Cell Structure Flashcards
M2 (41 cards)
Describe the features of a light microscope.
-It contains 2 lenses: the eyepiece and objective lens that magnify the specimen.
-It has a light source and a mirror to direct the light onto the specimen.
-Radiation used is through light waves, no vacuum is needed.
-It can view both live and dead specimen.
-Advantages: able to see colour, view live specimen, cheap, easy to use.
-Disadvantages: lower magnification and resolution.
List all the parts of a light microscope.
-Ocular eyepiece lens, body tube, revolving nose piece, objective lens, stage clips, diaphragm, light source, arm, stage, course adjustment knob, fine adjustment knob, base.
Describe the features of a transmission electron microscope (TEM).
-Radiation used is a beam of electrons, as they have a smaller wave length than light waves.
-Their method of focusing is through electromagnets.
-They require a vacuum.
-Electrons go through samples (transmitted).
-Advantages: higher magnification and resolution.
-Disadvantages: need to be trained to use it, expensive, large, only dead specimens can be viewed, presence of dead artifacts/ debris, thin surface.
Describe the features of a scanning electron microscope (SEM).
-The specimen is coated with metal or gold so that the beam of electrons is unable to penetrate it and electrons bounce of its surface (reflected)
-Black and white images can be colour enhanced to highlight features.
-Advantages: 3D images, doesn’t need to be thin.
-Disadvantages: lower magnification and resolution than TEM
What is the use of staining in light microscopy?
-They are used as cells are often transparent.
-Stains which act on a whole cell improve contrast, so the cell is more visible against the background and allows them to be identified. E.g. methylene blue can identify cheek cells.
-Some stains act on individual cell components, so they can be distinguished from one another.
-Differential staining= can be used to differentiate between organelles within a cell. By cell components taking up the stain in different amounts.
Describe the process of making an animal cell slide.
1.Using a sterile cotton bud, wipe the inside of your cheek to remove cells.
2.Wipe the cotton bud onto a clean slide.
3.Add a drop of methylene blue stain.
4.Gently lower a cover slip over the slide to avoid any air bubbles.
5.Remove any excess stain using a paper towel.
Describe the process of making an plant cell slide.
1.Select a small piece of onion and remove the epidermis using some forceps.
2.Place the epidermis, as flat as you can, onto a clean slide.
3.Add a couple of iodine solution on top of the epidermis.
4. Gently lower the coverslip.
Describe how to produce an ideal biological drawing.
-Use a sharp pencil, clear continuous lines that enclose shapes, no form of shading, accuracy, make it large enough, include a title, labels should be written horizontally, make sure label lines don’t cross each other.
What does magnification mean?
magnification is the number of times larger the image is than the actual size of the specimen.
State all the magnification calculations.
Magnification = image size/actual size
-Actual length = scale line
Total Magnification = mag of objective lens x mag of eyepiece lens
What does resolution mean?
it is the distance two objects need to be apart to see them as separate entities.
What does ultrastructure mean?
the ultrastructure of a cell is those features that can be seen with an electron microscope.
Name all the organelles in an animal cell.
-Nucleus, nucleolus, nuclear envelope, nuclear pore, centrioles, ribosomes, Golgi vesicle, rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), lysosome, mitochondria, cytoplasm, plasma membrane, Golgi apparatus, chromatin, cytoskeleton, cilia, microtubule.
Name all the organelles in a plant cell.
-Nucleus, nucleolus, nuclear envelope, nuclear pore, centrioles, ribosomes, Golgi vesicle, rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), plasma membrane, cytoplasm, mitochondria, plasmodesma, middle lamella, cellulose cell wall.
-Permanent vacuole- tonoplast, cell sap.
-Chloroplast- grana, envelope.
What is the function of the nucleus?
-Contains DNA and ribosomes that carry the code that instructs the cell what proteins to make.
-Produces the ribosomes.
What is the function of the nuclear envelope?
-A double membrane that surrounds the nucleus containing nuclear pores. It controls what goes in and out the nucleus.
What is the function of the nuclear pore?
-A protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and cytoplasm.
What is the function of the chromatin?
-To package long DNA molecules into more compact, denser structures.
What are the functions of both SER and RER?
-Rough endoplasmic reticulum (RER): a network of membranes, which is continuous with the nuclear envelope and is attached to the surface with ribosomes. The proteins accumulate in the cisternae (gap between the membranes) and can then transport proteins to other parts of the cell.
-Smooth endoplasmic reticulum (SER): has various roles depending on the cell type, but can include lipid synthesis, breakdown of toxins and carbohydrates synthesis.
What is the function of the centriole?
-In an animal cell, these produce and organise the microtubules that make up the spindle which separates the chromosomes during cell division.
What is the function of the lysosome?
-These contain hydrolytic enzymes used to digest unwanted material such as pathogens or old organelles.
-Surrounded by a single membrane, no internal structure, also contain digestive enzymes.
What is the function of the plasma membrane?
-Controls the exchange of materials between the internal cell environment and the external environment.
-Partially permeable.
-Formed from a phospholipid bilayer
-It acts as a barrier to separate the cell from its surrounding.
-It is important in cell to cell adhesion and cell signalling.
What is the function of the cytoplasm?
-Responsible for holding the components of the cell and protects them from damage.
-Contains cytosol fluid: liquid found inside of cells, water based solution in which organelles, proteins and other cell structures float.
What is the function of the Golgi apparatus and vesicle?
-Golgi apparatus: modifies proteins (e.g. adding carbohydrates or combining several polypeptides together) and packages them up into vesicles.
-Golgi vesicle: they ‘bud off’ the apparatus.
