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Chapter 16&17 (MUTATIONS (point v frameshift- one spot changes the…
Chapter 16&17
MUTATIONS
point v frameshift- one spot changes the nitrogen base v insertion or deletion causing the frame to shift
missense v silent- causes change of amino acid through change of base v change of base doesnt affect the amino acid produced
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transcription- occurs in the nucleus; done by RNA polymerase; is the creation of a RNA strand from DNA; part of replication
Transformation- named by Fredrick Griffith, means a change in genotype and phenotype due to the addition of external DNA.
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Bacteriophages were huge in the research of DNA. They infect cells and change take control of their metabolic processes
DNA has three key components: a nitrogenous base, a phosphate group and a pentose sugar. The base could be adenine or thymine (which group together) or guanine or cytosine (which group together).
Chargaffs rules:
- DNA base composition varies between species
- Each species the percentage of A&T are roughly the same and so are C&G.
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DNA's shape is a double helix with two-sugar antiparallel back bones meaning their subunits run . in opposite directions.
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Watson and Crick also came up with the idea of the semiconservative model of DNA replication which is that each daughter molecule's DNA is made of a strand of each parents DNA.
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A replication fork is a y shaped region where the parental strands of DNA are being broken apart. This unwinding is caused by many proteins.
These proteins are helicases , single-strand binding proteins and topoisomerase.
The initial nucleotide chain produced is actually an RNA strand called a primer which is synthesized using an enzyme called primase.
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A new DNA strand can only elongate in the 5 to 3 direction.The DNA strand is made by this mechanism called the leading strand.
To elongate the second new DNA strand it must elongate away from the replication fork and this is called the lagging strand. The lagging strand is synthesized in fragments known as Okazaki fragments which are joined together by DNA ligase.
Mismatch repair- enzymes remove and replace incorrectly paired nucleotides that have resulted from replication errors.
Nucleotide excision repair- when enzymes (DNA polymerase and DNA ligase) fill in the gaps made by nuclease which takes out damaged DNA
Telomeres are sections of repeating nucleotides that protect from the shortening of DNA strands and prevents the cell from carrying out a cells monitoring for DNA damage.
Translation is when the Codons (three base pair set) are read and turned into amino acids; part of replication ; there are 20 amino acids
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Codon- 3 bases on mRNA, codes for amino acids
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A promoter is the part of the strand that starts the production also known as the codon AUG or amino acid, methionine
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During this process introns (unimportant pieces of DNA) are cut off and the remaining exons are put together using spliceosomes.
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Amino acids are held together by peptide covalent bonds in a dehydration reaction; gives primary structure
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secondary and tertiary shape are determined by hydrogen bonds and disulfide bonds which both give 3-D shape; these are affected by temperature and pH
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