Chapter 6 Flashcards
A Tour of the Cell
Microscopy
A technical field that uses microscopes to view objects and areas of objects that cannot be seen with the naked eye
Light (visible)
Visible light is passed through the specimen & then through glass lenses. Refracts light in a way, becomes bigger
380 - 700 nm.
Magnification
Ratio of an objects (visual) size to real size
Resolution
A measure of clarity of image; it is the minimum distance between 2 points that can be separated and still be distinguished as separate points. Inversely related to wavelength. As resolution increases, wavelength decreases.
Wavelength
The distance over which a wave’s shape repeats. Inversely related to resolution. As wavelength increases, resolution decreases.
Contrast
Difference in brightness between light & dark areas
Stain
A discoloration that can be clearly distinguished from the surface, material, or medium it is found upon
Condenser
Device used to condense a substance from its gaseous to its liquid state
Robert Hooke
Cells. 1665. Dead bark.
Light Microscope (LM)
visible light is passed through the specimen and then through glass lenses. The lenses refract (bend) the light in such a way that the image of the specimen is magnified as it is projected into the eye or into a camera.
Electron microscope (EM)
Focuses a beam of electrons through the specimen or onto its surface. Electron beams have much shorter wavelengths than visible light.
SEM-Scanning EM
Scans surface, usually coated w/ a thin film of gold. Beam excites electrons on surface, secondary electrons are detected by device that translates pattern of e- into an electronic signal sent to a vid screen. 3D.
TEM- Transmission EM
Internal part of cell. The TEM aims an electron beam through a very thin section of the specimen. For the TEM, the specimen has been stained with atoms of heavy metals, which attach to certain cellular structures, thus enhancing the electron density of some parts of the cell more than others. The electrons passing through the specimen are scattered more in the denser regions, so fewer are transmitted.
Centrifuge(use)
Useful in cell fractionation, takes cell apart. Spins test tubes holding mixtures of disrupted cells at different speeds->results: subset of cell component comes to rest on bottom
Cell Fractionation
Takes cell apart & separates major organelles & other subcellular structure from one another.
Prokaryota
Domain Bacteria/Archaea. Avg. bacteria: 1-5 micrometers. DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid
Eukaryota
Domain Eukarya. Avg. Eukarya cell: 10-100 micrometers. DNA in an organelle called nucleus. Bound by a double membrane
Cytoplasm
Semifluid substance of a cell that’s external to the nuclear membrane, internal to the cellular membrane. Region between nucleus & plasma membrane.
Surface vs Volume of Cell
Smaller cell = greater ratio of surface area to volume. Plasma membrane to use.
Diffusion
The net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration.
Membrane Structure
Phospholipid bilayer + glycoproteins. ECM and microfilaments. Figure 6.6
Animal v Plant cells
Figure 6.8
Nucleus
Contains most of the genes in the eukaryotic cells.
Nuclear Envelope
Encloses Nucleus, separating its contents from the cytoplasm. A double membrane.
Nuclear Pores
Protein-lined channel in the nuclear envelope that regulates the entry and exit of proteins and RNAs, as well as large complexes of macromolecules
Nuclear matrix
a framework of protein fibers extending throughout the nuclear interior. Functions include gene expression, RNA splicing, and nuclear protein import/ export.
Chromatin
A complex of DNA and proteins called histones that packages the DNA double helix into a compact form that can fit in the cell nucleus.
Chromosomes
Structure that carry the genetic information. Each chromosome contains one long DNA molecule associated with many proteins.
Nucleolus
A mass of densely stained granules and fibers adjoining part of the chromatin. Where a type of RNA called ribosomal RNA (rRNA) is synthesized from genes in the DNA. Ribosomal proteins are also stored here.
Ribosomes
Complexes made of ribosomal RNAs and proteins. Site of protein synthesis.
Ribosome Function
Cellular components that carry out protein synthesis
Free vs. Bound Ribosomes
Free ribosomes are suspended in the cytosol, while bound ribosomes are attached to the outside of the endoplasmic reticulum or the nuclear envelope.