• Exam II Tuesday 5/10 – Bring a scantron with you! Announcements ● Tutoring Center SCI I, 407 M 12-3, 5:30-6:30; W 8-9, 5:30-6:30, Th 8-12, 6-7; F 8-9 ● MasteringBiology Assignment due Tuesday 5/10 • Exam II Tuesday 5/10 – Bring a scantron with you! 1

Nucleic Acids ● Include DNA and RNA Information storage molecules They provide the directions for building proteins Gene DNA RNA Protein Amino acid Nucleic acids 2

Nucleic Acids ●Nucleic acids are polymers of nucleotides Nitrogenous base (A,G,C, or T) Phosphate group Thymine (T) Sugar (deoxyribose) Base DNA, deoxyribonucleic acid RNA, ribonucleic acid Nitrogenous base A, G, C, or U Uracil U Phosphate group Sugar ribose 3

Nucleic Acids ●Each DNA nucleotide has one of the following bases: Adenine (A) Guanine (G) Cytosine (C) Thymine (T) Adenine A Guanine G ● Each RNA nucleotide has one of the following bases: Adenine (A) Guanine (G) Cytosine (C) Uracil (U) Thymine T Cytosine C 4

Nucleic Acids ●Nucleic Acid Structure Sugar-phosphate backbone Bases pair Nucleotide Hydrogen bond Bases a DNA strand polynucleotide b Double helix two polynucleotide strands 5

DNA Structure Phosphate group Nitrogenous base Nitrogenous base (can be A, G, C, or T) Sugar Nucleotide Thymine (T) DNA double helix Phosphate group Sugar (deoxyribose) DNA nucleotide Polynucleotide Sugar-phosphate backbone

DNA Structure *Early 1950’s Rosalind Franklin *1953 Watson and Crick

DNA Structure

Flow of Genetic Information DNA functions as the inherited directions for a cell or organism. How are these directions carried out? Gene DNA RNA Protein Amino acid Nucleic acids

Flow of Genetic Information An organism’s genotype is its genetic makeup, the sequence of nucleotide bases in DNA. The phenotype is the organism’s physical traits, which arise from the actions of a wide variety of proteins. Gene DNA RNA Protein Amino acid Nucleic acids

Flow of Genetic Information DNA strand TRANSCRIPTION RNA TRANSLATION Codon Polypeptide Amino acid

Second base of RNA codon Phenylalanine (Phe) Tyrosine (Tyr) Cysteine (Cys) Serine (Ser) Stop Stop Leucine (Leu) Stop Tryptophan (Trp) Histidine (His) Leucine (Leu) Proline (Pro) Arginine (Arg) Glutamine (Gln) First base of RNA codon Third base of RNA codon Asparagine (Asn) Serine (Ser) Isoleucine (Ile) Threonine (Thr) Lysine (Lys) Arginine (Arg) Figure 10.11 The dictionary of the genetic code, listed by RNA codons. Met or start Aspartic acid (Asp) Valine (Val) Alanine (Ala) Glycine (Gly) Glutamic acid (Glu) Figure 10.11

Transcription (a) A close-up view of transcription RNA polymerase DNA of gene Promoter DNA Initiation Terminator DNA RNA Area shown in part (a) at left Elongation RNA nucleotides RNA polymerase Termination Growing RNA Figure 10.13 Transcription Newly made RNA Completed RNA Direction of transcription Template strand of DNA RNA polymerase (a) A close-up view of transcription (b) Transcription of a gene Figure 10.13

Translation Translation requires: mRNA ATP Enzymes Ribosomes Cap Start of genetic message Translation requires: mRNA ATP Enzymes Ribosomes Transfer RNA (tRNA) End Tail

Translation Transfer RNA (tRNA): Acts as a molecular interpreter Amino acid attachment site Transfer RNA (tRNA): Acts as a molecular interpreter Carries amino acids Matches amino acids with codons in mRNA using anticodons Hydrogen bond RNA polynucleotide chain Anticodon tRNA (simplified representation) tRNA polynucleotide (ribbon model)

Translation Ribosomes are organelles that: Coordinate the functions of mRNA and tRNA Are made of two protein subunits Contain ribosomal RNA (rRNA) Next amino acid to be added to polypeptide tRNA binding sites Growing polypeptide P site A site Ribosome tRNA Large subunit mRNA binding site mRNA Small subunit Codons (a) A simplified diagram of a ribosome (b) The “players” of translation

Initiation of Translation Met Large ribosomal subunit Initiator tRNA P site A site mRNA Start codon Small ribosomal subunit

Peptide bond formation Amino acid Polypeptide P site mRNA Anticodon A site Codons Codon recognition ELONGATION Stop codon Peptide bond formation New peptide bond Figure 10.19 The elongation of a polypeptide. (Step 4) mRNA movement Translocation

Transcription Polypeptide Nucleus Stop codon Intron RNA processing Cap RNA polymerase Transcription Polypeptide Nucleus DNA mRNA Stop codon Intron RNA processing Cap Termination Tail mRNA Intron Anticodon Amino acid Ribosomal subunits Codon tRNA Figure 10.20 A summary of transcription and translation. (Step 6) Enzyme Elongation ATP Initiation of translation Amino acid attachment

Mutations A mutation is any change in the nucleotide sequence of DNA. Mutations can change the amino acids in a protein. Mutations can involve: Large regions of a chromosome Just a single nucleotide pair Normal hemoglobin DNA mRNA Normal hemoglobin Mutant hemoglobin DNA Sickle-cell hemoglobin

Mutations

Human Disorders