The Cell Flashcards
Define 3 important parameters in microscopy
Magnification: the ratio of an objects image size to its real size
Resolution: The measure of the clarity of the image aka the minimum distance two points can be separated and still be distinguished as separate points.
Contrast: the difference in brightness between the light and dark areas of an image
What are some methods to enhance contrast?
Staining or labelling cell components.
How is the resolution related to the source used by a microscope?
The resolution is inversely proportional to the wavelength of the light or electrons used for imaging
List the four basic tenets of cell theory.
1) All living things are composed of cells
2) The cell is the basic fundamental and functional unit of life
3) Cells arise from pre existing cells
4) Cells carry genetic material in the form of DNA
What are the similarities between Eukaryotic and prokaryotic cells?
They are both bounded by a selective plasma membrane
They both have a cytosol in which sub cellular components are suspended in.
They contain chromosomes which carry genes in the form of DNA
They both contain ribosomes which form proteins according to the instructions from the genes.
What are the major differences between
The DNA in a eukaryote is stored in the NucleusIn prokaryotes the DNA is concentrated in a region that is not enclosed in a membrane called the nucleoide.Prokaryotes carry membrane bound structures which are absent in eukaryotic cells.
Eukaryotic cells are much larger than prokaryotic cells
Define the structure and function of the nucleus in a eukaryotic cell.
Structure:
The nucleus is about 5 micrometers in diameter and is enclosed by a nuclear envelope separating its contents from the cytoplasm. The nuclear envelope is a double membrane and each membrane is a lipid bilayer with its own associated proteins. These membranes are about 20-40 nanometers apart and the envelope has porous structures of about 100nm in diameter. The nuclear side of the envelope is lined by the nuclear lamina which is a net like array of protein filaments that maintain the shape of the nucleus by supporting the nuclear envelope mechanically. The genetic material is organised by the nuclear matrix. The DNA is stored in the nucleus within structures called chromosomes and each chromosome carries one long DNA molecule that’s associated with many proteins and these proteins help coiled the DNA molecule so that its length can be reduced to fit fit into the nucleus. A typical human cell has 46 chromosomes in its nucleus (except sperm and egg cells)
