1. What are the 3 components of this DNA nucleotide? 2. What is the function of DNA in the cell?

Unit Overview – pages Genetics DNA and Genes DNA: The Molecule of Heredity

Contributors to DNA Discovery 1943 Oswald Avery: DNA carries genetic information 1952 Franklin took the first picture of DNA using X-RAY

Contributors to DNA Discovery Watson & Crick proposed the structure of DNA Nobel Prize to Watson and Crick “FATHERS OF DNA”

Contributors to DNA Discovery So? Was it that clear cut?? What event occurred allowing Watson and Crick to discover the DNA structure?

Section 11.1 Summary – pages Deoxyribonucleic Acid –determines an organism’s traits –ultimately determines the structure of proteins. body is made up of proteins body’s functions depend on proteins called enzymes. What is DNA?

Section 11.1 Summary – pages DNA is a polymer made of nucleotides. Nucleotides have three parts: – simple sugar – phosphate group – nitrogenous base. The Structure of DNA

Section 11.1 Summary – pages composed of one atom of phosphorus surrounded by four oxygen atoms. Deoxyribose is the simple sugar in DNA Phosphate group Sugar (deoxyribose) Nitrogenous base carbon ring structure that contains one or more atoms of nitrogen.

Section 11.1 Summary – pages In DNA, there are four possible nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Adenine (A) Guanine (G)Thymine (T) Cytosine (C) The structure of nucleotides *always pair * always pair

Section 11.1 Summary – pages Thus, in DNA there are four possible nucleotides, each containing one of these four bases. Nucleotides join together to form long chains. –Formed by covalent bonds –These chains are known as the Double Helix The structure of nucleotides

Section 11.1 Summary – pages The structure of nucleotides ****

Section 11.1 Summary – pages The importance of nucleotide sequences Chromosome The sequence of nucleotides in each gene contains information for assembling the string of amino acids that make up a single protein.

Genes and Proteins Proteins make up the structure of an organism AND control all of the organism’s chemical reactions to keep it alive

DNA and Cell Division

DNA to Protiens Remember…DNA ultimately determines structure of proteins. These proteins are what makes “us” and enables “us” to function….. So how do we get these specific proteins???

Section 11.1 Summary – pages Replication of DNA Before a cell can divide by mitosis or meiosis, it must first make a copy of its chromosomes.( Interphase) The DNA in the chromosomes is copied in a process called DNA replication. Without DNA replication, new cells would have only half the DNA of their parents.

Section 11.2 Summary – pages Cells Start Here: Transcription Transcription results in the formation of one single-stranded RNA molecule. –takes place in the nucleus mRNA, which is seen in here, takes the instructions from the nucleus to the cytoplasm.

Section 11.2 Summary – pages RNA is single stranded What is RNA? The sugar is ribose Rather than thymine, RNA contains a similar base called uracil (U). Uracil Adenine Hydrogen bonds

DNA provides workers with the instructions for making the proteins, and workers build the proteins. The workers for protein synthesis are RNA molecules. Why RNA???

Back to Copying DNA…. Once mRNA is in the cytoplasm… Ribosomal RNA (rRNA) binds to the mRNA and uses the instructions to assemble the amino acids in the correct order. This starts Translation

Section 11.2 Summary – pages Translation: From mRNA to Protein Translation is the process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein. Translation takes place at the ribosomes in the cytoplasm.

Section 11.2 Summary – pages Each tRNA molecule attaches to only one type of amino acid. An anticodon is a sequence of three bases found on tRNA. Amino acid Chain of RNA nucleotides Transfer RNA molecule Anticondon The role of transfer RNA

Section 11.2 Summary – pages The role of transfer RNA Ribosome mRNA codon

Section 11.2 Summary – pages The first codon on mRNA is AUG, which codes for the amino acid methionine. AUG signals the start of protein synthesis. Then the ribosome slides along the mRNA to the next codon. The role of transfer RNA

Section 11.2 Summary – pages tRNA anticodon Methionine The role of transfer RNA

Section 11.2 Summary – pages A new tRNA molecule carrying an amino acid pairs with the second mRNA codon. Alanine The role of transfer RNA

Section 11.2 Summary – pages The amino acids are joined when a peptide bond is formed between them. Alanine Methionine Peptide bond The role of transfer RNA

Section 11.2 Summary – pages A chain of amino acids is formed until the stop codon is reached on the mRNA strand. Stop codon The role of transfer RNA

Section 11.2 Summary – pages The Genetic Code The Messenger RNA Genetic Code First Letter Second Letter U U C A G Third Letter U C A G U C A G U C A G U C A G C A G Phenylalanine (UUU) Phenylalanine (UUC) Leucine (UUA) Leucine (UUG) Leucine (CUU) Leucine (CUC) Leucine (CUA) Leucine (CUG) Isoleucine (AUU) Isoleucine (AUC) Isoleucine (AUA) Methionine; Start (AUG) Valine (GUU) Valine (GUC) Valine (GUA) Valine (GUG) Serine (UCU) Serine (UCC) Serine (UCA) Serine (UCG) Proline (CCU) Proline (CCC) Proline (CCA) Proline (CCG) Threonine (ACU) Threonine (ACC) Threonine (ACA) Threonine (ACG) Alanine (GCU) Alanine (GCC) Alanine (GCA) Alanine (GCG) Tyrosine (UAU) Tyrosine (UAC) Stop (UAA) Stop (UAG) Histadine (CAU) Histadine (CAC) Glutamine (CAA) Glutamine (CAG) Asparagine (AAU) Asparagine (AAC) Lysine (AAA) Lysine (AAG) Aspartate (GAU) Aspartate (GAC) Glutamate (GAA) Glutamate (GAG) Cysteine (UGU) Cysteine (UGC) Stop (UGA) Tryptophan (UGG) Arginine (CGU) Arginine (CGC) Arginine (CGA) Arginine (CGG) Serine (AGU) Serine (AGC) Arginine (AGA) Arginine (AGG) Glycine (GGU) Glycine (GGC) Glycine (GGA) Glycine (GGG)

DNAi Triplet code Translation

11.3 Section Objectives – page Why is this exact base sequence important? 2. What may be the result of “wrong” base sequencing?

11.3 Section Summary 6.3 – pages Organisms have evolved many ways to protect their DNA from changes. Mutations In spite of these mechanisms, however, changes in the DNA occasionally do occur. A mutation is any change in a DNA sequence. Mutations can be caused by errors in replication, transcription, cell division, or by external agents.

11.3 Section Summary 6.3 – pages Mutations can occur in the reproductive cells. – This then becomes part of the genetic makeup of the offspring. –If the change makes a protein nonfunctional, the embryo may not survive. Mutations in reproductive cells

11.3 Section Summary 6.3 – pages What happens if powerful radiation, such as gamma radiation, hits the DNA of a nonreproductive cell, a cell of the body such as in skin, muscle, or bone? If the body cell’s DNA is changed, this mutation would not be passed on to offspring. The mutation may cause problems for the individual. Mutations in body cells

11.3 Section Summary 6.3 – pages A point mutation is a change in a single base pair in DNA. A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein. The effects of point mutations

11.3 Section Summary 6.3 – pages The effects of point mutations Normal Point mutation mRNA Protein Stop mRNA Protein Replace G with A

11.3 Section Summary 6.3 – pages Frameshift mutations This mutation would cause nearly every amino acid in the protein after the deletion to be changed. A frameshift mutation is a mutation in which a single base is added or deleted from DNA. A frameshift mutation shifts the reading of codons by one base.

11.3 Section Summary 6.3 – pages Frameshift mutations mRNA Protein Frameshift mutation Deletion of U

11.3 Section Summary 6.3 – pages Chromosomal mutations are structural changes in chromosomes. When a part of a chromosome is left out, a deletion occurs Chromosomal Alterations A B C D E F G H Deletion A B C E F G H

11.3 Section Summary 6.3 – pages When part of a chromatid breaks off and attaches to its sister chromatid, an insertion occurs. The result is a duplication of genes on the same chromosome. Insertion A B C D E F G H A B C B C D E F G H Chromosomal Alterations

11.3 Section Summary 6.3 – pages When part of a chromosome breaks off and reattaches backwards, an inversion occurs. Inversion A B C D E F G H A D C B E F G H Chromosomal Alterations

11.3 Section Summary 6.3 – pages When part of one chromosome breaks off and is added to a different chromosome, a translocation occurs. A B E F DCBX A W C H G G E H D F W XYZYZ Translocation Chromosomal Alterations

11.3 Section Summary 6.3 – pages A mutagen is any agent that can cause a change in DNA. Mutagens include radiation, chemicals, and even high temperatures. Forms of radiation, such as X rays, cosmic rays, ultraviolet light, and nuclear radiation, are dangerous mutagens because the energy they contain can damage or break apart DNA. Causes of Mutations

11.3 Section Summary 6.3 – pages Causes of Mutations The breaking and reforming of a double- stranded DNA molecule can result in deletions. Chemical mutagens include dioxins, asbestos, benzene, and formaldehyde, substances that are commonly found in buildings and in the environment. Chemical mutagens usually cause substitution mutations.

11.3 Section Summary 6.3 – pages Repairing DNA Repair mechanisms that fix mutations in cells have evolved. Enzymes proofread the DNA and replace incorrect nucleotides with correct nucleotides. These repair mechanisms work extremely well, but they are not perfect. The greater the exposure to a mutagen such as UV light, the more likely is the chance that a mistake will not be corrected.