General Biology 1: Cell Structure & Function PDF

GENERAL BIOLOGY 1 **STEM CELL RESEARCH** -The research started simple question "How can the various parts of the human body began forming and how may it be possible to replicate the processes. **Modern Cell Theory** Modern Cell Theory contains 4 statements, in addition to the original Cell Theor...

GENERAL BIOLOGY 1 **STEM CELL RESEARCH** -The research started simple question "How can the various parts of the human body began forming and how may it be possible to replicate the processes. **Modern Cell Theory** Modern Cell Theory contains 4 statements, in addition to the original Cell Theory: 1\. The cell contains hereditary information (DNA) which is passed on from cell to cell during cell division. \*DNA- Deoxyribonucleic acid 2\. All cells are basically the same in chemical composition and metabolic activities. 3\. All basic chemical & physiological functions are carried out inside the cells. (movement, digestion, etc.) 4\. Cell activity depends on the activities of sub-cellular structures within the cell (organelles, nucleus, plasma membrane) Modern cell theory was created from these observations and is summed up in the following three statements:  - All living things are made up of cells.  - Cells are the basic units of structure and function in living things.  - Living cells come only from other living cells. Credit for developing cell theory is usually given to two scientists:  - Theodor Schwann - Matthias Jakob Schleiden. - The cell theory states that all: - Biological organisms are composed of cells; - cells are the unit of life and all life come from preexisting life. - The cell theory is so established today that it forms one of the unifying principles of biology. Humans are just an intricately designed community of cells, which must work together to survive. **CELL: Structure and Function** Proposed by **Matthais Schleiden** and **Theodor Schwann** in 1839 - All living things are made up of cells. - Cells are the smallest working unit of all living things. - Cells come from pre-existing cells through cell division. - Different substances that make a cell are collectively called **[Protoplasm.]** - Protoplasm is composed of 1)Water - **70-80% Water** 2)Carbohydrates 3)Lipids 4)Proteins 5)Electrolyte - Sodium (Na+), Potassium (K+), Magnesium (Mg2+), Calcium (Ca2+), Phosphate , Chloride (Cl-), and Bicarbonate (HC03 - ). Major Structures Present in a cell are: - Cell Membrane - Cytoplasm and its Organelles - Nucleus **[Cell Membrane]** - Thin pliable elastic outermost structure which envelops the cell. - It consists of bilipid layer with embedded proteins that are- i. Integral Proteins- any protein which has a special functional region for the purpose of securing its position within the cellular membrane ii. Peripheral proteins- a protein that is found temporarily attached to the cell or mitochondrial membrane **Functions of Cell Membrane** 1. **Protective** 2. **Digestive** 3. **[Selective Permeability]**: **a)Non-Polar Molecules**- Gases (like O~2~ ,CO~2~, N~2~ ), Lipids,Steroid Hormones, Alcohols can dissolve in the non --polar regions of the membrane and move rapidly across the membrane 4. **Polar molecules** 5. **Chemical and Physical Properties** 6. **Links adjacent cells** together by junctional complexes to form tissues. 7. **Insulating Properties**:- It acts as dielectric material of a charged condenser, thus cell membrane have very high insulating value **\ **Cytoplasm - **Thick, gel-like semitransparent fluid** that is found in both plant and animal cell. - The constituent parts of cytoplasm are **cytosol, cell organelles and cytoplasmic inclusions.** Cytosol - aqueous part of the cytoplasm - 70% of the cell volume - **Gelatinous substance** consisting mainly of cytoskeleton filaments, organic molecules, salt and water. - composed of many chemical elements in the form of atoms, ions and molecules. Organelles - Mitochondria Endoplasmic Reticulum Lysosomes, Golgi Appartus, Peroxisomes Vacuole - Each organelle is bounded by a lipid membrane, and has specific functions Mitochondria - Observed by Kolliker in 1850 as granular structures in striated muscles - Powerhouse of the cell - Filamentous or globular - Power generating unit - Maintains proper concentration of calcium ions within the cell - Energy transduction through respiration through respiration - Thermogenesis - Contains ATPase and other enzymes concerned with synthesis and metabolism of ATP - Oxidative Phosporylation and synthesis of ATP Adenosine triphosphate (ATP) is the source of energy for use and storage at the cellular level. The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and three serially bonded phosphate groups. Endoplasmic Reticulum - Network of tubular and flat vesicular structures in the cytosplasm - Extensive network of closed, flattened membrane-bounded sacs called **cisternae** - Space inside the tubules is filled with Endoplasmic Matrix.  - Proteinsynthesis and segregation - Muscle contraction. ER is known as Sarcoplasmic Reticulum in muscle fibers - Unsaturation of fatty acid Golgi Bodies - Golgi Bodies is a collection of membrane enclosed sacs composed of four or more stacked layers of thin, flat enclosed vessels lying near the side of the nucleus. - Wrapping and Packaging department of the cell - Site of formation of lysosomes Lysosomes - **Diameter**- 250 -750nm - These are the irregular structures surrounded by the unit membrane - Acts as a form of digestive (lytic ) system or the cell - Engulf exogenous substances e.g. bacteria and degrade them - Autolysis, Suicidal Bags Peroxisomes - Surrounded by lipid bilayer - is similar to that of the lysosomes chemical composition - H~2~O~2~ metabolism and detoxification - Helps in Photorespiration in plants - Biosynthesis of lipids Cytoskeleton - Chromo & cell movement Nucleous - chromatin, RNAs, and nuclear proteins **CELL STRUCTURE: EUKARYOTES AND PROKARYOTES** All living organisms can be sorted into one of two groups: Prokaryotes and the Eukaryotes. **Prokaryotes** - (*pro* = before; *karyon*-- = nucleus). - All prokaryotic organisms are unicellular - Simplest type of cell - Oldest appeared, 4B years - Unicellular organisms that are found in all environments - Lack a cell nucleus or any membrane-encased organelles - Circular, Singleloop DNA - Bacteria and Archaea (Unique life form that can indefinitely live in extreme environments) - Cocci = spherical (round) - Bacillus = (rod shaped) - Spirilla = helical (spiral) **Eukaryotes** - (eu = true; karyon-- = nucleus). - Eukaryotic organisms unlike prokaryotic can be unicellular or multicellular. - 1B Years ago - Nuclear membrane surrounds linear genetic material (DNA) - more advanced - Coverings known as cell membranes - Larger than prokaryotes - Animal cells, plant cells, fungi    Cells have evolved two different architectures: - Prokaryote style - Capsule - Cell wall - Cell membrane - cytoplasm: inner liquid filling - DNA - pilli: for sticking to things - flagella: for swimming - ribosomes: for building proteins - unicellular: all alone - colony: forms a film - filamentous: forms a chain of cells Eukaryote style -has parts of a eukaryotic