BSCI201 Exam 2 Notes March 2nd 2015 The Cell Cycle Two Phases 1 Interphase a G1 protein synthesis hence chromatin is in euchromatin active form i Protein Synthesis 1 Fibrous proteins increase in the fibrous proteins in the cell increases the cell size 2 Globular proteins increase in ii Longest phase iii Shorter in rapidly dividing cells such as epidermal cells or epithelial cells compared to the dormant cells such as hepatocytes b S Euchromatin the double helical DNA unwinds into two polynucleotides strands i Polynucleotide chain ii Polynucleotide chain iii This will act as a template for the synthesis of a new polynucleotide chain iv DNA template T A C G C G New ring A T G C G C At the end of DNA replication you have two molecules of DNA each DNA molecule is composed of an old polynucleotide chain which acted as a template and the newly synthesized polynucleotide semi conservative replication half of the old strand was conserved DNA replication to produce two molecules of DNA must occur for mitosis to be initiated Preventing replication prevents mitosis c G2 the shortest phase the euchromatin i Protein synthesis particularly the globular functional proteins which are required for initiating and maintaining cell division ii These globular proteins are referred to as the GO proteins because they allow the cell to go into cell division Hence inhibition of the synthesis or the inhibition of the actions of the these GO proteins also inhibits cell division a Mitosis nuclear division b Cytokinesis cytoplasmic division around the two nuclei produced in 2 Cell Division mitosis Creates multi nucleated cells Cell growth by increases cell size in termed hypertrophy Cells growth by increase in cell number via mitosis hyperplasia Growth in the human body occurs via both hyperplasia and hypertrophy Cancer cells Neoplasm excessive proliferating of cells considered abnormal Benign grows slowly and its confided to one location o You can still die from benign Malignant CANCER grows fast and aggressively and metastasizes to other organs Show no respect for other cells have a mind of their own and their boundaries but either they invade and go through whatever they come across in their path Discuss the ways you may design cancer chemotherapeutic drugs Should prevent DNA replication should prevent production of the GO proteins Want to disrupt the One way Protein Synthesis 2 phases in sequence 1 First phase Transcription involves the DNA double helical structure unwinds and separates into two polynucleotide chains Regions of DNA that can be transcribed and translated to form specific proteins are called GENES several genes on the DNA molecule DNA unwinds and separates Polynucleotide this one is a template T A C G G G pre mRNA A U G C C C Polynucleotide A T G C C C nucleotide that was left behind it has similar bases to the new RNA except the U and T This unused strand is known as the coding strand During transcription the pre mRNA is transcribed from the DNA template the polynucleotide chain of the DNA NOT used is called the coding strand because the bases are coded like the pre mRNA except T in the coding strand is replaced with U in the pre mRNA The three bases sequence in the DNA is called a triplet ex TAC The three base sequence in the pre mRNA and mRNA is called a codon Pre mRNA contains introns and exons after splicing the introns are taken out of the chain to form mRNA DNA template transcription pre mRNA containing introns and exons editing splicing removes introns mRNA containing only exons 2 Translation DNA produces pre mRNA RNA processing slicing to cut out introns mRNA amino acid March 4 th 2015 mRNA contains only exons Introns are the non sensible sequences meaning they do not code for amino acids Exons are amino acid specificity sequence The structural difference between pre mRNA and mRNA is that pre contains both introns and exons nd phase of Protein Synthesis Translation 2 Occurs in the cytoplasm and involves mRNA functional ribosomes and tRNA transfer RNA Process by which codons specifiy for amino acids using anti codons and attach amino acids on tRNA The three base sequence is called a codon on the mRNA The three base sequence on the tRNA which is complimentary to the codon is referred to as the anticodon The three base sequence in a DNA is called a triplet When a codon on the mRNA is covered by a functional ribosome the tRNA with complimentary bases to the covered codon will bind bringing along an amino acid Covered codon AUG GCG anti codon UAC CGC o The original triplet was TAC CGC o Triplet transcribe into mRNA translation o Anti codon is the same as the triplet except the T and U We have 20 naturally occurring amino acids but at least two types of tRNAs per amino acid due to the redundancy in the genetic code Redundancy allows for minor mistakes not to affect the type of amino acid coded The minor change normally occurs on the third base Tissues 3rd level of structural complexity in the human body Tissues composed of similar cells to perform specific functions Four Types 1 Epithelial Tissue all cells are avascular and receive nutrients oxygen from the underlying vascularized connective tissue Epithelial Basal Lamina Reticular Lamina Connective Tissue Basement membrane sandwiched between the underlying epithelial tissue and the underlying connective tissue acts as a selective membrane which allows only nutrients and oxygen to enter to the epithelial tissue Epithelial tissue is a high regenerative capacity undergo cell division Epithelial tissues epithelia Two major classes Membranous sheet like epithelial o The name is based on the number of layers of the cell present 1 layer simple More than one stratified o The name is also based on the cell type present Squamous flattened cells with flattened nuclei Cuboidal cube shaped cells box with spherical centrally placed nuclei Columnar elongated like columns with oval shaped nuclei located toward the bases of the cells Pseudostratfied Transitional Apical surface are the free cells at the top Exam Stratified epithelial layer has at least one layer of cells False its at least 2 layers More in depth Simple squamous used for diffusion filtration Endothelium gives a specific composition as well as specific location o Specific composition simple squamous o Specific location lined structures in the circulatory systems Circulatory systems consists of both the cardiovascular system blood circulates and the lymphatic system lymph circulates
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