Biochemistry Lecture (4) 2024 PDF

Introduction to Biochemistry NUR 103 LECTURE 4 Dr. Usama Abdullah Al-Zaabi  Multiple Choice Question The figure given below shows the structure of a mitochondrion with its four parts labeled A, B, C and D. Which letter represents cristae: A. M B. N C. O D. P ...

Introduction to Biochemistry NUR 103 LECTURE 4 Dr. Usama Abdullah Al-Zaabi  Multiple Choice Question The figure given below shows the structure of a mitochondrion with its four parts labeled A, B, C and D. Which letter represents cristae: A. M B. N C. O D. P  Multiple Choice Question What organelle has digestive enzymes? A. Nucleus. B. Lysosome. C. Rough ER. D. Golgi Complex.  Matching Question Match the terms in Column 1 with their examples in Column 2 Column 1 Column 2 1. Inorganic cations in the cell. A. Mitochondria, lysosomes, nucleus 2. Human subcellular organelles. B. Water, vitamins, certain fatty acids 3. Chief chemicals for dietary intake C. Fungi, yeast, protozoa 4. Eukaryotes D. sodium, potassium, copper, iron  Short Answer Questions Why is the nucleus called storage of DNA? Why is mitochondrion called the powerhouse of the body? 1.2 The Cell Objective: Describe the structure, composition and biochemical functions of subcellular organelles of the eukaryotic cell. Subcellular Organelles of a typical eukaryotic cell ✓ Cell membrane ✓ Lysosomes ✓ Nucleus + Nucleolus Peroxisomes ✓ Cytosol/cytoplasm Golgi bodies ✓ Mitochondria Vacuoles Smooth endoplasmic reticulum Cytoskeleton Rough endoplasmic reticulum  Abbreviations in today's lecture Abbreviation is a shortened form of a word or phrase. Abbreviations are on pages xvii and xviii RER: Rough Endoplasmic Reticulum SER: Smooth Endoplasmic Reticulum  Peroxisomes Structure: Small vesicles surrounded by a membrane. They are also known as microbodies. When they have a very high concentration of protein, they may occur in crystalline form.  Peroxisomes Functions: Hydrogen peroxide 1) They contain enzymes of H2O2 metabolism. 2) Oxidation of long-chain fatty acids.  Search for the answers to these questions on Google. Use Google to search for the following information: The differences between metabolism, catabolism and anabolism. Anabolism Catabolism  Peroxisomes Functions: 3) Glycerophospholipids are also synthesized in peroxisomes. usually a saturated fatty acid some other small molecule usually an unsaturated fatty acid  Peroxisomes Functions: 4) The enzymes of H2O2 catabolism present in peroxisomes are peroxidase and catalase. 5) They also contain other enzymes like D, L-amino acid oxidase, uric acid oxidase and L-hydroxy fatty acid oxidase.  Biological importance of peroxisomes  Lack of peroxisomes results in Zellweger’s syndrome. Peroxisomes- Structure and Function  Zellweger’s syndrome Zellweger syndrome is a genetic disorder passed from parents to children. Newborns can have brain, liver and kidney problems, as well as difficulty feeding or moving. There is no cure or treatment.  Cytomembranes They are an extensive network of membranes in the cytoplasm. They are called cytomembranes. They are divided into: Rough Endoplasmic Reticulum (RER) 1 Endoplasmic reticulum (ER) Smooth Endoplasmic Reticulum (SER) 2 Golgi complex  Endoplasmic Reticulum (ER) 1) Where is RER located in the cell? 2) Where is SER located in the cell? 3) What is the main difference between RER and SER? 4) What is ribosomes?  Endoplasmic Reticulum (ER) 1) Where is RER located in the cell? It is continuous with the outer nuclear membrane. 2) Where is SER located in the cell? It is continuous with RER. 3) What is the main difference between RER and SER? RER is coated with ribosomes. 4) What is ribosomes? Ribosomes are complexes of protein + RNA. Endoplasmic Reticulum (ER) Endoplasmic reticulum Rough endoplasmic reticulum Smooth endoplasmic reticulum (RER) (SER) Structure: Structure: It is continuous with the outer nuclear It is continuous with RER. membrane. It differs from RER by the absence of Its cytoplasmic surface is coated with ribosomes. ribosomes. When isolated (in the lab), SER is Ribosomes are complexes of protein and called microsomes. RNA. Membrane-enclosed channels of ER are called cisternae. Rough endoplasmic reticulum Smooth endoplasmic reticulum (RER) (SER) Functions: Functions: Ribosomes and RER are involved SER of intestinal cells is involved in protein synthesis. in the formation of triglycerides. Synthesized protein enters cisternae In the adrenal cortex, SER is the and is later extruded. site for steroid formation. Cytochrome P450 dependent mono-oxygenases are present in the liver cell SER.  Golgi bodies Structure: It consists of a cluster of paired cytomembranes. The margins of these cytomembranes are flattened. It also contains several small vesicles, which are pinched off from the flattened margins of membranes.  Golgi bodies Functions: 1. They are well-developed in cells that are involved in secretion. The material produced in the cell for export is processed by the Golgi body and packaged as vesicle and is pinched off. Export of proteins ( + digestive enzymes of pancreas and insulin hormones) by process known as exocytosis. 2. They help in the formation of other subcellular organelles like lysosomes and peroxisomes. 3. They are involved in protein targeting. 4. They are involved in glycosylation and sulfation of proteins.  Golgi bodies Biological importance: Defective processing of insulin in Golgi complex → causes some cases of diabetes.  Vacuoles ▪ Some animal cells contain vacuoles. ▪ In animal cells, vacuoles are small compared to plant cells. ▪ They are membrane-enclosed vesicles containing fluid. Mostly they contain nutrients. Vacuoles  Cell Coat ▪ Some mammalian cells contain a thin coat called cell coat. ▪ It is on the outer surface of the cell membrane. ▪ It is flexible and sticky. ▪ It is composed of mucopolysaccharides, glycolipids and glycoproteins.  Cell Coat Functions: ▪ It controls the adhesive properties of the cell and the organization of tissue.  Cytoskeleton Meaning of skeleton What does the prefix cyto- mean?  Cytoskeleton Cell Cytoskeleton Structure & Functions 1. What is the main function of the cytoskeleton? 2. What is the cytoskeleton? 3. The cytoskeleton in the eukaryotic cell has four components, what are they?  Cytoskeleton What is the main function of the cytoskeleton? Provides physical support to the cell. Determines the shape of the cell. Movement of organelles inside the cell. What is the cytoskeleton? A network of fibrillar proteins The cytoskeleton in the eukaryotic cell has four components, what are they? 1- Microfilaments 2- Myosin fibers 3- Microtubules 4- Intermediate filaments The cytoskeleton has four different types of protein elements that differ in size and protein composition.  Cytoskeleton Filament-like structures made up of proteins present in the cytoplasm. Non-muscle cells perform mechanical work with this intracellular network of proteins (cytoskeleton) Cytoskeletons are: Microfilaments Myosin fibers Microtubules Intermediate filaments