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Genetic control of protein structure and function AS Biology. Gnetic control of protein structure and function The structure of DNA and RNA Genetic material of living organisms is either DNA or RNA. DNA – Deoxyribonucleic acid RNA – Ribonucleic acid Genes are lengths of DNA that code for particular proteins. AS Biology. Gnetic control of protein structure and function DNA and RNA are polynucleotides Both DNA and RNA are polynucleotides. They are made up of smaller molecules called nucleotides. Nucleotide DNA is made of two polynucleotide strands: Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide Nucleotide RNA is made of a single polynucleotide strand: Nucleotide Nucleotide Nucleotide Nucleotide AS Biology. Gnetic control of protein structure and function Nucleotide Structure of a nucleotide A nucleotide is made of 3 components: A Pentose sugar This is a 5 carbon sugar The sugar in DNA is deoxyribose. The sugar in RNA is ribose. AS Biology. Gnetic control of protein structure and function Structure of a nucleotide A Phosphate group Phosphate groups are important because they link the sugar on one nucleotide onto the phosphate of the next nucleotide to make a polynucleotide. AS Biology. Gnetic control of protein structure and function Structure of a nucleotide A Nitogenous base In DNA the four bases are: – – – – Thymine Adenine Cytosine Guanine In RNA the four bases are: – – – – Uracil Adenine Cytosine Guanine AS Biology. Gnetic control of protein structure and function Nitrogenous bases – Two types Pyramidines Purines Thymine - T Cytosine - C Uracil - U Adenine - A Guanine - G AS Biology. Gnetic control of protein structure and function Adenine AS Biology. Gnetic control of protein structure and function Guanine AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function Sugar phosphate bonds (backbone of DNA) Nucleotides are connected to each other via the phosphate on one nucleotide and the sugar on the next nucleotide A Polynucleotide AS Biology. Gnetic control of protein structure and function James Watson (L) and Francis Crick (R), and the model they built of the structure of DNA AS Biology. Gnetic control of protein structure and function X-ray diffraction photograph of the DNA double helix AS Biology. Gnetic control of protein structure and function Base pairing The Nitrogenous Bases pair up with other bases. For example the bases of one strand of DNA base pair with the bases on the opposite strand of the DNA. AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function The Rule: Adenine always base pairs with Thymine (or Uracil if RNA) Cytosine Guanine. always base pairs with This is beacuse there is exactly enough room for one purine and one pyramide base between the two polynucleotide strands of DNA. AS Biology. Gnetic control of protein structure and function Complementary base pairing Purines Pyramidines Adenine Adenine Thymine Uracil Guanine Cytosine AS Biology. Gnetic control of protein structure and function Nature of the Genetic Material Property 1 - it must contain, in a stable form, information encoding the organism’s structure, function, development and reproduction Property 2 - it must replicate accurately so progeny cells have the same genetic makeup Property 3 - it must be capable of some variation (mutation) to AS Biology. Gnetic control of protein structure and function Speed Replication of DNA and Chromosomes of DNA replication: 3,000 nucleotides/min in human 30,000 nucleotides/min in E.coli Accuracy of DNA replication: Very precise (1 error/1,000,000,000 nt) AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function Taylor and co-workers (1957) 3H-labelled after chromosomes AS Biology. Gnetic control of one further replication protein structure and function in unlabelled media Meselson and Stahl (1958) AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function A replicating Drosophila chromosome AS Biology. Gnetic control of protein structure and function Success criteria 1. To discuss the process of DNA replication Unistructual Multistructual Relational Extended Abstract I can name an enzyme involved and what its function is I can name the three enzymes involved and what their functions are I can sequence how the enzymes work together two allow two stands of DNA to be produced I can discuss why the process is semiconservative AND What aspects control accuracy Origins initiate replication at different times. AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function Sequence the order of the enzymes AS Biology. Gnetic control of protein structure and function Complete the parts whole map AS Biology. Gnetic control of protein structure and function Sequence DNA replication: DNA unwinds via enzyme helicase (this forms a replication bubble and replication forks) Two semi-conservative DNA molecules have been produced Ligase joins okazaki fragments together on lagging strand DNA polymerases (3) start synthesising complementary bases to DNA strands in 3’ – 5’ direction (old strand number). Replication bubble extends in one 3- 5 direction leading to one strand becomingASthe leading strand, the other the Biology. Gnetic control of protein structure and function lagging strand. Sequence DNA replication: ANSWERS 1. DNA unwinds via enzyme helicase (this forms a replication bubble and replication forks) 5. Two semi-conservative DNA molecules have been produced 4. Ligase joins okazaki fragments together on lagging strand 2. DNA polymerases (3) start synthesising complementary bases to DNA strands in 3’ – 5’ direction (old strand number). 3. Replication bubble extends in one 3- 5 direction leading to one strand becoming the leading strand, the other the lagging strand. Extended Abstract Discuss what the consequence would be to the new cells in DNA replication was not 100% accurate. Explain what factors (TWO) ensure errors are prevented. AS Biology. Gnetic control of protein structure and function Answer The consequence for the new cells if DNA replication was not accurate would be a change in the sequence of bases. This change could lead to genes producing different proteins or no proteins at all. Many of these genes code for enzymes the cell may not be able to carry out in desired functions (e.g. a nerve cell). Errors are minimised by the DNA being double stranded so complementary bases will always be matched up. When DNA polymerase is adding free nucleotides to the new strand only the correct base pair will be matched up. This ensures the new strand will have the correct complementary base sequence. 1. To discuss the process of DNA replication Unistructual Multistructual Relational Extended Abstract I can name an enzyme involved and what its function is I can name the three enzymes involved and what their functions are I can sequence how the enzymes work together to allow two stands of DNA to be produced I can discuss why the process is semiconservative AND What aspects control accuracy AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function AS Biology. Gnetic control of protein structure and function This powerpoint was kindly donated to www.worldofteaching.com http://www.worldofteaching.com is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching. AS Biology. Gnetic control of protein structure and function