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2-Cells - Coggle Diagram
2-Cells
cells are made up of various parts
cell membrane
it is a very thin layer of protein and fat
it is partially permeable since it controls what goes out and into the cell itself
it is difficult to see since it is tightly pressed against the cell wall
cell wall
it is made of cellulose, so it is only present in plant cells
cellulose forms fibres which go one over the other and form a very strong covering
if the cell absorbs too much water, the cel wall stops it from bursting
it is fully permeable
cytoplasm
it is a clear jelly made up of nearly only water
it contains many substances dissolved in it, especially proteins
many metabolic reactions take place here
vacuole
it is a fluid-filled space inside a a cell, surrounded by its own membrane
they are large and permanent in plant cells
in animal cells they are smaller and they are called "vesicles"
when full they help the cell mantain its own shape
nucleus
it is present in only eukaryotic cells
in prokaryotic cells it is not present
it is where the chromosomes are
they are made of DNA and they store genetic information inherited from the parents
the information on what proteins are to be made in the cell are stored here
they are so long and thin that they cannot be seen even with a electron microscope, but when a cell is dividing they get short and thick
chloroplasts
they are only found in plant cells, never in animal cells
they contain the green pigment called "chlorophyll"
it absorbs energy from sunlight, and this energy is used in making photosynthesis
mitochondria
they can only be seen clearly by using an electron microscope
they are found in almost all plant and animal cells
it is where aerobic respiration takes place
it is how energy is released from glucose
it is the main way through which cells get the energy they require
the more energy an organisms requires, the more mitochondria it has
ribosomes
they are tiny structures found in almost all plant and animal cells
so small that they can be seen only through an electron microscope
they are where the cell makes proteins
the information in DNA tells ribosomes how to link amino acids in a particular sequence
all organisms are made of cells
some, since cells are so small, contain milions of them
multicellular organisms
some are made up of only one cell
unicellular organisms
new cells form from the division of fully grown cells
there are many types of special cells
bacterial cells
one of this type of cells forms a bacterium
it has a cell wall as in plant cells, but it is not made of cellulose
it has a partially permeable cell membrane
it has cytoplasms and rybosomes but not mitochondira and chloroplasts
so it is an unicellular organism
it does not have a nucleus
so it is prokaryotic
so it has a circle of DNA instead (sometimes called "bacterial chromosomes") with the instructions on how to make proteins
it also has smaller circles of DNA, called "plasmids"
cells that specialise in the same activity and found together form a "tissue"
a group of different tissues that carry out a function together form an "organ"
different organs that carry out a particular function form an "organ system"
cells are so small that they cannot be seen by humans
so microscopes are used
light microscopes shine light through what you are looking at
it makes it possible to observe a cell as a whole
the image given is called a "photomicrograph"
electron microscopes send a beam of electrons through what you are looking at
the image given is a "electron micrograph"
it makes it possible to observe details and structures inside a cell not previously observable
microscopes give images much bigger than the actual specimen
we can tell by how much this is by giving the magnification
it is calculated by dividing the size of the image by the size of the actual object