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Semester 1: Basics of Biochemistry
Carbohydrates: classification, structure, configurations, anomeric forms, monosaccharides, disaccharides, polysaccharides
Carbohydrates
Classification
Carbohydrates are classified into three main categories: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are simple sugars, disaccharides are formed from two monosaccharides, and polysaccharides are long chains of monosaccharides.
Structure
Carbohydrates consist of carbon, hydrogen, and oxygen atoms. They have a general formula of (CH2O)n, where n is the number of carbon atoms. Their structure can be classified as linear or ring forms.
Configurations
Carbohydrates can exist in different configurations, primarily D and L forms, based on the orientation of the hydroxyl group on the penultimate carbon.
Anomeric Forms
The anomeric carbon is the carbon derived from the carbonyl group in the sugar. Anomers are isomers that differ in configuration at this carbon. They exist as alpha and beta forms.
Monosaccharides
Monosaccharides are the simplest form of carbohydrates, consisting of single sugar units like glucose, fructose, and galactose. They are classified based on the number of carbon atoms and functional groups.
Disaccharides
Disaccharides are formed by the condensation of two monosaccharides linked by glycosidic bonds. Common examples include sucrose, lactose, and maltose.
Polysaccharides
Polysaccharides are complex carbohydrates that consist of long chains of monosaccharide units. They serve various functions such as energy storage (e.g., starch, glycogen) and structural roles (e.g., cellulose, chitin).
Lipids: classification, structure, fatty acids, phospholipids, glycolipids, steroids, eicosanoids
Lipids
Classification of Lipids
Lipids can be classified into three main categories: simple lipids, compound lipids, and derived lipids. Simple lipids, like fats and oils, are esters of fatty acids and glycerol. Compound lipids include phospholipids and glycolipids, which contain additional functional groups. Derived lipids are substances that are derived from lipids, such as cholesterol.
Structure of Lipids
Lipids are generally hydrophobic molecules composed primarily of hydrocarbons. Their structure can vary significantly: triglycerides have a glycerol backbone with three fatty acid chains, while phospholipids consist of two fatty acids, a glycerol, and a phosphate group. This structural diversity leads to various functions in biological systems.
Fatty Acids
Fatty acids are carboxylic acids with a long hydrocarbon tail. They can be saturated, having no double bonds, or unsaturated, containing one or more double bonds. Fatty acids are crucial for energy storage and membrane structure.
Phospholipids
Phospholipids are a main component of cell membranes, composed of two fatty acids, a phosphate group, and glycerol. Their amphipathic nature, containing both hydrophobic and hydrophilic regions, allows them to form bilayers in an aqueous environment.
Glycolipids
Glycolipids are lipids with carbohydrate groups attached. They play significant roles in cell recognition and signaling processes. Glycolipids are found on the extracellular surface of cell membranes.
Steroids
Steroids are lipids characterized by a four-ring structure. Cholesterol is a well-known steroid involved in membrane fluidity and is a precursor for the synthesis of other steroids, such as hormones.
Eicosanoids
Eicosanoids are signaling molecules derived from fatty acids, particularly arachidonic acid. They include prostaglandins, thromboxanes, and leukotrienes, and are involved in various physiological responses including inflammation and immune functions.
Amino acids and Proteins: classification, structure, properties, protein structure levels, collagen, hemoglobin
Amino acids and Proteins
Classification of Amino Acids
Amino acids are classified based on their side chains. There are 20 standard amino acids, which can be grouped into categories such as essential vs non-essential amino acids, polar vs non-polar, and acidic vs basic. Essential amino acids must be obtained from the diet, while non-essential can be synthesized by the body.
Structure of Amino Acids
Amino acids consist of a central carbon atom bound to an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group). The nature of the R group determines the characteristics of the amino acid.
Properties of Amino Acids
Amino acids exhibit various properties including solubility in water, ionization at different pH levels, and reactivity due to functional groups. These properties play a crucial role in their function within proteins.
Protein Structure Levels
Proteins have four levels of structure: primary (sequence of amino acids), secondary (local folding patterns such as alpha-helices and beta-sheets), tertiary (overall three-dimensional shape), and quaternary (assembly of multiple polypeptide chains).
Collagen
Collagen is a structural protein that provides strength and support to connective tissues. It consists of three polypeptide chains that form a triple helix. Collagen is crucial for skin, bones, and cartilage.
Hemoglobin
Hemoglobin is a protein in red blood cells responsible for transporting oxygen. It consists of four polypeptide subunits and contains heme groups that bind to oxygen. Hemoglobin's structure allows it to pick up oxygen in the lungs and release it in tissues.
Membrane proteins and cytoskeleton proteins, membrane structure - fluid mosaic model
Membrane proteins and cytoskeleton proteins, membrane structure - fluid mosaic model
Membrane Structure
The plasma membrane is composed of a phospholipid bilayer with embedded proteins. This structure allows for fluidity and flexibility, enabling the movement of proteins and lipids within the membrane.
Fluid Mosaic Model
The fluid mosaic model describes the plasma membrane as a dynamic and flexible structure. Lipids form a bilayer that is fluid, while proteins are interspersed, creating a mosaic appearance. This model explains how different components can move laterally within the membrane.
Membrane Proteins
Membrane proteins are classified into two categories: integral and peripheral. Integral proteins span the membrane and are involved in transport and communication. Peripheral proteins are attached to the exterior or interior surfaces and play roles in signaling and maintaining the cell shape.
Cytoskeleton Proteins
Cytoskeletal proteins provide structural support to the cell and are involved in cellular movement. Major components include microfilaments, intermediate filaments, and microtubules. They interact with membrane proteins, assisting in cell signaling and maintaining cell integrity.
Interactions between Membrane and Cytoskeleton
The cytoskeleton interacts with membrane proteins to regulate cell shape, motility, and intracellular transport. This interaction is crucial for various cellular functions, such as signaling pathways, endocytosis, and exocytosis.
Nucleic acids: types and forms, DNA and RNA structure, sequencing methods, nucleic acid properties
Nucleic acids: types and forms, DNA and RNA structure, sequencing methods, nucleic acid properties
Types of Nucleic Acids
Nucleic acids are primarily classified into two main types: DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid). DNA is the genetic material found in most organisms and carries the instructions for development and function. RNA is involved in protein synthesis and other roles related to the expression of genes.
Forms of Nucleic Acids
Nucleic acids can exist in various forms, including single-stranded RNA (ssRNA), double-stranded RNA (dsRNA), and double-stranded DNA (dsDNA). The most common form of DNA is the double helix, while RNA can also form complex structures such as hairpins and loops.
DNA Structure
DNA consists of two long strands of nucleotides twisted into a double helix. Each nucleotide comprises a phosphate group, a sugar (deoxyribose), and a nitrogenous base (adenine, thymine, cytosine, or guanine). The strands are complementary, with adenine pairing with thymine and cytosine pairing with guanine.
RNA Structure
RNA is typically single-stranded and contains ribose sugar instead of deoxyribose. Its nitrogenous bases include adenine, uracil, cytosine, and guanine. RNA can fold into various shapes and structures, allowing it to carry out diverse functions in the cell.
Sequencing Methods
Nucleic acid sequencing methods are techniques used to determine the exact sequence of nucleotides in a DNA or RNA molecule. Common methods include Sanger sequencing, next-generation sequencing (NGS), and RNA sequencing (RNA-seq). These techniques have revolutionized genomics and transcriptomics.
Properties of Nucleic Acids
Nucleic acids exhibit several key properties: they can store and transmit genetic information, they have the ability to replicate, and they play a crucial role in the synthesis of proteins. Their stability and ability to form hydrogen bonds between complementary bases are also important properties that facilitate their functions in biological systems.
