image from kaiserscience.wordpress.com Show In the DNA Replication, Transcription and Translation unit you will learn the details of how and why DNA Replicates. You will also learn how the DNA codes for specific amino acids and how this information is transcribed from the DNA to make proteins. The unit is planned to take 3 school days. Essential Idea:
Nature of science:
Understanding: 2.7.U1 The replication of DNA is semi-conservative and depends on complementary base pairing. (Oxford Biology Course Companion page 111).
DNA replication is a semi-conservative process, because when a new double-stranded DNA molecule is formed:
The base sequence on the template strand determines the base sequence on the new strand, only a nucleotide carrying a base that is complementary to the next base on the template strand can
successfully be added to the new strand.
2.7.U2 Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds. (Oxford Biology Course Companion page 114).
DNA replication is a semi-conservative process whereby pre-existing strands act as templates for newly synthesised strands. The process of DNA replication is coordinated by two key enzymes – helicase and DNA polymerase. To separate the two strands of molecules, this separation is carried out by helicases
2.7.U3 DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template. (Oxford Biology Course Companion page 115).
The creation of new strands is carried out by enzyme DNA polymerase
image from study.com 2.7.U4 Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase. Sequence of bases in a gene does not, in itself, give any observable characteristic in an organism. Function of most genes is to specify the sequence of amino acids in a particular polypeptide – it is proteins that are often directly or indirectly determine the observable characteristics of an individual. Two processes are needed to produce a specific polypeptide, using the base sequence of a gene Transcription – the synthesis of RNA, using DNA as a template, because RNA is a single-stranded, transcription only occurs along one of the two strands of DNA
2.7.U5 Translation is the synthesis of polypeptides on ribosomes.
Translation is synthesis of polypeptides on ribosomes. This is the second of the two processes needed to produce a specific polypeptide
Messenger RNA and the genetic code
Translation Mnemonic (from BioNinja) The key components of translation are:
Mnemonic: Mr Cat App
image from discoveryandinnovation.com/ 2.7.U6 The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
Condons help the cellular machinery to convert the base sequence on the mRNA into an amino acid sequence is called the genetic code.
The genetic code is the set of rules by which information encoded within mRNA sequences is converted into amino acid sequences (polypeptides) by living cells. The genetic code identifies the corresponding amino acid for each codon combination. As there are four possible bases in a nucleotide sequence, and three bases per codon, there are 64 codon possibilities (43). The coding region of an mRNA sequence always begins with a START codon (AUG) and terminates with a STOP codon
2.7.U7 Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
The base sequence in a DNA molecule, represented by the letters A T C G, make up the genetic code. The bases hydrogen bond together in a complementary manner between strands. A will always go with T (U in RNA) and G will always go with C. This code determines the type of amino acids and the order in which they are joined together to make a specific protein. The sequence of amino acids in a protein determines its structure and function. The DNA code is a triplet code. Each triplet, a group of three bases, codes for a specific amino acid:
2.7.U8 Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA.
Translation is the process of protein synthesis in which the genetic information encoded in mRNA is translated into a sequence of amino acids on a polypeptide chain
Application 2.7.A1 Use of Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR). (Oxford Biology Course Companion page 115).
The polymerase chain reaction (PCR) is an artificial method of replicating DNA under laboratory conditions. The PCR technique is used to amplify large quantities of a specific sequence of DNA from an initial minute sample
2.7.A2 Production of human insulin in bacteria as an example of the universality of the genetic code allowing gene transfer between species.
The set of DNA and RNA sequences that determine the amino acid sequences used in the synthesis of an organism's proteins. It is the biochemical basis of heredity and nearly universal in all organisms. The same genetic code appears to operate in all living things, but exceptions to this universality are known. Since the same codons code for the same amino acids in all living things, genetic information is transferrable between species. The ability to transfer genes between species has been utilised to produce human insulin in bacteria (for mass production)
image from discoveryandinnovation.com Skill: 2.7.S1 Use a table of the genetic code to deduce which codon(s) corresponds to which amino acid.
Typically the genetic code shows the codon combinations expressed on an mRNA molecule. Various tables displaying the genetic code may occasionally show the sequence on the sense strand of DNA (non-coding strand). These sequences are identical to the mRNA codons with the exception of thymine (T) being present instead of uracil (U)
2.7.S2 Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA. (Oxford Biology Course Companion page 113).
The theory that DNA replication was semi-conservative was confirmed by the Meselson-Stahl experiment in 1958 Prior to this experiment, three hypotheses had been proposed for the method of replication of DNA:
S 2.7.3 Use a table of mRNA codons and their corresponding amino acids to deduce the sequence of amino acids coded by a short mRNA strand of known base sequence.
In order to translate an mRNA sequence into a polypeptide chain, it is important to establish the correct sequence The mRNA transcript is organised into triplets of bases called codons, and as such three different reading sequences exists An open sequence will always start with AUG and will continue in triplets to a termination codon. A blocked sequence may be interrupted by termination codons. Once the start codon (AUG) has been located and sequence established, the corresponding amino acid sequence can be determined by using the genetic code
2.7.S4 Deducing the DNA base sequence for the mRNA strand.
mRNA is a complementary copy of a DNA segment (gene) and consequently can be used to deduce the gene sequence. For converting a sequence from mRNA to the original DNA code, apply the rules of complementary base pairing:
Key Terms:
Powerpoint and Notes on Topic 2.7 by Chris Payne Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary. Video Clips: DNA replication animation in real time. It's
amazing to think that millions of your DNA containing cells are doing this in your body right now. Remember, this is how fast DNA replicates in real time!
Paul Andersen explains how DNA replication ensures that each cell formed during the cell cycle has an exact copy of the DNA. He describes the Meselson-Stahl experiment and how it showed that DNA copies itself through a semi-conservative process. He then explains how multiple enzymes, like DNA polymerase, helicase, primase, ligase, and single strand binding proteins copy DNA. He also differentiates between the leading and the lagging strand. He explains how DNA is anti-parallel in nature and how eukaryotic cells have multiple origins of replication.
DNA Structure and Replication: Crash Course Biology #10 Hank introduces us to that wondrous molecule deoxyribonucleic acid - also known as DNA - and explains how it replicates itself in our cells.
Hank imagines himself breaking into the Hot Pockets factory to steal their secret recipes and instruction manuals in order to help us understand how the processes known as DNA transcription and translation allow our cells to build proteins.
Explore the steps of transcription and translation in protein synthesis! This video explains several reasons why proteins are so important before explaining the roles of mRNA, rRNA, and tRNA in the steps of protein synthesis! Expand details for contents and resources
DNA transcription and translation
What is the correct order of steps for transcription and translation?Transcription is the name given to the process in which DNA is copied to make a complementary strand of RNA. RNA then undergoes translation to make proteins. The major steps of transcription are initiation, promoter clearance, elongation, and termination.
What are the 5 steps in transcription and translation?Stages of Transcription. Initiation. Transcription is catalysed by the enzyme RNA polymerase, which attaches to and moves along the DNA molecule until it recognises a promoter sequence. ... . Elongation. ... . Termination. ... . 5' Capping. ... . Polyadenylation. ... . Splicing.. What are the steps of transcription in order?Transcription has three stages: initiation, elongation, and termination.
What are the 8 steps of translation?Each step in more detail:. 1 – Source Language Files. ... . 2 – Scope Analysis. ... . 3, 4 and 5 – Translate, Edit and Proofread. ... . 6 – Format Document. ... . 7 – Quality Assurance. ... . 8 – Delivery.. |