Basic Genetic & Molecular Biology - Cell Biology (PDML 4813)

PDML 4813 Basic Genetic & Molecular Biology Cell Biology NURUL AINI BINTI AHMAD  LEARNING OUTCOMES Define the terms of cells Describe the Eukaryote & Prokaryote Identify the cell structure Identify the function of organelles Define virus  INTRODUCTION Cell th...

PDML 4813 Basic Genetic & Molecular Biology Cell Biology NURUL AINI BINTI AHMAD  LEARNING OUTCOMES Define the terms of cells Describe the Eukaryote & Prokaryote Identify the cell structure Identify the function of organelles Define virus  INTRODUCTION Cell theory: ▪ All living organisms are made up of cells ▪ New cells are formed by the division of pre-existing cells. ▪ Cells contain genetic materials of an organism which is passed from parents to daughter cells. ▪ All metabolic reactions take place within cells.  WHAT IS A CELL? ▪ Cell is the basic building blocks of all organisms. ▪ A cell contains internal structures known as organelles that are specialised to perform specific functions. ▪ The cell of an organisms can be either: Unicellular - Organism made up of just one cell (eg. Bacteria) Multicellular - Organism that are consist of many cells (eg.humans, animals, plants)  WHAT IS A CELL? ▪ All cells share certain basic features: Bounded by a selective barrier known as plasma membrane Inside the cell is a semifluid, jelly-like substance called cytoplasm that contain subcellular components contain chromosomes, which carry genes in the form of DNA tiny complexes that made proteins known as ribosomes  WHAT IS A CELL? ▪ The cells can be differentiated and thus broadly categories as: Prokaryotic cell Eukaryotic cell  PROKARYOTIC CELL ▪ Structurally more simpler ▪ Eg. Bacteria and Archea ▪ The term ‘prokarya’ means ‘before nucleus’ – lacks of ‘true nucleus’ ▪ the chromosome is circular and is not enclosed in a nucleus- located in a region known as nucleoid region ▪ No membrane-bound organelles PROKARYOTIC CELL  PROKARYOTIC CELL ▪ Rigid cell wall (peptidoglycan) that surrounds the plasma membrane and gives shape to the organism ▪ Plasma membrane- membrane enclosing cytoplasm ▪ Ribosomes- complexes that synthesis protein. In prokaryotic cells, the ribosomes are scattered and floating freely throughout the cytoplasm. The ribosomes in prokaryotic cells also have smaller subunits.  PROKARYOTIC CELL ▪ Some prokaryotes consists of the following structures: ▪ Flagella- long fibers that projects from the surface of the cells- act as propellers- for locomotion ▪ Capsule- outer coating / slime layer ▪ Plasmid – extrachromosomal DNA carries virulent genes/ antibiotic resistant genes ▪ Fimbriae/pili - attachment structure  EUKARYOTIC CELL ▪ Eg. Protozoa, Fungi, Plant, Animal ▪ size are larger than prokaryotic cells ▪ Eukaryotic means ‘true nucleus’ ▪ The chromosome is enclosed in a nucleus ▪ Highly organised membrane-enclosed organelles including nucleus, mitochondria, golgi apparatus, smooth and rough endoplasmic reticulum ribosomes etc. ▪ The ribosomes are bigger, more complex and bound by a membrane- can be found in various places (in cytoplasm; on the ER; or attached to the nuclear membrane)  EUKARYOTIC CELL ▪ A cytoskeleton- containing the structural and motility components called actin microfilaments and microtubules. ▪ Chromosomes- each consisting of a linear DNA molecule coiled around proteins called histones. ▪ Flagella and cilia- organelles associated with cell motility in some eukaryotes (eg protozoa)  Chromatin Nuclear envelope Nucleolus Nucleus Smooth endoplasmic reticulum Cytosol Plasma Mitochondrion membrane Lysosome Centrioles Rough endoplasmic Centrosome reticulum matrix Ribosomes Golgi apparatus Microvilli Microfilament Secretion being released Microtubule from cell by exocytosis Intermediate filaments Peroxisome Figure 3.2  CELL STRUCTURE & FUNCTIONS PLASMA MEMBRANE ❖Forms the boundary between a cell and environment ❖Function: a) selectively permeable to ions and organic molecules b) regulate movement of materials in and out of cell c) involved in a variety of cellular processes such as cell adhesion and cell signaling d) serve as the attachment surface for the extracellular glycocalyx and cell wall and intracellular cytoskeleton (in prokaryotes) CELL STRUCTURE & FUNCTIONS FLUID MOSAIC MODEL OF THE PLASMA MEMBRANE  CELL STRUCTURE & FUNCTIONS ORGANELLES Made of macromolecules. Nucleus Performs a particular function. Mitochondria Ribosomes Endoplasmic Reticulum Golgi Apparatus/body Lysosomes Cytoskeleton Vacuoles Centrioles  CELL STRUCTURE & FUNCTIONS NUCLEUS ▪ a membrane-bound structure that contains a cell's genetic information (DNA) ▪ Control center for most of cell’s activity including its growth and reproduction ▪ Surrounded by nuclear envelope - separates the contents of the nucleus from the cytoplasm; perforated by nuclear pore that control entry and exit of material ▪ Nucleoplasm is the gelatinous substance within the nuclear envelope ▪ The nucleolus where ribosome subunits are synthesised. CELL STRUCTURE & FUNCTIONS Nucleus structure  CELL STRUCTURE & FUNCTIONS RIBOSOME ▪ Site for protein synthesis ▪ Free ribosomes are suspended in cytosol while bound ribosomes are attached to the outside of endoplasmic reticulum or nuclear envelope.  CELL STRUCTURE & FUNCTIONS ENDOPLASMIC RETICULUM ▪ Endoplasmic means “within the cytoplasm” reticulum is Latin for “little net” ▪ Consist of network of membranous tubules and sacs called cisternae ▪ role in the production, processing, and transport of proteins and lipids. ▪ 2 distinct ER: ▪ Smooth ER – outer surface lacks ribosome - synthesizes lipids and steroids. ▪ Rough ER – studed with ribosome thus appears rough - synthesizes proteins  CELL STRUCTURE & FUNCTIONS GOLGI APPARATUS ▪ Warehouse for receiving, sorting, shipping and manufacturing products from ER ▪ Eg. Protein are modified and stored and then sent to other destinations ▪ Consist of a group of associated, flattened membranous sacs, cisternae, looking like a stack of pita bread. ▪ Two sides of Golgi stack – cis face and trans face  CELL STRUCTURE & FUNCTIONS LYSOSOME ▪ A membranous sac of hydrolytic enzymes use to digest (hydrolyse) macromolecules. ▪ Made by rough ER and then transferred to Golgi apparatus for further processing. ▪ Carry out intracellular digestion by fuses with food vacuole/ vesicles and digest food particle via hydrolytic enzymes. CELL STRUCTURE & FUNCTIONS Relationship among organelles of the endomembrane system  CELL STRUCTURE & FUNCTIONS VACUOLES ▪ found in both animal and plant cells but are much larger in plant cells ▪ functions to hold various solutions or materials. ▪ For digestion, storage, water disposal, water balance, cell growth and protection. ▪ In plant, the large central vacuole absorbs water  CELL STRUCTURE & FUNCTIONS MITOCHONDRIA ▪ Known as the powerhouse of the cell ▪ Site for cellular respiration ▪ Main function is to generate energy in the form of ATP ▪ Number of mitochondria in a cell correlated with the cell’s level of metabolic activity. ▪ The structure consist of smooth outer membrane while the inner membrane is convoluted with infoldings called ‘cristae’ ▪ The inner membrane divides into intermembrane space and mitochondrial matrix.  CELL STRUCTURE & FUNCTIONS CHLOROPLAST ▪ contain the green pigment chlorophyll and functions in the photosynthesis. ▪ The chlorplast consist of structure known as thylakoids which are stacked like poker chips. Each stack is called granum. The fluid outside thylakoids is called stroma. ▪ The compartmental organisation enables the chloprolast to convert light energy to chemical energy during photosynthesis.  CELL STRUCTURE & FUNCTIONS PEROXISOMES ▪ Specialised metabolic compartment bounded by a single membrane. ▪ Morphologically similar to lysosomes ▪ contain enzymes involved in a variety of metabolic reactions ▪ Eg.carry out oxidation reactions leading to the production of hydrogen peroxide which converted to water by catalase  CELL STRUCTURE & FUNCTIONS CYTOSKELETON ▪ Role is to give mechanical support to cell and maintain its shape. ▪ Especially important for animal cells that lacks cell wall ▪ 3 main types of fibers that make up cytoskeleton: a) Microtubules b) Microfilaments (actin filaments) c) Intermediate fillaments  CELL STRUCTURE & FUNCTIONS MICROTUBULE ▪ Hollow rods constructed from globular proteins ▪ Shape and support the cell and also serve as tracks along which organelles equipped with motor proteins can move. i. Guide vesicles from ER to Golgi apparatus and from Golgi to plasma membrane ii. Involved in the separation of chromosomes during cell division  CELL STRUCTURE & FUNCTIONS CENTRIOLE ▪ the major microtubule-organizing center is the centrosome. ▪ The centrosomes of most animal cells contain a pair of centrioles, a cylindrical structures consisting of nine triplets of microtubules found close to the nucleus. ▪ During mitosis, microtubules extend outward from duplicated centrosomes to form the mitotic spindle, which is responsible for the separation and distribution of chromosomes to daughter cells.  CELL STRUCTURE & FUNCTIONS CILIA AND FLAGELLA ▪ A specialised arrangement of microtubules responsible for the beating of flagella and cilia ▪ Many unicellular eukaryotes are propelled through water by cilia or flagella that act as locomotor. CLASSIFICATION OF LIFE CLASSIFICATION OF LIFE  MICROORGANISMS BACTERIA ▪ Study of bacteria→Bacteriology (most thoroughly studied) ▪ Prokaryotes; ▪ Kingdom Prokaryotae or Monera ▪ Reproduce by binary fission ▪ Shapes: spherical, rod, spiral, few form filaments ▪ Absorb nutrients from environment, some make their own nutrients (cyanobacteria), motile and non-motile ▪ Eg. Staphylococcus aureus Escherichia coli  MICROORGANISMS FUNGI ▪ The study of fungi → Mycology ▪ Eukaryotic organisms ▪ Absorb ready-made nutrients from dead organisms. ▪ Reproduce asexually by budding and form pseudohyphae ▪ widely distributed in water and soil as decomposers ▪ May cause disease/infection (eg. ringworm, candidiasis) ▪ Some are beneficial to humans as a source for a) antibiotics (eg. Penicillin) b) food (eg. beer, wine, cheese, mushrooms) ▪ eg: yeasts, molds, mushrooms, Candida spp. Saccharomyces cerevisiae  MICROORGANISMS PROTOZOA ▪ Kingdom Protista: ‘animal-like’ ▪ Single-celled, eukaryotic organisms → May have one or more nuclei and numerous organelles ▪ Large, some are visible with naked eyes ▪ Obtain food by engulfing smaller m/o ▪ Reproduce asexually or sexually by fusion of gametes. ▪ Some protozoa form resistant cysts that can survive in the environment. ▪ Move independently either by cilia, flagella or pseudopodia ▪ Protozoa can be found in variety of water and soil environments  MICROORGANISMS ALGAE (Plant-like) ▪ Some algae are unicellular, filamentous (chain of cell) ▪ Mostly aquatic, some in soil, on trees (when moisture available) ▪ Simple eukaryotic photoautotrophs ▪ Lack tissue of plants (roots, stem and leaves) and lack enclosed reproductive structures (like flowers and cones.) ▪ Photosynthetic- chlorophyll (green pigment) for photosynthesis ▪ Location depends on availability of nutrients, light, and surface on which to grow  MICROORGANISMS VIRUS ▪ the study of viruses → virology ▪ Not considered as living organisms. ▪ Tiny (~20nm) acellular entities –too small to be seen with light microscope- only by using electron microscope ▪ contain nucleic acid (DNA or RNA) and are coated with protein known as capsid ▪ Replicate and display other properties of living organisms only when they have invaded cells → obligate intracellular parasites- requires a host to live ▪ May invade human cells and cause disease