outside of the helix. The purine and pyrimidine bases project inwards at 900 to the axis of the helix. 3. The two strands are held together by hydrogen bonding between pairs of bases such that guanine always pairs with cytosine and adenine always pairs with thymine; this is called complementary base pairing 3. The diameter of the helix is 2.0 nm and adjacent bases are separated by 0.34 nm and inclined at 360 relative to each other. This means that each complete turn of the double helix contains about
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and explain the limitations of those experiments. Give a detailed description of the structure of a polynucleotide‚ and summarize the chemical differences between DNA and RNA. Discuss the evidence that Watson and Crick used to deduce the double helix structure of DNA and describe the key features of this structure. Distinguish between coding and functional RNA and give examples of each type. Describe in outline how RNA is synthesized and processed in the cell. Give a detailed description of
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In their 1953 Nature publication‚ Watson and Crick announced their landmark discovery: DNA exists in the form of a right handed‚ three-dimensional double helix. They described their DNA model as two DNA strands connected by hydrogen bonds between complementary bases. Adenine bases are always paired with thymines‚ and cytosines are always paired with guanines. Watson and Crick identified the anti-parallel configuration of DNA strands; each 5’ end of one strand is paired with the 3’ end of its complementary
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Guanine≡Cytosine Chargaff’s rule: (Purine + Pyrimidine)A+C=T+G‚ ‘any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases’ DNA is a double helix in a right handed manner. There is no relation between genome size and animal size. Central Dogma of Genetics: All DNA flows from DNA > mRNA > protein Size: The helix has a 2nm diameter‚ and for each helical turn‚ there is ~10 nucleotides. (note that the smallest viruses are~60nm) It is named DNA because: D: Deoxyribo- The pentose
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Protein Structure Study Guide 1. Draw the structure of a peptide bond between two amino acids. Why is it said that the C-N bond has a partial double bond structure. Draw the resonance states of the double bond. Between each amino acid residue is a C=O and N-H bond. Due to the double bond that C=O has it is a good accepter for hydrogen bonding‚ while N-H is a good donor for hydrogen bonding. The C=O bonds and the N-H bonds both are used to stabilize the protein sequence. [pic] 2.
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MOLECULAR STRUCTURE OF DNA AND RNA •Adapted from Chapter 9 in Genetics: Analysis and Principles (Robert J. Brooker) Copyright ©The McGraw-Hill Companies‚ Inc. Permission required for reproduction or display IDENTIFICATION OF DNA AS THE GENETIC MATERIAL • To fulfill its role‚ the genetic material must meet several criteria – 1. Information: It must contain the information necessary to make an entire organism – 2. Transmission: It must be passed from parent to offspring – 3. Replication:
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conformation of its side chains or to its relationship with other segments.” Basically‚ the secondary structure of a protein is the initial arrangement of the primary structure. Sometimes part of the amino acid sequence folds into a coil called a helix. Sometimes part of the amino acid sequence folds into a sheet of parallel strands. The complete protein may have some parts where the secondary structure
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different primary structure the haemoglobin protein is soluble in water whereas the collagen protein is not. Secondary structure; Formed when the chain of amino acid coils or folds to form an alpha helix or beta pleated sheet. Haemoglobin is comprised of four polypeptide subunits‚ two with alpha helix secondary structure and two with beta pleated sheet form. All four components carry a heme group that
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the quantity of thymine and thus was also true with the other two bases. After he published his research‚ those rules became known as Chargaff’s rule. Clever as he was however‚ he couldn’t put two and two together to realize that DNA was a double helix. His work however‚ was quite beneficial to Watson and Crick as they toiled away on what would become the first true model of DNA‚ It gave them intel that the base pairs should look
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DNA is composed of two polynucleotide strands wound together into a structure known as a double helix. Each nucleotide consists of a sugar base .Nucleotides form together creating a sugar phosphate backbone to each strand. There are three forms of DNA that differ significantly. The most common‚ B form‚ is the structure most people have heard of. It consists of the right handed double helix‚ with a large major groove and a smaller but accessible minor groove. These grooves are spaces between
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