Download Biology brief note dealing molecular and cell biology terms and more Cheat Sheet Molecular biology in PDF only on Docsity! Studynotes (brief notes) Biology ### Lecture 1: Introduction to Molecular and Cell Biology **Overview of Cell Theory** - **All living organisms are composed of cells:** This foundational concept states that the cell is the basic building block of all living things, whether single-celled organisms like bacteria or multicellular organisms like humans. - **The cell is the basic unit of life:** Every cell carries out essential life functions, including energy production, waste elimination, and reproduction. - **All cells arise from pre-existing cells:** Cells divide to produce new cells, ensuring the continuity of life. ### Lecture 2: Biomolecules - **Types of Biomolecules** - **Carbohydrates:** Serve as energy sources and structural components. - **Monosaccharides:** Simple sugars (e.g., glucose). - **Disaccharides:** Composed of two monosaccharides (e.g., sucrose). - **Polysaccharides:** Long chains of monosaccharides (e.g., starch, glycogen). - **Lipids:** Store energy, form cell membranes, and act as signaling molecules. - **Fatty acids:** Building blocks of lipids. - **Triglycerides:** Fats and oils. - **Phospholipids:** Key components of cell membranes. - **Steroids:** Include hormones like estrogen and testosterone. - **Proteins:** Perform a vast array of functions, including catalysis, transport, and support. - **Amino acids:** The building blocks of proteins. - **Protein structure:** Primary (sequence of amino acids), secondary (alpha-helices and beta-sheets), tertiary (3D shape), and quaternary (multiple protein subunits). - **Nucleic Acids:** Store and transmit genetic information. - **DNA:** Carries genetic blueprint. - **RNA:** Involved in protein synthesis. ### Lecture 3: Cell Structure and Function - **Prokaryotic vs. Eukaryotic Cells** - **Prokaryotic:** Lack a nucleus and organelles; simpler (e.g., bacteria). - **Eukaryotic:** Have a nucleus and organelles; more complex (e.g., animals, plants). - **G2 phase:** Cell prepares for division. - **Mitotic Phase:** Cell divides into two daughter cells. - **Mitosis:** Division of the nucleus. - **Cytokinesis:** Division of the cytoplasm. - **Mitosis** - **Prophase:** Chromosomes condense, nuclear envelope breaks down. - **Metaphase:** Chromosomes align at the cell equator. - **Anaphase:** Sister chromatids are pulled apart to opposite poles. - **Telophase:** Nuclear envelopes re-form around separated chromosomes. - **Meiosis** - **Meiosis I:** Homologous chromosomes separate, resulting in two haploid cells. - **Meiosis II:** Sister chromatids separate, resulting in four haploid cells, increasing genetic diversity. ### Lecture 7: DNA Replication, Repair, and Recombination - **DNA Replication** - **Semi-conservative mechanism:** Each new DNA molecule consists of one old strand and one new strand. - **Leading and lagging strands:** Leading strand synthesized continuously, lagging strand synthesized in fragments (Okazaki fragments). - **Replication forks:** Y-shaped regions where new DNA strands are synthesized. - **DNA Repair Mechanisms** - **Mismatch repair:** Corrects errors introduced during DNA replication. - **Nucleotide excision repair:** Removes and replaces damaged DNA. - **Base excision repair:** Fixes single-base errors. - **Genetic Recombination** - **Homologous recombination:** Exchange of genetic material between homologous DNA molecules. - **Transposons:** DNA sequences that can change positions within the genome. ### Lecture 8: Transcription and RNA Processing - **Transcription** - **Initiation:** RNA polymerase binds to the promoter region of DNA. - **Elongation:** RNA polymerase synthesizes RNA from the DNA template. - **Termination:** RNA synthesis ends when RNA polymerase reaches a terminator sequence. - **RNA Processing** - **5’ capping:** Addition of a modified guanine nucleotide to the 5’ end of the RNA. - **3’ polyadenylation:** Addition of a poly-A tail to the 3’ end of the RNA. - **Splicing:** Removal of introns (non-coding regions) and joining of exons (coding regions). ### Lecture 9: Translation and Protein Synthesis - **Genetic Code** - **Codons:** Triplets of nucleotides in mRNA that specify amino acids. - **Start and stop codons:** Signal the beginning and end of translation. - **Mechanisms of Translation** - **Initiation:** Ribosome assembles around the start codon of the mRNA. - **Elongation:** tRNAs bring amino acids to the ribosome, which are added to the growing polypeptide chain. - **Termination:** Ribosome reaches a stop codon and releases the completed polypeptide. - **Ribosomes:** Complexes of rRNA and proteins that facilitate translation. - **tRNA:** Transfer RNA molecules that carry amino acids to the ribosome. ### Lecture 10: Regulation of Gene Expression - **Prokaryotic vs. Eukaryotic Regulation**
