The Cell & Cell Organisation Biomedical Science 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...

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 he 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 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 With proteins & layers. 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 Act as Allows directed molecules Contains cell transport in receptors cell or contents provide and out of cell (recognition organelle immunological sites) e.g. for motility identity hormones 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 Features: (RER) Series of 0 interconnecting Covered in ribosomes membranous canals which make proteins 04 1 which enclose flattened sacs called cisternae Extension of outer 02 nuclear membrane Large surface area for chemical reactions 03 Function of Rough Endoplasmic Reticulum Produces proteins A especially enzymes Pathway for transport B of materials through the cell Collecting & storing C synthesized material Providing a structural D skeleton to maintain cellular shape Smooth Endoplasmic Reticulum (SER) Found in large amounts in Similar features to cells which secrete RER, but no steroids e.g. adrenal ribosomes cortex in the kidney Concerned with Also contains enzymes for synthesis of lipids & detoxifying chemicals steroid hormones including drugs and pesticides Golgi Apparatus Feature s: 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. digestive Transporting & enzymes storing lipids Receives glyco- Secreting Forming proteins such as carbohydrates lysosomes mucin required in e.g. in cell wall secretions, by production adding the carbohydrate part to the protein  Lysosomes A secretory vesicle formed by 1 the Golgi apparatus Contain enzymes responsible for 2 degrading proteins & membranes in the cell Aids degradation of materials ingested 3 by the cell – due to hydrolytic (digestive) enzymes These are kept apart from the cell 4 otherwise they would destroy the contents of the cell Kept inactive by an alkaline 5 Abundant in cells with a phagocytic activity e.g. leucocytes environment within lysosome Lysosomes continued…. Functions: Digest materials which the cell consumed from A Autophagy: A process involving the degradation of the environment e.g. a cell's own components bacteria through the lysosomal. machinery B D They release enzymes Autolysis: The destruction C outside the cell of a cell through the (exocytosis) in order to action of its own enzymes break down other cells 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 Can also carry out protein fibres, 3-6 nm cellular movements in diameter 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 bound organelle oxidative enzymes such as catalase A major Important in function is the delaying cell breakdown of ageing fatty acid 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 centrioles appear chromatids 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 Chromatin Nuclei begin to fibres of form at chromosomes opposite poles uncoil Cytokinesis, the division of the At the end of original cell's cytokinesis, cytoplasm, begins there are two before the end of mitosis and distinct completes shortly daughter cells after 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 occurs in the formation maturity in the ovaries of reproductive cells of the female and the known as the gametes - spermatozoa in the the ova and testes 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 Homologous The stages The Homologous pairs of the diploid (similar) are as for homologous divide and 2 daughter cells replicate chromosomes mitosis pairs swap cells are produced, pair up some DNA 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 Active Passive Transport Transport Diffusion or uses ATP osmosis Bulk Transport pinocytosi s or phagocyto sis Cell Transport B D A C E 1. Diffusion 2. Osmosis 3. Active 4. 5. Transport Phagocytosis 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 hyperplasia are two (SIZE MATTERS) distinct process, they frequently occur together Metaplasia The If the stimulus transformatio is removed or n of one type 0 ceases, tissues 03 return to their of cell into 1 normal pattern another state Generally Can you give caused by an example some sort of 0 0 inside the abnormal 2 4 mouth? Or stimulus generally? Dysplasia Generally, consists of an A term used in expansion of pathology to immature refer to an cells, with a abnormality in corresponding maturation of decrease in cells within a the number tissue and location of mature cells Neoplasia The abnormal It usually proliferation of causes a lump cells or tumour The growth of this Neoplasms may clone of cells exceeds & is be benign, pre- uncoordinated malignant or with the normal malignant tissues around it