Exam 2 Study Guide

Exam 2 Study Guide - Study Guide for Medical...

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Bio 225 Exam 2 Objectives Chapter 8 Microbial Genetics Introduction and Terms Genetics - study of what genes are, how information is carried, expressed, replicated, & passed to subsequent generations or other organisms · Genotype - genetic composition of organism - all of its DNA & genes contained in DNA. · Phenotype - result of expression of genes - proteins of cell & properties they confer on organism. · Gene - specific sequence of nucleotides coding for a functional product, usually a protein Structure and Function of Genetic Material DNA molecule - double-stranded helix Antiparallel strands - two strands of a double stranded DNA molecule are oriented in opposite directions Eukaryotic Chromosomes Contained in Nuclear envelop Chromatin coils into chromosomes during replication
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Histones - basic proteins Prokaryotic Chromosomes No Nuclear envelop Chromatin does not coils into chromosomes during replication No Histones DNA Replication Enzymes at replication fork unwind parental double helix DNA Proteins stabilize unwound DNA DNA polymerase continuously synthesizes new DNA strand, in 5' to 3' direction RNA polymerase synthesizes short RNA primer RNA primer extended by DNA polymerase DNA polymerase digests RNA primer replacing it with DNA Small DNA joined by DNA ligase 3’end – hydroxyl attached to carbon, DNA polymerases can add new nucleotides only to this end 5' end – phosphate attached to carbon DNA directed DNA polymerase - DNA-template-directed extension of the 3'-end of a DNA strand by one nucleotide at a time RNA polymerase - responsible for building RNA transcripts (mRNA, tRNA, rRNA) complementary to
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template strands of double stranded DNA, and regulation of their activity is often the final step in cellular pathways that control the expression of genes RNA primer – short piece of RNA starting synthesis of nucleotides to 3' (OH) end of DNA Leading strand – not fragmented, synthesized continuously in the 5' to 3' direction Lagging strand - delayed, fragmented, daughter DNA, synthesized discontinuously in the 3' to 5' direction DNA ligase - catalyzes formation of a phosphodiester bond between 5' phosphate of one strand of DNA & 3' hydroxyl of an other, used to covalently link or ligate fragments of DNA together Gene Expression: Transcription and Translation DNA directed RNA polymerase - RNA synthesis by addition of ribonucleotide units to an RNA chain using DNA as a template mRNA – Messenger RNA carries code for specific protein from DNA to ribosome rRNA - Ribosomal RNA, a molecular component of a ribosome, makes polypeptides (assemblies of amino acids) that go to make up proteins. tRNA – transfer RNA, recognizes codons & transports required
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Exam 2 Study Guide - Study Guide for Medical...

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