Topic 1 Flashcards
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Key Statements of Cell Theory (3)
Living organisms are composed of one or more cells.
Cells come from pre-existing cells.
There is no smaller unit of life than cells.
Exceptions of Cell Theory (3)
Giant Algae > Up to 10cm > Single Nucleus
Striated Muscle Cell > Very Long > Multi Nucleated
Aseptate Fungal Hyphae > No dividing cell walls > Multi Nucleated
Name the Functions of Life (7)
METABOLISM RESPIRATION HOMEOSTASIS GROWTH RESPONSE EXCRETION NUTRITION
What happens as a cell grows?
Volume increases by a power of 3
Surface area increases by a power of 2
Therefore, the SA:V ratio decreases.
What happens if a cells surface area is too small?
Not enough of necessary molecules can enter quick enough and not enough waste can be expelled quick enough which may lead to the cell to overheat.
The larger the surface area the…
As cell size increases…
Which increases before the other?
The larger the surface area the greater the rate of material exchange.
As cell size increases the SA:V ratio decreases.
Volume increases faster than surface area.
Multi-cellular organisms show ____ properties.
EMERGENT
- meaning all parts of a cell or organ work together.
Give two characteristics of stem cells.
Stem cells can continually divide (self sustaining)
Stem cells are undifferentiated and can differentiate into almost any type of cell.
What is Stargardt’s disease?
Stargardt’s disease is a genetic disease that causes macular degeneration in children and young adults. Photoreceptor cells in the retina become damaged and are progressively lost.
Patients gradually lose their vision, usually resulting in them being classified as legally blind.
How would you treat someone with stem cells?
(stem cells) have/retain the capacity to divide;
can be used to produce cell cultures/large number of identical cells;
can be used to repair/replace damaged/lost cells/tissue;
(stem cells) are undifferentiated / have not yet differentiated/specialized;
can differentiate/specialize in different ways / are pluripotent/totipotent;
can be used to form a variety of different tissues / form organs;
used in medical research;
used in treatment of (named) disease;
How do cells in multi cellular organisms differentiate?
They express some of their genes but not others.
What are the ethical considerations of using embryonic stem cells?
One debate focuses on when a human life begins. Some argue at the point of conception so killing an embryo is equivalent to taking a human life. Others think that life starts when a nervous system has formed so the early stage of an embryo can be used.
The creation of embryos just for research is opposed because human life should never be created and not get the chance to live (even though the law prevents implantation). Some think it is a waste not to use left-over embryos from IVF that are never implanted and they should be used to benefit the lives of others.
Resolution of Electron and light microscope?
Electron Microscope uses electrons so has a wavelength of less than 1nm so it can produce a higher resolution than light which is 200nm.
What are stem cells?
Stem cells are cells that retain the ability to differentiate and divide.
Which structure found in eukaryotes has a single membrane?
Lysosome
