molecular biology (.ppsx)

Molecular Biology

Molecular BiologyTodays TopicsChromosomesThe Double Helix - DNAThe Molecules of DNADNA ReplicationThe Central DogmaDNA TranscriptionDNA TranslationProteomics

Chapter 9

BIO156Paradise Valley Community College#

1

Paired DNA Strands

Paired DNA Strands


ChromosomesA eukaryotic chromosome is a molecule of DNA together with associated proteins.

ChromosomeStructure made of DNAand associated proteinsCarries a part of a cellsgenetic information

Source: www.beltina.org. 2015.


3

3/29/2017Paradise Valley Community CollegeChapter 6 - DNA Structure and Function

DNA Packaging

DNA Packaging


DNA StructureProteins organize DNA structurally.Histones allow chromosomesto pack tightly. Histone octomersType of protein that structurally organizes eukaryotic chromosomesNucleosomeA length of DNAwound around a spool of histone proteins

Naked DNA

Source: www.ncbe.reading.ac.uk. 2015.

Beads-on-a-stringNucleosomes

30 nm solenoid

Extended form of chromosome

Condensed sectionof chromatin

Chromosome(metaphase)


5

Chromosome NumberA eukaryotic cells DNA is divided into a characteristic number of chromosomes.Chromosome numberSum of all chromosomesA human body cell has 23 pairsDiploidCells having two of each type of chromosome characteristic (2n)

Source: www.washington.edu. 2015.


6


Examples of Chromosome NumberSpecies# Chrom.Fruit fly8Amoeba13Garden Pea14Frog26Cat38Human46Species# Chrom.Potato48Pineapple50Cow60Dog78Vizcacha rat102Horsetail216Adders Tongue1,260


7


Examples of Chromosome Number

Source: www.flickr.com. 2015.

Source: www.highlanddiary.co.uk. 2015.Adders tonguefern (1,260)Vizcacha rat (102)

Source: www.planet-mammiferes.org. 2015.

Horsetail (216)A living fossilSource: en.wikipedia.org. 2015.


Types of ChromosomesTwo types of eukaryotic chromosomes:autosomes and sex chromosomesAutosomesPaired chromosomes with same length,shape, centromere location, and genes Any chromosome other than a sexchromosome Sex chromosomesMembers of a pair of chromosomesthat differ between males and femalesLooking at the chromosomes,Which one is the Y chromosome?Which one is the X chromosome?



9


KaryotypeThe karyotype of an organism reveals characteristics of an organisms chromosomes.

KaryotypeImage of an individualscomplement of chromosomes arrangedbysize,length,shape, andcentromere location12345678910111213141516171819202122

Source: fineartamerica.com. 2015.



10


KaryotypingSource: S. Belliappa. Modified from slideshare.com. 2017.

Source: keyword-suggestions.com. 2017.KaryogramDigitize orphotograph

AnalyzemetaphasespreadDigest withtrypsinand stain

Spread cellson slideAddcolchicine(stops mitosisat metaphase)

MitosisinducedAdd toculture medium(3 days @ 37C)

5 mLvenousblood


The Double Helix - DNA


A DNA molecule consists of two strands of nucleotide monomers running in opposite directions and coiled into a double helix(a twisting staircase).Three parts of a DNA nucleotideOne nitrogen-containing base(Adenine, Thymine, Guanine, or Cytosine) A five-carbon sugar (pentose, deoxyribose)Three phosphate groupsThe Double Helix

Credit: Modified from Chris Bickel, spectrum.ieee.org. 2017.CytosineSource: Modified from commons.wikimedia.org. 2017.


13


Fame and Glory

1916-2004

1905-2002Erwin ChargaffDiscovered the relationships between DNA bases, A, T, G, C.Rosalind Franklin & Maurice WilkinsDiscovered the basic structure of DNA by x-ray crystallographyJames Watson andFrancis CrickBuilt the first accurate model of a DNA molecule

1920-1958

1916-2004

1928-

1962

1962

1962

1949Photo 51


14


The Double HelixTwo double-helix strands are held together by hydrogen bonds between nucleotide bases.Base-Pairing Rules (Chargaff) A pairs with T C pairs with G [A] ~ [T] [C] ~ [G]

Source: Modified from undsci.berkeley.edu. 2015.Guanine (G) Cytosine (C)Adenine (A) Thymine (T)

CGTA


15


Its about the code, not the chemistry!TGCA

The single-letter codes can now be read into a computer to create the genome database.

AGTCCATTACGAAAATCGACTATCGAAGGGTAAAGGCTTATAAGCCATAGTCAGGTAATGCTTTTAGCTGATAGCTTCCCATTTCCGAATATTCGGTATC


Patterns of Base Pairing The DNA sequence varies among species and among individualsEach species has characteristic DNA sequencesDNA sequenceThe order of nucleotide bases in a strand of DNABase pairs:TGTTCTATGTTTACTTAGTACCTCTTTAACAAGATACAAATGAATCATGGAGAAAT


17


DNA Replication


DNA ReplicationThe two strands of a DNA molecule are complementary.Their nucleotides match up according to base-pairing rules(G to C, T to A).Each strand is labelled to indicate directionality.five-prime to three-prime5533ACTATCGACTGTGATAGCTGAC


19


DNA Replication

DNA ReplicationSource: interactmedical.co.uk. 2017.


Semi-ConservativeReplication

TGATAACTATThe base sequences of both DNA molecules is identical.Each parent strand becomes a template for a new DNA strand.Free nucleotides match their opposite on each strand.As replication startsDNA unwinds.parentparentnewnewCGTTTTAAAA


DNA Repair Mechanisms


MutationsUncorrected errors in DNA replication may become mutations.Mutation: A permanent change in DNA sequence

Source: Modified from biology-igcse.weebly.com. 2017.correctcopyparentparentmutantcopy


23


DNA, RNA, & Protein Synthesis

Replication: DNA to DNA (Not part of protein synthesis)Occurs before mitosis & meiosis ONLYDuplication of DNA during S stage of InterphaseTranscription: DNA to RNADNA blueprint of gene is decodedResult: RNATranslation: RNA to ProteinRNA decoded & reconstructed (mRNA)Result: ProteinTheCentralDogma


DNA Replication


DNA Replication in Action

ChromosomeOriginal DNAReplication ForkFreeNucleotidesFree NucleotidesDNA PolymeraseDNA PolymeraseLeading StrandLagging StrandSource: Modified from philschatz.com. 2016.

Helicase


Molecular BiologyTodays TopicsChromosomesThe Double Helix - DNAThe Molecules of DNADNA ReplicationThe Central DogmaDNA TranscriptionDNA TranslationProteomics

Chapter 9


27

The Central Dogma





TranscriptionCentral Dogma of Molecular Biology

TranslationDNARNAProteinGenetic Determinism

MakesMakes

Gene Product


Transcription: DNA to mRNA





Translation: mRNA to Protein


Codons-AnticodonsThe finished polypeptide

LHIMUAA

STOPUAC

LEUCINEGUA

HISTIDINE

ISOLEUCINEUAA

METHIONINEUAC

tRNA aaCODON

ANTICODONssDNAmRNA3 TACTAAGTACTATAAAATGA 55 AUGAUUCAUGAUAUUUUACU 3


The Genetic CodeThere are 4 different letters within RNA.There are 20 different amino acids in a protein.How can 4 letters code for20 amino acids?Possible combinations of 4 letters:44 = 256 combinations

AUGUACGUACUACAUAAUGAGGUUCUAUGUUUACUUAGUACCUCUUUAUGA35

GUUGUCGUAGUGAla A

UCAGUCAGUUUUUCUUAUUGPhe FLeu L

CUUCUCCUACUGLeu L

AUUAUCAUAAUGIle IMet M

GUUGUCGUAGUGVal V

UCUUCCUCAUCGSer S

CCUCCCCCACCGPro P

ACUACCACAACGThr T

UAUUACUAAUAGTyr YStop Stop

CAUCACCAACAGHis H Gln Q

AAUAACAAAAAGAsn NLys K

UGUUGCUGAUGGCys CStopTyr W

CGUCGCCGACGGArg R

AGUAGCAGAAGGSer SArg R

GGUGGCGGAGGGGly G

GAUGACGAAGAGAsp DGlu E

UCGAUCGAUCGAUCGASecond LetterFirst LetterThird Letter L N N E V L C L L S T L L VYM

Stop

*


Sidebar: Why All the Colors?

ATCUGCGATTACTAGCGACTCCGACTTATCUGCGATTACTAGCGACTCCGACTT


eukaryotes & ProkaryotesEukaryotesNucleus (DNA within)RNA transcription occurs prior to protein translation in the nucleusMany RNA post-processing eventsGene expression is regulated at many levelsProkaryotesLack nucleusRNA transcription and protein translation are simultaneousNo RNA post-processing eventsGene expression is regulated at the transcriptional levelGene Expression (Protein Synthesis)


Gene Expression (Protein synthesis)Prokaryotes

PlasmamembraneDNA

mRNA

ProteinsRibosomes


Gene Expression (Protein synthesis)

NucleusDNACytosol

ProteinsMaturemRNA

Pre-mRNARibosomes

Eukaryotes


Introns removedEnd-capping

Nuclear membraneEukaryotic Gene RegulationGene regulation is the process of turning genes on and off. Transcription rates altered byTranscription factorsEnhancer proteinsSilencers (DNA sequences)Insulators (DNA sequences)Promoters (TATA boxes)End-capping andremoval of introns is crucial.Golgi apparatus responsible for finishing protein and tagging it for delivery.

TranscriptioncontrolPreRNAsynthesiscontrolRNAtransportcontrolTranslationcontrolmRNAPrimarytranscript

ProteinDNAgeneTranslationTranscription


Proteomics


proteomics1986: Genomics: the study of the entire genome1994: Proteomics (protein + genomics)the entire set of proteins, produced or modified by an organism or systemthe next step in the study of biological systemsstudy the protein, then work back to the gene

Source: Modified from majordifferences.com. 2017.

GenomicsResearch

ProteomicsResearch

Source: Modified from tuniselyoum.maktoobblog.com. 2017.


Cystic FibrosisGene is located on Chromosome 7The primary structure1,485 amino acidsThe secondary structure5 domainsThe tertiary structureGate for chloride ion transport

MQKTEKASIFSQSREEEVQDTRL

From the primary structure, deduce the mRNA and DNA of the gene.

CFTR: Cystic Fibrosis Transmembrane conductance Regulator

7q31.1


Cystic Fibrosis

Mucus accumulates & bacteria grow, creatingrespiratory infectionsResult:Protein misfolded creating a conductancedefectLocus 508:Phenylalanine is deleted

Chloride ionsExtracellular MatrixCytoplasm

NormalAbnormal


MQKTPLEKASIFSQIFFSWTKPILWKGYRQRLELSDIYQIHPGDSADNLSERLEREWDREVATSKKNPKLINALKRCFFWKFLFYGILLYLGEVTKAVQPLLLGRIIASYDRDNEHERSIAYYLAIGLCLLFVVRMLLLHPAIFGLHHIGMQMRIAMFSLIYKKTLKLSSKVLDKISTGQLVSLLSNNLNKFDEGLALAHFVWIAPLQVLLLMGLLWDLLQASAFCGLGFLIILALFQAWLGRMMMKYRDKRAGKINERLVITSQIIENIQSVKAYCWENAMEKIIETIRETELKLTRKAAYVRYFNSSAFFFSGFFVVFLSIVPHLLLDGISLRKIFTTISFSIVLRMAVTRQFPWAVQTWYDSLGVINKIQEFLQKEEYKSLEYNLTTTEVAMENVSASWDEGIGEFFEKAKLEVNGGNISNEDPSAFFSNFSLHVAPVLRNINFKIEKGQLLAIAGSTGAGKTSLLMMIMGELEPSAGKIKHSGRISFSPQVSWIMPGTIKENIVFGVSYDQYRYLSVIKACQLEEDISKFPEKDNTVLGEGGITLSGGQRARISLARAVYKDADLYLLDSPFSYLDLFTEKEIFESCVCKLMANKTRILVTSKVEQLKKADKVLILHEGSCYFYGTFSELQDQRPEFSSHLIGFDHFNAERRNSIITETLRRCSIDSDPTGVRNEVKNKSFKQVGDFSEKRKSSIINPRKSSRKFSVMQKSQPQMSGIEEEDVPAVQGERKLSLVPESDQGEASLPRSNIFNTGPTFQARRRQSVLNLMTRTSISQGSNAFATRKTSVRKMSVSSYSNSSFEVDIYNRRLSQDSILEVSEDINEEDLKECFLDDTDSPSTTTTWNTYLRFLTAHKNFIFILVFCIVIFLAEVVASSAGLWVLKSNAPVINTTSNGNGSEISDTLSVIVTHTSFYYVFYIYVGVVDSLLALGIFRGLPLVHSLISVSKVLHKKMLHAILHAPMSTFNTMRAGRILNRFSKDTAILDDILPLSIFDLTQLVLIVIGAITVVSLLEPYIFLATVPVIVAFILLRSYFLHTSQQLKQLESEARSPIFAHLITSLKGLWTLRAFGRQPYFETLFHKALNLHTANWFLYLSTLRWFQMTIEMIFVIFFIAVSFISIATSGAGEEKVGIVLTLAMNIMNTLQWAVNASIDVDSLMRSVSRIFRFIDLPVEELINENKNKEEQLSEVLIYENDYIKKTQVWPSGGQMTVKNLSANYIDGGNTVLENISFSLSPGQRVGLLGRTGSGKSTLLSAFLRLLSTQGDIQIDGVSWQTIPLQKWRKAFGVIPQKVFIFSGSIRKNLDPYGKWSDEELLKVTEEVGLKLIIDQFPGQLDFVLLDGGCVLSHGHKQLVCLARSVLSKAKILLLDEPSAHLDPITFQIIRKTLKHAFADCTVILSEHRLEAMLECQRFLVIEDNTVRQYDSIQKLVNEKSFFKQAISHSDRLKLFPLHRRNSSKRKSRPQISALQEETEEEVQDTRLProteomicsLDLFTELeu - Asp - Leu-Phe - Thr - Glu5055065075085095101,485 amino acids

LDLFTE1-letter code for each aa:3-letter code for each aa:This is only the primary structure.At this point we have no idea what the DNA will look like.Amino Acid Sequence for CFTR protein (primary structure)


Deciphering the Protein

5 TTAGATCTTTTTACAGAA 3TTAGATCTTTTTACAGAA

5,952 possible RNA sequencesUUUUUAGAUUUAUUUACGGAAUUGGACUUGUUCACAGAGCUUCUUACCCUCCUCACUCUACUACUGCUGGAAACACUUGAUUUAUUAUUGCUUCUCCUACUGUUAUUGCUUCUCCUACUGDNA ContigAll possible codons

LDLFTELeu -Asp-Leu-Phe-Thr-Glu505506507508509510


Molecular Biology


molecular biology (.ppsx)

Science