Molecular Biology in a Nutshell

1. Molecular Biology in a Nutshell

2. Molecular Biology the study of biology at a molecular level biology and chemistry, particularly genetics and biochemistry interrelationship & interactions between DNA, RNA and protein biosynthesis how these interactions are regulated.

3. Outline Molecular Biology in the Cell Gene Expression Regulation of Gene Expression

4. Molecular Biology in the Cell Prokaryotes: single cells without nucleus, (generally) no internal membranes, like bacteria Eukaryotes: multicellular-nucleus, genetic materials in nucleus, all higher organisms

5. An Animal Cell with major organelles (1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles

6. Four Classes of Biological Molecules Carbohydrates: storage and transport of energy (starch, glycogen); structural components (cellulose in plants, chitin in animals) Lipids: nutrients, energy storage, structural components; hydrophobic character Proteins Nucleic Acids

7. Protein Structure a chain of amino acids Each amino acid has a central carbon (Ca), an amino (NH2) group, a carboxyl (COOH) group, a hydrogen (H) atom, and one side chain(R). 20 amino acids vary only at side chains function is derived from 3D structure, and 3D structure is specified by amino acid sequence

8. Protein Function build up framework of the cell (structure & movement) control the transcription and translation control the degradation of proteins

9. Nucleic Acids A chain of nucleotides Nucleotide: a nucleoside and a phosphate Nucleoside: a base and a pentose(sugar)

10. Nucleic Acids Deoxyribonucleic Acid (DNA) Ribonucleic Acid (RNA)

11. DNA the molecule storing genetic information Double stranded chain of nucleotides with 4 types of bases: A T C G

12. DNA Replication The process of DNA to make an exact copy of itself Denaturation: strand separation Renaturation: two separated complementary strands to reform a double helix Hybridization: two separated strands to reform a double helix

13. RNA Transfer genetic information from DNA to protein synthesis Single strand 4 types of bases: A U C G Less stable than DNA 3 major types: mRNA: messenger RNAs, code for proteins rRNA: ribosomal RNAs, form the basic structure of the ribosome and catalyze protein synthesis tRNA: transfer RNAs, adaptors in protein synthesis between mRNA and amino acids

14. RNA Structure primary structure secondary structure A) single stranded regions B) duplex C) hairpin D) internal loop E) bulge loop F) junction G) pseudoknot

15. RNA Structure primary structure secondary structure tertiary structure

16. Molecular Biology in the Cell Molecules are held together by chemical bonds and forces(ionic, covalent, hydrogen bond, nonpolar association, van der Waals forces) Properties of molecules determine possible interaction Complex interactions of molecules determine cell structures and processes

17. Gene Expression The process during which the genetic information of certain gene is translated into protein Products of Gene Expression: RNA & Protein Transcription Posttranscription Translation Central Dogma

19. Gene Gene: a segment in DNA molecule, located in a particular position on a specific chromosome, whose base sequence contains the information necessary for protein synthesis Chromosomes a molecule of DNA in a cell Genome an organism�s complete set of DNA (600,000bp-3billion bp)

20. Gene Comprise only about 2% of the human genome The size of a gene is on average 3,000 bp, but vary greatly More than half of predicted genes are function-unknown Repeats make up half of the genome Non-coding regions: do not code for the gene products, but regulate gene expression Promoter: regulatory region of DNA located upstream of a gene, providing a control point for regulated gene transcription

21. Genetic code set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins defines a mapping between codons and amino acids Codon: tri-nucleotide sequence specifying a single amino acid start/stop codons: Translation begin/stop signals

22. Open reading frame(ORF) a portion of an organism's genome which contains a sequence of bases that could potentially encode a protein locatied between a start codon(AUG/ATG) and a stop codon

23. Transcription(DNA-mRNA) the synthesis of an RNA employing a DNA region as a template different types of enzyme responsible for the synthesis of different RNA proceeds in the 5' ? 3' direction, and uses base pairing complimentarity

24. Post-transcription pre-mRNA is converted into mature mRNA Modification: RNA splicing

25. Post-transcription each exon contains part of the open reading frame (ORF) that codes for a specific portion of the complete protein Alternative Splicing: combination of exons

26. Translation occurs in the cytoplasm where the ribosomes are located According to genetic code, mRNAs are decoded to produce a chain of amino acids that form a protein tRNA: a sequence of three complementary base; a single amino acid the amino acid is added to the growing protein chain

27. Steps Leading from Gene to Protein

28. Procedure 1) DNA->pre-mRNA 2) pre-mRNA->mature mRNA 3) nucleus-> cytoplasm 4) mature mRNA->protein 5) protein remain in cytoplasm 6)-10) proteins transferred to and stored in other organelles

29. Central Dogma DNA has the genetic information RNA is the intermidiate Information flow: once �information� has passed into protein, it cannot get out again Possible: nucleic acid-> nucleic acid; nucleic acid-> protein Impossible: protein-> nucleic acid protein-> protein

30. Regulation of Gene Expression Regulatory mechanisms which repress or enhance the level of gene expression so that only certain genes in an organism can be expressed in a specific cell. Result: control the amount & timing of changes of functional product of a gene(RNA or protein) control the structure and function of a cell Any step of the gene's expression may be modulated: from DNA-RNA transcription to post-translational modification of a protein

31. Regulation of transcription controls when transcription occurs and how much RNA is created Repressors: a DNA-binding protein that decreases the rate of transcription; binds to non-coding sequences on the DNA strand that are close to the promoter region, impeding RNA enzyme's progress along the strand, thus impeding the expression of the gene Activators: a DNA-binding protein that increases the rate of transcription; enhances the interaction between RNA enzyme and a particular promoter, encouraging the expression of the gene.

32. Posttranscriptional Regulation regulation on how much the mRNA is translated into Proteins Capping Splicing Addition of poly(A) tails

33. Up-regulation& down-regulation triggered by a signal (internal or external to the cell) Up-regulation: a process resulting in increased expression of genes and the protein encoded by those genes Down-regulation: a process resulting in decreased expression of genes and corresponding protein expression

34. Image Credits U.S. Department of Energy Human Genome Program, http://www.ornl.gov/hgmis Molecular Biology of the Cell http://www.ncbi.nlm.nih.gov/books Access Excellence, Graphics Gallery http://www.accessexcellence.org/AB/GG/