Term
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Definition
| a molecules consisting of a five-carbon sugar, a phosphate group and a nitrogenous base |
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Term
| what is the nitrogenous base linked to in a nucelotide |
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Definition
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Term
| what is the phosphate group linked to in a nucleotide? |
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Definition
| either carbon 3 or carbon 5 of the sugar |
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Term
| what are the components of a nucleotide joined together by? |
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Definition
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Term
| what type of reaction joins the components of a nucleotide together? |
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Definition
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Term
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Definition
| a pentose sugar called RIBOSE |
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Term
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Definition
| a pentose sugar called DEOXYRIBOSE |
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Term
| what do nucleotides form? |
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Definition
| they form the monomers of nucleic acids, DNA and RNA |
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Term
| what do nucleotides become when they contain more than one phosphate group? |
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Definition
| phosphorylated nucleotides |
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Term
| name 2 examples of phosphorylated nucleotides |
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Definition
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Term
| name 2 functions of nucleotides |
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Definition
| 1. help regulate metabolic pathways 2. can be components of many coenzymes |
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Term
| give an example of nucleotides being components of coenzymes |
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Definition
| adenine nucleotides are components of the coenzyme NADP, used in photosynthesis |
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Term
| besides NADP, name 2 other coenzymes and state where they are used |
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Definition
| 1. NAD = used in respiration 2. FAD = used in respiration |
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Term
| draw the structre of a nucleotide |
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Definition
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Term
| what is the difference between AMP, ADP and ATP |
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Definition
| AMP has a monophosphate, ADP has a diphosphate, ATP has a triphosphate |
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Term
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Definition
| 1. a nucleic acid 2. a macromolecule |
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Term
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Definition
| a molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer |
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Term
| DNA is a polymer made up of monomers called what? |
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Definition
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Term
| how many polynucleotide strands does 1 DNA molecule have? |
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Definition
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Term
| name one feature of the 2 polynucleotide strands in terms of direction |
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Definition
| they run in opposite directions, so they are antiparallel |
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Term
| what does each DNA nucleotide consist of? |
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Definition
| a phosphate group, deoxyribose and one of four nitrogenous bases |
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Term
| what is the name of the covalent bond between the sugar and phosphate group in a DNA nucleotide? |
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Definition
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Term
| what is the phosphodiester bond formed in? |
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Definition
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Term
| what is the phosphodiester bond broken down in? |
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Definition
| polynucelotide break down |
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Term
| name 2 characteristics of DNA molecules? |
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Definition
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Term
| what type of reaction are nucleotides formed by? |
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Definition
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Term
| explain where and how the phosphodiester bond forms |
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Definition
| it forms between the OH of the phosphate and OH of the sugar |
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Term
| how many types of nucleotide does DNA have? |
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Definition
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Term
| the organic nitrogenous base can either be... |
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Definition
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Term
| what is the difference between purine and pyrimidine? |
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Definition
| purine is 2 rings and pyrimidine is 1 ring |
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Term
| which 2 nitrogenous bases are purine? |
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Definition
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Term
| which 2 nitrogenous bases are pyrimidine? |
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Definition
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Term
| what joins the 2 antiparallel DNA strands together? |
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Definition
| hydrogen bonds between the nitrogenous bases |
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Term
| Adenine always pairs with... |
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Definition
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Term
| how many hydrogen bonds are there between A and T? |
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Definition
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Term
| Guanine always pairs with... |
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Definition
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Term
| how many hydrogen bonds are there between G and C? |
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Definition
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Term
| what does a purine always pair with? |
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Definition
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Term
| why does a purine always pair with a pyrimidine? |
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Definition
| because it gives equal sized rungs on the DNA 'ladder' |
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Term
| what is the shape of a DNA molecule? |
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Definition
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Term
| what causes the double helix? |
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Definition
| the coiling of the 2 sugar-phosphate backbone strands into a right-handed spiral configuration |
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Term
| what do the hydrogen bonds allow? |
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Definition
| they allow the molecules to unzip for transcription and replication |
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Term
| the sugar-phosphate backbones run antiparallel from 5' to 3' or 3' to 5'. What does the opposite directions of the 2 strands refer to? |
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Definition
| it refers to the direction that the 3rd and 5th carbon molecules on the deoxyribose are facing |
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Term
| what is the 5' end of the molecule? |
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Definition
| where the phosphate group is attached to the 5th carbon atom of the deoxyribose sugar |
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Term
| what is the 3' end of the molecule? |
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Definition
| where the phosphate group is attached to the 3rd carbon atom of the deoxyribose sugar |
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Term
| what makes up the antiparallel sugar-phosphate backbone? |
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Definition
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Term
| explain how DNA is organised in eukaryotic cells |
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Definition
| 1. majority of genome is in nucleus 2. each large DNA molecule is wound around histone proteins into chromosomes (1 chromosome = 1 DNA molecules)3. loop of DNA in mitochondria & chloroplasts (no histone proteins) |
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Term
| explain how DNA is organised in prokaryotic cells |
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Definition
| in a loop in the cytoplasm (naked (not wound around histone proteins)) |
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Term
| what is DNA in terms of replication? |
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Definition
| a self-replicating molecule |
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Term
| why does DNA have to be copied each time a cell divides? |
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Definition
| so that each new daughter cell receives the full set of instructions |
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Term
| when does DNA replication take place? |
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Definition
| interphase (pre-division) |
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Term
| what does DNA replicate by? |
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Definition
| semi-conservative replication |
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Term
| what does semi-conservative replication result in? |
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Definition
| 2 new molecules, each of which contains one old strand and one new strand |
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Term
| Explain in detail the stages in semi-conservative replication |
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Definition
| 1. DNA gyrase (enzyme) unwinds the double helix 2. DNA helicase (enzyme) unzips double helix into 2 strands by breaking hydrogen bonds between complementary base pairs 3. free phophorylated nucleotides bond to the exposed DNA bases on the original double helix following complementary base pairing rules 4. DNA polymerase (enzyme) adds new nucleotide bases in the 5' to 3' direction using the unzipped DNA as a template 5. the leading strand is synthesised continuously (5' to 3'). the lagging strand is synthesised discontinuously in okazaki fragments 6. DNA ligase joins the lagging strand fragments together |
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Term
| summarise the stages in semi-conservative replication |
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Definition
| 1. gyrase unwinds 2. helicase unzips 3. free nucleotides join bases 4. polymerase adds new bases 5' to 3' 5. leading & lagging strand 6. ligase joins lagging strand fragments |
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Term
| what supplies the energy to make phosphodiester bonds between the sugar residue of one nucleotide and the phosphate group of the next nucleotide? |
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Definition
| hydrolysis of the activated nucleotides to release the extra phosphate group |
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Term
| how do mutations occur in semi-conservative replication? |
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Definition
| a wrong nucleotide may be inserted = changes genetic code |
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Term
| what is the chance of a wrong nucleotide being inserted? |
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Definition
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Term
| are all mutations harmful? |
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Definition
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Term
| how can the number of mutations be reduced? |
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Definition
| some enzymes edit out incorrect nucleotides |
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Term
| Name 4 differences between RNA and DNA |
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Definition
| 1. RNA = ribonucleic acid DNA = deoxyribonucleic acid 2. RNA = has uracil instead of thymine DNA = has thymine 3. RNA = ribose sugar DNA = deoxyribose sugar 4. RNA = single stranded DNA = double stranded |
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Term
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Definition
| a length of DNA that codes for a polypeptide or for a length of RNA that is involved in regulating gene expression |
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Term
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Definition
| a large polypeptide (100 + amino acids) |
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Term
| what do you find within each gene? |
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Definition
| a sequence of DNA base triplets |
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Term
| what do DNA base triplets determine? |
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Definition
| the amino acid sequence of a polypeptide |
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Term
| what happens if the primary structure coded by the base triplets is correct? |
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Definition
| the protein will fold correctly to be held in its tertiary shape and perform the correct function |
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Term
| name 3 terms used to describe the genetic code |
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Definition
| 1. universal 2. degenerate 3. non-overlapping |
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Term
| explain what is meant by 'universal' |
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Definition
| in almost all living organisms the same triplet of DNA bases codes for the same amino acid |
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Term
| explain what is meant by 'degenerate' |
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Definition
| for all amino acids there is more than one base triplet |
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Term
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Definition
| 1. messengerRNA 2. transferRNA 3. ribosomalRNA |
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Term
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Definition
| to bring the message out of the nucleus |
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Term
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Definition
| to bring the correct amino acid |
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Term
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Definition
| to hold things together/scaffolds |
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Term
| name the 2 big stages of how DNA codes for proteins |
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Definition
| TRANSCRIPTION & TRANSLATION |
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Term
| explain the 3 stages in transcription |
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Definition
| 1. DNA unwinds & unzips (hydrogen bonds between complementary nucleotide bases break) 2. free mRNA nucleotides bond to exposed DNA bases following complementary base pairing rules (RNA polymerase joins nucleotides to form a new mRNA strand) 3. mRNA leaves nucleus via pores & attaches to a ribosome in cytoplasm |
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Term
| how is the ribosome fomred? |
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Definition
| it is made in the nucleus as 2 subunits. they pass separately out of the nucleus & then bind using magnesium ions |
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Term
| explain the 5 stages in translation |
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Definition
| 1. the mRNA binds with the tRNA due to hydrogen bonds 2. tRNA reads the triplet code on mRNA. The anticodon on the tRNA is complementary to the triplet code on the mRNA. The tRNA brings the correct amino acid the codon codes for 3. this continues all the way down the mRNA. when 2 amino acids are adjacent, a peptide bond forms (requires ATP) 4. after the polypeptide has been assembled, the mRNA breaks down 5. the polypeptide folds into its tertiary structure using chaperone proteins |
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