Bodies of organisms are made of tiny units called Cells. Cell have outer boundary called cell membrane [made up of lipids and proteins], most cells have a nucleus and inside the cell membrane or plasma membrane is present cytoplasm.
Nucleus, cytoplasm and membrane are basic components of cell.
Endoplasmic reticulum is of two types Rough ER – it has ribosome attached to it. Ribosome manufactures proteins. Smooth ER has a role in manufacturing lipids. ER also serves as a transport channel between various regions of cytoplasm or cytoplasm and nucleus.
In vertebrates, SER detoxifies poisons and drugs.
Nucleus contains chromatin material, during division of cell it gets organized into chromosomes. These contain information to be inherited by the next generation in form of DNA.
Functional units of DNA are genes. DNA contains information necessary for organizing and constructing cells.
A single large Vacuole is present in plant cells and multiple small vacuoles in animal cells. Vacuoles store liquids or solid contents.
Centrioles are seen only in animal cells. Plastids are found only in plant cell.
Green plastids called chloroplasts carry chlorophyll. White plastids are called leucoplasts; they store starch, oil and proteins. They have their own DNA and ribosome.
Membranes are porous and allow nutrients and substances to move in or out. Hence it’s selectively permeable. Diffusion plays an important role in exchange of gases. Water is moved by osmosis [Solvent moves from dilute to concentrated solution]. Food is taken in by endocytosis. Cytoplasm and nucleus are called protoplasm.
Plant cells and bacterial cells have cell wall [made of cellulose] outside the membrane. No cell wall in animal cells. Because of cell walls plant cells can withstand much greater variations in surrounding medium than animal cells.
Viruses lack membranes and hence do not show any characteristics of life till they enter a host and use its cell machinery to multiply. They have few biochemical mechanisms on their own; they enter the host and use his processes for their work. They have either DNA or RNA not both. RNA acts genetic material only in viruses.
Cellular respiration involves using oxygen [aerobic] to break down food [glucose] into energy; carbon dioxide and water are released.
If
this process takes
place in absence of oxygen [in yeast] then alcohol,
carbon dioxide and energy
are formed. This is anaerobic respiration.
Hence
Yeast [single celled organisms] is used in making wine
and beer.
They convert sugar to alcohol; this process is called fermentation
[discovered
by Louis Pasteur].
Lactobacillus helps in conversion of milk into curd. Bio fertilizers are organisms that enrich the quality of soil.
Yeast multiplies rapidly and produces carbon dioxide by respiration this causes bubbles of gas that fill the dough and increase its volume. So it’s used in making bread, pastries and cakes.