2.1 Cell Theory Flashcards
Discuss evidence of cell theory: All known living things are made of one or more cells.
When living things are observed under a microscope they consistently appear to be comprised of cells.
Exceptions: skeletal muscle cells, fungi.
Outline cell theory
1) All known living things are made up of one or more cells.
2) All cells come from pre-existing cells by division.
3) The cell is the fundamental functional and structural unit of life.
State that unicellular organisms carry out all the functions of life.
Movement Reproduction Sensitivity Growth Respiration Excretion Nutrition
(MRS GREN)
Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit.
1nm - Molecules 10nm - Cell membranes 100nm - Viruses 1um - Bacteria 10um - Organelles 100um - Cells
Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification.
Actual size = Image size/Magnification
AIM
State the effect of size on a cell’s SA/V
The larger the cell, the lower it’s SA/V ratio. The smaller the cell, the higher it’s SA/V ratio.
List three things cells can do if their SA/V ratio is too low.
They can divide into smaller cells, change their shape (grow microvilli), slow their metabolism.
State that multicellular organisms show emergent properties.
Scientists obverse component parts that make up a system, and observe the properties that emerge from the system, that could not have been predicted from the individual parts themselves.
“The whole is greater than the sum of its part”.
List three consequences if a cell’s SA/V ratio is too low.
Products needed for reactions to occur will not enter the cell as quickly as required. Waste products will accumulate faster than they can be excreted. Cells may overheat as metabolism produces heat faster than it is lost over the cells surface.
Outline how cells differentiate.
Cells differentiate to carry out specialised functions by expressing some of their genes but not others, by switching off genes in a carefully controlled sequence. The sequence in which the genes are expressed controls the differentiation process.
What is unique about stem cells
Stem cells retain the ability to divide and have the ability to differentiate along different pathways.
Outline one therapeutic use of stem cells.
- Leukemia is when bone marrow cells divide uncontrollably, producing far too many white blood cells.
- Hematopoietic stem cell transplantation can be used to treat it.
- Stem cells are derived from donor bone marrow- Recipients bone marrow cells destroyed using chemotherapy, killing the cells causing leukemia
- Stem cells then introduced into recipients bloodstream, and establish themselves into the recipients bone marrow where they divide and build up a population of bone marrow cells to replace those killed by chemotherapy
