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chapter 14-15: DNA
DNA and Molecular Genetics
| Question | Answer |
|---|---|
| What is required of genetic molecules? | pass information from one generation to another, and have information coding properties (storing Properties) also need 1. Five Carbon Sugar, 2. Phosphate Group, 3. Nitrogenous Base |
| Transcription | DNA to RNA |
| Translation | RNA to protein |
| Why were proteins originally thought to carry hereditary information | Little was known about DNA, DNA was too simple and too uniform, and DNA equals 4 different nucleotides, while protein equals 20 different amino acids and also because proteins were already know to have a wide variety of functions. |
| What happens to DNA of eukaryotic cells prior to mitosis? | they copy themselves |
| Whan does DNA copie itelf prior to mitosis? | S-phase of interphase |
| How does your DNA distribute among the daughter cells by the end of mitosis? | pulled to poles by microtubules |
| How does the DNA in a haploid cell compare to a diploid cell? | Haploid is 1 set, diploid is 2 sets |
| Chargoff's rules | A = T, G = C A+G=T+C |
| Franklin and Wilkins | made crystallography pictures that gave evidence for double helix |
| DNA NUCLEOTIDES were known to be the monomer of what | nucleic acids |
| Watson and Crick | credited for discovery of double helix |
| chromatin | uncoiled DNA + protein |
| histones | packaging proteins (positive charge) binds to DNA (negative charge) |
| Nucleosomes | DNA + histone ( DNA winds around the histone ) |
| scaffolding proteins | non histone proteins that hold "supercoils" of chromatin in condensed form |
| heterochromatin | eukaryotic, not transcribed (not copied), remains condensed and stains DARK |
| Euchromatin | eukaryotic, transcribed into RNA; active genes; not tightly condensed during interphase |
| DNA | store and transmit genetic information |
| mRNA | bring DNA message to ribosome, its a messenger |
| tRNA | tranfer RNA, it transports amino acids to ribosome to use in building polypeptide (protein) |
| rRNA | ribosomal RNA, provides site where polypeptides are assembled |
| snRNA | small nuclear RNA, removal of introns; splicing of mRNA; maintenance of telomers |
| miRNA | micro RNA; bind to mRNA and prevent translation |
| siRNA | small interfering RNA; degrades mRNA after transcription, but before translation |
| structure of DNA | double helix |
| structure of RNA | chain, folded, globular |
| Nitrogen Bases: A, G, T, C, U | adenine, guanine, thymine, cytosine, Uracil |
| what are the nitrogen bases A and G | purines, have 2 rings (double ringed) |
| what are the nitrogen bases T and C | pyramidines, have 1 ring (single ringed) |
| summary of DNA | double helix, has a sugar-phosphate backbone, and its anti-parallel (1 side = 5'-3', and other side = 3'-5' and hydrogen bonding between purines and pyramidines |
| when does DNA replicate | S phase of interphase before mitosis or meiosis |
| Semiconservative replication | each original strand serves as a template for new strands |
| nucleotide | phosphate, sugar, amino acid |
| DNA polymerase | most important, requires RNA Primer, ADDS new Nucleotides, adds to 3' end of molecule only, reads in the 3'-5' direction, then removes RNA Primer, and fills in gaps between okazaki fragments |
| Helicase | untwists the DNA double helix for replication |
| RNA primase | adds the RNA primer, joins RNA nucleotides to make the primer |
| single stranded binding protein | molecules that keep the DNA strands apart from each other |
| Ligase | joins fragments of DNA to one another |
| Endonuclease | cuts nucleotides inside the DNA strand |
| Exonuclease | cuts nucleotides outside the DNA strand |
| Topoisomerse | releives strain on open helix; prevents supercoiling |
| Leading strand (continuous strand) | leading strand can be made continuously and will grow in a 5'-3' direction. |
| Lagging strand (discontinuous strand) | laggin strands grow in several smaller strands (okazaki fragments) that appear as more DNA is unwound |
| what is the problem when DNA molecules cause problems for replication? | there is a gap |
| why is the problem that DNA causes problems for replication seen only in eukaryotes | prokaryotic DNA is circular there is no end. |
| How do eukaryotes solve the problem; DNA causes problems fore replication | special ends called telomers, because they have no genes so if they are not replicated no important material is lost |
| Telomers | repetitive sequence GGATT |
| Telomerase | extends 3' end when RNA primer is removed. found in cancer cells |
| what happens if there s MISTAKE in reading the DNA strand | thymine Dimer distorts DNA molecules (A split from T) is lost. a nuclease enzyme cuts the Damaged DNA strand at two points. and repair synthesis by a DNA polymerase fills the gap, DNA ligase seals the remaining |
| what is the job of RNA | catalyze protein synthesis |
| Central Dogma of Biology | DNA -> RNA > Protein |
| Triplet | group of three nucleotides on DNA |
| Codon | Group of three nucleotides on mRNA (corresponds to amino acid) MET AUG are the start codon for always start!!!! |
| Anticodon | group of three nucleotides on tRNA |
| Leader | beginning of mRNA; allows for proper positioning of ribosome (not translated) |
| Sense Strand | mRNA made from antisense strand of DNA |
| Promoter Site | RNA polymerase binding site |
| DNA Dependent RNA Polymerase | recognizes the promoter on DNA, adds RNA nucleotides to create mRNA |
| Anticodons | complementary 3-nulceotide sequence to bind to exposed codon on mRNA |
| Amino-acyl-tRNA synthetase | activating enzymes that contain specific amino acids to tRNA molecules |
| (in Ribosomal RNA) A SITE | where amino acids bearing tRNA binds |
| (in Ribosomal RNA) P Site | where peptide bonds forms |
| (in Ribosomal RNA) E site | exit site |
| (in Ribosomal RNA) mRNA binding Site | where mRNA fits |
| (in Transcription) Initiation | Binding of RNA polymerase to promoter (without unwinding double helix) and RNA polymerase recognizes TATA box and DNA begins to unwind |
| (in Transcription) Elongation | No primer required, no proofreading; many copies can be made, and RNA polymerase adds RNA bases, and transcpriton bubbles are used |
| (in Transcription) Termination | "stop" sequence at end of gene, RNA transcript forms hairpin loop, adds 4 U's to 4 A's (weakest bond) and the primary transcript is Pre-MRNA |
| RNA processing in prokaryotes | translating mRNA before it is completely formed |
| RNA processing for Eukaryotes | cap at 5', add methyl Group (methyl cap) |
| CAP | protects 5' end from degradation |
| Tail | series of A residues on 3' end (poly A tool), stabilizes the 3' end |
| (in transcription) terminator | series of G-C pairs used to stop the sequence at the end of the gene |
| Splicing | removal of introns |
| Exons | expression sequences - coding sequences |
| Introns | intervening sequences - noncoding sequences |
| snRNP | recognize intron/exon junction |
| spliceosome | responsible for removal of introns |
| pseudogenes | accumulated DNA, unusable relatives of actual genes, used to study evolutionary relationships |
| (in Translation) initiation | begins with initiation comples at codon AUG (start codon), first small ribosomal subunit, then tRNA with Met bringing Large ribosomal subunit to bind |
| (in Translation) elongation | addition of amino acids, peptide bond is formed by the enzyme peptidal transferase |
| Peptidal Transferase | forms the peptide bonds to do elongation in translation |
| Termination | elongation continues until stop codon in exposed, then the protein moves to the Endoplasmic Reticulum for processing |
| Translocation | movement of ribosome along mRNA |
| Point Mutation( base substitution) | consists of silent mutation, missense mutation, and nonsense mutation |
| Silent Mutation | same amino acid is transcribes; codon is altered; occurs in introns |
| Missense Mutation | different amino acid is transcribed |
| Nonsense mutation | stop codon is placed where it should'nt be ex; in the middle of the code |
| Frame shift Mutation | insertation or deletion causes genes to be read in wrong 3 - base groupings |
| Triplet Repeat expansion mutation | the triplet repeats, expanded in disease relative to the normal allele, the triplets repeat continuously |
| Chromosomal Mutations | deletions, duplications, inversions, and translocations |
| Deletion | loss of portion of chromosome |
| Duplications | copy of region of chromosome |
| Inversions | part of chromosome is reversed |
| Translocations | piece of one chromosome is broken off and joined to another |
| Transposons | movable sequences of DNA, They'er the "jump to" sections of DNA |
| Hot Spots | regions of DNA that are especially prone to mutations |
| Mutagens | physical or chemical agent that induces mutations |
| Carcinogens | Cancer causing substances |
Created by:
sonic7emeral
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