Characteristic #1 All living things are complex chemical systems Living things are made of molecules that interact Metabolism is the collective set of chemical processes & reactions in an organism Molecules breaking apart (releasing energy) Molecules forming (to store energy) Enzymes molecules that help reactions occur Characteristic #4 All living things reproduce using the same genetic mechanism (code) Each organism reproduces its own species Offspring inherit genetic instructions from their parents through a molecule called DNA Offspring can differ from their parents (genetic variation) Review Proteins are one of the four organic molecules (organic molecules) of life Proteins are made from a chain of amino acids that are folded in specific ways 20 different amino acids are used to make proteins The sequence of amino acids forms the shape of the protein shape of the protein determines its function Amino Acids and Proteins Review Proteins are the workhorses of the cell and the body Most of the body is made of proteins Examples of proteins: Skin Ligaments Hormones Muscle Hemoglobin (the part of blood that carries O2) Enzymes (help reactions to happen in the body) The Cell The cell has a nucleus in the center Outside of the nucleus is a watery substance called cytoplasm Cytoplasm is like the white of an egg Cells, DNA, and Proteins Proteins are made in the cytoplasm DNA (chromosomes) are in the nucleus Genes and Chromosomes DNA is divided into chromosomes Chromosomes are made of genes Each gene provides instructions for making a single protein GenesGenes GenesGenes Genes are on chromosomes One gene One protein Protein Synthesis The Structure of DNA DNA is made of nucleotides 5-carbon sugar (deoxyribose) Phosphate molecule One of four bases (A, G, C, and T). A Gateway Example of DNA Recap: The DNA Ladder Rails = sugars and phosphates Rungs = pairs of nitrogen bases Bases from each side bond together. The ladder is twisted into a double helix DNA Sequence Each DNA strand has a specific sequence of bases The bases on one strand are complementary to the bases on the other strand Strand 1: AGATTCGCATAC Strand 2: TCTAAGCGTATG Triplets The DNA bases (A, C, G, & T) form a 4- letter alphabet Each sequence of 3 bases forms a 3-letter word called a triplet DNA sequence: TTACGGTGACTC The same sequence divided into triplets: TTA CGG TGA CTC Replicating DNA DNA must make copies of itself for cell division The new DNA molecule will be EXACTLY like the one that is copied DNA Replication How it Works 1.DNA Polymerase- is an enzyme that unzips the two strands of DNA apart DNA Replication How it Works 2.DNA polymerase adds the new nucleotides to the exposed DNA strand DNA Replication How it Works 3.Enzymes join the nucleotides on the new strand and a new DNA is born!! DNA Replication What DNA Replication Might Look Like on the Gateway In the following slide, put the replication steps in the right order A B C D RNA RNA is a copy of DNA Three differences between DNA & RNA The sugar in RNA is Ribose RNA has only one strand The bases in RNA are A, G, C, and U DNA vs. RNA RNA Bases Like DNA, RNA is divided into 3-base words The 3-base words in RNA are called codons Each RNA codon corresponds to a DNA triplet RNA sequence: AUGUCAGAUAGG RNA codons: AUG UCA GAU AGG Transcription Transcription is when RNA is made from DNA How does Transcription Work 1. Enzymes unzip sections of DNA How does Transcription Work 2. RNA nucleotides attach to the bases in the DNA strand How does Transcription Work 3. Enzymes remove the new RNA and rezip the DNA molecule. RNA leaves the nucleus The same DNA molecule can be used over and over to make many RNA molecules. Gateway Examples of Transcription How to Recognize Transcription Only one strand is made The new strand has U and no T Gateway Examples of Transcription Put the steps in order in the following slide AB CDE Why is RNA important? It is small enough to leave the nucleus though the pores in the membrane & deliver information to the cytoplasm where protein is made Translation and the Genetic Code Translation Protein Synthesis Translation = building proteins from the instructions in DNA Translation & protein synthesis (building a protein) takes place on a ribosome What is needed to build proteins? rRNA makes up the ribosome where proteins are built tRNA carries amino acids to the ribosome mRNA carries information from the nucleus to the cytoplasm. Translation: Step 1 DNA strand separates- template for mRNA- (Messenger RNA) Translation: Step 2 RNA carries the information from nuclear DNA to the ribosome in the cytoplasm Translation: Step 3 3. mRNA attaches to a ribosome where protein synthesis will occur Translation: Step 4 The instructions from DNA tells tRNA which amino acids to bring to the ribosome Translation: Step 5 The amino acids on the ribosome are joined together by enzymes and the new protein is released Translation: The Whole Process The Genetic Code and Translation The sequence of amino acids in a protein determine its function How do the tRNA molecules know the proper sequence of amino acids for each protein? The Genetic Code and Translation Each DNA triplet is used to make a codon in RNA Each codon stands for a specific amino acid The triplets & codons create a sentence that tells the cell which amino acids to use when building a protein Example: DNA: TACCCG DNA triplets: TAC CGG RNA: AUGGGC RNA codons: AUG GCC Amino acids: AUG = methionine GCC = alanine The protein: methionine - alanine Example of a protein with 3 amino acids DNA TAC CGA TGG ACT RNA AUG GCU ACC UGA Amino Acids Methionine (start) Alanine Threonine - Stop Gateway Examples of Translation Mutations Mutations = mistakes in DNA or RNA (incorrect bases) Can happen during replication or transcription A wrong base in RNA may lead to wrong amino acids in the protein Mistakes in Meiosis Mutations & mistakes can happen in replication or transcription Mistakes can also happen in meiosis Meiosis mistakes: chromosomes fail to separate results in too many or too few chromosomes in a gamete Turner Syndrome Missing an X in the sex chromosomes girls are X instead of XX(monosom y) Patau Syndrome Trisomy 13 lots of facial and nervous system abnormalities. Most dont survive gestation, and few survive first year Symptoms: Brain fails to form lobes; cleft palate; open spinal cord; eyes close together and sometimes fused; profound mental retardation; microcephaly; heart defects; permanently clenched hands; incomplete development of eyesight or smell; extra fingers or toes; kidney defects; seizures. Down Syndrome Trisomy 21: flat facial features, upward slant to eyes; enlarged tongue, heart defects; hearing or eyesight problems; mental retardation; poor muscle tone; loose joints Mutations: Good or Evil? Most mutations harm the affected organism they are bad. Some mutations dont affect the organism at all, or affect them minimally. A very, very, very tiny percentage of mutations can be helpful and are passed on to offspring. This is rare, but is a source of change for species. Quiz 1.What is a mutation? 2.During what processes can mutations occur? 3.Name three kinds of mutations 4.What is the least harmful kind of mutation 5.What kind of mutation is shown below: AUGCCAUGCAAU AUGCAUGCAAU DNA Fingerprinting Done to determine relationships between different organisms, individuals, and/or crime scene samples/suspects/victims DNA fragments are placed in gel electrophoresis chamber and exposed to electricity and a polar charge Each persons DNA is unique and will respond differently to a magnetic charge DNA Fingerprinting Fragments travel specific distances based on their size, creating bands of DNA in the gel Related samples have similar patterns of bands Does the crime scene sample belong to the victim or suspect? Whose DNA matches that found at the crime scene? Who is guilty? Which are most closely related? Who is the real dad? DNA Testing for Previously Convicted Felons DNA evidence can be used to clear those wrongly convicted for crimes that they did not commit Humans started with selective breeding. Encouraging breeding of species with good traits Ex. Corn, sheep, Nazis Cows who produce more milk breed with cows resistant to disease produce cows with both. DNA Technology Genetic Engineering Recombinant DNA Transgenic Organisms Cloning Mapping the Human Genome Genetic Engineering Altering the genetic code by artificial means. Changes who we are! Examples of Genetic Engineering Spider silk is very strong, but hard to produce artificially Spider genes placed in goat Goat produces milk with silk Silk extracted from milk Silk used medically for artificial tendons, ligaments, sutures Recombinant DNA- Made by connecting fragments (DNA) from different sources (organisms) Once changes made they get passed on Example: inserting frog DNA into another species (for example, into dinosaurs, like in Jurrasic park) Transgenic Organisms Creating new organisms by mixing of DNA from different species Modified mice help scientists study human diseases. Modified pig organs can be used in humans Modified fish grow faster for food or glow in the dark Modified corn resists disease or draught Cloning Using the DNA from one diploid organism to create an identical offspring. Make it reproduce asexually. The most famous clone: Dolly the Sheep Since Dolly, cattle, sheep, goats, mice have been cloned How cloning is done Another View Mapping the Genome Using the Triplet Code: For example: AAA = A AGA = B ACA = C ATA = D AAG = E AAC = F AAT = G AGG = H To make the sentence, He had a bad cab you may write this: AGG AAG (He) AGG (had) AAA (a) AGA AAA ATA (bad) ACA AAA AGA (cab) Now you try it: Work with a partner to develop an alphabet using triplets of bases, and then come up with a secret message that instructs the reader to do something (between 15 and 30 words) Put your names on your message Exchange messages with the other table on your row, interpret their message, and follow their instructions The Genetic Code and Translation There are 64 possible combinations of triplets Only 20 different amino acids are used to make proteins Therefore, most amino acids correspond to more than one triplet combination Some codons tell the protein to start (AUG) and stop (UAA, UAG, UGA)