The Cell Cell organisation DHT23 student copy - Tagged.pdf

The Cell & Cell Organisation Biomedical Science Coralie Frances GDC Learning Outcomes 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their application to patient management 1.1.6 Describe relevant and appropriate physiology and explain i...

The Cell & Cell Organisation Biomedical Science Coralie Frances GDC Learning Outcomes 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their application to patient management 1.1.6 Describe relevant and appropriate physiology and explain its application to patient management Learning Outcomes At the end of the session the student should have a broad understanding of the structure and components of the cell Be able to: Label and state the function of the cell & its components Explain the processes of cell division - mitosis and meiosis Understand the abnormalities of cell growth and function Assess your knowledge pre lecture What is cytology? Look at the next slide What is this? Can you identify the structures? What are their functions? 4 How did you do? Rate your knowledge on a score of 1-5 (1 least knowledge; 5 greatest knowledge) Continue with the PPT to refresh your knowledge then answer the same questions again What are your scores now? 6 Features of the cell Smallest functional unit of the body All organisms are made of cells They carry out all vital chemical processes Humans are multi-cellular Cells are differentiated and adapted for different tasks The order of development Groups of cells TISSUES Groups of tissues ORGANS Groups of organs SYSTEMS Cell Structure Plasma membrane Microtubules Cytoplasm Centrioles Nucleus Peroxisomes Mitochondria Ribosomes Golgi Apparatus Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Lysosomes Microfilaments The Human Cell Nucleus The nucleus is a highly specialised organelle that serves as the information processor & administrative centre of the cell Features: 1. One nucleus per cell usually 2. Skeletal muscle & some other cells have several 3. Missing from erythrocytes (red blood cells) 4. Largest feature in a cell Nuclear Envelope Bound by a double membrane, the nuclear envelope – outer layer being continuous with Endoplasmic Reticulum (ER) Pores in the membrane allow the passage of substances The Nucleus continued……. Functions: Stores the genetic material (DNA) Directs all metabolic activities of the cell include growth, metabolism, protein synthesis, and reproduction (cell division) Involved in cell division Instructs the synthesis of proteins/ribosomes & RNA Plasma (cell) Membrane Partially permeable 02 Phospholipids (fatty substances) Embedded 01 03 Made up of 2 layers With proteins &. 04 carbohydrate molecules Double layer (bilayer) of lipids mostly phospholipids Phospholipids are hydrophilic ("water-loving") at their phosphate ends – facing outwards, and hydrophobic ("water-fearing") along their lipid tail regions – orientated inwards 15 Plasma Membrane Structural Components Some proteins are embedded in the bilayer, while others attach to the surface Many proteins play a part in selective transport of substances across the membrane Others act as surface receptors for substances such as hormones, or act as enzymes Functions of Membrane & its Proteins Carbohydrate Regulate transport Act as receptors Allows directed molecules provide Contains cell in and out of cell (recognition sites) cell or organelle contents immunological e.g. for hormones motility identity Cytoplasm Gelatinous, semi-transparent fluid that fills most cells & is where metabolic reactions occur Mainly water, with many solutes including glucose, proteins & ions Contains many vital cellular chemicals e.g. Na, phosphates, chlorides, amino acids, ATP & storage material – oil droplets Mitochondrion (mitochondria) The ‘powerhouse of the cell’ Outer & inner membranes Cristae: Folded inner membrane allowing maximum surface area for chemical reactions to occur Mitochondrion (mitochondria) Involved with cellular aerobic (O2) respiration- the process by which chemical energy is made available in the cell Energy = ATP (Adenosine triphosphate) is formed from the catabolism of carbohydrates, fats and proteins in the cell Occur in varying numbers, depending on the cell & its function, greatest number in cells which are physically & metabolically active e.g., skeletal muscles Rough Endoplasmic Reticulum (RER) Features: Series of interconnecting membranous canals which Covered in ribosomes which 01 enclose flattened sacs called make proteins 04 cisternae Extension of outer nuclear 02 membrane Large surface area for chemical reactions 03 Function of Rough Endoplasmic Reticulum Produces proteins especially A enzymes Pathway for transport of B materials through the cell Collecting & storing C synthesized material Providing a structural skeleton D to maintain cellular shape Smooth Endoplasmic Reticulum (SER) Found in large amounts in cells Similar features to RER, which secrete steroids e.g. but no ribosomes adrenal cortex in the kidney Concerned with synthesis of Also contains enzymes for lipids & steroid hormones detoxifying chemicals including drugs and pesticides Golgi Apparatus Features: Composed of stacks of flattened membranous sacs called cisternae Sacs are fluid filled & pinch off smaller membranous sacs, called vesicles Normally only 1 Golgi apparatus in each animal cell Function of Golgi Apparatus It packages & processes proteins received from the ER into vesicles prior to secretion Vesicles then deliver them to their destinations e.g., lysosomes or cell membrane Thus it plays a key role in the secretory pathway  Golgi Apparatus continued……. Functions: Producing secretory enzymes e.g. Transporting & digestive enzymes storing lipids Receives glyco-proteins Secreting carbohydrates Forming lysosomes such as mucin required e.g. in cell wall in secretions, by adding production the carbohydrate part to the protein  Lysosomes A secretory vesicle formed by the 1 Golgi apparatus Contain enzymes responsible for degrading 2 proteins & membranes in the cell Aids degradation of materials ingested by the cell 3 – due to hydrolytic (digestive) enzymes These are kept apart from the cell otherwise 4 they would destroy the contents of the cell Kept inactive by an alkaline environment 5 Abundant in cells with a phagocytic activity e.g. leucocytes within lysosome Lysosomes continued…. Functions: Digest materials which the cell consumed from the A Autophagy: A process involving the degradation of a cell's own environment e.g. bacteria components through the lysosomal. machinery B D They release enzymes outside Autolysis: The destruction of a C the cell (exocytosis) in order cell through the action of its to break down other cells own enzymes Recap Can you state what a lysosome is? What are a lysosome’s functions? What does apoptosis mean? 29 Lysosome & its function If cell damaged beyond repair Lysosomes can help it to self-destruct by apoptosis (programmed cell death) They destroy invading viruses & bacteria They break down excess or worn-out cell parts A lysosome is a membrane bound cell organelle that contains digestive enzymes Centrosome Directs organisation of microtubules within the cell Comprises a pair of centrioles (small clusters of microtubules) Plays an important part during cell division 31 Centrosome 2 centrioles, cylindrical structures, orientated at right angles to each other Cylindrical structures, held at right angles to one another Act as organisers of the nuclear spindle during cell division  Microfilaments Composed predominantly of a contractile protein called actin, which is the most abundant cellular protein Fine, thread-like protein Can also carry out cellular fibres, 3-6 nm in diameter movements including gliding, contraction & cytokinesis (the division of cytoplasm following division of a nucleus) Association with the protein myosin is responsible for muscle contraction Microtubules Involved in intracellular Cylindrical tubes, 20- transport, e.g. movement of 25 nm in diameter mitochondria Composed of subunits of Form the spindle fibres for the protein – tubulin separating chromosomes during mitosis When arranged in geometric Act as a scaffold to patterns inside flagellae e.g. determine cell shape and cilia, they are used for locomotion Peroxisome A membrane – Contains oxidative bound organelle enzymes such as catalase A major function is Important in the breakdown of delaying cell ageing fatty acid molecules Label the diagram & state their functions 36 Cell Division Mitosis Process by which a cell duplicates the chromosomes in its cell nucleus - in order to generate two genetically identical daughter nuclei (each containing 46 chromosomes) The process of mitosis is complex and highly regulated Mitosis --- Stages: A 1. Interphase B 2. Prophase C 3. Metaphase D 4. Anaphase E 5. Telophase Interphase Cell growth DNA synthesis Chromosome 2 pairs of replicates into – pairs of chromatids centrioles appear Early Prophase Each chromosome has two chromatids joined at a centromere The mitotic spindle, composed of microtubules and proteins, forms in the cytoplasm The two pair of centrioles move away from one another toward opposite ends of the cell Late Prophase Nuclear envelope breaks up Microtubules that make up the spindle fibres, reach from each cell pole to the cell's equator Chromosomes /chromatids begin to migrate toward the cell centre Metaphase Nuclear membrane disappears completely Two pair of centrioles align at opposite poles of the cell Chromosomes /chromatids align at the metaphase plate at right angles to the spindle poles Anaphase The paired chromatids in each distinct chromosome begin to move apart Once the paired sister chromatids separate from one another, each is considered a "full" chromosome, referred to as daughter chromosomes The daughter chromosomes move to the poles at opposite ends of the cell Telophase Nuclei begin to Chromatin fibres of form at opposite chromosomes poles uncoil Cytokinesis, the division At the end of of the original cell's cytoplasm, begins before cytokinesis, there the end of mitosis and are two distinct completes shortly after daughter cells telophase  Videos of mitosis www.youtube.com/watch?v=RNwJbMovnVQ https://www.youtube.com/watch?v=DwAFZb8juMQ 47 Meiosis 01 This type of cell division The ova grow to maturity in occurs in the formation of the ovaries of the female and reproductive cells known as the spermatozoa in the testes the gametes - the ova and of the male spermatozoa 02  After division each of the daughter cells has only 23 chromosomes When the ovum is fertilized the resultant zygote has the full complement of 46 chromosomes, half from the father and half from the mother Stages of Meiosis - Meiosis I Chromosomes of Homologous (similar) The stages are The homologous Homologous pairs divide and the diploid cells chromosomes pair as for mitosis pairs swap some 2 daughter cells are replicate up DNA produced, each with 23 chromosomes only – haploid Stages of Meiosis- Meiosis II Meiosis II is similar to mitosis & 4 daughter haploid cells are produced Video comparing & contrasting mitosis & meiosis https://www.youtube.com/watch?v=zrKdz93WlVk&vl=en 53 Cellular Transport Transport of substances across cell membranes Passive Transport Active Transport Diffusion or osmosis uses ATP Bulk Transport pinocytosis or phagocytosis Cell Transport B D A C E 1. Diffusion 2. Osmosis 3. Active Transport 4. Phagocytosis 5. Pinocytosis Diffusion Diffusion is the process by which a substance moves from a region of high concentration to a region of low concentration Rate is variable: Concentration gradient, distance, the size of area, structure in path, & size of molecule Osmosis The passage of water down its concentration gradient towards equilibrium across a semi permanent membrane Occurs when solute molecules are too large to pass through the pores in the membrane by diffusion YouTube - Osmosis Active Transport 1 The transport of substances up their concentration gradient i.e. from a lower to a higher concentration 2 Chemical energy (ATP) drives protein molecules in the membrane that transport substances across the membrane in either direction 3 E.g. the sodium-potassium pump maintains homeostasis of electrolytes sodium and potassium Phagocytosis The process by which the cell can obtain particles which are too large to be absorbed by diffusion or active transport White blood cell engulfing bacterium Pinocytosis ‘Cell drinking’ is very similar to phagocytosis except vesicles are produced called ‘pinocytotic vesicles’ Used for intake of liquids rather than solids Both pinocytosis & phagocytosis are methods by which materials are taken into the cell in bulk - ENDOCYTOSIS The reverse process materials are removed from the cell e.g. waste products – EXOCYTOSIS YouTube - Cell Membrane, Exocytosis & Endocytosis Abnormal Cell Growth Hyperplasia A term referring to the proliferation of cells within an organ or tissue beyond that which is ordinarily seen i.e. constant cell division What may cause this? Hypoplasia Underdevelopment or incomplete development of a tissue or organ Refers to an inadequate or below-normal number of cells Hypoplasia is a congenital condition, while hyperplasia generally refers to excessive cell growth later in life Atrophy The partial or complete wasting away of a part of the body Possible causes? Hypertrophy The increase in the volume of an organ or tissue due to the enlargement of its Although hypertrophy & component cells (SIZE hyperplasia are two distinct MATTERS) process, they frequently occur together Metaplasia The If the stimulus is removed or ceases, transformation 0 of one type of 03 tissues return to cell into another 1 their normal pattern state Can you give an Generally caused by some sort of 0 0 example inside the mouth? Or abnormal stimulus 2 4 generally? Dysplasia Generally, consists of an A term used in pathology expansion of immature to refer to an abnormality cells, with a in maturation of cells corresponding decrease within a tissue in the number and location of mature cells Neoplasia The abnormal It usually causes a proliferation of lump or tumour cells The growth of this clone of cells exceeds Neoplasms may be & is uncoordinated benign, pre- with the normal malignant or tissues around it malignant