Zusammenfassung der Ressource
A-level Applied Science: Biology B1
- Conversions from M to mm, μm and nm:
M -> mm = x1000, M -> μm = x1000 (x2)
and M -> nm = x1000 (x3)
- To convert from nm to M just divide by 1000 each time:
eg. nm -> mm - Divide by 1000 THEN divide by 1000 again
- Cell Theory
- Cell theory is the concept that cells are the fundamental unit of structure, function and
organisation in all living organisms
- History of Cell theory
- In the early 1600's dutch scientist Anton Van Leeuwenhoek created
his own microscope. and started studying different objects. He
discovered bacteria by studying dental scrapings. When leewenhoek
wrote about his discoveries he called them animalcules
- In England a scientist called Robert Hooke was looking at a cork under a
microscope. when he noticed the little chambers which reminded him of
cells. that monks had This is where the name cells came from.
- in 1800's two German scientists (Matthias Schleiden and
Theodore Schwann) helped tie together what we know now as
the cell theory. Schleiden was a botanist who realized that every
plant he looked at under a microscope was made of cell.s. At the
same time Schwann also came up with the same conclusion
with animals. He looked at many animal cells under a
microscope and realized that all animals are made of cells...
However, when it came to cell formation both scientists
disagreed with each other. Schleiden stated that cells formed
from Free cell formation and not from pre-existing cells.. Whilst
Theordore Schwann believed that cells were formed from pre
exisiting cells.
- It was Rudolf Virchow who stepped in and proved to
Schleiden that cells were formed from pre existing
cells. He used research from Robert Remak to prove it.
- Prokaryotes and Eukaryotes
- Prokaryotes - Bacteria. These DO
NOT have a nuclues (membrane
bound or otherwise)
- Eukrayotes - plant and animal cells
have a membrane bound nucelus
- Structure of Animal/plant/bacteria cells
- Plant and Animal cells
- Bacteria
- Plant Cells
- Plant cells are made from Cellulose. Micro fibrils are cross linked
to provide high mechanical strength. Its freely permeable and a
complex carbohydrate
- Xylem pits allow the water to enter and leave the plant. Pores in the
cell walls of xylem vessels (the tubes in plants that carry water
around the plant)
- Chloroplast its got a double membrane. The Fluid inside is called the
stroma. Internal membranes form flattened sacs called Thylakoids.
Several Thylakoids stacked is known as a Granum. The Granum, is
where photosynthesis takes place.
- Plasmodesta are tiny channels across cell walls of adjacent plant cells. It
allows transport and communication between cells.
- Amyloplasts are double membrane bound sacs containing starch granules.
Its responsible for the synthesis and storage of starch. Amyloplasts also
convert this starch back into sugar when the plant needs energy
- Vacuole is membrane bound. it contains sap and the membrane is called
a Tonoplast. Tonoplasts are selectively permeable <-- allows small
molecules to pass through membrane lined sacs
- Gram Staining
- Gram positive stains purple
- To tell difference between bacterias
we use gram staining
- Gram negative stains pink
- Gram positive bacteria - Antibiotics can kill them.
However, Gram negative bacteria - Antibiotics cant kill
them.