Cell structure Flashcards
Define magnification.
How many times bigger the image is when compared to the object.
What is the resolution?
The minimum distance apart that two objects need to be in order for them to be distinguished as separate.
Why is the solution before fractionation cold?
To reduce enzyme activity which might break down organelles.
Why is the solution before fractionation isotonic?
To prevent cells bursting from movement of water due to different water potentials.
Why is the solution before fractionation buffered?
So that pH does not fluctuate, changing enzyme activity or damaging organelles.
What are the two processes in fractionation?
- Homogenisation,
- Ultracentrifugation.
Name 4 limitations of the transmission electron microscope.
- May contain artefacts,
- The sample must be extremely thin,
- A complex colour staining process is required,
- The whole system much be in a vaccum so cannot be operated on living organisms.
What piece of equipment is used when measuring the size of objects though a light microscope?
Eye-piece graticule.
What piece of equipment is used to calibrate an eye-piece graticule?
Stage micrometer.
What are the folds in the inner membrane of the mitochondrion called?
Cristae.
Which form of ribosome is found in Eukaryotic cells and are they larger or smaller?
80S, larger than in prokaryotic cells.
Where do you find epithelial tissues?
Lining the walls of organelles.
Name 3 organ systems.
- Digestive,
- Circulatory,
- Respiratory.
What is the cell wall of bacteria made up of?
Murein.
What happens in prophase?
- Chromosomes become visible, shorten and thicken,
- Spindle fibres develop at the poles of the cell,
What happens in metaphase?
- Spindle fibres attach to the centromere of the two sister chromatids,
- Sister chromatids line up along the equator of the cell.
What happens in anaphase?
- Centromeres divide in two as spindle fibres contract,
- Sister chromatids are pulled to the poles of the cell.
What happens in telophase?
- Chromatids reach poles of cell,
- Elongate and become thinner back into chromosome form as chromatin.
What is cytokinesis?
When the cytoplasm of the cell divides.
What is cell division in prokaryotic cells called?
Binary Fission
What are the three stages that make up the cell cycle?
- Interphase,
- Nuclear division,
- Cytokinesis.
How does chemotherapy interupt the cell cycle? Two ways.
- Preventing the DNA from replicating,
- Inhibiting the metaphase stage by interfering with spindle formation.
Name 2 structures in a eukaryotic cell that cannot be identified using an optical microscope.
- Ribosomes,
- Endoplasmic Reticulum.
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains through an optical microscope.
Place a few drops of water on the slide,
Obtain a thin slide of plant tissue and place on slide,
Stain with iodine,
Lower cover slip using mounted needle.
