Exam 3: Cells and Membrane Flashcards
What occurs when the power of magnification increases to the diameter of field?
The diameter of field decreases
Depth of Focus
The depth of focus refers to the depth or thickness of the specimen that is simultaneously in focus. At any time, you will only be able to focus the microscope upon a certain level or plane of the specimen.
Who viewed cells for the first time?
Rober Hook in 1665
Compound Light Microscope
-Illumination source?
-Power of magnification?
- Preparation of specimens?
-Illuminating source, light.
-Power of magnification, 2000x
-Preparation? prepared with a cover slip or cover glass over the specimen, with a mount of fluid, and carefully at an angle to prevent air bubbles.
Characteristics of an Electron Microscope?
-Illumination source?
-Power of magnification?
-Illumination source, electrons
-Power of magnification, 100,000x to 5 million times.
Scanning Electron Microscope
-Scans the overall surface
- Sometimes coated in gold.
- 3-D image
-100,000x magnification
Transmission Electron Microscope
- View internally
-Thin slices - Stain with heavy metals
-Electromagnets used to focus.
-up to 5 million times magnification.
Francesco Redi 1668
Conducted controlled experiments, redi showed maggots only appeared on flesh in open jars that allowed flies to visit. So maggots do not spontaneously generate from rotting flesh.
Louis Pasteur 1862
Disapproved spontaneous generation once and for all with broth.
What cell theory point is known as the biogenesis law? (Virchow 1858)
All cells arise from pre-existing living cells.
The cell theory points by Schleiden & Schwann (1839)
- The cell is the basic structural and functional unit of life.
-All living things are made up of cells.
Surface to Volume Ratio
As cells increase in size, volume increases proportionately faster than surface area.
Prokaryotes
-Nucleus?
-Organelles
-Examples:
Lack nucleus
Lack organelles
Example: bacteria, archae, cyanobacteria.
Eukaryotes
-Nucleus?
-Organelle?
-Examples:
Nucleus present
Organelles present
Examples: protists, fungi, plants and animals.
Rough Endoplasmic Reticulum
Modification of polypeptides to form a protein.
Smooth Endoplasmic Reticulum
Lipid synthesis, detoxification, and storage.
Lysosome
Intracellular digestion.
Peroxisomes
Digestion of wastes (hydrogen peroxide)
Centrosomes
initiate microtubule formation.
Flagella
long , few in number and locomotion.
Cilia
shorter, numerous, and locomotion, the movement of surrounding fluids.
Capsules
Protective layer surrounding the cell wall. Stinky for attachments. Prevents WBC from recognizing and destroying the bacterium.
Fimbriae
Important in infection for some cells, helps the bacteria adhere to its host
Interaction of Organelles in the process of secretion.
- Begins in nucleus, genetic code copied into RNA.
- RNA is carried to the ribosomes, where the assembly of polypeptides is begun.
- Rough ER then modifies the protein and transports
- Golgi Apparatus packages
- Secretion vesicles pinch off from the Golgi’s ends, then are pushed to the plasma membrane through EXOCYTOSIS.
Bacterial Structure
Lack nucleus (nucleoid region)
Lacks organelles
Plasmids, cytoplasm, ribosomes, PM, cell wall, capsules, and fimbriae.
Flagella is common.
What do prokaryotes HAVE?
Plasma membrane, nucleoid region, plasmids, capsules, ribosomes, cytoplasm, cell wall, fimbriae, and flagella is common.
What do animals NOT have in their cells?
Cell wall, chloroplast, central vacuole, plasmids, capsules, fimbriae, nucleoid region.
What do animal cells have that are common?
Flagella and cilia
What do plants do NOT have?
Plasmids, capsules, nucleoid region, and fimbriae.
Are centrosomes in plant cells?
Some plant cells, no centrioles.
Is cilia and flagella seen in plant cells?
Some plant cells.
Xylem
dead at maturity, perforations in cells;form tubes for water transport. Hollow tube (cohesion and adhesion)
Pholem
Alive at maturity but no nucleus, perforations, form tubes for sugar transport.
Gram positive bacteria
Primary cell component is peptidoglycan, penicillin acts on this.
Gram negative bacteria
Primary component of the cell wall is lipopolysaccharide and penicillin is not effective.
Will stain pink
Coccus
Spherical
Bacillus
Rod shaped
plasmids
additional pieces of DNA, may contain antibiotic-resistant genes.
Infolding of plasma membrane
formed ER, Golgi, and nuclear membrane.
What cells came from what cells?
Eukaryotic cells came from prokaryotic cells.
Endosymbiotic Theory
Mitochondria and chloroplasts were once free-living prokaryotes, they came to reside within larger cells. Eukaryotic cells originated from membrane infolding and prokaryotes establishing permanent residence within larger cells.
What is some evidence that supports the endosymbiotic theory?
Same size as bacteria
Own DNA, very different from the nucleus.
Reproduce independently.
Own ribosomes (prokaryote size)
Some bacteria today resembles mitochondria and chloroplasts
Origin of multicellularity
aggregate of colonies of single-celled organisms began chemical communication; division of labor (some feed other, reproduce) for example? Slime mold
Desmosomes (adhering junctions)
Protein fibers extend between adjacent cells “weaving” them together.
Common in skin, uterus, stomach, and heart.
Tight junctions
Proteins in the membrane between adjacent cells bond. Very little space between.
Prevents fluid from moving across a layer of cells
example: bladder and intestine.
Gap junctions
Hollow channel proteins bond between adjacent cells for rapid transport between them.
Example: Cardiac and embryonic cells.
Plasmodesmata
Specialized openings in their cell walls. The cytoplasm of adjoining cells is connected.
Examples: phloem cells
Glycoproteins and Glycolipids
Carbohydrate chain extends to exterior. For cell identity, immunity, tissue typing, and organ transplant.
Appropriate opposite charges and shapes.
What structures are included in the fluid mosaic model?
Phospholipids, cholesterol, proteins, glycoproteins, glycolipids and receptors.
