MOLECULAR GENETICS CHAPTER 10 and 13

The Blue People of Troublesome Creek

Analysis Questions for The Blue People of Troublesome Creek What physical TRAIT did Martin Fugate and his wife pass on to their many generations of offspring? What physical VARIATION of this trait did Martin Fugate and his wife pass on to their many generations of offspring? Why did this condition occur? What role did genes play in both the appearance of the trait and the passing on of the trait? Based on this reading and your responses to the above questions, how might you begin to define the term “genetics”? Based on this reading and your responses to the above questions, how might you begin to define the term “trait”? Based on this reading and your responses to the above questions, describe the relationship between enzymes (proteins) and traits.

CENTRAL DOGMA OF MOLECULAR BIOLOGY DNA Transcription RNA Translation Protein Trait Replication CENTRAL DOGMA OF MOLECULAR BIOLOGY

On the road to discovery of DNA…. Hershey and Chase 1952 worked with viruses that infect bacteria called bacteriophages and E. Coli bacteria Found DNA, not protein, is the hereditary molecule. Chargaff 1947 For all organisms, adenine = thymine and cytosine = guanine Wilkins and Rosalind Franklin, early 1950’s studied the structure of DNA crystals using X-rays. Found double helix with equal subunits Watson and Crick, 1953 Used Chargaff's base data and Franklin’s X-ray diffraction data to construct a model of DNA.

DNA Deoxyribonucleic acid A large polymer used to carry the genetic code of all living organisms

DNA bound protein is called CHROMATIN DNA is found packed in the nucleus of eukaryotic organisms; it is found in the cytoplasm of prokaryotic organisms DNA is packed together and wrapped around special proteins called HISTONES DNA bound protein is called CHROMATIN When chromatin condenses (gets thicker) it forms CHROMOSOMES Gene  DNA  Chromatin  Chromosomes

DNA structure Double Helix - twisted ladder Made of monomers called nucleotides Nucleotides are composed of: Deoxyribose: 5 carbon sugar (side of helix) Phosphate group (side of helix) Purine and Pyrimidine Base (steps ladder) Hydrogen bonds hold sides together

Nucleotide

Nitrogenous Bases Two types: Purines (2 RINGS) Pyrimidines (1 RING) Purines (two rings) larger bases Pyrimidines (one ring) smaller bases Purines (2 RINGS) Adenine and Guanine Pyrimidines (1 RING) Thymine and Cytosine Purines Adenine Guanine Pyrimidines Cytosine Thymine Deoxyribose Phosphate group

Chargaff’s rules: Base pairing rule is A-T and G-C Thymine is replaced by Uracil in RNA Bases are bonded to each other by weak hydrogen bonds Discovered because of the relative percent of each base; (notice that A-T is similar and C-G are similar) there was complementary base pairing of a purine with a pyrimidine The paired bases can occur in any order, giving an overwhelming diversity of sequences http://www.dnatube.com/video/1358/Structure-of-DNA-explained-in-detail

DNA REPLICATION Making a complete copy of an entire length of DNA Occurs in S phase of cell cycle for both Mitosis and Meiosis Occurs in the nucleus of the cell Complimentary sides are formed due to nitrogenous base pairing joined by hydrogen bond

Semi Conservative Model Explains process of replication 1 original DNA serves as template (guide) for making another DNA side Replication will work in opposite directions on both sides at same time

How Does Replication Start? an enzyme called helicase “unzips” the DNA to create a replicating bubble. Single stranded binding proteins keep 2 sides apart and stable Another enzyme, DNA polymerase, moves along the bases on each side and connects complementary nucleotides.

Anti Parallel Strand DNA runs in opposite directions It is read in a 5  3 direction 5’Carbon of Deoxyribose has phosphate attached to it 1’ Carbon of sugar has nitrogen base attached to it 3’ Carbon of sugar has an open bond (connector site for next nucleotide)

Leading vs. Lagging Strand in replication fork Runs in a continuous 5’  3’ direction as it opens Lagging Doesn’t run in 5’  3’ direction Slower, works backward making Okazaki fragment http://www.dnatube.com/video/2335/Video-for-DNA-Replication http://www.dnatube.com/video/335/Animated-DNA-Replication

How does DNA get the genetic code out of the nucleus??? Transcription and Translation with RNA

RNA Ribonucleic acid Single-stranded Sugar is ribose Thymine is replaced by URACIL

Differences between DNA & RNA Structure: Double stranded Sugar Deoxyribose Bases: Adenine Guanine Cytosine Thymine RNA Structure: Single stranded Sugar Ribose Bases: Adenine Guanine Cytosine Uracil

Transcription- how RNA is made Occurs in Nucleus Makes a disposable copy of DNA, just in form of RNA RNA polymerase temporarily separates the strands of a small section of the DNA molecule exposing some of the bases of the DNA molecule. Along one strand, the RNA polymerase binds complementary RNA nucleotides to the exposed DNA bases. As the RNA polymerase moves along, it makes a strand of messenger RNA (mRNA). It carries DNA’s message out of the nucleus and into the cytoplasm.

Types of RNA: Messenger RNA (mRNA) Ribosomal RNA (rRNA) carries information from DNA to ribosome Ribosomal RNA (rRNA) Combines with proteins that makes up ribosomes Transfer RNA (tRNA) Carries amino acids to ribosome

PROTEIN SYNTHESIS TRANSCRIPTION – the synthesis of RNA under the direction of DNA TRANSLATION – the actual synthesis of a protein, which occurs under the direction of mRNA

http://www.dnatube.com/video/3450/DNA-Transcription http://www.dnatube.com/video/5763/DNA-Transcription-animation

Codons a sequence of 3 nitrogen bases on mRNA that code for 1 amino acid, it’s a triplet code; Universal with all life. 61 of 64 codons code for 20 amino acids on earth Codons match up with anticodons to create a protein

The Genetic Code The Messenger RNA Genetic Code Second Letter U C A G First Letter Third Letter Second Letter U C A G U Phenylalanine (UUU) Serine (UCU) Tyrosine (UAU) Cysteine (UGU) U Phenylalanine (UUC) Serine (UCC) Tyrosine (UAC) Cysteine (UGC) C Leucine (UUA) Serine (UCA) Stop (UAA) Stop (UGA) A Leucine (UUG) Serine (UCG) Stop (UAG) Tryptophan (UGG) G C Leucine (CUU) Proline (CCU) Histadine (CAU) Arginine (CGU) U Leucine (CUC) Proline (CCC) Histadine (CAC) Arginine (CGC) C Leucine (CUA) Proline (CCA) Glutamine (CAA) Arginine (CGA) A Leucine (CUG) Proline (CCG) Glutamine (CAG) Arginine (CGG) G A Isoleucine (AUU) Threonine (ACU) Asparagine (AAU) Serine (AGU) U Isoleucine (AUC) Threonine (ACC) Asparagine (AAC) Serine (AGC) C Isoleucine (AUA) Threonine (ACA) Lysine (AAA) Arginine (AGA) A Methionine;Start (AUG) Threonine (ACG) Lysine (AAG) Arginine (AGG) G G Valine (GUU) Alanine (GCU) Aspartate (GAU) Glycine (GGU) U Valine (GUC) Alanine (GCC) Aspartate (GAC) Glycine (GGC) Glycine (GGC) C Valine (GUA) Alanine (GCA) Glutamate (GAA) Glycine (GGA) A Valine (GUG) Alanine (GCG) Glutamate (GAG) Glycine (GGG) G

Translation Occurs in cytoplasm mRNA combines with a ribosome mRNA carries the codon tRNA carries the anticodon which pairs up with the codon These amino acid links form a protein

SO: Say the mRNA strand reads: tRNA would bring the amino acids: mRNA (codon) AUG–GAC–CAG-UGA tRNA (anticodon) UAC-CUG-GUC-ACU tRNA would bring the amino acids: Methionine-Aspartic acid-Glutamine-stop http://www.dnatube.com/video/4195/Translation http://www.dnatube.com/video/5934/Basic-explanation-of-mRNA-Translation

TRANSCRIPTION AND TRANSLATION http://www.dnatube.com/video/28981/What-is-Transcription-and-Translation

MUTATION Change in nucleotide sequence of DNA or mRNA that code for a protein Caused by mutagens (physical or chemical interactions that change the nucleotide sequence of DNA)

2 types of mutations Point mutations Single nucleotide mutates and affects a single codon Reading Frameshift Alter codon sequence Insertion: adding nucleotides to the sequence Deletion: taking out nucleotides from the sequence

GENETIC ENGINEERING A new form of manipulation that biologists created where they can engineer a set of genetic changes directly into an organisms DNA

BIOTECHNOLOGY Computers and other devices used to help in performing science DNA gene cloning is an example

POLYMERASE CHAIN REACTION Requires no organism in the production of new DNA molecules Turns a single molecule of DNA into a large, identical DNA molecules Used in forensics

Recombinant DNA Major focus of genetic engineering The sequence of nucleotides in the gene being manipulated are read Desired gene is cut from surrounding genes DNA from 2 different sources is joined into one molecule (hybrid) http://www.dnatube.com/video/193/Contruction-of-Recombinant-DNA

Plasmids molecules of DNA found in bacteria separate from the bacterial chromosome. small (a few thousand base pairs) and circular usually carry only one or a few genes

TRANSFORMATION Genetic alteration of a cell that is caused from directly taking in DNA from outside the cell membrane. It can occur naturally in some species of bacteria, but it can also be effected by artificial means in other cells http://www.dnatube.com/video/202/Understanding-Bacterial-Transformation

DNA Fingerprinting Pattern of bands made up of specific fragments from an individuals DNA Restriction enzymes can cut the DNA at specific sites with “sticky ends” DNA Ligase can join DNA at specific sites The DNA created artificially is called recombinant DNA

Gel Electrophoresis Creates a DNA fingerprint Different DNA samples are exposed to the SAME restriction enzyme creating RFLP (fragments of different lengths of DNA) Those fragments are loaded into agarose gel and electric currents are used RFLP’s will separate according to length/size of the fragments which create a unique fingerprint

Transgenic Organisms Recombined DNA from 2 different organisms to make 1 organism that has traits from BOTH parents. These traits will then be carried on to offspring

Human Genome Project Began 1990 ended in 2003 Mapped out entire DNA genome nucleotide sequences for all humans as a species Contains approximately 40,000 different genes

What is DNA technology used for? Gene therapy Pharmaceuticals Criminal Forensics Environmental Clean-up Agriculture Livestock