biology (cell structure)

• The cytoplasm is the gel-like substance inside the cell that contains various organelles and is the site of many cellular processes.
• The cell surface membrane is made up of lipids and proteins. It'


  s a partially permeable membrane.
• The nucleus consists of a small round mass of denser protoplasm called nucleoplasm.
• what does the nucleus consists of?

  small round mass of protoplasm and nucleoplasm
• Functions of the nucleus: control cell activities, cell growth, and cell regeneration.
• The nucleus is essential for cell division/reproduction as it houses the DNA.
• The cell wall encloses the entire plant cell, surrounding the cell surface membrane.
• The cell wall is made out of cellulose and protects the plant from injuries, as well as providing structure and a fixed shape.
• The cell wall is fully permeable. However is absent in animal cells.
• Chloroplasts are found only in plants and algae. They contain chlorophyll which absorbs light energy to produce glucose through photosynthesis.
• Mitochondria are responsible for producing ATP by aerobic respiration. It contains its own circular DNA and ribosomes.
• Ribosomes are small structures that float freely within the cytoplasm or attached to the endoplasmic reticulum. Ribosomes synthesise proteins using mRNA.
• Each chromatin thread is made up of proteins and a compound called DNA. DNA carries instructions that a cell needs for carrying out its activities.
• Vacuoles store water, nutrients and pigments. They also act as storage organelles for waste products such as carbon dioxide and urea.
• There are two types of ER - rough ER has ribosomes on its outer surface while smooth ER does not have any ribosomes
• Rough endoplasmic reticulum (RER): consists of a network of flattened spaces lined with a membrane.
• Smooth Endoplasmic Reticulum (SER): consists of a series of interconnected tubes and sacs which do not contain ribosomes.
• Mitochondria: The powerhouse of the cell, responsible for producing energy through respiration.
• Ribosomes: small round structures that are found in the cytoplasm or attached to the RER. They are needed to synthesize proteins in the cell.
• Golgi apparatus: A stack of flat membranes involved in protein modification and packaging into vesicles.
• SER converts harmful substances into harmless materials, this process is called detoxification.
• SER synthesizes substances such as fats and steroids.
• The Golgi Apparatus modifies and packages proteins produced by the rough ER
• Plant cells have a large central vacuole which takes up most of the volume of the cell
• Animal cells do not contain chloroplasts because they cannot make their own food from sunlight like plants can
• Centrioles can only be found in animal cells.
• Centrioles help determine the locations of the nucleus and other organelles within the cell.
• Plant cells have a large vacuole that contains cell sap. cell sap contains disclosed substances such as sugars, mineral salts, and amino acids.
• The large vacuole is enclosed by a partially permeable membrane called the tonoplast.