2.1 Cell Structure Flashcards
What is the Nuclear Envelope
A Double Membrane surrounding the nucleus
What is the nuclear pore
Holes which RNA can exit
What is the DNA wound around histone proteins called?
Chromatin
What do the mitochondria do?
Site of ATP production during aerobic respiration with an inner cristae
Which structure is a stack of membrane flattened sacks where proteins are modified and sent?
The Golgi complex
What are centrioles
Two bundles of microtubules made of tubulin and arranged to form a cylinder
What provides shape and support to the cells?
Microtubules
What is the purpose of a micro tubule?
Provide shape and support
Help substances move through the cell
Form spindles to move chromosomes
Made of tubulin
Form cilia,centrioles and undolphia
What organelle contains hydrolytic isotopes so they can engulf old organelles?
Lysosomes
What is the difference between rough and smooth ER?
Rough Er- Ribosomes creating an intracellular transport system
Smooth ER- No ribosomes Contain enzymes involved with lipid metabolism
How large are intermediate filaments and what are there purpose?
- 10 nm
- Strengthen the cell
What are the three plant organelles?
- Vacuole- Surrounded by toroplast and maintains cell stability
- Chloroplasts- Large organelle with a double membrane
- Cell wall- Permeable and provides strength and support
What are the four points of modern cell theory?
- Cells contain hereditary info which is passed from cell to cell
- All cells are basically the same in chemical composition
- All basic chemical and physiological are carried out inside cell
- Cell activity depends on sub cellular activity
Why are stains used in microscopes?
- Chemicals bind to the specimen to create a contrast
What is an eyepiece graticule?
The scale on the eyepiece that does not change in size when you magnify the image
What is the stage micrometer?
A small ruler of a known length (usually 1mm) which is on the slide and changes based on magnification
Stages of using graticules?
- Insert eyepiece graticule (100 divisions)
- Place stage micrometer and focus
- ## align graticule and stage micrometer
How are samples made?
Sectioning: Specimens embedded in wax or dehydrated then sections are cut without changing structure (risk of material distorting)
What are artefacts?
- Damage caused in specimen preparation and can be confused for structure
- Result of mechanical or chemical action
What is the idea of Endosymbiosis?
The idea that organelles were originally prokaryotic cells that were engulfed by other prokaryotic cells but not digested
What is the evidence for Endosymbiosis?
- Mitochondria and chloroplast divide like bacteria
- Divide independently of the cell
- Independent DNA in organelles
- Same size as prokaryotes
What is a mesosome?
The infolding of a plasma membrane associated with DNA during cell division which helps with the formation of new cell walls
What are pilli?
For prokaryotes to attach to other cells or surfaces involved in sexual production
What are the cell membranes made of in prokaryotes?
- Peptidoglycan cross linked
What is Gram staining?
- Microscopy stain in order to identify the types of bacteria
- Can be gram + or gram -
What are the stages of gram staining and why?
1) Crystal Violet- Stains all of the bacteria to provide a contrast and is left for 60s
2) Iodine solution- stains them all blue which attaches to the gram + cocci (60s)
3) Alcohol- washes the stain of negative bacilli (5-10s)
4) Eosin- stains negative bacilli pink (45s)
Why are the gram stains different colours?
Gram positive have a larger amount of peptidoglycan
What are microtubules made from?
Protein subunits called tubulin
What are the roles of microfilaments?
- Give support and mechanical strength
- Allows for cell movement
What is Atomic force microscopy useful for?
- Normal cell systems and living systems
- How drugs interact
- Identifying compounds
CANNOT SEE INSIDE CELLS
What are the features of Transmission Electron Microscope?
- Beam of electrons
- Resolution of 0.5 nm
- Magnification of x500 000 to x2 000 000
- Metal salts as a stain
What are the advantages and disadvantages of Transmission Electron Microscopes?
Advantages- Seeing cell ultrastructure, high magnification
Disadvantages- Samples have to be killed and fixed,expensive,artefacts
What are the features of a scanning electron microscope?
- BEam of electrons sent across surface
- Magnification is x15 to 200 000
- Stain = COated with a fine layer of metal
What are the advantages and disadvantages of an SEM microscope?
- Advantages- Useful for 3D images, studying the appearance of organisms
- Very large and expensive
What are the features of super resolved fluorescence microscopy?
- Uses light and images
- High resolution
- Fluorescent dyes used as stain
What are the advantages and disadvantages of super resolved fluorescence microscopy?
Advantages- High resolution,viewing DNA
Disadvantages- Dyes may effect cell function
What are the features of Laser Scanning?
- Lasers
- Resolution- 500 nm
- Stain- Fluorescent dyes
What are the advantages and disadvantages of Laser scanning?
Advantages- 3D images overlapped,non invasive
Disadvantages- Resolution limited, dyes may interfere with cell functions
