Cell Biology 1 Flashcards
Name 3 types of microscopy and give examples
Optical microscopy:
Conventional microscopy, Fluorescence microscopy, confocal/multiphoton microscopy and stimulated emission depletion microscopy
Scanning probe microscopy:
Scanning Tunneling Microscope (STM), Atomic Force Microscopy, Near-field scanning optical microscopy and more
2. Electron microscopy
Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), focus ion beam microscopy (FIB)
What is the definition of magnification and resolution?
Magnification- the increase in the apparent size of an object
Resolution- the measure of the clarity of an image. In other words, it is the ability of an instrument to show two objects as separate
Steps of optical microscopy
- Light passed through specimen- focused by glass lenses
- Image formed on human retina
- Max magnification about 1000 x
- Resolves objects separated by 0.2 micrometer, 500 x better than human eye
Describe the details of a Transmission Electron Microscope
Electrons are passed through the specimen
Focused by magnetic lenses
Image formed on fluorescent screen- similar to TV screen- image is then photographed
Resolves objects separated by 0.00002 micrometers, 100,000x better than human eye
Describe the details of confocal microscopy
- Narrow laser beam scanned across transparent specimen
- Beam is focused at a very thin plane
- Allows microscopist to optically section a specimen
- Sections made at different levels
- Allows assembly of 3D image on the computer screen that can be rotated
What is the average range in cell size?
1mm - 1 micrometer
Why do cells need a large surface area of plasma membrane?
To adequately exchange materials
The SA to volume ratio requires that cells be small
Large cells- SA to volume ratio requires that cells be small
Large cells- SA to volume decreases
Volume is living cytoplasm- demands nutrients and produces wastes
Cells specialized in absorption utilize membrane modifications eg. microvilli to gently increase SA per unit volume
Describe a prokaryotic cell
Lack a membrane-bound nucleus
Structurally smaller and simpler than eukaryotic cells
Placed in 2 taxonomic domains (bacteria, archae)
Domains are structurally similar but biochemically different
Archae- live in extreme habitats
What is the average size of bacteria?
Extremely small- 1 - 1.5 micrometers wide and 2 - 6 micrometers long
What are the 3 basic shapes?
Spherical coccus, rod-shaped bacillus, spiral spirillum (if rigid) and spirochete (if flexible)
What does the cell envelope include?
Plasma membrane
mesosomes
cell wall
Glycocalyx
Capsule
Flagella
Ribosomes
Nucleoid
What do eukaryotic cells (domain eukarya) include?
Protists
Fungi
Plants
Animals
Cells contain membrane-bound nucleus that houses DNA, specialized organelles, plasma membrane & much larger than prokaryotic cells
What is the cell membrane structure and function like?
Phospholipid bilayer with proteins that function as channels, markers & receptors
Contains cholesterol- gives rigidity
Cell membrane function- selectively permeable boundary between the cell and the external environment
What is the nucleus structure and function?
Is a sphere that contains another sphere (nucleolus)
function- storage center of cell’s DNA & manages cell functions
What is the cell wall’s structure and function?
A rigid wall made up of cellulose, proteins & carbohydrates
Function- boundary around the plant cell membrane that provides structure and support
What is the cytoplasm’s structure and function?
Gelatin-like fluid that lies inside the cell membrane
Function- contains salts, minerals and organic molecules, surrounds the organelles- NOT CYTOSOL
What is the cytoskeleton’s structure and function?
A network of thin, fibrous elements made up of microtubules (hollow tubes) and microfilaments (threads made out of actin)
Function- acts as a support system for organelles and maintains cell shape
What are the ribosomes structure and function?
Consists of 2 subunits made of protein and RNA
Function- location of protein synthesis
What is the endoplasmic reticulum’s structure and function?
A system of membraneous tubules and sacs
Function- intercellular highway- a path along which molecules move from one part of the cell to another
Two types- rER & sER