BioMG 3320 1st Edition Lecture 2Outline of Last Lecture I. SyllabusII. DNA as the Genetic MaterialIII. Nucleic AcidsIV. Structure of DNAOutline of Current LectureI. Alterations in DNAII. Definition of GeneIII. Bacterial CellsIV. Eukaryotic CellsV. Transposons VI. Human GenomeCurrent LectureI. Alterations in DNA- One alteration of DNA is known as sequence-specific alteration-Occurs when there are sequences with repeats of adenines, causing the helix to bend/kink- Guanosine tetraplexes-Many consecutive guanines causes formation of tetraplexes-Found in RNA and DNA, single strands, and double strandsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Stable-May occur in nature-Can interfere with behavior of synthetic DNA/RNA sequences- Palindromic DNA sequences-string of symbols that have the same sequence in both directions - Chemical changes in nucleic acids-Deamination: convert one base to another, changing hydrogen bonding. This is mutagenic. Cytosine to uracil is the most frequent alteration.-Depurination: base is removed from the nucleotide.- When there are adjacent thymines, they can become covalently linked, blocking DNA replication. This is mutagenic. There are pathways that exist to reverse/repair this process. II. Definition of a Gene- A gene has three characteristics-Ability to be transcribed-It is regulated-It is functional III. Bacterial Cells- The bacterial genome consists of one circular DNA molecule. It has 5 million base pairs and 5000 genes. - Transcription-A promoter region is needed for transcription to occur. -The transcription unit is transcribed to mRNA which is then translated to a protein.-Bacterial mRNA structure consists of a 5’ end, a coding sequence and a 3’ end- Genes with related functions are often clustered in operons. This clustering facilitates coordinate regulation.- Plasmids are typical in bacteria. They are autonomous mobile genetic elements. They encode proteins that make bacteria resistant to antibiotics. IV. Eukaryotic Cells - Eukaryotic cells have a nucleus and multiple linear DNA molecules.- Transcription-Needs a promoter just like bacterial cells; however, enhancer also required. A single gene can have multiple different enhancers.-Transcription unit is transcribed to precursor mRNA which is then spliced to eukaryotic mRNA structure, which will later be translated to a protein.-Exons are the material that is actually made into a gene. Introns are the part of the sequence that is removed.- The genome structure is classified as either euchromatin or heterochromatin.-Euchromatin: less packed, gene rich regions of chromosomes-Heterochromatin: densely packed, gene poor regions of chromosomes- Chromatin is double stranded DNA that is wrapped up into specialized proteins. It is compacted because DNA must be small enough to fit inside a cell.V. Transposons- Transposons are mobile segments of DNA that can move within a genome. They are not beneficial to the organism. Their only purpose is to replicate. They are often present in many copies per genome and not all copies are functional. - They are located in both eukaryotes and bacteria.- Contribute to insertions, deletions, and translocations.VI. Human Genome- Only a tiny portion of our genome is present as genes, actually only 1.5%.- The rest of the genome consists of introns, long interspersed nuclear elements, short interspersed nuclear elements, retroviruses, etc. - Human mitochondrial genome and plant chloroplast genomes look like bacteria genomes, suggesting the endosymbiotic theory. The endosymbiotic theory states that eukaryotic mitochondria originated as bacteria, which were assimilated by