NUR 101 HB1 Lecture 2- Cells Tissues 100923_organized-34-66.pdf

Protein Synthesis Transcription • The DNA of the nucleus controls cell structure and function through synthesis of specific proteins • Protein synthesis is the assembling of functional polypeptides in the cytoplasm • The major events of protein synthesis are Transcription and Translation Transcri...

Protein Synthesis Transcription • The DNA of the nucleus controls cell structure and function through synthesis of specific proteins • Protein synthesis is the assembling of functional polypeptides in the cytoplasm • The major events of protein synthesis are Transcription and Translation Transcription DNA ➔ Translation Translation RNA ➔ Protein (Marieb, 2019) Transcription Nucleus • Transcription is the synthesis of messenger RNA (mRNA) from a DNA template catalyzed by RNA polymerase • Occurs in the cell nucleus • Start at a DNA nucleotide sequence called promoter • Consists of 3 steps: Initiation 01 • The RNA polymerase first bind to the DNA promoter and unwine the double strain DNA • Synthesis of mRNA begins at the start site of the gene sequence Elongation 02 • RNA polymerase elongates the RNA chain by adding the ribonucleotides to the mRNA using 05 the complementary base pairs matching method Termination 03 • RNA polymerase dissociates from the DNA template at a specific sequence of the DNA called terminator and ends the mRNA synthesis • The mRNA then leave the nucleus to the cytoplasm through the nuclear pore • Translation is the synthesis of a linear chain of amino acids using the transcribed information provided by the mRNA • Occurs in the cytoplasm • Each amino acid in a protein specify by three nitrogen bases in the DNA sequences called codon • Consists of 3 steps: Translation Initiation Cytoplasm 01 • The ribosome read the start codon for the translation- “AUG” from the mRNA • First tRNA with matched anti-codon brings the specific amino acid to the ribosome binding site and start the translation process Elongation 02 tRNA • Codon recognition- Second tRNA with matched anticodon bring another amino acid to the second ribosome binding site • Base pair complementation between mRNA codon and tRNA anticodon • Peptide bond formation- happens between the amino acids that the tRNAs bought within the ribosome 05 • Translocation- Ribosome translocate by one codon along the mRNA. First tRNA left without amino acid and new tRNA bring new amino acid to the vacant ribosome site and continue the amino acids binding by base pair complementation Termination 03 • Stop codon- “UAG, UAA or UGA” was read by the ribosome • Peptidyl Transferase cleaved the linkage between the amino acids with RNA • The completed amino acid chain released Process of Translation tRNA (Martini, 2015) Codons for Protein Synthesis tRNA (Shier, 2015) Gene Mutation • • • A gene mutation involves a change in the order of the nitrogen bases (A, C, G, T) that makes up the genes The change in the DNA sequence can lead to a subsequent change in the mRNA sequence The altered mRNA sequence would lead to a change in the amino acid sequence (the primary protein structure) and may alter bonding in the protein molecule leading to the protein being inactive or problem-causing Types of mutation 01 • Deletion- base missing • E.g. AGTCTGC ➔ AGCTGC • Addition- extra base added • E.g. AGTCTGC ➔ AGTCGTGC • Substitution- one base is replaced by another base • E.g. AGTCTGC ➔ AGGCTGC Effects of gene mutation 02 • Proteins produced may be beneficial or harmful, or may have no effect at all • The effect can be positive, negative or neutral Protein Package, Processing & Secretion tRNA (Martini, 2015) Cell Cycle • A cell life from it forms until it divides consists of a series of phases called cell cycle • The major phases are • Interphase • Mitosis • Cytokinesis (Cytoplasmic division) (Shier, 2015) Types of Cell Division Reproductive Cell Division Somatic Cell Division • Any cell of the body except sex cells • Undergo nuclear division (Mitosis) and cytoplasmic division (Cytokinesis) • Produce 2 genetically identically cells- same number and kind of chromosomes as the original cell, i.e. 23 pairs of chromosomes cell (n=46) called Diploid cells Reproductive Cell Division • Undergo 2-step division called Meiosis • The number of chromosomes in the nucleus is reduced by half (n=23) to become Haploid cells Somatic Cell Division (Shier, 2015) Cell Cycle- Interphase Interphase consists of 4 phases: • G0 Phase- Resting phase • G1 Phase- Organelle duplication and protein synthesis occur • S Phase- Cell duplicate centrioles and conduct DNA replication • G2 Phase- Cell continue growing to: • Makes more organelles • Finishes replicating centrioles • Synthesis enzymes for cell division • Checks DNA and repairs any errors tRNA (Shier, 2015) DNA Replication Occur in S phase: • DNA helix unwinded by helicases into single template strand and expose the nitrogenous bases, ATP required • DNA polymerase read the exposed short segments of nitrogenous bases and assemble the sequence of the new strand with complementary nitrogenous bases with the RNA primers • DNA ligase joins the short segments together tRNA (Martini, 2013) • Happens in the nucleus • Functions- Growth, repair, replace, wore out cells • The replicated chromatin becomes tightly coiled and easier to see under the microscope • Consists of 4 sub-phases: • Prophase • Metaphase • Anaphase • Telophase Mitosis (M Phase) (Shier, 2015) Process of Mitosis (Marieb, 2019) Early Prophase • Chromatin fibers condense and shorten into chromosomes • Each chromosome consists of a pair of identical strands called chromatids Late Prophase • Centrioles get pushed apart to each pole of the cell by spindle fibers • Spindle fibers attached to the centromere on chromosomes • Nucleoli disappear and the nuclear envelope breaks down Metaphase • The chromatids align on the center of the spindle fibers, attached by their centromeres Anaphase Telophase • Centromeres split by enzyme • Sister chromatids separated and move toward opposite poles of the cell • Chromatids become chromosomes after separated • Chromosomes are in opposite ends, uncoil and revert to chromatin form • Nuclear envelope reform, nucleoli reappear in the identical nuclei • Mitotic spindle breaks up • Following telophase, cytokinesis occurs- the cytosol, intracellular organelles and plasma membrane split to form 2 identical daughter cells • Sex cells are produced through Meiosis • Involves 2 cell division instead of one, and produces four genetically unique cells rather than two identical cells • Sex cells are haploid cells that contain only half of the full set of 46 chromosomes • Because of haploid and genetically unique, it can combine with another sex cell during fertilization to create offspring with genetic variation • Detail process discuss in reproductive system Meiosis Cell Differentiation • All cells in human body comes from stem cells, through the processes of mitosis and differentiation- process enables cells to specialize and become mature cells (Shier, 2015) Section Break TOILET TIME Tissues • Groups of similar cells working together to perform a particular function • 8 types of tissues- blood, bone, epithelial tissue, cartilage tissue, adipose tissue, connective tissue, muscle tissue, and nervous tissue Types of Body Tissues Epithelial Tissue • Cover body surface • Line hollow organs, body cavities and ducts • Form glands and membranes Classification of Epithelial Tissue tRNA Simple Epithelial Tissue Function Location • Found in heart, blood and lymphatic vessels linings • Epithelial layer of peritoneum, pleura and pericardium • • • • • Located at glands, ducts, kidney tubules • Makes up secreting portion of thyroid gland and ducts of pancreas • Secretion and absorption • Lining of stomach, guts, gall bladder, uterine tubes, collecting ducts of kidney • Secretion • Absorption • Protection • Ciliated: Lining of nasal cavity, trachea and bronchi • Non-ciliated: Lining of large ducts, epididymis, and part of male urethra • Secrete mucus to trap foreign particles • Cilia sweep away mucus for elimination from the body • Absorption and protection tRNA Reduce friction Control vessels permeability Perform diffusion Perform secretion Stratified & Transitional Epithelial Tissue Location Function • Found in skin surface • Linings of mouth, throat, oesophagus, rectum and vagina • Covers tongue • Protect against abrasion, water loss, ultraviolet radiation, and foreign invasion • Form the first line of defense against microbes • Ducts of sweat glands and oesophageal glands • Part of male urethra • Protection • Limited secretion and absorption • Part of urethra, large excretory ducts • Protection and secretion tRNA • Lines several parts of the urinary tract, including bladder • Variable appearance, subject to expansion Glandular Epithelium • • • • Found in cells or organs that secrets substances for use in other body parts Include Endocrine and Exocrine glands Endocrine • No ducts • Secrete directly into blood • Secretions are known as hormones Exocrine • Contact with the surface by means of ductan epithelial tube that brings secretion to surface, e.g. Sweat and tears • Secretion released to body surface or into the cavity or lumen of another organic, e.g. Saliva and digestive enzymes (Martini, 2015) (Shier, 2015) Membranes in the Body Line body cavities and cover the viscera (internal organs) • Cutaneous Membrane (Skin) • Largest membrane in the body • Dry • Mucous Membrane (Mucosa) • Line all body cavities that open to the outside of the body, e.g. Digestive tract, Respiratory tract, Urogenital tract • Serous Membrane (Serosa) • Internal membrane that covers organs and lines walls of body cavities, e.g. Pleura, Pericardium, Peritoneum (Martini, 2015) Connective Tissue • • • The most abundant tissue and widely distributed Materials found between cells Functions: • Support and binds structures together, e.g. Bone, Cartilage, Ligament, and Tendon • Store energy, e.g. Adipose tissue • Provides immunity to disease, e.g. White blood cells Loose Connective Tissues • • • • • • Fill up space between organs Act as cushion and stabilize cells Surround and support blood vessels and nerves Store Lipids Provide a route for diffusion of materials E.g. Matrix as in areolar, adipose tissue, finely woven reticular fibers tRNA (Martini, 2015) Dense Connective Tissues • • • • tRNA (Martini, 2015) Collagenous tissues Contain elastic fibers Can tolerate cycles of extension and recoil, e.g. Lung, Vessels Connect, provide strength and support, e.g. Tendon Fluid Connective Tissue • Transports oxygen from lungs to body cells • Bring waste, carbon dioxide from cells to lungs • Transports nutrients and hormones, regulate body temperature, body defense and prevent excessive blood loss from injury • Consists of Red blood cells, White blood cells and Platelet • Diffuse lymphatic tissue • Found in connective tissue of almost all organs • Found in lymphatic ducts and nodules Lymph Supporting Connective Tissues- Cartilage • • • • • Strong, flexible and avascular Covers the ends of long bones Connects bones Resists compressions and absorbs shock 3 types: • Hyaline cartilage • Elastic cartilage • Fibrocartilage tRNA (Martini, 2015) Supporting Connective Tissue- Bone Bone/ Osseous Tissue • • Hardest form of connective tissue Functions: • Protection to visceral organs • Support • Blood cell formation (Hemopoiesis) • Red bone marrow produces red blood cells, white blood cells and platelets • Storage of minerals & lipid • Calcium, phosphate • Yellow bone marrow consists adipose cells which store triglycerides and act as energy reserve • Leverage for muscles • Provide balance for the body • Assistance in movement (Marieb, 2019) Muscle Tissue • Able to contract and relax • Functions: • Provide movement within the body and of the body itself • Muscle contraction requires a rich blood supply providing sufficient oxygen, calcium and nutrients and removing waste products • 3 types of contractile cells: • Skeletal muscle cell • Smooth muscle cell • Cardiac muscle cell (Martini, 2015) Types of Muscle Tissue Skeletal Muscle Cardiac Muscle tRNA Smooth Muscle (Martini, 2015) Nervous Tissue • Located in the brain, spinal cord and nerves • Function: • Transmit the information from one part of the body to another, by means of nerve impulse • Nervous cells called Neurons consists of 3 parts• Cell body: Contain nucleus and other organelles • Dendrites: Short projections to receive inputs • Axon: Single, thin and long projection to conduct output impulse • Cells support them called neuroglia (Shier, 2015)