Cells Flashcards
What are cancer cells?
Cells that are able to divide indefinitely and uncontrollably (uncontrolled cell division), resulting in tumours or flooding the blood with abnormal cells
Why are cancer cells able to divide indefinitely
cellular dysfunction - there is no contact inhibition to stop cell division after initiation of proliferation
Some possible causes of cancer
Chemical carcinogens, Radiation and infectious diseases
What does a cell culture medium contain?
Growth factors (signalling proteins, hormones), water, sugar, anti-biotics, pH indicators, salt
What are primary cell cultures?
cultures obtained directly from body tissues and have a limited number of replications.
What are stem cell cultures?
cell cultures from tissues or induced and have an extensive number of replications.
What are immortalised cell lines?
cell lines that have acquired the ability to propagate indefinitely. Almost all are cancerous.
Advantages:
Good control of growth environment
Disadvantages:
Hard to maintain for some cell types
Cells in culture may no longer be the same as initial explants.
What is senescene
It is the lost of ability to divide and grow of a cell
What is the cell membrane made of?
Phospholipid bilayer with protein channels
What is the function of the cell membrane?
- Encloses the cell and internal cellular compartments
2. Is a selectively permeable membrane that controls the movement of substances in and out of the cell.
What is the function of the extra-cellular matrix?
It provides support, segregates cells from each other and regulates intercellular communication.
Examples of membrane-enclosed organelles
Mitochondria, endoplasmic reticulum, chloroplasts, nucleus, Golgi apparatus, Peroxisome, vacuole
What is the function of the cytoskeleton?
Maintains and changes cell shape
What is the function of microRNA?
Moves around the body to communicate with other cells
Weight composition of a cell
approx. 70% water and 23% biochemicals (proteins, carbohydrates, lipids and nucleic acids) and 4% of other chemicals (vitamins, phosphates etc)
Why is water a polar molecule?
The oxygen nucleus is more electronegative than the hydrogen nucleus. Hence, it attracts the electrons more strongly and pulls the electron cloud/density towards itself. This results in unequal sharing of electron density between the oxygen and hydrogen atom. Hence, there is a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atom. This unequal distribution of electron density gives the water molecule a net positive dipole moment, thus making water a polar molecule
How are amphipathic molecules soluble in water?
water molecules will surround the polar groups - forming a hydration shell and the number of water molecules surrounding the solute is known as the hydration number (this process is known as hydration)
How can hydrophobic or non-polar molecules cross the cell membrane?
They can cross via diffusion. Polar substances cross the cell membrane through special protein molecules which forms “channels” or “carriers” (e.g. aquaporins - water channels in cells)
What is a clathrate?
It is a ‘cage-like structure’ that forces hydrophobic molecules together by surrounding these molecules, forming a cage. The hydrophobic molecules are stick together by hydrophobic interaction as they do not like the environment.
