GA2 Flashcards
(29 cards)
What does ‘magnification’ mean?
The process of enlarging the physical image or appearance of something.
What does resolution mean?
The ability to distinguish between two points as separate structures.
How to you work out image size?
Image = Actual size x magnification
How do you work out the total magnification?
Total magnification = eyepiece lens x objective lens
What is the maximum magnification of a light microscope?
X1500
What is the maximum resolution of a light microscope?
0.0001mm
What is the maximum magnification of an electron microscope?
X2000000
What is the maximum resolution of an electron microscope?
2.0x10-7
What does differentiation mean?
“Making them adapted to carry out a particular function”
What can cell differentiation cause changes to?
- The number or size of a particular organelle found in a cell. (Eg mitochondria in a muscle cell)
- The shape of the cell
- Changes to some of the contents of a cell (eg red blood cells having no nucleus)
Tissues
- Animal and plant cells can form tissues
- A living tissue is made up from a group of cells with a similar structure and function, which all work together to do a particular job.
Organs
- An organ is made from a group of different tissues, which all work together to do a particular job.
Organ System
- An organ system is made from a group of different organs, which all work together to do a particular job.
What is cell fractionation?
- Process where cells are broken up and different organelles they contain spread out.
- It is used to help us study cell organelle structures and function.
What must the tissue be before cell fractionation?
- Cold = reduces enzyme activity
- Isotonic = to make sure cells don’t burst or swell
- Buffered = keeps it a sensible ph so proteins aren’t denatured.
Process of cell fractionation
- Cells are homogenised (broken up) and are in a solution called homogenate.
- filtered to remove any large cells/ debris
- some homogenate is put in a test tube and centrifuged. The pellet is then removed where the nuclei will be (first to come out)
- This process is then repeated until the organelle wanting to be studied is spun out.
What order do organelles come out the centrifuge?
- Nuclei
- Chloroplasts
- Mitochondria
- Lysosomes
- Endoplasmic reticulum
- Ribosomes
What is DNA?
A molecule which carries the instructions (genes) which control the activity of the cell.
What is chromatin?
The DNA & histone proteins together
Relaxed single chromosome
One long, linear DNA molecule, histone proteins and the centromere. Single chromosomes are not visible under a light microscope.
Relaxed duplicated chromosome
Before a cell divides, chromosomes are replicated. Each chromosome consists of two genetically identical copies called sister chromatids, held together by a centromere.
Supercoiled duplicated chromosome
During mitosis chromosomes shorten and thicken so they are sturdy enough to move round the cell. Individual chromosomes are only visible when supercoiled.
What is the cell cycle?
Describes the events that take place as one cell divides to produce two new daughter cells which then grow to full size.
What main stages is the cell cycle divided into?
Interphase, mitosis and cytokinesis.
