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ArianaMejiaCh6-7 Cell/Membrane Structure and Function (Cells (All Cells…
ArianaMejiaCh6-7 Cell/Membrane Structure and Function
Microscope & Biochemistry of cells
Microscopy
Important Parameters
Resolution- the measure of the clarity of the image, or minimum distance of two distinguishable points
Contrast- visible differences in brightness between parts of the sample
Magnification-the ratio of an object's image size to its real size
Light Microscope (LM)
Vision light is passed throughthe specimenand then through glass lenses
Brightfield (Unstained Specimen)(Stained Specimen)
Electron Microscope(EMs)
Scanning electron microscope (SEMs)
Is useful for detailed study of the topography of a specimen
Transmission electron microscopes(TEMs)
Is used to study the internal structure of cells
Focuses a beam of electrons through the specimen or onto its surface
Cell Fractionation
Takes cells apart and separates the major organelles from one another
Enables scientists to determine the functions of organelles
Useful technique for studying cell structure and function
Cells
Prokaryotic
No nucleus
DNA in an unbound region called Nucleoid
No membrane-bound organelles
Cytoplasm bound by the plasma membrane
"Before Nucleus"
All Cells
All bounded by selective barrier, called Plasma Membrane
Allows sufficient passage of oxygen, nutrients, and wasre to service the volume of every cell
Semifluid substance called cytosol
Chromosomes(carry genes)
Ribosomes (make proteins)
Lysosomes
small membranous sacs that contain digestive enzymes
Golgi Apparatus
synthesis digestive enzymes for lysosomes
a complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involved in secretion and intracellular transport.
Rough Endoplasmic Reticulum
Has bound ribosomes, which secrete glycoproteins
Distributes transport vesicles, secretory proteins surrounded by membranes
Smooth Endoplasmic Reticulum
Synthesizes lipids
Metabolizes carbohydrates
stores calcium ions
Eukaryotic
DNA in a nucleus that is bounded by double membrane
Membrane bound organelles
Cytoplasm in the region between the plasma membrane and nucleus
Much larger than prokaryotic cells
As a cell increases in size, its volume grows proportionately more than its surface area
Surface area To Volume (S-to-V) ratio [surface area ÷ volume]
Nucleus- House DNA
Nucleolus- a small dense spherical structure in the nucleus of a cell during interphase.
Nucleoplasm- the substance of a cell nucleus, especially that not forming part of a nucleolus.
Nuclear Envelope- a double membrane that encloses the nucleus
Diffusion-is the tendency for molecules to spread out evenly into the available space
Osmosis- diffusion of water across a permeable membrane
Tonicity is the ability of a surrounding solution to cause a cell to gain or lose water
Isotonic solution: Solute concentration is the same as that inside the cell
Hypertonic solution: Solute concentration is greater than that inside the cell; cell loses water
Hypotonic solution: Solute concentration is less than that inside the cell; cell gains water
Hemolysis- The destruction of red blood cells which leads to the release of hemoglobin from within the red blood cells into the blood plasma.
Lysis- as a result of viral or osmotic mechanisms that compromise the integrity of the cell membrane.
Osmoregulation, the control of solute concentrations and water balance, is a necessary adaptation for life in such environments
Passive Transport- The diffusion of a substance across a biological membrane, because no energy is expended by the cell to make it happen
Facilitated diffusion- transport protein required
Plasma Membrane
A membrane surrounding all animal cells
Functions of plasma membrane
Electrical chemical gradient- establishes and maintains a electrical charge difference across the plasma membrane
Physical Barrier- protects cellular contents and supports cell structure
Contains receptors that recognize and respondsto molecular signals.
Membrane proteins structures and function
Integral proteins- embedd and extend through the lipid balayer
Receptor-is a protein molecule that receives chemical signals from outside a cell
Ligand- substance that forms a complex with a biomolecule to serve a biological purpose
Carrier transport- integral membrane proteins
Peripheral proteins- bound to the surface of the membrane
Both Peripheral and Integral
Enzymes-attached to eighter internal or external surfaces of cells
Linker-filaments inside and outside the plasma membrane
Glycoprotein-protein that has carbohydrate groups attached to the polypeptide chain
Active process-requires the expenditure of cellular energy
Active Transport-the movement of ions or molecules across a cell membrane into a region of higher concentration
Vesicular transport- involves a vesicle
Exocytosis- vesicular contents realized from cell
Phagocytosis
Pinocytosis
Endocytosis- material brought into cell
