Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
3.1 Magnification and Resolution
What is the equation for Magnification? |
Magnification = size of image/size of sample
|
|
|
What is a micrometer and nanometer in term of a meter?
|
1 micrometer= 10 to the power of -3
1 nanometer= 10 to the power of -9 |
|
|
Define Cell Fractionation
|
The process by which cells are broken up in order to study the different organelles
|
|
|
In what conditions can cell fractionation occur and why?
|
Cold = to reduce enzyme activity which could break down the organelles
Isotonic = stopping damage via osmosis Buffered = to maintain pH |
|
|
What are the steps of Cell Fractionation?
|
Homogenisation - blending cells to release organelles
Filtration - to get organelles from the homogenate Ultracentrifugation - placing the filtrate into a test tube, spinning (heaviest organelles fall to the bottom), removing light top layer, spinning, removing the next lightest organelles (repeat) |
|
|
3.2 Microscopes
What is the advantage of an Electron Microscope and compare it to the light microscope? |
Light Microscopes have a longer wavelength - thus the resolution is poor
Electron Microscopes have a shorter wavelength - it has a high resolving power. The beam can be focused via electromagnets (neg charge) |
|
|
How does a Transmission Electron Microscope work?
|
A condenser electromagnet focuses the beam of electron on a thin specimen - parts absorb the electrons (and are darker) than those who do not
|
|
|
Name one advantage and three limitations of the TEM
|
Advantage = You can take a Photomicrograph
Limitations - must be in a vacuum - cannot be alive . complex staining process - only black and white . Image may contain an artefact |
|
|
How does a Scanning Electron Microscope work?
|
A beam of electrons is passed from above and moved back and forth in a regular pattern. The scattering of the electrons determines the contours of the specimen surface.
|
|
|
Name one advantage and three limitations of the SEM
|
Advantage = You can construct a 3D image
Limitations = must be in a vacuum - cannot be alive . complex staining process - can be in colour . Lower resolving power than TEM |
|
|
3.3 Structure of an Epithelial Cell
Define Ultrastructure |
The internal structure of a cell which is suited to its job
|
|
|
What are the different parts of the Nucleus and what are their functions?
|
Nuclear Envelope - double membrane, controls reactions
Nuclear Pores - large molecules can exit (ie. RNA) Nucleoplasm - granular, jelly like majority of nucleus Chromatin - different form of chromosomes, DNA Nucleolus - in Nucleoplasm, manafactures RNA and ribosomes |
|
|
What are the different parts of the Mitochondria and what do they do?
|
Double Membrane - controls entry and exit of molecules
Cristae - large surface area for enzymes for respiration Matrix - site for proteins, lipids and DNA, enzymes found here. |
|
|
What are the two types of Endoplasmic Reticulum and what do they do?
|
Rough Endoplasmic Reticulum (ribosomes on surface) - large surface area for the synthesis of proteins and glycoproteins, pathway for transport (ie.protein) in the cell
Smooth Endoplasmic Reticulum - synthesise, store and transport lipids and carbohydrates |
|
|
What is the Golgi Body and what does it do?
|
It is formed of flattened sacs (Cisternae) and vesicles.
It - Receives proteins and lipids from the ER . Adds carbohydrates to proteins to form glycoproteins . Produces secretory enzymes . Secretes Carbohydrates . Transport, modifies and store lipids . Form lysosomes |
|
|
What are Lysosomes and what do they do?
|
Vesicles produced by the Golgi Body containing enzymes
They - break down material ingested by the phagocytic . Exocytosis to break down external cell material . Digest worn out organelles to re-use chemicals . Autolysis (break down worn out cells) |
|
|
What are Ribosomes and what do they do?
|
Small cytoplasmic granules. They are important in protein synthesis
|
|
|
3.4 Lipids
What are the four common characteristics of Lipids? |
. Contain carbon, hydrogen and oxygen
. Smaller oxygen to carbon and hydrogen is smaller than in carbohydrates . Insoluble in water . Soluble in organic solvents (i.e. alcohol) |
|
|
What are the five main roles of lipids?
|
. Plasma Membranes (phospholipids) for the movement of lipid soluble material and flexibility
. Energy Source (when oxidised) . Waterproofing . Insulation . Protection |
|
|
What is a triglyceride?
|
Fats and oils
|
