Chap#2|Cytoplasm and Genetic material in bacteria|Fsc Biology part 1 скачать в хорошем качестве

Chap#2|Cytoplasm and Genetic material in bacteria|Fsc Biology part 1

Chap#2|Cytoplasm and Genetic material in bacteria|Fsc Biology part 1 Here’s a detailed explanation for your YouTube study channel (F.Sc. Biology Part 1, Chapter 2: Bacteria and Viruses) — focusing on “Cytoplasm and Genetic Material in Bacteria.” --- 🎬 📘 Chapter 2: Bacteria and Viruses Topic: Cytoplasm and Genetic Material in Bacteria --- 1️⃣ Cytoplasm of Bacteria The cytoplasm is the semi-fluid, jelly-like substance that fills the interior of a bacterial cell. It is enclosed by the plasma membrane and serves as the site of most metabolic activities. Main Characteristics: It is viscous (thick) and transparent. Lacks membrane-bound organelles (like mitochondria or endoplasmic reticulum) found in eukaryotic cells. Contains enzymes, nutrients, ions, and waste products dissolved in water. The cytoplasm is mainly composed of: Water (about 80%) Proteins Carbohydrates Lipids Inorganic ions --- 2️⃣ Dissolved Substances in Cytoplasm Within the cytoplasm, many chemical substances are dissolved, such as: Enzymes for respiration and biosynthetic reactions Amino acids and nucleotides (building blocks for proteins and nucleic acids) Sugars and fatty acids Mineral salts and vitamins These substances help the cell carry out metabolism, growth, and energy production. --- 3️⃣ Large Structures in Cytoplasm Although bacteria lack membrane-bound organelles, they contain some important internal structures: (a) Ribosomes Tiny spherical granules made of rRNA and proteins. They are 70S type (smaller than eukaryotic ribosomes which are 80S). Function: Protein synthesis (translation of mRNA into proteins). During protein synthesis, many ribosomes attach to a single mRNA forming a polyribosome (polysome). (b) Granules and Inclusions These are reserve food materials stored in the cytoplasm. Examples: Glycogen granules (energy reserve) Polyphosphate granules (metabolic reserve) Sulphur granules and lipid droplets in some species. --- 4️⃣ Genetic Material in Bacteria Unlike eukaryotes, bacteria lack a true nucleus. Their genetic material is not enclosed in a nuclear membrane and there are no histone proteins. (a) Bacterial Chromosome (Nucleoid) The main genetic material is a single, circular double-stranded DNA molecule. It lies freely in the cytoplasm in a region called the nucleoid. This DNA contains all the essential genes required for bacterial growth, metabolism, and reproduction. The DNA is supercoiled and attached to the plasma membrane for support. Since it is not enclosed by a nuclear membrane, we say that bacteria are prokaryotic. (b) Plasmids Small, circular, double-stranded DNA molecules separate from the main chromosome. They contain non-essential genes, such as those for: Antibiotic resistance Toxin production Fertility (F-plasmid) for conjugation Plasmids can replicate independently of the bacterial chromosome and can be transferred between bacteria, providing genetic variation. --- 5️⃣ Summary Table Component Description Function Cytoplasm Semi-fluid medium inside the cell Site of metabolic reactions Ribosomes (70S) RNA + protein granules Protein synthesis Inclusion bodies Stored nutrients Energy and metabolic reserves Nucleoid Circular DNA molecule Contains essential genes Plasmid Small circular DNA Provides extra traits like antibiotic resistance --- 🎓 Key Points to Remember: Bacteria are prokaryotic, meaning no true nucleus or membrane-bound organelles. Genetic material lies freely in the cytoplasm (nucleoid). Plasmids play an important role in genetic diversity and antibiotic resistance. Ribosomes are the only organelle involved in protein synthesis.