Plant and Animal Cell

Plant and Animal Cell: Important Points

Plant and Animal Cell
  • Cell was discovered by Robert Hooke in 1665.
  • Cell is a structural and functional unit of living beings which consists of a membrane covered mass of protoplasm.
  • Unicellular Organisms
  1. Also called as acellular organisms.
  2. The body of the organism is made of a single cell.
  3. Example- Amoeba, Chlamydomonas, Paramecium, Chlorella, Acetabularia, Euglena.
  4. Amoeba does not have a fixed body shape and moves around by producing certain projections in the body called pseudopodia.
  5. Paramecium possesses tiny hair-like, structures distributed all over its body called cilia which help it in locomotion.
  6. Euglena and Chlamydomonas possess one or two whip-like locomotory structures called flagella.
  • Multicellular Organisms
  1. The body of the organisms is made of a many cells.
  2. Example- plants (metaphyta) and animals (metozoa).
  3. The cells are fewer and similar in coenobial or colonial organisms like Pandorina, Eudorina, Proterospongia and Volvox.
  • Cells have diverse shapes. They may be flat, oval, spherical, cylindrical, cuboidal, spindle-shaped or irregular in shape.
  • Guard cells found in leaves are bean shaped. Two guard cells are closely opposed to each other leaving a pore called stomata through which exchange of gases takes place.
  • Cyanobacteria also called blue-green algae.

Plant and Animal Cell:

Cell wall:

  • The cell wall is the outermost rigid protective covering found only in plant cell.
  • It is a non-living structure and provides shape and rigidity to the plant cell.

Cell membrane:

  • The cell membrane is a delicate covering that surrounds the jelly-like cytoplasm present inside the cell.
  • In animal cells, it is the outermost layer while in plant cells it is surrounded by the cell wall on the outside.
  • It is a living structure and has tiny holes which allow materials to move in and out of the cell.
  • It is made up of lipids of proteins.
  • The cell membrane is also called plasma membrane.

Cytoplasm:

  • It is a jelly-like substance present inside the cell.
  • It contains several structures called cell organelles floating in it.

Nucleus:

  • Nucleus is a dense body found generally in the center of the cell.
  • It has a double-layered covering- the nuclear membrane which encloses a jelly-like ground substance.

Cell Organelles:

  • Cell organelles are extremely small structure present in cytoplasm and concerned with cell function.
  • Following cell organelles are commonly found in cells.
Endoplasmic Reticulum:
  • Endoplasmic Reticulum is a network of tubular channels present throughout the cytoplasm.
  • The channels are connected to the nuclear membrane on the one and to the cell membrane on the other, thereby forming a skeletal support system for the cell.
  • Endoplasmic Reticulum also helps in the storage and transport of materials inside the cell.
Mitochondria:
  • Mitochondria are tiny rod like structures found in the cytoplasm.
  • Also known as power houses of cell, because during oxidation of food, the energy released is stored in the ATP (Adenosine triphosphate) molecules.
Golgi Bodies:
  • Golgi bodies are flattened sac-like structures and are involved in the secretion of certain substances in the cell.
  • The Golgi appartus is known as dictyosome in plants.
Ribosomes:
  • Small organelles found in all types of cells.
  • Composed of approximately equal amount of RNA (ribonucleic acid) and protein.
  • Sites of protein synthesis.
Lysosomes:
  • Lysosomes are tiny sacs containing digestive enzymes and are often called suicide bags because under adverse condition they can eat the very cell in which they are present.
  • Lysosomes are formed directly from Endoplasmic reticulum or Golgi complex.
Centrosome:
  • Centrosome is a small body present close to the nucleus in animal cells.
  • It contains two tiny granular bodies called centrioles.
  • The centrioles help in cell division.
Plastids:
  • Plastids are specialised bodies found in plant cells. Depending on their colour, the plastids can be categorised as under:
  1. Leucoplasts- Colourless plastids.
  2. Chloroplasts- Green plastids. It is an important plastids because they contain a green pigment called chlorophyll which manufactures food for the plant using solar energy through the process of photosynthesis. Produce starch and found in leaves.
  3. Chromoplasts- yellow, orange or red-coloured plastids. Give colour to fruits and flower.
Vacuole:
  • A space within the cytoplasm of a plant cell, containing cell sap.
  • Animal cells normally have many small vacuoles while plant cells generally have one big vacuole.
  • Provide turgidity and rigidity to plant cells.

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