BSCI201 Anatomy Notes for Exam 2 10 1 14 Lecture Cellular Level DNA The largest macromolecule in the human cell Confined to the nucleus DNA consists of several genes Gene the part of DNA that can be transcribed and subsequently translated to produce a protein Protein Synthesis Simplified scheme of information flow from the DNA gene to protein structure Transcription 2 sequential phases Transcription and Translation o Occurs in the nucleus DNA is transcribed into pre mRNA o Region part of a DNA unwinds separates to produce 2 polynucleotide strands Template strand DNA strand used in transcription Used for the synthesis of pre mRNA with complementary bases to the DNA template Coding strand Not used in transcription Complementary bases to the DNA template o Base sequences similar except when U is present in the pre mRNA T in the coding strand o o Triplet 3 base sequence in DNA o Codon 3 base sequence in mRNA Ex triplet TAC is transcribed into the codon AUG DNA template Coding strand T A A A U T C G G 1 o The genetic code indicates how the base sequences in a mRNA the codons transcribed from a gene are translated into amino acids There are 20 naturally occurring amino acids however there are 64 codons 43 which indicates a redundancy in the genetic code each amino acid is specified by at least 2 different codons What is the significance of the redundancy in the genetic code To make sure minor mistakes that may occur will not affect the primary sequence and its subsequent function won t be affected o After transcription the product is pre mRNA o Pre mRNA composed of introns and exons Introns do not specify amino acids Exons specify for amino acids Pre mRNA is too large to pass through the nuclear pores size exclusion hence the pre mRNA is edited or spliced or processed to remove the introns from leaving exons So mRNA is composed of the exons o mRNA passes through the nuclear pores into the cytoplasm where translation occurs Translation o Occurs in the cytoplasm o o Involves all 3 types of RNA 1 mRNA exons 2 rRNA forms out of the ribosomal subunits 3 tRNA has a head and a tail Head contains the 3 base sequence called the anticodon Tail is attached by a specific amino acid 2 o When a codon in the mRNA is covered by a functional ribosome the tRNA with complementary bases to the covered codon attaches with its anticodon and hence bringing the attached amino acid in a specific position to form the primary sequence of a protein o The base sequence of an anticodon is the same as the base sequence of a triplet except thymine in a triplet is replaced by uracil in the anticodon Triplet DNA GGG AAA TTT AGT Codon mRNA CCC UUU AAA UCA Anticodon head of the tRNA GGG AAA UUU AGU Lecture Tissues The Living Fabric Tissue a group of similar cells that perform a common function Tissues Epithelial Connectiv e Muscle Nervous 4 primary tissues in the human body o Epithelial tissues covering o Connective tissues support o Muscle tissues movement o Nervous tissue control Epithelial tissues Epithelial tissues Membranous Glandular Simple Stratified Squamous Cuboidal Columnar Squamous Cuboidal Columnar Transitional Pseudostratified columnar o Exhibit polarity lower attached basal surface upper free apical surface apical surface may have cilia or microvilli Microvilli finger like projections of the plasma membrane of the epithelial cells o Avascular lack blood vessels o Supported by a basement membrane double layered superior basal lamina attributing the epithelial tissue and a deeper reticular lamina attributing the underlying connective tissue o Connective tissue underlies supports all epithelial tissues connective tissue is vascular and provides nutrients to the overlying avascular epithelial tissues by diffusing through the basement membrane o Have high regenerative capacity undergo cell division o They are innervated 3 o 3 major types of epithelial cells based on shape 1 Squamous flattened scale like cells with flattened disc shaped spindle shaped nuclei 2 Cuboidal Cube like box like cells with centrally placed spherical nuclei 3 Columnar tall column shaped cells with elongated nuclei placed closer to the base of the cells o 2 main classes of epithelial tissues 1 Membranous epithelia covering and lining epithelia 2 part name o 1st part indicates the of layers o 2nd part indicates cell type 2 types Simple and Stratified 1 Simple epithelia composed of single layer of epithelial cells 4 types squamous cuboidal columnar pseudostratified 10 3 14 Simple squamous Location Forms part of respiratory membrane in the lungs Forms part of the filtration membrane in the kidneys Lines structures in the circulatory system referred to as the endothelium gives composition and location cardiovascular blood circulates lymphatic lymph circulates Lining of the serosae serous membrane in the ventral body cavity referred to as the mesothelium Function For diffusion of gases Involved in the filtration of blood in the kidneys Provides a slick frictionless surface acts as a lubricant for substances to be transported through the organs Secretes lubricating substances in serosae Simple cuboidal Location Lines structures of the kidneys called tubules Function Secretion of substances between the blood and the fluid in the tubules 4 Outer covering of each ovary referred to as the germinal epithelium gives a specific location and composition Serves as the outer boundary of each ovary not involved in secretion Simple columnar Function Secretes digestive juices Non ciliated Location Lines structures in the gastrointestinal GI tract between the esophagus and anal canal In certain organs small intestine these cells have microvilli to increase the surface area for absorption Ciliated Location Found in bronchi tube like structures that branch off the trachea and lead into the lungs Function Found in bronchi tube like structures that branch off the trachea and lead into the lungs Cilia beat to create a unidirectional current to move the conceptus product of fertilization into the uterus for implantation Lines the fallopian tubes uterine tubes oviducts which extend from the uterus sites for fertilization 5 Pseudostratified columnar Function Secrete products to maintain sperm viability Non ciliated Location Lines the male reproductive ducts that carry sperm by muscular contractions Ciliated Endowed with globlet cells specifically referred to as the respiratory epithelial certain composition and location Line most structures in the respiratory
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