Molecular Cell Biology: Life Begins With Cells PDF
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Near East University
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This document provides a comprehensive overview of molecular cell biology, beginning with the order of cells and discussing their evolutionary adaptations, regulation, and responses to the environment, alongside energy processing, reproduction, and growth. It explores the components of cells, modern cell theory, and the major components, like water, nucleic acids, proteins, carbohydrates, and lipids. Examples like white and whole-grain bread are also included, illustrating differences in digestion and glucose release.
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# **Molecular Cell Biology** ## **Life Begins With Cells** ### **Order of Cells** * Order * Evolutionary Adaptations * Regulation * Response to the Environment * Homeostasis * Energy Processing * Reproduction * Growth & Development ## **Cells** * Small membrane-bounded compartments filled with...
# **Molecular Cell Biology** ## **Life Begins With Cells** ### **Order of Cells** * Order * Evolutionary Adaptations * Regulation * Response to the Environment * Homeostasis * Energy Processing * Reproduction * Growth & Development ## **Cells** * Small membrane-bounded compartments filled with concentrated aqueous solutions of chemicals * Simplest form of life are solitary cells that reproduce by dividing into two * Higher organisms (humans) - cellular cities where groups of cells perform specialized functions ## **Cells: A "sac" Surrounded by the Membrane with Gates (Proteins & Lipids)** * **Lipids (fatty acids)** composed of carbon, hydrogen, and carbon dioxide. * Carboxylic acid * Lipids contain little amounts of oxygen in the "head" * **Proteins** - composed of amino acids used for structural support ## **Modern Cell Theory** * Cells are the structural and functional unit of all living things * Come from pre-existing cells by division * Contain DNA passed from cell to cell during division * Composed of 6 elements: C, H, O, N, P, S * Energy flow (metabolism) of life occurs * **Plasma membrane:** permeable to specific molecules that a cell needs * **Transport proteins in cell membrane:** allow selective passage of molecules. * Each transport protein is specific to a certain molecule. ## **Major Components of a Cell** * 70% H2O - most abundant molecule, inorganic ions, and carbon containing * **Nucleic Acids:** deoxyribonucleic (DNA) & ribonucleic acid (RNA) * Proteins * Simple & Complex Carbohydrates * Lipids * Organelles **Eg. White bread** - digest quick & spike blood sugar faster **Eg. Whole-grain bread** - digest slower & release glucose into the bloodstream slower. ## **Organelles:** * Orderly arrangements of molecules → Produce Energy **Eg. Mitochondria:** Animals **Eg. Chloroplasts:** Plants ## **Different Types of Cells** * **Two types of cells:** * **Prokaryotic** - DNA not separated from the cytoplasm. * Bacteria & Archea * Single cells * **Eukaryotic** - DNA is partitioned off in its own membrane, *nucleus* * Some are free living single cells * Some are part of multicellular organisms * **Similarities:** Chromosomes, DNA as genetic material, ribosomes, cytoplasm, plasma membrane, vacuoles ## **Types of Microorganisms** * Bacteria * Fungi * Virus * Prions * Parasites * Protozoans ## **The Evolution of the Cell** * **Natural Selection:** involves 2 processes 1. **Random variation** is passed from an individual to its descendant. 2. **Selection in favor of genetic information** helps to survive and propagate. ## **From Molecules to the First Cells** * **Organic molecules in cells:** amino acids, sugars, purines & pyrimidines for making nucleotides. * **DNA, RNA, Proteins:** are made of H, C, N, O, S, P * **Amino Acids & Nucleotides:** associate to form polymers: * **Polypeptides:** (protein) * **Polynucleotides:** (DNA, RNA) * **Polysaccharides:** (carbohydrates) * **Polynucleotides:** direct their own synthesis. * **Self-replicating molecules:** undergo natural selection * **RNA:** can catalyze biochemical reactions * **Info flows from polynucleotides to polypeptides** * **DNA:** hereditary material **Friedrich Wohler (1800-1882): synthesis of urea** * **Proteins:** 20 types of amino acids * **Phospholipids:** fundamental building blocks of all cell membranes. * *Oil-water interface* → hydrophilic head & lipophilic tail (head in water, tail in alcohol) * **Polypeptides:** Proteins * **Polynucleotides:** DNA/RNA * **Polysaccharides:** Carbohydrates. * **Nucleus** is covered by outer and inner nuclear membranes (ONM & INM) & surrounded by cytoplasm, where organelles float ## **How are Cells Studied?** * **Microscopes:** * **Electron microscopes:** higher magnification, higher resolution, more detailed compared to light microscopes. * **R Hook:** discovered a new world in cells using microscopes. ## **Classification of Living Things: Domains of Life** * **Three domains:** 1. **Bacteria:** domain and kingdom 2. **Eukaryota:** kingdoms: fungi, plants, animals, protists (single-celled) 3. **Archea:** domain and kingdom ## **Prokaryotic Cell Structure** * **Appendages:** Pili, flagella, axial filaments * **Cell envelope:** * Capsule (glycocalyx) outer membrane --> inner layer: phospholipids, outer layer: lipopolysaccharides = bilayer * **Cell wall:** peptidoglycan * **Periplasm**: space between cell membrane & peptidoglycan cell wall. * **Plasma/Cell membrane:** encloses cytoplasm, composed of membrane lipids & proteins & contains cholesterol. * **DNA in nucleoid:** not enclosed in a membrane * **Cytoplasm** * **Bacteria cells:** 0.1-5.0 μm diameter, much smaller than eukaryotic cell. * **Eg. ** E.coli weighs 25 × 10⁹ g * **Bacteria in the human body:** weighs 1-1.5 kg * **Number of bacteria on earth:** is 5 × 10³⁰ & weighs 10²⁴ kg ## **Eukaryotes Cell Structure** * **Appendages**: cilia, flagella * **Cell walls:** composed of cellulose, chitin (only in plants) - Animal cells = no cell walls. * **Plasma/Cell membrane:** encloses cytoplasm, composed of membrane lipids proteins and contains cholesterol * **Glycocalyx** * **Cytoplasm** * **Nucleus:** * **Ribosomes** * **Membrane-bound organelles** * **10-100 μm:** much larger than bacteria ## **Archea - Bacteria** * **Halophiles:** "salt loving" need high concentrations of salts to survive --> chemoheterotrophic * **Thermacidophiles:** "heat and acid loving" (80°C Sulfur, pH < 2) * **Methanogens:** "methane producers", live in an oxygen-free environment --> autotrophs ## **Single-celled Organisms Produce:** * **Sexually mating by meiosis** * **Asexually:** budding by mitosis ## **Viruses** * Ultimate parasites: infect a host cell to grow & reproduce + transport genetic material * Much smaller than cells: 100 nm * Composed of a protein coat: encloses genetic material * Protein coat provides: protection from the environment, allows virus to enter the host cell. * **Eg. Bacteriophage:** virus attacks bacteria.
