Access to Higher Education Core Biology Assignment
The name of the cell organelle, or structure, to which each of the following statements refers:
a)Fully permeable layer found outside the membrane of some cells. Cell Wall
b)Series of membranes in the cytoplasm through which materials can be transported and in which proteins accumulate. Endoplasmic Reticulum
c)Site of ribosomal RNA synthesis. Nucleus
d)Partially permeable layer about 7.5nm thick. Cell Membrane
e)Structures responsible for producing spindle apparatus. Centrosomes
f)Contains membrane stacks called grana. Chloroplast
g)Site of aerobic respiration. Mitochondria
h)Structure containing cell sap. Vacuole
i)Proteins are assembled here. Ribosome
j)Structures made of the protein tubulin. Golgi body
The Fluid Mosaic Model
The fluid mosaic model produced the idea that proteins are suspended directly in the membrane bilayer. Singer and Nicholson in 1972 first used fluid mosaic model this was used because:
Fluid - the individual molecules of the cell surface membrane move relative to one another.
The membrane has a flexible structure that is constantly changing shape.
Mosaic - the proteins embedded themselves in to the phospholipid bilayer in shape, size and pattern just in the same way as a mosaic tile or stone does.
Lipids are a varied group of substances that have the following characteristics:
oThey include carbon, hydrogen and oxygen
oThe production of oxygen is not as great as the production of oxygen by carbohydrates
oThey are not soluble in water
oThey are soluble in organic solvents such as alcohols and acetone
Lipids perform different functions in living organisms. These are:
Energy sources - they provide more than twice as much more energy as a carbohydrate when they are oxidised. This makes them excellent at storing energy, particularly in animals and plant seeds that need to keep their mass to a minimal in order to move from place to...