Biology Notes

Topic: Protein SynthesisObjective: Alabama Course of Study #8Glencoe High SchoolMeredith BarkleyBiology Notes

List of Note-Cards (AL COS #8)#8-1 What is relationship between chromosomes, DNA, & genes?#8-2 Notable Scientists #8-3 Simplified Structure of DNA#8-4 DNA Replication#8-5 DNA versus RNA#8-6 Protein Synthesis#8-7 Protein Synthesis Practice Problems#8-8 Genetic Variation#8-9 Examples of Biotechnology #8-10 Types of Mutations#8-11 Genetic Disorders#8-1 What is the relationship between chromosomes, DNA, and genes?Chromosomes unravel into strand of DNASegments or sub-units of DNA are called genes.The human genome contains ~ 20,000 genes that codes for proteins, such as enzymes (biological catalysts) within your body!

What kind of genes do you have???Remember that genes are basically coded information cells use in order to produce proteins, like enzymes, that are responsible for important jobs within your body. For example, the BRCA 1 and BRCA 2 genes are found on human chromosomes 13 and 17. These genes act as tumor suppressors, preventing uncontrolled cell growth that could lead to malignant tumors.

#8-2 Notable Scientists 190019151930194519601975199020052020(1928)Griffith(1944)Avery(1949)Chargaff(1952)Hershey & Chase(1953)Watson & Crick(1952)Wilkins & Franklin

#8-2 Notable Scientists 190019151930194519601975199020052020(1928)Griffith(1944)Avery(1949)Chargaff(1952)Hershey & Chase(1953)Watson & Crick(1952)Wilkins & Franklin

#8-2 Notable Scientists Scientist(s)Contributions to GeneticsGriffith (1928)Avery (1944)Chargaff (1949)Hershey and Chase (1952)Wilkins and Rosalind Franklin (1952)Watson and Crick (1953)#8-2 Notable Scientists Scientist(s)Contributions to GeneticsGriffith (1928)Discovered process of transformation, which is a change in the genotype of an individual and is caused when cell take up foreign genetic material. Avery (1944)Demonstrated the DNA was responsible for transformation.Chargaff (1949)Developed base-pairing rules for nitrogen bases within DNA: The amount of adenine is equal to the amount of thymine, and the amount of cytosine is equal to the amount of guanine. (Amounts of A=T and C=G)Hershey and Chase (1952)Reaffirmed discovery made by Avery , reproving DNA was the genetic material within cells by experimenting with bacteriophages.Wilkins and Rosalind Franklin (1952)They developed x-ray diffraction photographs of strand of DNA. Rosalind Franklin died of ovarian cancer due to the nature of their work at the age of 37. Watson and Crick (1953)Built 3-D model of DNA in the form of a double helix.Griffiths Experiment Illustrated

Griffiths Experiments SummarizedMade accidental discovery while preparing vaccines against the bacteria Streptococcus pneumoniaeGriffith worked with 2 strains of pneumoniae: S. pneumoniae (enclosed in capsule & forms smooth colonies)R. pneumoniae (no capsule & forms rough-edged colonies)Bacterial colonies with capsules were protected against the bodies immune system and were considered virulent, or able to cause disease. Through a series of 4 experiments he discovered the process of transformation (change in genotype caused when body takes up foreign genetic DNA)Hershey and Chases Experiment Illustrated

Hershey and Chases Experiments Summarized Question: What is the genetic material within cell?Answer: DNAExperiments were used to prove this concept involved T2 bacteriophagesbacteriophage : virus that infects bacteriaT2 bacteriophages have phosphorus in their DNA.T2 bacteriophages have sulfur in their protein coat.They labeled both phosphorus and sulfur with radioactive isotopes in order to track their location.After the phages infected E. coli bacteria, the radioactive phosphorus moved into the cell, while the sulfur remained within the phage. #8-2 Notable Scientists Match each scientists name with the illustrations provided:GriffithAveryChargaff Hershey & ChaseWilkins & Rosalind FranklinWatson & Crick

#8-3 Simplified Structure of DNAComponentDescriptionDNAShapeSub-UnitsOrganization (Sides of Ladder)Organization (Rungs of Ladder)Student Skills Needed#8-3 Simplified Structure of DNA

#8-3 Simplified Structure of DNAComponentDescriptionDNADeoxyribose (sugar) nucleic acid: genetic info within cellsShapeSpiral ladder called a double helixSub-UnitsNucleotides (sugar, phosphate, and base)Organization (Sides of Ladder)Each side is made up of alternating sugars and phosphates, and the sides are anti-parallel in nature (one strand will be shown from 5 prime (5) to 3 prime (3) and the other strand will be shown from 3 to 5Organization (Rungs of Ladder)Made up of complementary nitrogen base pairs (based on Chargaffs Rule)Student Skills NeededBe able to record complementary strands of DNA, based on sequence given. Be able to draw or identify the components of DNA.#8-3 Simplified Structure of DNADraw sketches as needed to accompany your notes!

Nucleotide

Practice ProblemsRecord the complementary strand of DNA that corresponds to the sequence given.AGG TCA

GTT ACC

GCA TAC

TCC AGT would be the complementary DNA strand.CAA TGG would be the complementary DNA strand.CGT ATG would be the complementary DNA strand.#8-4 DNA ReplicationRefer to this diagram as you go through your notes, remembering there is more detail here than you will be responsible for Dont get overwhelmed!!!

#8-4 DNA ReplicationProkaryotesPictureBefore we talk about the copying / replication of DNA, its helpful to remember that DNA within prokaryotes will be found within the cells cytoplasm in a single loop.Prokaryotic cells may also contain plastids with additional DNA.

#8-4 DNA ReplicationPictureEukaryotesBefore we talk about the copying / replication of DNA, its helpful to remember that DNA within eukaryotes will be found within the cells nucleus.Extra-nuclear DNA can also be found within the mitochondria and chloroplasts of eukaryotic cells. (connection to Endosymbiotic Theory)

#8-4 DNA ReplicationPrior to all forms of cell division, DNA is replicated/copied. DNA Replication occurs during the S Phase (synthesis) of Interphase within the cell cycle for eukaryotic cells. Remember, this is why a typical cell spends 90% of its life in interphasetakes time to copy DNA and other cellular components.DNA replication involves a series of complex processess that we can simply summarize into the following steps.DNA is unwound/unzipped.New nucleotide sequences are added.The end result of DNA replication is that two DNA molecules have been formed, each composed of a new strand and an original strand. (semi-conservative model)#8-4 DNA Replication: InitiationDNA replication will take place at certain points called origins.This process is aided by special proteins.Remember all enzymes are classified as proteins. These enzymes speed up biological processes.This picture represents the semi-conservative model of DNA replication, meaning each DNA molecule will be made of one new and one original stand.)

#8-4 DNA Replication: ElongationThe enzyme DNA helicase opens up / unzips the double helix of DNA by breaking the hydrogen bonds that linked the complimentary nitrogen bases between the strands.The areas where the DNA separates are called replication forks because of their y-shape.

Prokaryotic and Eukaryotic DNA have a different number of replication forksProkaryotes EukaryotesRemember, DNA within prokaryotes is found within a nucleoid (nucleus like region) in a single loop.The replication of a human chromosome with only one pair of replication forks from a single origin would take 33 days!!! Therefore, a human chromosome is replicated in ~100 sections, reducing the time to replicate the DNA to about 8 hours.

#8-4 DNA Replication: ElongationAs DNA helicase unwinds/unzips DNA a replication bubble is formed. This bubble is where DNA will be copied.Single stranded binding proteins help hold and temporarily separate each original strand of DNA.

#8-4 DNA Replication: ElongationAs the double helix is pulled apart, the enzyme DNA polymerase adds new nucleotides to the exposed nitrogen bases, according to base-pairing rules. DNA polymerase also functions in proofreading in an attempt to correct any incorrect sequences.

#8-4 DNA Replication: ElongationOne strand will work ahead of the other, because of the structure of the strand. The one that works at a quicker pace is known as the leading strand. The lagging strand works like a sewing machine back-stitching

#8-4 DNA ReplicationThis process produces two DNA molecules, each made up of a new strand and an original strand.This is referred to as the semi-conservative model of DNA replication.Simple, right??

#8-5 RNA versus DNACharacteristicRNADNAType of SugarStructureNitrogen Bases#8-5 RNA versus DNA

#8-5 RNA versus DNACharacteristicRNADNAType of SugarRibose Deoxyribose StructureSingle StrandDouble StrandNitrogen BasesA, U, C, G

AdenineUracilCytosineGuanineA, T, C, G AdenineThymineCytosineGuanineWhy is RNA important? RNA plays an essential role in protein synthesis within your body.#8-6 Protein Synthesis Protein SynthesisDescriptionProcess in which proteins are made from info encoded within DNAAKAGene expressionSteps TranscriptionTranslationLocation (for eukaryotes)Transcription takes place in nucleus.Translation takes place in the cytoplasm.AnalogyImagine there is a Spanish reference book (master code) that cannot leave the library that contains info you would like to use to build your research paper You could copy info from the book within the library and then take the temporary copy to your Spanish teachers classroom where it can translated and used to construct your final research paper

#8-6 Protein Synthesis Transcription The instructions for making a protein are transferred from a gene in DNA to a RNA molecule called mRNA (messenger RNA).The RNA instructions are written as a series of three-nucleotide sequences on the mRNA called codons.This messenger RNA will carry the instructions for making the protein from a gene and deliver it to a site of translation. #8-6 Protein Synthesis Notice that during transcription, DNA within the nucleus is used as a template to make mRNA. DNA temporarily elongates and unwinds. After the mRNA has been made, the double helix reforms, and mRNA leaves the nucleus with its copy of the instructions to make a protein written in RNA code.

#8-6 Protein Synthesis Ribosomes Function in Synthesizing ProteinsTranslationThe information to make proteins is transferred from the language of RNA (nucleotides) to the language of proteins (amino acids).This takes place in cytoplasm where ribosomes are located. There are 64 possible codon sequences that can be translated into 20 different amino acids.

#8-6 Protein Synthesis Translation of codons into amino acids

Interpreting the Genetic Code of Codons into Amino Acids, the Building blocks of Proteins (pg 211)

Notice the Codon sequences that will START or STOP the process of protein synthesis!#8-7 Protein Synthesis PracticeExample 1Example 2Example 3DNAmRNA codonAmino Acid (Protein)*Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete translation which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.#8-7 Protein Synthesis PracticeExample 1Example 2Example 3DNAACCTTAAAAmRNA codonAmino Acid (Protein)*Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete translation which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.#8-7 Protein Synthesis PracticeExample 1Example 2Example 3DNAACCTTAAAAmRNA codonUGGAmino Acid (Protein)*Remember, you will need a table (like the one found on page 211 of your Holt Biology textbook) in order to complete translation which involves recording the name of the amino acid that corresponds to the mRNA codon you recorded/transcribed.#8-7 Protein Synthesis PracticeExample 1Example 2Example 3DNAACCTTAAAAmRNA codonUGGAAUUUUAmino Acid (Protein)Tryptophan

Click here for info about this amino acid found in protein supplements!Asparagine

Click here for info about this amino acid found in protein supplements!Phenylalanine

Click here for info about this amino acid found in protein supplements!

Do you know what PKU is?Gene Regulation and StructureThis section will be added later for Pre-AP Bio Students

#8-8 Genetic VariationGenetic variation describes naturally occurring genetic differences among individuals of the same speciesThis variation permits flexibility and survival of a population in the face of changing environmental circumstances.Consequently, genetic variation is often considered an advantage, as it is a form of preparation for the unexpected.

Genetic variation may increase through the following processesIndependent Assortment Crossing OverRandom FertilizationGenetic Engineering / Biotechnology Mutation

#8-9 Examples of BiotechnologyBiotechnology (AKA genetic engineering): process of manipulating genes for practical purposesThis may involve building recombinant DNA: DNA made from 2 or more different organisms

Human Genome ProjectGenetically engineered drugs and vaccinesDNA fingerprintingAgricultureAnimal Farming

#8-10 Mutations within DNAWhat is a mutation and who can it affect???Major Types of MutationMutation: change in DNAMutation to somatic cells (body cells) affect only the individual in which they occur.Mutations to gametes (sex cells) can be passed on to the offspring of an affected individual.

Point Mutation: changes a single nucleotide within a DNA sequence. This may or may not affect function of the gene in regards to protein synthesis. (Ex: inversion)Reading Frame Shift Mutation: alters entire reading frame of DNA sequence, affecting function in protein synthesis. (Example: addition, deletion) pg.220 Case Study: Knowing Your Genome Actress Angelina Jolie announced in a New York Times op-ed article on Tuesday that she underwent a preventive double mastectomy after learning that she carries a mutation of theBRCA1 gene, which sharply increases her risk of developing breast cancer and ovarian cancer.(2013 CNN) "My doctors estimated that I had an 87 percent risk of breast cancer and a 50 percent risk of ovarian cancer, although the risk is different in the case of each womanOnce I knew that this was my reality, I decided to be proactive and to minimize the risk as much I could. I made a decision to have a preventive double mastectomy. Angelina Jolie

Case Study: Knowing Your Genome Additional InformationBRCA 1 and 2 Genes: Mutation to These Genes Associated With Increased Risk of Breast CancerRead this Readers Digest article 5 Surprising Facts You Didnt Know About the Breast Cancer Gene, to find out more about Angelina Jolies decision.KEY QUESTION: What are potential benefits AND drawbacks of having your genome screened for potential disease???

#8-11 Genetic DisordersDisorderInheritance PatternCharacteristics (*denotes group that is at increased risk)Sickle cell anemiaTay-Sachs diseaseCystic fibrosisHemophilia AHuntingtonsColorblindness#8-11 Genetic DisordersDisorderInheritance PatternCharacteristics (*denotes group that is at increased risk)Sickle cell anemiarecessivePoor blood circulation (*African Americans)Tay-Sachs diseaserecessiveDeterioration of CNS, causes death (*Jewish)Cystic fibrosisrecessiveExcessive mucus production (*Caucasians)Hemophilia ASex-Linked rec.Failure of blood to clot (*men)HuntingtonsDominantDeterioration of brain in mid-life, eventually deathColorblindnessSex-Linked rec.Defective color vision (*men)

Sickle Cell AnemiaRecessive disorderProduces a defective form of hemoglobin, which bends the red blood cells (RBCs) into a sickle shapeWhy do people with sickle cell anemia have poor blood circulation? Normal RBCs live ~120 days, while sickle cells live ~10-20 daysSickle shaped RBCs rupture easily and tend to get stuck in blood vessels which is painful and cuts off blood supply to organs and decreases oxygen carrying capacityPeople with Sickle Cell Anemia, as well as carriers (heterozygous individuals) are resistant to Malaria! (Malaria is caused by a protozoan that invades RBCs.)