...Biology: Midterm 1 (Friday, October 2, 2015) Outcomes for Exam In multiple choice format questions, identify the following: 1. Characteristics of viruses and why they are not generally considered to be “alive”. * virus= infectious biological particles; 1+ nucleic acid molecules surrounded by protein capsid or envelope * nucleic acid: DNA or RNA, composed of single/double strand (genes encode coat proteins, proteins of regulation of transcription) * capsid: protein coat of virus, viral genome packaging * envelope: lipid bilayer that contains proteins * enveloped viruses: genomes contain genes for synthesis of envelope proteins * viral genomes= virus-specific enzymes (nucleic acid replication) * non-living organism/not “alive” - lack that properties of life (no independent reproduction, no metabolic system= no energy, dependent on host cells 2. Why viral infections are usually difficult to treat with drugs, and exceptions to this general principle. * viruses= hidden in host cells, use host cell machinery to replicate (no obvious viral product to be targeted by drugs/antibiotics - not like bacteria) * symptoms can only be relieved not treated - natural immune function treats — some viruses deadly symptoms= prevention w/ vaccinations (e.g. measles, polio) * Viruses using own polymerases (e.g. RNA viruses - influenza)= more obvious targets - antiviral drugs to treat 3. Whether viruses...
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...acid? • Nucleic acids like DNA (deoxyribo nucleic acid) and RNA (ribo nucleic acid) are long linear polymers that carry information in a form that can be passed from one generation to the next. • DNA and RNA are composed of series of linked nucleotides What is a nucleotide? • It is composed of a sugar, a base and a phosphate Nucleotide = sugar + base + phosphate Nucleoside = sugar + base 3 Composition of a gene What are the bases? (A) (G) (C) (U) (T) 4 Difference between DNA and RNA RNA and DNA Differ in the Sugar Component and One of the Bases 2’ carbon atom of the sugar lacks the oxygen atom in DNA • In RNA : Uracil (U) • In DNA : Thymine (T) In RNA : adenosine, guanosine, cytidine, and uridine In DNA : deoxyadenosine, deoxyguanosine, deoxycytidine, and thymidine 5 Nucleic acid: an information carrier What is the form of information? • Sequence of bases along a nucleic acid chain • DNA, RNA molecules are linear polymers built up from similar units connected end to end • Each unit consists of three components: a sugar, a phosphate, and a base 6 Gene : a portion of nucleic acid What is gene? • A gene is the basic unit of heredity in a living organism. In a cell, gene is a portion of DNA and RNA which define a protein or RNA. What is the path of getting protein from DNA? • DNA is not the direct template for protein synthesis (Central dogma of molecular biology) 7 Backbones of DNA and RNA •...
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...DNA Replication 1. DNA Replication take place by breaking the hydrogen bonds between bases of the two antiparallel strands. The unwinding of the two strands is the starting point. 2. Helicase (enzyme) splits the two strands. The initiation point, where the splitting starts, is called “origin of replication”. The structure that is created is known as “Replication Fork”. 3. Molecules of single-strand binding protein stabilize the unwound template strads. 4. Topoisomerase helps relieve the strain by breaking, swiveling, and rejoining DNA strands. 5. RNA Primase (enzyme) binds in the initiation point of the 3’ – 5’ parent chain. It can attract RNA nucleotides which bind to the DNA nucleotides of the 3’ – 5’ strand due to the hydrogen bonds between the bases. RNA nucleotides are the primers (starters) for the binding of DNA nucleotides. 6. DNA Polymerase III (enzyme) link up the free, matched nucleotide triphosphates by removing the terminal di-phosphate and using energy so released to carry out the very non-spontaneous chemical reaction of joining the phosphate to the deoxyribose sugar. 7. The strand that is synthesized continuously is called the leading strand and the strand that is synthesized in short pieces is called the lagging strand. The short pieces of synthesized DNA, which make up the lagging strand are called the Okazaki fragments. 8. Only one primer is required for DNA Polymerase III to synthesize the leading strand. 9. The...
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...their mistakes or concepts. 3. If the tutorial questions are not yet covered in the lecture, it should be carried forward to the next tutorial. [Source : Final Examination Sept 2015] 1. A bacterium consisting of a radioactive DNA molecule is transferred into a non-radioactive medium and left to replicate n times. At the end of the process, a total of four DNA molecules are formed. Out of the four DNA molecules, two are composed of one radioactive strand and one non-radioactive molecules. The other two are composed entirely of non-radioactive strands. (i) Determine the number of times, n replication takes place that results in the formation of four DNA molecules. (1 mark) (ii) State the replication model indicated by the experiment and briefly explain about it. (3 marks) (iii) Identify the protein(s) involved in the initiation of DNA replication that are responsible for: (A) Unwinding parental double helix at replication forks. (1 mark) (B) Relieveing overwinding strain ahead of replication forks. (1 mark) (C) Stabilizing single-stranded DNA until it is used as a template. (1 mark) (D) Starting an RNA chain using parental DNA as template. (1 mark) [Source : Final Examination April 2015] 2. Figure 2.1 shows a piece of nucleic acid undergoing a cellular process. Figure 2.1 Answer the following questions based on Figure 2.1. (i) What process...
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...HSC Biology – Blueprint of Life 4. The structure of DNA can be changed and such changes may be reflected in the phenotype of the affected organism. The phenotype of an organism is its total appearance determined during development by an interaction between its genetic make-up (genotype) and the environment. A genome is all of the genetic material (DNA) within a cell and is specific to each organism. Genomes influence nearly all the traits or phenotypes. The phenotypic appearance is therefore directly affected by gene expression. The extent of phenotypic differences depends on how different the DNA sequences are in individuals, but may also be influenced by the environment. • Outline evidence that led to Beadle and Tatum’s ‘one gene-one protein’ hypothesis and explain why this was altered to the ‘one gene – one polypeptide’ hypothesis Beadle and Tatum carried out experiments with red bread mould. The normal variety of mould can manufacture certain substances that it needs for living, including vitamin B1, B2, B4 and B12. The normal moult possesses specific enzymes that catalyse the different reactions that produce these vitamins. Beadle and Tatum produced several varieties of the bread mould, each of which had a change in one of its genes. They tested these varieties and found that some had lost their ability to make vitamin B2 while others could no longer make vitamin B4 and so on. The results obtained by Beadle and Tatum showed that a change in various...
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...Deleting Oncogenes in Cancer Cells with DNA Strand Slippage Abstract Oncogenes are DNA sequences which code for proteins that can cause cancer. Therefore, one way to treat cancer is to disrupt or destroy these genes. Lars Zender and colleagues recently discovered two genes that are the most likely causes of liver cancer (1). Zender claims oncogenes cIAP1 and Yap promote tumor growth, and are overexpressed in liver cancer cells. Garcia-Diaz and coworkers have also found that the slipping of DNA strands during synthesis by DNA polymerase can cause single bases to be deleted (2). Applying conditions for this slippage to the replication of the oncogenes in liver cancer cells will cause base deletion and render the gene unable to encode a protein that promotes tumor growth. The experimental control will be DNA sequences matching the oncogenes that will be treated with DNA polymerase λ due to its high rate of base deletion (2). A second experimental control will be DNA treated with DNA polymerase μ. The negative control will consist of untreated DNA. The crystallization process used by Garcia-Diaz and colleagues to uncover the structure of the polymerase and DNA will be used to determine which DNA bases, if any, are deleted. The oncogene will become unable to promote tumor malignancy if its bases are targeted for deletion. Background Zender applied genome analysis to human hepatocellular carcinoma cells, or liver cancer cells, and mouse liver tumors to determine...
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...1. Write an essay on protein structure and synthesis Protein synthesis is a cellular process leading to the production of proteins. This term is also synonymous to protein translation. It begins with a sequential process of transcription of DNA into mRNA, which is then used as input for translation after exon-intron splicing. The addition of successive tRNA molecules based on the code of mRNA matched up by base-pairing through their anti-codons in the ribosomes creates the nascent protein. After the protein chain has been synthesized, post-translation modification occurs, e.g. phosphorylation, motifs added to the protein. This may happen at various levels: secondary (alpha-helix, beta-sheets, turn, random coiling), tertiary and quarternary. Protein synthesis is also the process wherein peptide bonds between two amino acids whose formation is controlled. The synthesis begun when the mRNA combines in a little subunit of ribosomes close to an AUG sequence in mRNA. Start codon which is the AUG codon is being such because it does the coding of the first amino acid to be made of protein. “The AUG codon base-pairs with the anticodon of tRNA carrying methionine. A large ribosomal subunit binds to the complex, and the reactions of protein synthesis itself can begin. The aminoacyl-tRNA to be called for next is determined by the next codon (the next three bases) on the mRNA. Each amino acid is coded for by one or more (up to six) codons” (Center for Bioenergy and Photosynthesis...
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...following terms: chromatin, chromosomes, DNA, gene. DNA, CHROMOSOMES AND GENES 2. What is a polynucleotide? 3. Diagram a typical nucleotide and name the three principle parts. COMPOSITION OF NUCLEIC ACIDS 4. Nucleosides differ from nucleotides in what way? 5. There are five Nitrogen bases in nucleic acids. Name them and group them according to their structure. Which of the five bases is found only in RNA and which base does it substitute? 6. Draw a ribose and a deoxyribose sugar side-by-side and highlight what makes them different. Identify the carbon atoms in your diagrams by their proper number. NUCLEOSIDES 7. Summarize the differences between DNA and RNA. NUCLEOTIDES 8. Between what two atoms do ester bonds occur? 9. What types of bonds join individual nucleotides WITHIN a single DNA strand? 10. What does the term "antiparallel" mean when applied to a DNA double helix? Why is this term necessary? 1. Draw a normal ladder and compare it to the structure of DNA. THE STRUCTURE OF NUCLEIC ACID CHAINS 12. What force holds the two halves of the DNA double helix together? 13. Explain what is meant by "Complementary Base Pairing" and don't forget to mention the numbers of hydrogen bonds involved! THE WATSON-CRICK MODEL: BASE PAIRING IN DNA 14. Diagram and explain the Central Dogma of Molecular Genetics. NUCLEIC ACIDS AND HEREDITY 15. Explain how DNA is replicated including all relevant enzymes and other terms. 16. How does the DNA polymerase "know" which base needs to be...
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...Module 4 6. In animal cells a cleavage furrow forms during cytokinesis. While in plant cells a cell plate forms in the middle of the cell. The furrow in animal cells is a contractile ring of actin microfilaments associated with molecules of the protein myosin. Action reacts with myosin causing ring to contract. The furrow deepens until parent cell divides into two producing two separate cells with their own nucleus and share of cytosol, organelles, and other subcellular structures. In plant cells vesicles from the Golgi apparatus move along the microtubules to the middle of the cell, where they coalesce, producing a cell plate. The plate enlarges until its surrounding membrane fuses with the plasma membrane along the perimeter of the cell. Two daughter cells result, each with its own plasma membrane. Meanwhile, a new cell wall arising from the contents of the cell plate has formed between the daughter cells. 7. Eukaryotic cells have a true nucleus, bound by a double membrane Prokaryotic cells have no nucleus. Eukaryotic DNA is linear; prokaryotic DNA is circular (it has no ends). Eukaryotes go through every phase of Mitosis including prophase, metaphase, anaphase, and telophase. Prokaryotic cell simply divides by cytokinesis after DNA replication which is known as binary fission. 8. Checkpoints make sure that the eukaryotic cell completes each phase with no problems. Without checkpoints it may affect cell growth which is very important. 9. The Hershey-Chase experiments...
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...How DNA is packed in the nucleus of an eukaryotic cell 1) Introduction DNA, deoxynucleic acid, is known to be able to condense to form a smaller structure known as chromosomes. However, it is hard to imagine how does a 2m long DNA molecule can be packed into something which only have a rough diameter of 10µm in the eukaryotic cell. This report provides an overview on how DNA is packed in the nucleus of an eukaryotic cell. It will cover the structure of the human DNA, levels of packing the DNA and the necessity and benefits of DNA packing. 2) Structure of Human DNA The human DNA is made up of two polynucleotide strands wrapped around each other in a double helix structure. The two DNA strands in the double helix structure is oriented in opposite direction. A 3’ end of a DNA strand at the start of the strand has an OH group at its terminal, and ends with a 5’ end with a phosphate group attached to its terminal....
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...Jacob Cohn Mr. Lander Period 4 1/20/2011 When the two strands of DNA double helix are separated, each can serve as a template for the replication of a new complementary strand, producing two daughter molecules each of which contains two DNA strands with an antiparallel orientation. The enzymes involved in DNA replication process are template-directed polymerases that can synthesize the complementary sequence of each strand with extraordinary fidelity. This complex leads to the local denaturation and unwinding of an adjacent A + T rich region of DNA. The interaction of proteins with the origin is what defines the start site of replication and provides a short region of single stranded DNA essential to initiation of synthesis of the nascent DNA strand. Then helicase binds and allows for processive unwinding of double stranded DNA into single stranded DNA. As helicase unwinds the DNA, DNA single stranded protiens bind and stabilize the single stranded DNA. The polymerase III holoenzyme binds to template DNA as a part of a multi protein complex that consists of several polymerase accessory factors. DNA polymerase synthesizes DNA only in the 5 ' to 3 ' direction and only one of the several different types of polymerases is involved at the replication fork. As the DNA strands are anti parallel, the DNA polymerase functions asymmetrically. On the leading (forward) strand, the DNA is synthesized continuously. On the lagging strand (retro strand) the DNA is synthesized in short (1-5...
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...will touch upon those concepts that complement the cellular aspects of transcription. In particular, we will look at the genetic code, called the CODON, frameshift mutations, the structure of theTRANSCRIPTIONAL UNIT, and the phases of transcription. I will point out those aspects of transcription that I feel are important to this course. The study guide will also help you to focus on those parts of transcription that the examination will cover. CHAPTER 19 1. What important event (related to DNA) occurs in G1 before the cell enters the S phase? 2. What important event (related to DNA) occurs in G2 before the cell enters mitosis? 3. Why are G1 and G2 called gap phases? What happens during S phase? 4. Can mitosis occur without cytokinesis? (hint, Drosophila) 5. During which phase of mitosis do sister chromatids separate? 6. How do the experiments of Meselson and Stahl verify the semiconservative model of DNA replication? 7. What is the name of the locus (location) from which DNA replication begins? Does DNA replication occur uni- or bi-directionally? 8. Name the two major components of the primosome. 9. What are the functions of DNA polymerase III, the primosome, primase, DNA polymerase I, and DNA ligase? 10. What structure along the lagging strand allows the replisome to replicate both strands in the same direction? 11. How does cell cycle relate to cell type? 12. What is MPF? What two molecules make up MPF? Which one cycles in concentration throughout the cell cycle...
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...DNA Worksheet REVISED Part1: Basic structure of DNA The nucleotide bases of a DNA consists of specific codes and particular strands of this codes are known as the genes. The genes codes for a particular protein which eventually be a specific trait. The pairing of the base in a DNA molecule is very specific. Adenine usually pairs with Thymine while Guanine normally pairs with Cytosine. A segment of a gene from DNA usually gives the necessary directions to build a RNA molecule and eventually translated into a protein (Simon, Reece and Dickey, 2010). Reason why DNA is referred to as a protein recipe DNA is referred to as a protein recipe because its molecules are made up of amino acid proteins which are in form of a long strand. The DNA structure is composed of codons. Basically, the DNA codes for RNA codon or a transcription which is used to form proteins which is the translation of the codon. Each group of tri-codons are then read by the ribosomes where for each group of 3 such codons, there is an amino acid. These amino acids are then bound together to make a protein chain. The complexity of a protein depends on the number and type of chains (Simon, Reece and Dickey, 2010). Part 2: Differences between DNA and RNA DNA is used for long-term storage of genetic information, transmission of genetic information so as to make other cells and new organisms and to transfer the genetic code to the ribosomes from the nucleus to manufacture proteins. On the other hand, RNA is used...
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...definition of DNA replication. Dna replication is when they copy a double stranded dna molecule. The bases are matched and edited to match their partner. Each strand acts as a main component for the replication What is the importance of replication? Why do cells replicate their DNA before dividing? They replace their data so the could get rid of the old dna so that the cell may be able to be healthy. Use the clues and words to help you write the vocabulary terms from the chapter in the blanks. You may use a word once or not at all. 3. tip of a chromosome telomere 4. enzyme that joins nucleotides to make a new strand of DNA Dna Polymerase 5. virus that infects bacteria bacteriophage...
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...CITY AND ISLINGTON COLLEGE Assignment BriefFront Cover Centre: | Centre for Applied Sciences | | | Learner name: | Mohamed elrraik | | | Course Code: | AS2212A11/AS2211A11 | | | Programme Level &Title: | BTEC Level 3 Extended Diploma in Applied Science | | | Unit Number & Title: | Unit 18 Genetics & Genetic Engineering | | | Assignment Title: | Assignment 1 – DNA & Protein synthesis | | | Assessor Name: | Jasmin Bongrani | | | Date Issued: | AS2212A11 12/09/11AS2211A11 30/01/12 | DateDue: | AS2212A11 10/10/11AS2211A11 05/03/12 | | | | | Turn It In Score: | | Referral Due Date: | | | | | | Internal Verifier Name: | Lee Walker | Date IVed: | 08/09/11 | Grading criteria | Y/N | Feedback(including action where necessary) | P1 | Compare and contrast the structure of various nucleic acids | | | M1 | Explain how genetic information an be stored in a sequence of nitrogenous bases in DNA | | | D1 | Explain the steps involved in biosynthesis of protein including the roles of RNA | | | Additional Feedback and/or Action Plan: Date marked: | | Learner Declaration | I declare that all the work submitted for this assignment is my own work or, in the case of group work,the work of myself and the other members of the group in which I worked, and that no part of it has beencopied from any source. I understand that if any part of the...
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