BIOL 3451: STUDY GUIDE
65 Cards in this Set
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Pedigree Analysis
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a diagram showing the ancestral relationships and transmission of genetic traits over several generations
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How will the symbol look if the phenotype is expressed?
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Completely shaded in
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Oculocutaneous albinism type 1 (OCA-1)
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-Autosomal Recessive disorder
-Absence of pigment
-Locus 11q14-q21
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Oculocutaneous albinism type II (OCA2)
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-Autosomal Recessive Disorder
-Locus 15q11.2-q12
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What is unique about Albinism?
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There are two different types of mutations within the genome on different chromosomes
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Cystic Fibrosis
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-Autosomal recessive disorder
-Effects the lungs and pancreas, creates excess mucus
-Mutation in the CFTR gene
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Marfan syndrome
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-Autosomal Dominant
-elongated fingers and arm bones
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Brachydactyly
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-Autosomal dominant trait
-size of digits (fingers) are not developed normally
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Huntington's Disease
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-Autosomal dominant
-Effects central nervous system
-50% chance of passing it along
-Phenotypes don't show until your 40s
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Achondroplasia
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-Dwarfism
-Autosomal dominant
-Effects bone growth
-Mutation in genes that code for "Fibroblast Growth Factor Receptor"
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Color Blindness
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-X-linked recessive
-female will usually not show phenotype unless homozygous for mutant allele on X chromosome
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Duchenne Muscular Dystroophy (DMD)
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-X-linked disorder
-Primarily found in males
-mutated in the gene that encodes dystrophin. Locus- Xp21.2 12q21
-Skeletal and cardiac muscles are severely affected
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Hemophilia
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-X-linked
-Bleeding disorder, can't form clots
-Locus Heterogenity
-Two types of hemophilia
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Locus Heterogeneity
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Same clinical phenotype (disease) can result from mutations at any one of several different loci
ex: hearing loss
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Sporadic Mutations
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-New mutations that have no known family history
-Usually can't produce offspring
-Occurs during meiosis, mutated germ cell is produced
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Hutchinson-Gilford progeria Syndrom
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-"Progeria, or HGPS"
-Accelerated aging in children
-Die at an average age of 13
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Allelic Heterogeneity
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-Different mutations within a given gene can be seen in different patients with a certain genetics
-Same gene is effected although the phenotypes are different.
-Relates to the severity of the phenotype
ex: muscular dystrophy
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Clinical Heterogeneity
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-Mutations in the same gene produce two or more different diseases
ex: CFTR mutation can lead to CF or bilateral absence of vas deferens
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complementation
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normal phenotype when two mutations are combined
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Variable expression
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-Non-penetrance:
-Other genes, or the environment can influence development of phenotypes
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Cerebral Cavernous Malformation (CCM)
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-Autosomal dominant
-Vascular malformation disease
-Irregular structure of smaller blood vessels
-Symptoms occur later in life (30-50)
-Seen freq in hispanic families
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aneuploidy
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cells having too many or too few copies of a chromosome
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Sex Determination
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X-Y sytems
Humans, fruit flies
Male xy, Female xx
X-O systems
grasshoppers
Male x, Female xx
S-W systems
Birds, fish, butterflies
males zz, females zw
Haplo-diplidy
bees, ants
males N, females 2N
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dosage compensation
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Equalization in males and females of the amount of protein produced by X-linked genes. In placental mammals, dosage compensation is accomplished by the random inactivation of one X chromosome in the cells of females
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Barr Body
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dark staining body in interphase cells of females
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X-Inactivation
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Occurs in all sexual reproducing female organisms at about 200 cells
Inactivate one x chromosome (have two in each cell, one from each parent)
Initial inactivation is random
Inactivated chromosomes form Barr bodies
Results in mosaicism
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Nondisjunction
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occurs when chromosomes fail to separate at either the first or second meiotic division
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Lyon hypothesis
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in a given cell there is only one active X chromosome (allows for dosage compensation) inactivated X forms Barr body.
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monosomy
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only one of a particular type of chromosome
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trisomy
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extra copy of chromosome
ex) down's syndrome/trisomy 21
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gene family
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two or more loci with similar nucleotide sequences that have been derived from a common ancestral sequence
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In situ hybridization
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technique used to localize the expression of a specific DNA or RNA sequence in tissue
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phosphodiester bond
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the linkage between two sugars in the backbone of a nucleic acid molecule
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hydrogen bond
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type of bonds that link the base pairs on each strand of DNA
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Chromatin
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Granular material visible within the nucleus; consists of DNA tightly coiled around proteins
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Chromosome
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tightly coiled threadlike structure along which the genes are organized, like beads on a necklace- consist primarily of DNA
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Nucleosome
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Together the DNA & histone proteins forms a bead-like structure
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Nucleotide
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includes phosphate group, sugar deoxyribose and nitrogen bases
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nucleoside
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base (purine/pyrimidine) + sugar
Ex: adenosine, guanosine, citidine, thymidine, uridine
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nucleoside monophosphate
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AKA: nucleotides
names this way because of the single-phosphate linked to the sugar-base unit
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Codon
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Triplets of nucleotides in mRNA that encode the info for a specific amino acid in a protein
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Transcription
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The process of making a RNA strand from a DNA template
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Cis-Effect or cis-acting element
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A DNA sequence that must be adjacent to the gene(s) it regulates and is mediated by sequences that bind regulatory proteins. Example the lac operator.
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What is Trans element?
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Region of DNA/ RNA that regulate the expression of a gene located on a different molecule of DNA
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transciption factor
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generic term that includes both repressors and activators; have three functional domains:
1. DNA-binding domain
2. polymerase binding domain
3. effector binding pocket
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sigma factor
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a protein that allows RNA polymerase to bind properly to the promoter region
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Promoter
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The region of the gene where the RNA-synthesizing enzyme, RNA polymerase, binds to initiate transcription
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TATA box
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a short DNA sequence within the promotor region. Along with Basal transcription factors, the TATA Box allows RNA Polymerase to contact the DNA
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alternative splicing
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splicing the same pre-RNA in two or more ways to yield two or more different mRNA that produce two or more different protein products
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RNA polymerase
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produces primary transcript of RNA
Uses DNA tempate to make RNA chains
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spliceosome
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a large complex that splices pre-mRNA in eukaryotes
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exon
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sequence of DNA that codes info for protein synthesis
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Intron
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a section of DNA that does not code for an amino acid and that is transcribed into RNA but is removed before it is translated.
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Wobble Hypothesis
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complete set of 61 sense codons can be read by 40 distinct tRNAs because of pairing properties of the bases in the anticodon
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enhancer
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DNA seqeunce that controls the rate and efficiency of the polymerase. bind multiple TFs
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Group I
Splicing
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...
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General transcription factors
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Transcription Components
Template binding and initiation of transcription
Chain elongation
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Forward Genetic Screen: Isolation of mutants that show differences in phenotype for the process of interest
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...
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Reverse Genetic Screen
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- gene-centric
- mutate the gene of interest (requires prior knowledge about gene in question)
- looking for an expected phenotypic change
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RNA interference
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small RNA molecules bind to mRNA- gets cleaved and degraded. Can also bind to DNA and allow for DNA methylation
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EMS
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ethyl methanesulfonate alkylating agent induces a point mutation (bp substitution) and causes a transition (GC to AT). It is soluable and can be taken up by cells. However it causes random mutations, there is no selection, often more than one mutation per mutant, singl ebase pair change…
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What is a temperature-sensitive mutant?
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One that has a mutation in amino acid of a protein, so that protein is no longer functional at higher temperatures [nonpermissive temperature], but still functions at lower temperatures [permissive temperatures]
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Does the genome get altered in animals that have been subjected to RNAi?
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Expression is decreased
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Dr. Lee Hartwell: Steps used to identify genes that regulate cell division
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Exposed yeast to mutagen --- Plated yeast cells(replica plate) --- Screened for mutants that are (ts) for growth and collected 1500 ts mutants which can grow at 30°C but not 36°C
Used microscope to subscreen 148 cultures with 32 distinct genes (unique cells)
Identified genes for regulat…
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Genetic model for: Mitochondria structure
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