Cell is the structural and functional unit of a living body. Cell is the smallest unit of human body.
Divided the cell into three parts-
- Plasma membrane
- Cytoplasm
- Nucleus
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| Human healthy Cell Or Animal Cell |
Plasma membrane
Every cell has flexible outer surface that separating the
internal environment from the external environment. Various channels and
selective barrier are present on plasma membrane that regulate the flow of
material into and out of a cell.
Plasma membrane compose with double layer of phospholipids and
proteins.
Cytoplasm
Cytoplasm is consist
of all the cellular content between the plasma membrane and nucleus. Cytoplasm has two components
- Cytosol
- Organelles
- Cytosol : The fluid portion of the cytoplasm, which contains water, dissolved solutes and suspended particles.
- Organelles (Little organ) : Many tiny organs are suspended in cytoplasm. Each organ has particular shape and function. These organs are mitochondria, endoplasmic reticulum, golgi apparatus, ribosomes, lysosomes, centrosome, vesicles and peroxisomes.
Mitochondria
Mitochondria referred as a power house
of cell because they generate most of energy (in the form adenosine triphosphate -ATP). A cell may have large number of mitochondria. Mitochondria consist of an outer membrane and inner
membrane. Between the membrane, fluid is present. Fluid is
filled in mitochondria cavity, called mitochondrial matrix.
Tubular
like structures are form in inner mitochondrial membrane that know as
mitochondrial cristae. Some ribosomes are present on mitochondrial cristae and
some ribosomes are free in mitochondrial matrix.
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| Mitochondria |
Function
of mitochondria
- Supplying cellular energy
- Kreb’s cycle occur in mitochondria
- Mitochondria maintaining control of the cell cycle and cell growth
- Regulate cellular metabolism
- Mitochondria play a important role in apoptosis (programmed of cell death)
- Calcium ions are stored in mitochondria
- Steroid synthesis takes place in mitochondria
- Mitochondria is sites of several metabolic reactions
Metabolic reaction in outer
mitochondrial membrane :-
Oxidation of epinephrine
Degradation of tryptophan
Elongation of fatty acids
Metabolic reaction in inner
mitochondrial membrane :-
Oxidation of phosphorylation
Metabolic reaction in mitochondrial
matrix :-
Kreb’s cycle
Beta oxidation
Detoxification of ammonia in urea cycle
Storage of calcium ion
Detoxification of ammonia in urea cycle
Storage of calcium ion
Respiratory system - its Structure & Function
Endoplasmic reticulum(ER)
Endoplasmic reticulum is most extensive
cell organelle present in the cytoplasm. Endoplasmic reticulum is tubular like
structure. Various enzymes are synthesized in endoplasmic reticulum.
Endoplasmic reticulum is two types:
Endoplasmic reticulum is two types:
- Smooth endoplasmic reticulum: Tubular like structure. Ribosomes are absent. Smooth endoplasmic reticulum also known as agranular endoplasmic reticulum.
- Rough endoplasmic reticulum: Tubular like structure. Ribosomes are present on the surface of tubular. This type of ER also involve in protein synthesis. Rough endoplasmic reticulum is also known as granular endoplasmic reticulum.
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| Endoplasmic Reticulum |
Golgi Apparatus
The golgi apparatus is a major collection and
dispatch station of protein products, received from the endoplasmic reticulum.
Protein synthesis occur in endoplasmic reticulum, pack into vesicles and then
fused into golgi complex.
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| Golgi apparatus |
Ribosome
Ribosomes are tiny structure. Ribosomes are types 70S and 80S, both type of
ribosomes are consist with two subunits
- 70s ribosome : Two subunit: 50s and 30s.
- 80s ribosome : Two subunit: 60s and 40s.
Some ribosomes are attached to the surface of endoplasmic reticulum. Free ribosomes are synthesize proteins used in cytosol.
Ribosomes are also located within mitochondria, where they synthesize mitochondrial protein. Ribosomes main function is translation in which mRNA convert into protein.
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| Ribosome |
Lysosome
(Lyso means dissolving and somes means bodies). Lysosomes can contain as many
as 60 kinds of powerful digestive enzyme and hydrolytic enzyme that can break down a
wide variety of molecules. Lysosome can engulf another organelles, digest it
and return the digested components to the cytosol for reuse.
Centrosome
Centrosome are partially present in animal cell. Centrosome is located near the
nucleus. During cell division centrosomes replicate so that succeeding
generation of cells have capacity for cell division.
Peroxisomes
Similar structure like lysosome. Peroxisomes contains several oxidases enzymes
that oxidize (remove hydrogen atom from molecules).
Vesicle
Vesicles are involved in many metabolism, transport and temporary storage of enzyme and food. Vesicles from naturally during the processes of secretion, uptake and transport of compound with in the cytoplasm.
Microsomes
These
are small and sac like structure present in cytoplasm of cell. Endoplasmic
reticulum breakdown in fragments, these fragments forms microsomes. When a
tissue homogenate at very high speed (10,000 rmp), they can separated.
Microsomes contain ribosomes. Ribosome involve in synthesis of protein. Microsomes also contain granular matrix, that contain two enzymes – oxidases and catalases. Microsomes are not present in normal and healthy cells.
Microsomes contain ribosomes. Ribosome involve in synthesis of protein. Microsomes also contain granular matrix, that contain two enzymes – oxidases and catalases. Microsomes are not present in normal and healthy cells.
Function
of Microsomes
- Oxidases enzyme – This enzyme help to generate hydrogen peroxide.
- Catalases enzyme – This enzyme convert hydrogen peroxide to water.
Nucleus
Large organelle that houses most of a cell’s DNA. A
single molecule of DNA associated with several proteins and contains thousands
of hereditary units called genes. Genes control cellular structure and
function.
- Nucleus is spherical or oval shaped structure.
- Nucleus is consisting with lipid bilayer.
- Nucleus pores control the movement of substances between the cytoplasm and nucleus by diffusion.
Functions of Cell
- Ingestion
- Growth and repair
- Metabolism
Anabolism
Catabolism
- Respiration
- Excretion
- Irritability and conductivity
- Reproduction
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