what are the three key points of the cell theory?

Answer 1

Key Points

All organisms are made up of cells. The cell is the structural & functional unit of organisms, this is known as the cell theory. This theory was established by Schleiden and Schwann.
There are 2 main groups of cells: prokaryotic and eukaryotic cell; bacteria and blue green algae are prokaryotic. The prokaryotic cells are very simple with no organelles, while in the eukaryotic cells are organelles.
The organelles in the eukaryotic cell include nucleus, mitochondria, endopasmic reticulum, golgi complex, lysosomes, and ribsomes. Specifically in the plant cells are found chloroplasts, large water and vacuoles.
The nucleus of a cell contains the choromosomes, DNA and RNA and some ribosomes. These factors allow genetic inheritance during cell division / reproduction.
The mitochondria is like the "Power house" of the cell. It is where most metabolic reactions which require the release of energy using oxygen occur, a process known as oxidative phosphorylation. Mitochondria contain their own DNA, so they can multiply. Mitochondria stores cellular energy in the form of adensine triphosphate or ATP.
The chloroplasts contain chlorophyll, the green plant pigment. Other plant pigments are anthocyanin which give color to the fruits. Chloroplasts like mitochondria have their own DNA and ribosomes, and they can reproduce themselves.
Endoplasmic Reticulum (ER) is an organelle that functions in lipid a protein synthesis. Some ER carry ribosomes (rough or granular ER) so they assist the ribosomes in protein synthesis, other ER do not carry ribosomes (smooth ER or granular ER) and function only in the lipid synthesis
The Golgi complex functions in processing of lipids, carbohydrates, and proteins formed by the ER. The golgi produces gylcoproteins and glycolipids, and also enzymes. The golgi forms lysosomes.
Lysosomes contain digestive enzymes (or hydrolytic enzyme) in the cell.
The plant cell has a cellulose cell wall which makes the plant rigid; also in addition to the cellulose cell wall, the cell has a plasma membrane. The plasma membrane is selectively permeable to molecules. This plasma membrane is made up of a high % of phospholipid, some proteins and a small amount of carbohydrates.
The plasma membrane of a cell can allow both passive (diffusion, filtration, osmosis) transport processes that require no energy, and active transport processes that require energy to occur.
Plant cells have to be in isotonic solution (a solution which has equal salt concentration as the cell) to maintain normal physiological cell conditions. A plant cell placed in a hypotonic solution (a solution with less salt concentration in the cell) gains too much water and becomes turgid. A plant cell placed in a hypertomic solution (a solution with more salt concentration than the cell) loses water and shrinks (a process known as plasmolysis).

Answer 2

It's not exactly outdated. Darwin's theory of evolution through natural selection remains a part of the theory of evolution or evolutionary biology, but our understanding of life is much greater than during the time of Darwin: we've discovered the particles responsible for heredity (DNA), which has taught us a lot about other mechanism by which new life can form (mutation and genetic drift). Something else you should know is that Woese's theory is about the first life, and that's not exactly what evolutionary biology is all about. The origins of life and the evolution of life are independant problems in science.

Answer 3

1. All living things are made of cells.
2. The cell is the basic unit of structure and function in living things.
3. Cells are made by pre-existing cells.