Intro to Cell Biology Flashcards
Cell Theory
- All organisms are composed of cells
- The cell is the fundamental unit of life
- All cells arise from other cells
Scientists who developed the cell theory:
Schleidan, Schwann, and Virchow (1800s)
A modern definition of the cell:
The basic unit from which organisms are made, consisting of an aqueous solution of organic molecules enclosed by a membrane.
All cells arise from existing cells, usually by a process of division.
Three Domains:
Bacteria, Archaea, Eukarya
Defining features of Domain Eukarya:
True nucleus (membrane bound); membrane-bound organelles; exo-/endocytosis; linear DNA bound to histones, arranged in chromosomes; cell division via mitosis and meiosis; regulation of gene expression
Organelles
Internal membranes compartmentalize specific functions
Plasma membrane
Defines cell boundaries and retains contents
Mitochondria
Site of aerobic respiration
Found in all eukaryotic cells
Tissues with high energy demands have more mitochondria
Chloroplast
Site of photosynthesis in plants and algae
The Endosymbiont Theory
Mitochondria and Chloroplasts evolved from a symbiotic relationship between ancient bacteria (aerobic and/or photosynthetic) and early eukaryotic cells
Evidence:
circular DNA (like bacteria)
replication occurs separate from the cell
Double membrane
Endoplasmic Reticulum
A network of membranes found in the cytoplasm
Composed of cisternae - tubular membranes and flattened sacs
Smooth ER
Site of lipid synthesis
Rough ER
Embedded with ribosomes
Site of protein synthesis
Golgi Complex
Stack of flattened vesicles known as cisternae
Synthesis of complex polysaccharides
Processing and packaging of secretory proteins
Lysosomes
Single membrane organelles which store hydrolases - enzymes that can digest biological molecules
A special carbohydrate lining protects lipid membrane from hydrolases - need to keep hydrolases contained in order to not digest cell
Peroxisome
Single membrane organelle
Performs several functions depending on cell type
Ribosomes
They are not organelles - they are not membrane bound
Complexes of proteins and nucleic acids which synthesis proteins in translation
Cytoplasm
Defined as the interior of the cell not including the nucleus
Contains the cytosol (semifluid substance in which organelles are suspended) as well as organelles, and the cytoskeleton
Cytoskeleton
A three- dimensional array of interconnected microfilaments, microtubules, and intermediate filaments
Extracellular Matrix
Structures outside of the cell membrane; consists mainly of collagen fibers and proteoglycans
Challenges of imaging living cells and subcellular constituents:
Resolution
Contrast
Preservation
Three-dimensionality
Examples of Model Organisms
E. coli (bacteria). S. cerevisiae (yeast), mice, C. elegans (nematode), Drosophila (fruit fly), Arabidopsis
Types of Light Microscopy:
Brightfield (unstained and stained), Fluorescence, Phase Contrast, Differential Interference Contrast, Confocal
Fluorochromes
Absorb light at one wavelength and re-emit light an a longer wavelength
