CELL
STRUCTURE & FUNCTION
DEFINITION:
·
A cell is the
smallest unit that is capable of performing life functions.
CELL THEORY:
•
All living things are made up of cells.
•
Cells are the smallest working units of
all living things.
•
All cells come from preexisting cells
through cell division.
CELL
STRUCTURE:
FUNCTIONAL
DESCRIPTION:
The above figure cell structure are described below
·
The fundamental unit of every animal or plant
is cells. Combination of cells is called TISSUES. Every ORGAN in the body is made
up of combination of many tissues.
·
All cells are same and they contain a gelatinous
substance made up of or composed of water, protein, acids, fats, and various minerals.
·
Cell membrane protects the cell and surrounds
it that passes into and out of the cell.
·
The nucleus controls the structure of the
cell. Cell reproduction process is directed by the nucleus only and which determines
the function of the cell and the structure of the cell.
·
CHROMOSOMES
are rod-like structures inside the cell. Human body cells (other than sex cells,
the egg, and sperm cells) contain 23 pairs of chromosomes. Sex cells, such as sperm
and egg cells have 23single chromosomes only. When on egg cell unites with as sperm
cell to for an embryo, then the embryonic cell has 46 chromosomes i.e. 23pairs.
Understand the difference. A chromosome contains the regions called GENES. Thousands
of genes are in an orderly sequence on each chromosome. Gene is made up of a chemical
substance called DNA (deoxyribonucleic acid). DNA is an important compound that
regulates the activities of the cell in a sequential order one a each chromosome.
The DNA is a series of codes. When DNA activity carries out of the nucleus to other
parts of the cell, the activities of the cell i.e. cellular reproduction and the
manufacture of proteins are controlled by DNA.
·
CYTOPLASM
means cyto means cell, plasm means formation. Cytoplasm carries the work of
cell i.e .nerve cell conducts stimulation, muscle cell contracts. Cytoplasm contains
MITOCHODRIA and ENDOPLASMIC RETICULUM.
·
MITOCHONDRIA
is also called power center of the cell. This is small and sausage-shaped bodies
produce energy by burning food in the presence of oxygen. This process is called
catabolism (cata-down,bol-tocast,-ism-process). This process makes complex food
particles into simpler substances and energy is released after this action to do
the work of the cell.
·
ENDOPLASMIC
RETICULUM: These like canal- like structures-this is a network
within the cell. These canals contain very small structures called RIBOSOMES like
a tunnel system in this proteins are produced for the use of the cell. This process
is called ANABOLISM (ana-up,bol-tocast,-ism-process). After this process, complex
proteins are made up from the simpler parts of food.
·
Smaller proteins linked like a chain to become
complex proteins in this process. Both these catabolism and anabolism in combination
is called METABOLISM (meta-change,bol-tocast,-ism-process) i.e total chemical activities
that occurring in a cell. In this process, the sugars and fat in the food are used
up and burned quickly and so the ENERGY is released
·
Cell
membrane: All cells have a phospholipids based cell membrane.
The cell membrane is selectively permeable in that it allows some materials to pass
into or out of the cell but not others.
·
Cytoplasm:
Cells are filled with a complex collection of substances in a water based
solution. This substance is called cytoplasm. Across all cells there are a
number of common features to all cell cytoplasm. For example all cells have
ribosome's. Also, in all cells the first steps in cellular respiration take
place in the cytoplasm.
·
DNA:
All cells contain DNA. In the simplest cells, the DNA is in one loop more loop like
structures free in the cytoplasm. In some cells such as those making up our body
the DNA is isolated from the cytoplasm in a special structure called a nucleus.
Remember not all cells have a nucleus.
