ANIMAL AND PLANT CELLS HAVE SOME FEATURES IN COMMON
In animals and plants each cell is surrounded by a very thin plasma (cell surface) membrane, which is too thin to be seen with a light microscope.
Cell has a nucleus which is a relatively large structure. The deeply staining material in the nucleus is called chromatin and is mass of loosely coiled threads. This material collects together to form visible separate chromosomes during nuclear division. It contains DNA which controls the activities of the cell. Within the nucleus a more deeply staining area is the nucleolus.
The material between the nucleus and the plasma membrane is known as cytoplasm. Organelles themselves are often surrounded by membranes so that their activities can be separated from the surrounding cytoplasm. This is called compartmentalisation. Sine each type of organelle has its own function, the cell is said to show division of labour.
The most numerous organelles seen with the light microscope are usually mitochondria.
DIFFERENCES BETWEEN ANIMAL AND PLANT CELLS:
The only structure commonly found in animal cells which is absent from plant cells is the centriole. Under the light microscope it is a small structure close to the nucleus. It is involved in nuclear division.
Individual plant cells are more easily seen with a light microscope than animal cells are because they are usually larger and surrounded by a relatively rigid cell wall outside the plasma membrane. Plant cells are linked to neighboring cells by strands of cytoplasm called plasmodesmata (singular plasmodesma), which pass through pore like structures in the walls of these neighboring cells.
Mature plant cells differ from animal cells in having a large central vacuole and chloroplast in case of photosynthetic cell.
The vacuole is surrounded by a membrane, the tonoplast which controls exchange between the vacuole and the cytoplasm. The fluid in the vacuole is a solution of mineral salts, Sugars, oxygen, carbon dioxide, pigments, enzymes and other organic compounds, including some waste products.
Vacuoles also help to regulate the osmotic properties of cells.
|Animal Cell||Plant Cell|
|1. Usually smaller in size.||1. Comparatively larger in size.|
|2. Enclosed by plasma membrane only.||2. In addition to plasma membrane, mostly surrounded by a thick cell wall.|
|3. Plastids absent.||3. Plastids (chloroplast and chromoplast) are very common.|
|4. Cytoplasm consists largely of smaller vacuole.||4. Cytoplasm peripheral, central space occupied by a large vacuole.|
|5. Prominent and highly complex Golgi bodies.||5. Contain several subunits of Golgi bodies called dictyosomes.|
|6. Possess centrosome with one or two centrioles.||6. No centrioles present; instead two small clear area called polar caps are present.|
Comparing Plant Cells and Animal Cells
|Feature||Animal cell||Plant cell|
|Plastids, e.g., chloroplasts||Absent||Present|
A large proportion of the inside of the cell is taken up with a fluid-filled compartment known as the vacuole. Together, the wall and vacuole maintain the shape of the whole cell.
Plant cells have specialized organelles, the chloroplasts, which enable them to make their own food by photosynthesis.
Major Differences between Prokaryotes and Eukaryotes
|Property||Prokaryotic Cell||Eukaryotic Cell|
|Nuclear membrane||since there is no nuclear membrane||Present|
|Chromatin material||The genetic material (DNA) is without any nuclear membrane and freely present in the cytoplasm.||A nucleus is present in which nuclear material (chromosomes) is|
|Chromosome||Chromosome is formed of DNA only.||Chromosome is formed of DNA|
None are surrounded by an envelope (two membranes)
Internal membranes scarce; if present usually associated with respiration or photosynthesis.
|Many organelles envelope-bound organelles present, e.g., nucleus, mitochondria, chloroplasts
Great diversity of organelles present usually associated with bounded by single membranes e.g., lysosomes, Vacuoles, microbodies, endoplasmic reticulum etc.
|Ribosomes||Ribosomes are 70S. Smaller subunit is 30S while larger subunit is 50S.||Ribosomes are 80S. Smaller subunit is 40S while larger subunit is 60S.|
|Cell wall||Cell wall is composed of peptidoglycan or murein. When polysaccharide chains are bound covalently to shorter chains of amino acids, peptidoglycan is formed. The entire cell wall is considered as a single complex molecule called Sacculus.||The cell wall if present is formed of cellulose in most of the plant cells and is formed of chitin in fungi.|
|Cell division||In prokaryotes mitosis is missing and the cell divides by binary fission||Cell divides by mitosis.|
|Organisms||Organisms possessing prokaryotic cells are called Prokaryotes.||Organisms possessing eukaryotic cells are called eukaryotes.|
|Origin / evolution||Prokaryotes represent primitive stage of evolution.||Eukaryotes probably evolved from prokaryotes.|
|Flagella||Simple, lacking microtubules; extracellular (not enclosed by cell surface membrane) 20 nm diameter.||Complex, with ‘9+2’ arrangement of microtubules; intracellular (surrounded by cell surface membrane) 200 nm diameter.|
|Respiration||Mesosomes in bacteria, except cytoplasmic membrane in blue-green algae.||Mitochondria for aerobic respiration.|
|Photosynthesis||No chloroplasts; no membrane stacking.||Chloroplasts containing membranes which are usually stacked into lamellae or grana.|
|Nitrogen fixation||Some have the ability.||None have the ability.|
|Form||Mainly unicellular.||Mainly multicellular (except Protoctista, many of which are unicellular).|
|Cell size||Average diameter 0.5-10 µm.||10-100 µm diameter common; commonly 1000-10000 times volume of prokaryotic cells.|
|Examples||Prokaryotes include bacteria and blue green algae (cyanobacteria).||Eukaryotes include all other unicellular or multicellular organisms such as animals, plants, fungi and protista.|