DNA Nucleic Acids n DNA and RNA are

DNA

Nucleic Acids n DNA and RNA are examples – Deoxyribonucleic acid – Ribonucleic acid

Nucleic Acids n. A gene is a section of DNA that provides the code to make a protein.

Nucleic Acids n Built from monomers of nucleotides – Consists of a phosphate group, a sugar molecule, and a nitrogenous base

Nitrogenous bases n Purines – double ring -adenine, guanine n Pyrimidines – single ring – thymine, cytosine A=T C=G

Huge molecule over 3 billion base pairs per cell Condenses by wrapping/coiling around histones -called a chromosome DNA double helix (2 -nm diameter) Metaphase chromosome Tight helical fiber (30 -nm diameter) Linker “Beads on a string” Nucleosome (10 -nm diameter) Histones Supercoil (300 -nm diameter) 700 nm

How did we discover DNA is the genetic material? n In a group or individually, read through page 182 and figure 10. 1 B (183) n What did Fredrick Griffith discover? n What did Alfred Hershey and Martha Chase discover? What was their experiment?

Hershey Chase Animation

Phage Bacterium Radioactive protein Empty protein shell The radioactivity is in the liquid. Phage DNA Centrifuge Pellet Batch 1: Radioactive protein labeled in yellow Radioactive DNA Centrifuge Pellet Batch 2: Radioactive DNA labeled in green The radioactivity is in the pellet.

How was the double helix discovered? n Read pages 186 and 187

Thymine (T) Pyrimidines Cytosine (C) Adenine (A) Guanine (G) Purines

Recall: The experiment from Hershey and Chase (1952) demonstrated DNA is the passed from parents to offspring, but what is its structure? Phage Bacterium Radioactive protein DNA Empty protein shell The radioactivity is in the liquid. Phage DNA Centrifuge Pellet Batch 1: Radioactive protein labeled in yellow Radioactive DNA Centrifuge Pellet Batch 2: Radioactive DNA labeled in green The radioactivity is in the pellet.

Discovering the Structure of DNA n Watson and Crick were the first to discover the structure of DNA. – Used data x-ray crystallography data from Wilkins and Franklin without their permission

Earliest Model of DNA

Make our own models n Two simple steps – Label the nitrogenous bases – Fold it

DNA n We know the structure of DNA, and that more than 3 billion base pairs are in each cell, what about new cells?

DNA Replication n Depends pairs on specific base adenine – thymine guanine – cytosine If this is one half of DNA, what would the other half be?

DNA Replication n Semiconservative model – The two DNA strands separate (parent strands). – Each parent strand then becomes a template for a new, complementary strand (daughter strand) forming two new daughter molecules of DNA – Each new DNA helix has one old strand with one new strand.

Figure 10. 4 b A T G C A A Parental DNA molecule T A T C Daughter strand Parental strand G G C T T A G C C G G T T G C C A T A G A C C T A A T G A T T A C T Daughter DNA molecules

DNA Replication n Over a dozen enzymes and other proteins needed to replicate DNA n DNA polymerase – adds nucleotides one at a time to the strand – Other enzymes “proofread” and fix mistakes

DNA Replication n Replication same time occurs at multiple points at the

DNA Replication n The direction DNA polymerase moves is determined by the sugar phosphate backbone – There is a 5’ end a 3’ end – Nucleotides are added onto the 3’ end, moving towards the 5’ end Carbons are labeled

DNA polymerase molecule 5′ 3′ Parental DNA Replication fork 5′ 3′ DNA ligase Overall direction of replication 3′ This daughter 5′ strand is synthesized continuously This daughter strand is 3′ synthesized 5′ in pieces

Recall n. A gene is a section of DNA that provides the code to make a protein. n Genes carry different information on them n Human Genome mapped it out – ethical questions

n https: //www. youtube. com/watch? v=zwibg NGe 4 a. Y&feature=youtube_gdata_player

Parent molecule Daughter molecules

Parent strand Daughter strand

A T G C A A Parental DNA molecule T A T C Daughter strand G G C T T A Parental strand G C C G G T T G C C A T A G A C C T A A T G A T T A C T Daughter DNA molecules

Hypothetical DNA If this is the parent strand? What is the daughter strand? ATCCGTAA-

What was the main enzyme in DNA replication? What was unique as a result of the sugar phosphate backbone?

DNA polymerase molecule 5′ 3′ Parental DNA Replication fork 5′ 3′ DNA ligase Overall direction of replication 3′ This daughter 5′ strand is synthesized continuously This daughter strand is 3′ synthesized 5′ in pieces

https: //www. hhmi. org/biointeractive/dna-replication-basic-detail

n https: //www. hhmi. org/biointeractive/dna- replication-basic-detail

After DNA replicates, the cell divides Looking at that after break. Why is DNA Critical?

Transcription and Translation n DNA is transcribed into RNA n RNA is translated into protein DNA Transcription RNA NUCLEUS Translation Protein CYTOPLASM

DNA n Ingredientes: n 2 1 / 4 tazas de harina para todo uso 1 cucharadita de bicarbonato de soda 1 cucharadita de sal 1 taza (2 palos) de mantequilla, suavizada 3 / 4 taza de azúcar granulada 3 / 4 taza de azúcar morena 1 cucharadita de extracto de vainilla 2 huevos grandes 2 tazas (12 oz. Pkg. ) TELEPEAJE CASA NESTLÉ ® ® semi-dulce de chocolate bocados 1 taza de nueces picadas n n n n n

RNA n Ingredients: n To 2 1/4 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup brown sugar 1 teaspoon vanilla extract 2 large eggs 2 cups (12 oz. Pkg. ) NESTLÉ TOLL HOUSE ® ® semisweet chocolate morsels 1 cup chopped walnuts n n n n n

Protein

Transcription n Sections of DNA called genes are used n RNA polymerase attaches to the DNA at a ‘promoter’ site n It moves along the gene forming a new RNA strand using the base pair rules

Transcription n DNA Base pairs A-T G-C n RNA A-U G-C n There Base pairs is no thymine in RNA, a different nucleotide Uracil is used

DNA A C C G G C A A U U U G G C C G U U Transcription RNA Translation Codon Polypeptide Amino acid

Quick review

DNA replication n Lots of enzymes, DNA polymerase one of them

n DNA codes for protein n Only part of DNA is a gene

Transcription and Translation n DNA is transcribed into RNA n RNA is translated into protein DNA Transcription RNA NUCLEUS Translation Protein CYTOPLASM

DNA n Ingredientes: n 2 1 / 4 tazas de harina para todo uso 1 cucharadita de bicarbonato de soda 1 cucharadita de sal 1 taza (2 palos) de mantequilla, suavizada 3 / 4 taza de azúcar granulada 3 / 4 taza de azúcar morena 1 cucharadita de extracto de vainilla 2 huevos grandes 2 tazas (12 oz. Pkg. ) TELEPEAJE CASA NESTLÉ ® ® semi-dulce de chocolate bocados 1 taza de nueces picadas n n n n n

RNA n Ingredients: n To 2 1/4 cups all-purpose flour 1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup brown sugar 1 teaspoon vanilla extract 2 large eggs 2 cups (12 oz. Pkg. ) NESTLÉ TOLL HOUSE ® ® semisweet chocolate morsels 1 cup chopped walnuts n n n n n

Protein

Transcription n Sections of DNA called genes are used n RNA polymerase attaches to the DNA at a ‘promoter’ site n It moves along the gene forming a new RNA strand using the base pair rules

Transcription n DNA Base pairs A-T G-C n RNA A-U G-C n There Base pairs is no thymine in RNA, a different nucleotide Uracil is used

Transcription RNA polymerase recognizes part of the DNA strand attaches at the promoter region

Transcription RNA synthesis begins after attachment

Transcription Using DNA as a template, RNA polymerase adds RNA nucleotides one at a time

Transcription Using DNA as a template, RNA polymerase adds RNA nucleotides one at a time If the DNA strand is: ATAGGC Then the RNA will be: UAUCCG UUACGCAUAGCG DNA - A A T G C G T A T C G C

Transcription RNA synthesis ends when RNA polymerase reaches the terminator DNA sequence

Direction of transcription Initiation RNA synthesis begins after RNA polymerase attaches to the promoter. Unused strand of DNA RNA polymerase Terminator DNA Newly formed RNA Promoter Elongation Template strand of DNA Direction of transcription DNA strands reunite Free RNA nucleotide U T Using the DNA as a template, RNA polymerase adds free RNA nucleotides one at a time. C DNA of gene AT C C A A TG AU GAU C C A A A T A GG T T A DNA strands separate Newly made RNA Termination RNA synthesis ends when RNA polymerase reaches the terminator DNA sequence. Terminator DNA Completed RNA polymerase detaches

Transcription and Translation n DNA is transcribed into RNA n RNA is translated into protein DNA Transcription RNA NUCLEUS Translation Protein CYTOPLASM Before leaving the nucleus, the RNA is processed

Exon DNA Exon Intron Cap RNA transcript with cap and tail Exon Intron Transcription Addition of cap and tail Introns removed Tail Exons spliced together m. RNA Coding sequence NUCLEUS CYTOPLASM

RNA processing n. A ‘cap’ and ‘tail’ are added – helps protect the RNA n Introns (intervening sequences) are removed n Exons (expressed sequences) are spliced together Exon DNA Exon Intron

Transcription and Translation n DNA is transcribed into RNA n RNA is translated into protein DNA Transcription RNA NUCLEUS Translation Protein CYTOPLASM

Translation n The genetic code is the amino acid translations of each of the nucleotide triplets. n Three nucleotides specify one amino acid

Translation Sixty-one codons correspond to amino acids n AUG codes for methionine and signals the start of translation n Three “stop” codons signal the end of translation n 64 Total

Strand to be transcribed DNA T A C T T C A A T C A T A G T T A G G A

Strand to be transcribed DNA T A C T T C A A T C A T G A A G T T A G A U G A A G U U A G Transcription RNA

Strand to be transcribed DNA T A C T T C A A T C A T G A A G T T A G A U G A A G U U A G Transcription RNA Translation Start codon Polypeptide Met Stop codon Lys Phe

Translation n Types of RNA – Messenger RNA – RNA that will be coded into protein (m. RNA) – Transfer RNA – RNA that is used in the decoding process (t. RNA) – Ribosomal RNA – part of the ribosome that puts the protein together (adds amino acids together) (r. RNA)

Translation n t. RNA – There are 61, for each of the codons – Contains a section called the anticodon that base pairs with the codon on m. RNA

Translation n Ribosome – A complex of r. RNA and protein – A small subunit and a large subunit – Contains two sites for t. RNA – A site and P site

Translation n How does it actually work? Recall, m. RNA was just transcribed in the nucleus and then processed before entering the cytoplasm DNA Transcription RNA NUCLEUS Translation Protein CYTOPLASM

Translation n m. RNA binds to a the small subunit of a ribosome n a t. RNA recognizes the start codon and binds

Translation n The large ribosomal subunit binds to the small subunit n The t. RNA fits into the P site

Translation n. A new t. RNA carrying an amino acid moves into the A site, amino acids are combined n The t. RNAs shift over n This repeats until stop codon is reached

Amino acid Polypeptide Anticodon A site P site m. RNA Codons 1 Codon recognition

Amino acid Anticodon A site Polypeptide P site m. RNA Codons 1 Codon recognition 2 Peptide bond formation

Amino acid Anticodon A site Polypeptide P site m. RNA Codons 1 Codon recognition New peptide bond 3 Translocation 2 Peptide bond formation

Amino acid Anticodon A site Polypeptide P site m. RNA Codons 1 Codon recognition m. RNA movement Stop codon New peptide bond 3 Translocation 2 Peptide bond formation

Try it n DNA: TACAATCGTACG n RNA: AUGUUAGCAUGC n Amino Acid: Met – Leu – Ala – Cys (one strand)

https: //www. youtube. com/watch? v=h 5 m. Jb. P 23 Buo