10 1 14 Lecture 12 Protein synthesis DNA is the largest macromolecule in the human cell Confined to the nucleus Consists of several genes Amrita Bhatt Gene part of the DNA that can be transcribed and subsequently translated into a protein Protein synthesis transcription translation Transcription region part of DNA unwinds separates to provide 2 nucleotide sequences One strand acts as a template and the other acts as the coding strand the DNA template Template synthesis of pre mRNA with complementary bases to Coding complementary bases to the DNA template Base sequences are similar except when U is present in the pre mRNA t in coding strand For example if DNA template is TAC pre mRNA is AUG and coding strand will be ATG After transcription is over the product is pre mRNA o Composed of introns and exons Introns don t specify amino acids Pre mRNA is too large to pass through the nuclear pores size exclusion Hence the pre mRNA is edited or spliced to remove the introns mRNA is composed of the exons Translation Involves all types of RNA o mRNA exons o rRNA forms part of the ribosomal subunits o tRNA has a head and a tail Head contains the 3 base sequence called the anticodon Tail is attached by a specific amino acid When a codon in the mRNA is covered by a functional ribosome the tRNA with complementary bases to the covered codon attached with its anticodon hence bringing the attached amino acid in a specific position to form the primary sequence of a protein Triplet DNA GGG Codon mRNA CCC Anticodon need of the tRNA GGG Tissues 4 primary tissues o Epithelial 2 forms Membranous glandular Membranous covering and lining Glandular forms glands that secrete products in body o Connective o Muscle o Nervous Each has a 2 part name first part indicates the number of layer second part indicated the cell type epithelial o Simple or stratified squamous columnar or cuboidal Simple squamous epithelial tissue Lungs Forms part of the respiratory membrane Function diffusion of gases Forms part of the filtration membrane in the kidneys Lines structure in circulatory system Simple squamous epithelial is specifically referred to as the Involved in filtration of blood in kidneys endothelium composition and location o Lymphatic vessels Single layer of cube shaped cells with centrally placed spherical Amrita Bhatt 10 3 14 Lecture 13 Simple cuboidal epithelium nuclei Location o Lines tubules in kidneys o Outer covering of ovary Simple columnar epithelium Some ciliated some not Single layer of tall cells with oval shaped nuclei located towards the bases of the cells Ciliated cells are endowed w goblet cells which secrete mucus o Very important in the fallopian tubes to move egg to uterus for reproduction if egg is stuck in fallopian tube b c of no cilia can lead to ectopic pregnancy Non ciliated express microvilli which increase surface area for Location of ciliated o Areas in respiratory tract o Uterine tubes absorption Location of non ciliated o Large intestine o Small intestine o Stomach Pseudostratified columnar epithelium Single layer of columnar cells at different heights Ciliated have goblet cells secreting mucus lines most of the structure in the respiratory tract o Also called respiratory epithelium Non ciliated lines reproductive ducts that carry sperm o Function purely for protection of the internal surface of these ducts Stratified squamous epithelium Protection several layers 2 types o Keratinized Located in surface of skin Function abrasive resistance o Nonkeratinized Forms mucous membrane which lines structures in the body s tracts GI urinary reproductive respiratory Stratified columnar and cuboidal Rare in the human body Location ducts of exocrine gland pharynx male urethra Function protection secretion At least two layers of cells apical cells are columnar shaped 3 6 layers of cells with cuboidal or squamous cells on the apical Transitional Epithelium surfaces respectively Location o In structures in the urinary system that allow urine to flow through or for storage of urine o Ureters bladder urethra Function o Increase capacity of urinary structures increase urine flow or urine storage o Transitions from 6 to 4 cuboidal to squamous 10 6 14 Lecture 14 Tissue The Living Fiber Amrita Bhatt Glandular Epithelia 2 classes of glands o 1 Endocrine secretes hormones directly into extracellular o 2 Exocrine secrete their product onto internal or external fluid surfaces of the body 2 types unicellular multicellular only unicellular are goblet cells secrete mucin Glandular Epithelia Endocrine glands o Ductless glands o Secrete hormones Exocrine glands o Secrete their products called secretins into the internal external surfaces o Unicellular goblet cells only example in the human body Goblet cells disperse in some epithelial cells such as simple columnar tissue cells psuedostratified columnar epithelial tissue When these cells have goblet tissue they are ciliated b c the cilia is there to move the mucus Goblet cells secrete mucus moved through the internal surface of organs by ciliary action o Multicellular Composed of many cells that form two structures Secretory portion Ducts that carry the secretions out of the secretory Most common type of glands we will encounter in the portion human body Structural classification of the multicellular exocrine glands Have to describe the duct system which will be either And have to describe the secretory portion Possible structural classes of multicellular exocrine glands o Simple o Compound o Tubular o Alveolar o Tubulo alveolar o Simple tubular o Simple alveolar o Compound tubular o Compound alveolar o Compound tubulo alveolar Functional classification of multicellular exocrine glands Apocrine mode of secretion hasn t been ID in the human body Merocrine exocytosis Used by most of these cells Holocrine rare in the human body Connective Tissue 2nd primary tissue CT 4 classes o CT proper o Cartilage o Bone o Blood Secreted by 4 types of blast stem cells derived from mesenchyme o Fibroblast secrete CT proper o Chondroblast secrete cartilage o Osteoblast secrete bone osseous o Hematopoietic stem cells secrete blood After the connective tissue class has been secreted the blast cells mature into cytes o Fibroblast mature to fibrocyte in CT proper o Chondroblast mature to chondrocyte in cartilage o Osteoblast mature to osteocyte in bone tissue o Hematopoietic stem cells form blood cells in blood RBC and WBC Don t mature Connective tissue must have 2 portions Living
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