MCB 7200: Molecular Biology Welcome! Complete the student information form. Tell the class about you. All the course information is on the course web site; I do not use Blackboard. Let’s go over the syllabus. Get the 8th Edition of Molecular Cell Biology. Any questions?

MCB 7200: Molecular Biology Molecular Biology/Biotechnology terminology Milestones in molecular biotechnology Model organisms for molecular/cellular biology Transcription and translation Prokaryotic gene organization & expression

Terminology Molecular biology-The study of biology on a molecular level including the structure, function, and makeup of biologically important molecules such as DNA, RNA, and proteins Recombinant DNA technology-a set of techniques for manipulating DNA, including: the identification and cloning of genes; the study of the expression of cloned genes; and the production of large quantities of gene product Genetic engineering-the process of transferring DNA from one organism into another that results in a genetic modification Biotechnology-production of goods and services using biological organisms, systems, and processes Molecular biotechnology-rDNA technology + biotechnology

Table 1.1

Table 1.1 (Continued)

Many scientific disciplines contribute to molecular biotechnology, which generates a wide range of commercial products. Figure 1.1

Model Systems for Molecular/Cellular Biology https://www. dnalc Viruses Bacteria (E. coli) Yeast (Saccharomyces cerevisiae) Round worms (Caenorhabditis elegans) Planarian (Schmidtea mediterranea) Alga (Chlamydomonas reinhardtii) Fruit fly (Drosophila melanogaster) Zebrafish (Danio rerio) Arabidopsis thaliana (thale cress) Mouse (Mus musculus)

Figure 1.13 Each experimental organism used in cell biology has advantages for certain types of studies.

FIGURE 1-22 Each eukaryotic organism used in cell biology has advantages for certain types of studies. Model unicellular and multicellular eukaryotic organisms have distinct advantages for investigation of fundamental cell processes.

TABLE 1-2 Genome Sizes of Organisms Used in Molecular Cell Biology Research That Have Been Completely Sequenced E. coli grow in environments as diverse as soil and the human gut. Eubacteria and Archaea have fewer genes than single-cell and multicellular eukaryotes. E. coli – model organism used to investigate common cell activities such as gene regulation and membrane transport found in other organisms.

Central Dogma of Biology transcription translation DNA RNA Protein $$$ reverse transcription Molecular Biotechnology DNA replication

FIGURE 1-9 The information encoded in DNA is converted into the amino acid sequences of proteins by a multistep process. Genes – specific segments of DNA that encode proteins. Two gene parts: (1) coding region specifies amino acid sequence and (2) regulatory region. Transcription factor interaction with a gene regulatory region controls which subset of genes are turned on and when, which is specific for each cell type. Transcription: RNA polymerase uses base pairing on the coding region DNA template to catalyze linkage of nucleotides into an RNA strand with a sequence identical to the coding DNA strand. mRNA processing (eukaryotic cells): the initial pre-mRNA is processed into a smaller messenger mRNA by removal of noncoding intron regions. nuclear export: processed mRNA transported out of the nucleus to the cytoplasm. Translation: ribosome (complex molecular machine composed of structural RNAs and proteins) forms peptide bonds between amino acids in the precise order dictated by the mRNA sequence according to the nearly universal genetic code.

FIGURE 5-1 Overview of four basic molecular genetic processes. DNA – stable information molecule; information in its sequence of four bases is arranged in genes and used to build all cell proteins and RNAs (1) Transcription: the four-base DNA code specifying the amino acid sequence of a protein is copied, or transcribed, into a precursor messenger RNA (pre-mRNA) by the polymerization of ribonucleoside triphosphate monomers (rNTPs). (2) RNA processing: removal of noncoding sequences and other modifications to pre-mRNA to make mRNA, which is transported to the cytoplasm. (3) Translation: in ribosomes, tRNAs base pair with mRNA codons to position specific amino acids where they are linked into proteins. (4) DNA replication: occurs only in cells preparing to divide; deoxyribonucleoside triphosphate monomers (dNTPs) are polymerized to yield two identical copies of each chromosomal DNA molecule, one for each daughter cell. (left) Ribosome assembly: two subunits assembled in the nucleolus from ribosomal RNAs (rRNAs) and multiple proteins and transported to the cytoplasm. Viruses utilize host-cell machinery and therefore have been important models for studying these processes.

Chemical structure of DNA and RNA

Chemical structure of dsDNA

Chemical structure of dsDNA

Prokaryotic Gene Structure and Expression

In prokaryotes, RNA polymerase binds to the -10 and -35 regions of the promoter relative to the start site of transcription (+1) promoter operator

Review protein secretion and protein targeting Signal peptide sequences Consider gram negative vs. gram positive bacteria Consider eukaryotic cells In eukaryotic cells, short peptide sequences (or other modifications) tell a protein where to go See MCB Chapter 13 & 14-Protein sorting animations