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Biofinal 2-3
Bio review Lucia lecture 2-3
| Question | Answer |
|---|---|
| What is the central Dogma of Molecular Biology? | Replication - Transcription - Translation DNA stores information which is transcribed to RNA then translated into protein |
| What are the purines and pyrimidines? | adenine & guanine Cytosine, Uracil, Thymine |
| What is the correct complementary sequence to'5 AGGTCCTTAGG-3'... CCTAAGGACCT or TCCAGGAATCC | 5'-CCTAAGGACCT-3' |
| What is Tm? Which DNA base pairs have a higher Tm? Why? | Tm is the temp required to melt 50% of the DNA in a sample. GC have high TM because triple bond verses AT with double bonds |
| Where is the replication fork? What melts the origin of replication? | an AT rich sequence is melted by DnaA protein |
| What keep DNA from reannealing during replication? | single-stranded binding proteins |
| What unwinds the DNA at the replication fork? What lays down RNA primer for leading and lagging strands? | Helicase Primase |
| Why is Primase necessary? | DNA polymerase must have it to attach, cannot begin de novo |
| What removes RNA primer ('5-3' exo), replaces it with DNA (5'-3' pol) and proofreads work (3'-5')? | DNA polymerase I |
| What extends leading and lagging strands (5'-3' pol) and proofreads work (3'-5' exo)? | DNA polymerase II |
| What direction do Okazaki fragments synthesize? | way from the replication fork on the lagging strand |
| What joins DNA fragments? | DNA ligase |
| What cuts on strand of DNA while a second type cuts both strands to relieve supercoiling ahead of replication fork? | Topoisomerase I - cuts one strand Topoisomerase II - cuts two strands |
| What promotes supercoiling in prokaryotes? What relaxes supercoiling in prokaryotes? What inhibits it? | DNA gyrase coils it Topoisomerase II uncoils it quinolones inhibit supercoiling |
| What is the first thing put on the lagging strand for replication? What is the second thing? | primase lays down an RNA primer then DNA polymerase III recognizes the RNA primer and begins synthesis |
| To complete replication of circular DNA and joining of Okazaki fragments, what removes RNA primer and adds dNTPS? | RNA primer extended by Pol IIIuntil another RNA sequence encountered. DNA Pol I cuts out the primer, inserts dNTPS, DNA ligase seals nick |
| What cells or disease processes often use reverse transcription? What is a reverse transcriptase enzyme? | Cancer, viruses such as HIV enzyme: telomerase |
| Why is it hard to fight viruses that use reverse transcription? | They have no proofreading activity. Therefore, a high mutation rate exist. |
| What are three names for DNA repair enzyme? | endonuclease, excision endonuclease, excinuclease |
| How do excinucleases work? | cut DNA on both sides of damage, remove it, gap filled by DNA polymerase in Eukaryotes, DNA pol I in prokaryotes |
| What is a rare genetic disorder that results from excision endonuclease deficiency? | xeroderma pigmentosum |
| What two diseases have bad effects due to UV-light? | porphyria (heme syntesis problem) xeroderma pigmentosum (excision endonuclease |
| What is the difference in RNA transcription and DNA replication? | RNA polymerases do not require a primer while DNA polymerases do RNA pol synthesizes '5-3' only |
| RNA polymerase is constructed of what subunits? What is required for RNA polymerase to recognizes and bind promoter sequences? | two alpha subunits, one beta subunit, one beta' subunit Needs Sigma factor to bind |
| What is the compound that binds to prokaryotic RNA polymerase and prevents transciption initiation? What condition is this used to treat? | Rifampin (rifamycin) used to treat tuberculosis |
| What are the three Eukaryotic RNA polymerases? Activity of each? | RNA pol I - make rRNA RNA Pol II - make mRNA, some snRNA RNA Pol III - make tRNA, small rRNA (5S) |
| What stays and what goes in a splice? What is the machine for splicing? | Introns go, exons stay Spliceosome made primary transcript and snRNA |
| A patient comes in with a butterfly rash on her body. What might be her condition? Cause? | Systemic Lupus Erythematosus caused by autoimmune reaction produces antibodies against dsDNA, especially snRNP's |
| You want to kill an irritating member of your class. What should you put in their salad? Why will that work? | Add Amanita mushrooms. The alpha-amanitin noncompetively binds to RNA pol II in Eukaryotes. This prevents any mRNA synthesis |
| What are the three types of point mutations? | Silent mutation Missense Nonsense |
| If a single mutation occurs but no phenotype change happens what is the name? | silent |
| If a different nucleotide results from a point mutation and creates a different amino acid - what it be called? | Missense |
| If a different nucleotide changes from amino acid to stop codon what dat be? | Nonsense...Non-STop Fun |
| A Frame shift occurs with what sort of mutation? What frequently happens with frameshifts? | An insertion or deletion that is not in a multiple of 3...these often create a stop codon |
| What severe disease is caused by frameshift? What amino acid is messed up? | Duchenne and Becker Myotonic Dystrophy...problem with dystrophin |
| What happens as a result of a promoter mutation? example of disease | Usually less mRNA synthesis, less protein such as in beta Thalassemia |
| What occurs with splice site mutations? example of disease | incorrect splicing can lead to insertions or deletions, missing exons..occurs in beta thalassemia |
| Where are the three regions for Trinucleotide repeat expansions and a disease related to each? | 5' noncoding region = Fragile X Coding Region = Huntington 3' noncoding region = Myotonic dystrophy |
| What is a conservative mutation? | missense mutation that results in amino acid with similar properties to the original (ex. non-polar to non-polar) |
| What location is the worst place for a frameshift mutation to occur? | closer to the beginning of the protein |
| What causes cystic fibrosis? | A 3 base pair deletion that codes for the choloride transporter. The missing amino acid is phenyalanine |
| What mutation occurs with Thalassemia? | deficiency in globin chain due to splice site mutation. Most common is beta thalassemia. |
| What is the most common single gene disorder in humans? | fat girls in levi's or alpha and beta thalassemias |
| What are the components of ribosomes? Purpose? | rRNA's and many proteins that translate message on mRNA into specific protein |
| What are the subunits of Eukaryotic Ribosomes | 80S ribosome = 60S + 40S 60S = 5S RNA + 28S RNA + 5.8S RNA 40S = 18S |
| What are the subunits of Prokaryotic Ribosomes | 70S = 30S + 50S 50S = 5S + 23S 30S = 16S |
| What toxin inhibits translation in Eukaryotes? | diptheria/pseudomonas |
| What does a-amanitin inhibit in eukaryotes? | RNA pol II in liver so cannot make mRNA |
| What inhibits DNA gyrase (topoisomerase) to inhibit replication in prokaryotes? | Quinolones |
| What binds RNA polymerase in prokayotes to inhibit transcrition? | Rifampin |
| What inhibits translation in prokaryotes? | tetracycline |
| What does streptomycin inhibit? | aminoglycoside that inhibits translation in prokaryotes |
| What does erythromycin inhibit? | macrolide that inhibits protein synthesis in prokaryotes |
| How is chloramphenicol different from tetracycline, aminoglycosides, and macrolides? | inhibits translation, but also inhibits mitochondrial protein synthesis |
| Who does Diptheria actualy block translation? | inactivates eEF-2, preventing translocation |
| Where do C-peptides originate in the body? What compound is also secreted from the same location? | pancreatic cells insulin |
| What is the difference in the secretion of insulin and C-peptide? | C-peptide secreted in 5-10x higher concentration |
| Why is C-peptide useful in medicine? | Measure the levels to check insulin levels indirectly |
| What wonderful disease results from Vitamin C deficiency? Symptoms? | scurvy = collagen breakdown bruising, bleeding gums, loose teeth, poor bone development |
| Why would collagen break down with Vitamin C deficiency? | required as cofactor for enzymes involved in hydroxylating proline and lysine residues |
| What condition is caused by mutations to collagen genes? What amino acid is most commonly affected? | Osteogenesis imperfecta - glycine is substitued for bulky R-group amino acid |
| Which type of OI is mistaken for child abuse? Why? | Type I, Type II is fatal |
| If lysly-hydroxylase collagen pepsidase goes on the fritz, what condition results? Symptom? | damn loose = Ehlers-Danlos (EDS) hypermobile joints, hyperextensible skin |
| How soon will you die if you cannot phosphorylate Mannose? Why? symptoms | I-cell disease kills by age 8 severe physcomotor problems, joint restriction, coarse facial features |
| What exactly is I-cell disease? | A lysosomal storage problem- post-translational modification fails. proteins never get to lysosomes for proper storage |
| What is the pathway for the control of gene expression in gluconeogenesis? | glucagon binds receptor, induces signal transduction - cAMP increase - Protein Kinase A activated - CREB activated - CREB goes in Nucleus to bind CRE - PEPCK gene induced |
| What are CREB, CRE and PEPCK | cAMP Response Element Binding Protein cAMP Response Element Phosphoenoylpyrvate carboxykinase |
| What does PEPCK do? | converts oxaloacetate into pyruvate and CO2 |
| What test would you use to determine the presence or quantity of a protein? What type of probe would you use? | Western blot Antibody probe |
| What test would you use to determine the presence or absence, but NOT quantity of DNA | Southern Blot nucleic Acid probe |
| What test would be used to test for presence and quantity of mRNA molelule? probe? | Northern Blot nucleic acid probe |
| What are probes? How do they show the results? | single strand DNA molecules are labeled with radioactive material,exposed to a targe that is immoblized on nitrocellulose membrane. Complementary sequences bind - autoradiography shows target. |
| Who invented PCR? What are the four steps? | Kary Mullis: denature DNA, anneal primers to flanking regions, extend primers with DNA polymerase, repeat |
| PCR sequence and temp? What heat stable DNA pol is used? | Denature (95 C), Anneal (55C), Extend (72C) Taq polymerase |
| Problem with Northern blot? | look for mRNA levels, but only one gene at a time |
| Benefit and drawback of Western Blot? | use gel phoresis so more specific but labor intensive and less senstive |
| What does ASO measure? | Detects DNA mutations...such as paternity |
| What does ELISA measure? | test protein or antibodies |
| What test would be used to test for Sickle Cell anemia? | ASO probes - allele specific oligonucleotids |
| Why would you like a patient with Cystic Fibrosis? | Check for elevated chloride levels in sweat |
| Why do CF patients die by 30? | lack of chloride secretions leads to dehydration of mucus in lungs, recurrent infections |
| How would a PCR mutant product for CFTR differ from the normalCFTR? | 3 base pairs shorter |
| What is a gene, locus, allele | 1. basic unit of inheritance 2. physical location on gene of chromosome 3. alternative form of gene at given locus |
| What is genotype? Phenotype? | genetic constitution of individual observed expression of a gene (physical manifestation) |
| Are males circles or squares in pedigrees? | squares, females are curvy |
| What conditions are often Autosomal Dominant? | When non-catylytic proteins are involved |
| What is the recurrence risk or probablity for autosomal dominant? | each repro event is independed so 50-50 |
| Which sex is affected by autosomal recessive? Are the parents affected? | can be either sex, usually parent is not affected |
| What condition only affects males? What parent is the unaffected carrier? | X-Linked recessive are inheirited from the mother. |
| What condition cannot have any male to male inheiritance? | x-linked recessive |
| Who inherits the disease in mitochondrial inheritance? Who give it? Can it have male to male | all children are affected. Mothers give it. No male to male |
| What causes alpha-thalassemia? | insufficent synthesis of alpha-chain, beta chain accumulates |
| What causes beta-thalassemia? | insufficent synthesis of beta-chain, alpha chain accumulates |
| What is the simplest form of thalasemia? genotypes? | Beta-thalassemia: 2 normal, minor = 1 normal, 1 mutant major = 2 mutant |
| What are the six genotypes of alpha thalassemia? | aa/aa - normal -a/aa = silent carrier --/aa and -a/-a = alpha thalassemia trait --/-a = HbH disease -/-- = hydrops fetalis |
| What is unique about dystrophin? role in cells | Huge protein (427 kD) involved in cytoskeleton of muscle cells (skeletal, smooth and cardiac) |
| What are the conditions when dystrophin screws up? What is the screw-up? | Duchenne and Becker Muscular Dystrophy caused by frameshift mutation |
| What is the heterozygote advantage? | A good reason for me not to visit africa or central or south america |
| What is aneuploidy? | a deviation from the euploid number of chromosomes = loss or gain |
| How long do autosomal monosomies live? | not long, usually lethal in utero |
| What is the only monosomy that is survivable? | Turners, -X |
| What are the three trisomies? | Patua - 13 Andersons - 18 Edwards - 21 |
| What makes trisomies more likely as women age? | more frequent non-disjunction at meiosis I |
| What is most common autosomal trisomy? | Down syndrome |
| What is most common genetic cause of mental retardation? | Down syndrome |
| What condition has lack of secondary sex characteristics, gynemastia, low IQ, long arms and legs, sterile due to atrophy of seminiferous tubules, small atrophic testes | Klinfelter syndrome |
| What is the karyotype and only consistent finding? | 47, XXY: small, atrophic testes |
| What is a mosaic? | has different chromosomes within the same person example, a turner with 45,X and 46XX |
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El Diablo
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