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81 Cards in this Set
- Front
- Back
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What type of polarity do DNA strands have?
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5' to 3'
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What is DNA composed of?
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deoxyribose (a 5 carbon sugar), a phosphate group and a base (A, T, G, C)
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How many H bonds are between A and T?
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Two
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How many H bonds are between G and C?
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Three
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What unwinds DNA by breaking the H bonds?
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Helicase
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How many RNA primers are used by the leading strand?
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One
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How many RNA primers are used by the lagging strand?
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numerous, which form Okasaki fragments
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What is transcription?
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DNA is translated into RNA
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What direction are nucleotides added?
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5' to 3'
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What happens to the 5' end of eukaryotic RNA?
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it is capped
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What happens to the 3' end?
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a poly (A) tail is added
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Through what does the mRNA leave the nucleus?
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Nuclear pore
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Where does the RNA polymerase bind on DNA?
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promoter (at or close to the TATA box)
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What type of energy does translation use?
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GTP
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Where does translation occur?
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cytoplasm
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What delivers amino acids to the ribosomes?
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tRNA
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What type of bond exists between amino acids?
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peptide bond
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Name some examples of post-translational modification?
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-3-D folding
-addition of a carbohydrate, lipid or phosphate group, -cleavage of signal sequences |
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Base substitution
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one base is substituted for another
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Transition
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substitution of a pyrimidine by another pyrimidine
substitution of a purine by another purine |
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Transversion
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pyrimidine by a purine
purine by a pyrimidine |
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Deletion
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one or more nucleotides is lost from the sequence
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Insertion
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nucleotides inserted somewhere
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UV light can cause what type of formation
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formation of thymine dimers
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Ionizing radiation can cause what?
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double strand breaks
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Direct repair
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reverses DNA damage without cutting the deoxyribose phosphate backbone (removing a methyl group to restore the original base)
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Base excision repair
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used when inncorrect bases are present in the DNA
-the damaged base is recognized by glycosylase and is hydrolytically removed from the deoxyribose phosphate backbone, this leaves an apurinic or apyrimidic site where the correct base is then inserted and sealed with DNA ligase) |
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Mismatch repair
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used to remedy incorrect pairings of the normal bases
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Nucleotide excision repair
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removes thymine dimers and bulky adducts
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Exonuclease
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can remove bases
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Post replication repair
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repairs double breaks in the strands
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Nucleosome
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-the most basic unit
- consists of 8 histone proteins -DNA is wound almost twice around this protein core to produce a "bead-like" structure |
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30- nm Chromatin Fiber
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-nucleosomes are joined by linker DNA and coiled into 30 nm fiber which is organized into loops
-this structure is maintained by histone H1 protein that is attatched to linker DNA |
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Loop-Scaffold Complex
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provides the compact structures seen in metaphase chromosomes
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Euchromatin
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-single copy, genetically active DNA
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Heterochromatin
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repetitive stuctures that are genetically inactive
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Centromeres
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essential for proper chromosome segregation and the site of kinetochore formation
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Telomeres
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-cap the ends of chromosomes
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In meiosis, crossing over occurs between what?
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homologous chromosomes
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Constitutional chromosome abnormality
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found in all cells of the body
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Somatic chromosomal abnormality
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the abnormality is found only in cells or tissues
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Numerical chromosomal abnormality
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the gain or loss of complete chromosomes
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Structural chromosomal abnormality
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formation of abnormal chromosomes through the mispair of chromosome breaks or a malfunction in recombination
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Aneuploidy
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- one or more chromosomes are present or missing than the normal number
- this normally results from nondisjunction |
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Nondisjunction
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failure of paired chromosomes to separate during anaphase (MI)
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Monosomy
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-loss of one chromosome
-autosomal monosomy is always lethal |
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Monosomy of sex chromosome X can result in what?
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Turners syndrome (45, X)
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Trisomy
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gain of an extra chromosome
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What is Trisomy 21?
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Down Syndrome
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Tetrasomy
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gain of an extra pair of homologous chromosomes
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Euploidy
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an extra complete set of chromosomes is present or missing
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Polyploidy
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more than two sets of chromosomes are present
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Monoploidy
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a complete set of chromosomes is missing
(lethal) |
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Mosaicism
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two or more genetically different cell lines within a single individual derived from a single zygote
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Chimerism
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two or more gentically different cell lines within a single individual derived from different zygotes
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Robertsonian translocation
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the short arm of two chromosomes breaks off and the two long arms are fused together
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T/F
Autosomal monosomy is always lethal. |
True
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Negative control
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some repressor protein binds to DNA to keep transcription from happening
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Positive control
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some protein helps to initiate transcription
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T/F
The transcription of multiple genes into a primary transcript occurs only in prokaryotes. |
True
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Polycistronic RNA is found in?
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Prokaryotes
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PCR is used for what?
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to amplify DNA
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What do you need to add to the reaction vial when doing PCR?
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-DNA to be amplified
-primase -DNA ligase -DNA polymerase - dNTP's |
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Why do you heat the DNA in the first step of PCR?
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to allow the DNA strands to denature (separates the two DNA strands)
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What do you call the second step in PCR?
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annealing
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How is DNA sequencing different than PCR?
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The reactions in DNA sequencing are run in the presence of dideoxynucleotides, (ddNTP's) which lack a hydroxyl group at the 3' position
-this means that whenever a ddNTP is added replication stops -the reaction is run in polyacrilimide gel and then allow one to see the order fo the sequence |
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Mitochondrial genome
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consists of very short portion of triple stranded circular DNA
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Null mutation
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complete loss of function
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Leaky mutation
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partial loss of function
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Epigenic modifications
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result loss of function without altering the DNA function
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Founder effect
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a disease is typically only seen only within a certain population which shows that only the founders had the disease
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T/F
Mutations that produce a new function for a gene are rare among inherited disease but common in cancer |
True
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Mutational homogeneity
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the same phenotype typically only results from one or two specific mutations
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What is the most lethal genetic disease in the US?
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Cystic fibrosis
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If one does not have cystic fibrosis, what does the normal gene code for?
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a membrane protein that transports chloride ions in and out of cells
(defect results in build-up of airway secretions) |
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What are phenotypic manifestations of Huntington's disease?
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-uncontrolable movements
-personality alterations -memory loss |
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From what does Huntington's disease result?
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a gain of function mutation that produces and autosomal dominant disorder characterized by neurodegeneration
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When is the typical onset of Huntington's disease?
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35-40
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Proto-oncogenes
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non-mutant versions of genes that control cell proliferation
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What do most gene therapies focus on?
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insertion of a normal gene into the genome to replace a nonfunctional gene
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Proto-oncogene
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original version of the oncogene
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