chapter 3

• A eukaryotic cell contains membrane-bound organelles such as a nucleus, mitochondria, and an endoplasmic reticulum.
• Organisms based on the eukaryotic cell include protozoa, fungi, plants, and animals.
• Eukaryotic cells are larger and more complex than prokaryotic cells found in domains Archaea and Bacteria
• CYTOPLASMIC MEMBRANE It is also called plasma membrane or cell plasma membrane.
• In eukaryotic cells, the plasma membrane consists of proteins, carbohydrates and two layers of phospholipids (lipid with a phosphate group).
• The polar, hydrophilic (water-loving) heads face the outside and inside of the cell. These heads interact with the aqueous environment outside and within a cell.
• The non-polar, hydrophobic (water-repelling) tails are sandwiched between the heads and are protected from the aqueous environments
• CYTOPLASMIC MEMBRANE a semi-permeable membrane that separates the inside of a cell from the outside. is important in cell growth, secretion, and division.
• CELL WALL is a non-living, rigid structure outside the plasma membrane in plant cells and fungi.
• CELL WALL . It is absent in Eukaryotic cells of animals.
• CELL WALL ➢ Plants -Cellulose, hemicellulose, proteins, and pectin ➢ Fungi-Cellulose, galactans, mannans and calcium
• Middle lamella – It is the outermost layer and is made of calcium pectates. It holds adjoining cells together
• Primary wall – It is the middle layer and is made of cellulose and hemicellulose. It is present in young, growing cells and is capable of growth.
• Secondary wall – It is the innermost layer and similar in composition to the primary wall
• Middle lamella- It holds adjoining cells together.
• Primary wall- It is present in young, growing cells and is capable of growth
• ENDOPLASTIC RETICULUM It is a network of small, tubular structures
• The endoplasmic reticulum divides the space inside of Eukaryotic cells into two parts – luminal (inside ER) and extra-luminal (cytoplasm).
• Smooth Endoplasmic Reticulum:

  • Smooth due to lack of ribosomes
  • Main site of lipid synthesis
• Smooth Endoplasmic Reticulum is the main site of lipid synthesis
• Rough Endoplasmic Reticulum:

  • Rough due to the presence of ribosomes
  • Site of protein synthesis
• Golgi Apparatus is made of many flat, disc-shaped structures called cisternae.
• GOLGI APPARATUS It is present in all eukaryotic cells except human red blood cells and sieve cells of plants.
• Cis face (forming face) – It faces the plasma membrane and receives secreted material in vesicles.
• Trans face (maturing face) – It faces the nucleus and releases the received material into the cell.
• GOLGI APPARATUS An important site for packaging material within the cell.
• GOLGI APPARATUS An important site for the formation of glycolipids and glycoproteins.
• RIBOSOMES • These structures are not bound by a membrane.
• Ribosomes are also called ‘Protein factories’ since they are the main site of protein synthesis
• RIBOSOMES- A Major site for synthesis of proteins and polypeptides (chain of amino acids)
• chapter 3
• MITOCHONDRIA • They are membrane-bound organelles, also known as ‘powerhouses of the cell’.
• Mitochondria- Helps in regulating cell metabolism
• Mitochondria possess their own DNA, RNA and components required for protein synthesis
• Lysosomes are also called ‘suicidal bags’ since they are rich in hydrolytic enzymes such as lipases, proteases, carbohydrates etc.
• Lysosomes are enzymes are optimally active at acidic pH (less than 7).
• The main function of lysosomes is to digest lipids, proteins, carbohydrates and nucleic acids.
• Nucleus is the main organelle of a cell.
• Nucleus is a double membrane structure with all the genetic information. Therefore, it is also called the ‘brain’ of a cell.
• CYTOSKELETON • It is the filamentous network present in the cytoplasm of a cell.