Cell Theory And Microscopes Flashcards
Main Points of Cell Theory
- Cells make up all living things
- new cells are formed from the division of pre-existing cells
- Cells have genes which contain inherited information
- Cells are the functioning unit of life
Most of the time Cell Theory consists of only 3 principles. Why is the other one not considered?
“Cells have genes which contain inherited information”. This principle of cell Theory is often excluded since it was an additional statement that was given after the other 3 principles. During that time, microscopes weren’t strong enough to detect genes
Also because this principle has an exception: Red Blood cells do not have genes in them.
What are exceptions of the cell theory
Striated muscles
Giant algae
Aseptate fungi hyphate
Scientific name for bacteria
Escherichia Coli
Why are striated muscles considered an exception to the cell theory.
Striated muscles aren’t made up of different cells but are multiple cells fused together in a stage of their development hence they are much larger.
They have multiple nuclei on the inner sides of a single membrane. Hence these cells do not function independently but as a collective single cell.
This challenges the theory’s statement that cells are both small in size and function as an autonomous unit (functioning independently).
Why is Aseptate Fungi Hyphate considered an exception to the cell theory?
The structure of a fungi is made up of fine thin threads called hyphae. These are made up of cylindrycal cells that are joint end to end but seperated with internals walls/septa.
In Aseptate Fungi Hyphate, septa isn’t present which means all the cells are connected in a long continuous chain.
This challenges the idea that living structures are composed of discrete (seperate) cells
Why is the Giant Algae (Acetabularia) considered an exception?
This particular type of algae grows to the height of 10cm. However, it has a single nucleus present in the centre of the rhizoid(root near the base).
This challenges the idea that larger organisms are always made of many microscopic cells
What are the Function of Life/ Function of Cells?
- Metabolism
- Reproduction
- Sensitivity
- Homeostasis
- Excretion
- Nutrition
- Growth
What does the surface area of a cell contribute to?
Rate of material exchange (absorption and excretion)
What does the volume of the cell contribute to?
Rate of metabolism
Why do cells need to retain their SA:V ratio
Absorption of nutirents occour in proportion to the surface area. When a cell increases in size, its volume (m^3) increases much faster than its surface area (m^2). Therefore the cell’s metabolism increases but the supply of energy doesn’t. This causes the cell to perform insufficent metabolic procedures which leads to the cell dying.
How do cells increase surface area? Give Examples.
Through cell division. Once a cell is too large it divedes and produces 2 smaller cells.
We can see this in the villi present inside small intestines as the cells divide to produce finger-like projections rather than a flat surface.
Also seen in alveoli of our lungs which have membranous extensions called microvilli to increase surface area and help in respiration.
How does surface change with respect to the size of an animal.
Small animals have a large surface area compared
to volume. This means small animals loose more heat with contact to the environment and needs to eat more to sustain its metabolic rate.
When an animal is larger the surface area gets
progressively smaller compared to the volume. So
large animals lose less heat from their skin, and eat
proportionately less.
What are the different types of Microscopes
- Light microscope
- Eletron microscope (two types) : scanning and transmission
What is the light mircroscope?
- able to magnify from 500x to 200x
- uses a series of glass lens
- uses a focused beam of light which passes through the condenser/lens on the base.
- has multiple lens in the eyepiece.
