell Biology
- (^) In the 1950’s, the electron microscope was introduced - (^) Passes a beam of electrons through a specimen rather than light - (^) Much greater resolution (can magnify up to 100,000x) - (^) Allows scientists to examine the internal ‘anatomy’ of a cell
Light
microscope
image of a
Paramecium
Electron
microscope
image of a
Paramecium
Cell Biology
- (^) Most cells measure between 1-100μm (remember: there are 1,000,000 μm in 1 meter)
- (^) Prokaryote cells (bacteria and Archaea) are small; 1-10 μm
- (^) Eukaryote cells are slightly larger; 10-100 μm
- (^) The maximum size of a cell is limited by the amount of surface area needed to obtain nutrients and exchange gases with the environment
Cell Biology
- (^) A large cell may have more surface area but, a small cell has more surface area relative to its volume , than a large cell of the same shape Surface area of one large cube = 5,400 μm 2 Total surface area of 27 small cubes = 16,200 μm^2 Total volume is the same for both examples shown (27,000) 30μm 10μm Area of 1 small cube = 6*(10x10) = 600
Cell Biology
- (^) There are 2 types of cells:
- (^) Prokaryotic
- (^) Eukaryotic
- (^) All cells, however, share several basic features in common:
- (^) All are bounded by a plasma membrane
- (^) All have chromosomes carrying genes made of DNA
- (^) All contain ribosomes, which make proteins according to instructions from the genes
Prokaryote cells
- (^) Prokaryote cells are structurally simpler than eukaryote cells (and smaller)
- (^) They lack a nucleus containing DNA
- (^) Instead, their DNA is coiled into a region called the nucleoid (“nucleus-like”), and no membrane surrounds their DNA
- (^) Most antibiotics target prokaryotic cells for their smaller, structurally-different ribosomes
Eukaryote cells
- (^) Eukaryote cells are larger, and more complex than prokaryotic cells
- (^) Eukaryotic cells are partitioned into functional compartments and are distinguished by the presence of a membrane-bound nucleus
- (^) All eukaryotic cells, whether from animals, plants, protists, or fungi, are fundamentally similar to one another!
Eukaryotic cells
- (^) Eukaryotic cells contain various organelles, membrane-bound structures which perform specific tasks in the cell
- (^) Many of the chemical activities of cells, known collectively as cellular metabolism (we’ll come back to this) occur within organelles
- (^) Eukaryotic cells can be subdivided into animal cells and plant cells
NUCLEUS: Nuclear envelope Plasma membrane Mitochondrion Intermediate filament Microfilament Smooth endoplasmic reticulum Rough endoplasmic reticulum CYTOSKELETON: Chromosomes Nucleolus Ribosomes Golgi apparatus Peroxisome Centriole Lysosome Microtubule
An animal cell Nuclear envelope
Nucleus
Smooth endoplasmic reticulum Rough endoplasmic reticulum CYTOSKELETON: NUCLEUS: Nuclear envelope Chromosome Nucleolus Ribosomes Golgi apparatus Plasma membrane Mitochondrion Peroxisome Cell wall Central vacuole Microtubule Intermediate filament Microfilament Cell wall of adjacent cell Chloroplast Plasmodesmata
A plant cell
The plasma membrane
- (^) The plasma membrane forms a boundary between the cell and its surroundings and controls the traffic of materials into and out of the cell
- (^) The plasma membrane and the internal membranes of the cell perform diverse functions that depend on their structure
- (^) The phospholipid bilayer creates a hydrophobic/hydrophilic structure that regulate molecular traffic into and out of the cell
Hydrophilic heads Hydrophobic tails Proteins Hydrophobic region of protein Inside cell Hydrophilic region of protein Outside cell
The plasma membrane
- (^) Proteins form channels that allow specific ions and other hydrophilic molecules to cross the membrane
