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69 Cards in this Set
- Front
- Back
locus
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location of gene on a chromosome
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allele
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different versions of the same gene
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polymorphic site
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restriction sequence with more than one varient
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What are the 2 classes of genetic markers?
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microsatellites and SNPs
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What is an SNP? # of alleles? How many are found in genome?
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single base change in DNA sequence.
2 millions |
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How do you locate microsatellites?
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PCR
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Where are microsatellites NOT usually found?
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exons
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What are microsatellites? How many alleles do they have? How many are in genome?
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repetitive DNA sequences
multiple alleles >100000 dinucleotide repeat loci |
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Where are SNPs found? How are the located?
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exons; introns; and intergenic regions
PCR |
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Which marker is better for high throughput systems?
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SNPs
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What was primarily used for the bovine genome sequencing project?
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L1 Hereford cow
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Where is mtDNA inherited from?
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maternal side
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introgression
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incorporation of desirable alleles from unimproved lines into improved lines.
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gene expression
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the process with which a gene gives rise to a protein
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central dogma
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Sequence of nucleotides in gene specifies sequence in RNA; sequence in RNA specifies sequence of amino acids in polypeptide chain
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2 ways RNA and DNA differ?
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1. OH in ribose of RNA
2. RNA has uracil |
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4 stages of transcription?
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1. recognition
2. initiation 3. enlongation 4. termination |
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initiation
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RNA polymerase denatures DNA double helix; 1st DNA is placed at start site
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enlongation
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New RNA nucleotides are added to growing chain
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termination
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RNA polymerase terminates transcription when a loop forms in the transcript
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RNA processing (3 steps)
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1. splicing
2. capping 3. tail |
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RNA splicing
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excision of the introns and joining of the exons
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5' capping
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5' end is altered by the addition of guanosine
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Why is the 5' cap necessary?
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Necessary for ribosome binding to begin protein synthesis
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What is the final step of RNA processing?
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Addition of poly-A tail at 3' end for mRNA stability
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How long is the poly-A tail?
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~200 nucleotides
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What does the Booroola gene do? (2)
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1. Increases ovulation rate by 1.6 ova/copy
2. Increases litter size by 1 lamb/copy |
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mis-sense mutation
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single base substitution in a codon that results in an amino acid substitution
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What is the result of a mis-sense mutation?
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improper protein function
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Non-sense mutation
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single base substitution that changes a functional codon into a stop codon
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What's the result of a non-sense mutation?
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shortened protein
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genetic heterogenity
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recessive alleles cause one phenotype; dominant alleles cause a different phenotype
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Examples of genetic heterogenity
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Ehlers-Danlos Syndrome
recessive = enzymatic defect dominant = defect in collagen gene |
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What is a single gene disorder?
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Disorder caused by mutation w/in one gene
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Examples of single gene disorders?
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DUMPS; BLADS
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What is a polygenic disease?
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Disorder caused by collective action of alleles in many genes
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Examples of polygenic diseases?
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Resistance to mastitis; metritis; Johne's; milk fever
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What should you do if you think you have genetic disease in your herd? (4)
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1. Report to appropriate agency
2. Necropsy afflicted animal 3. Do herd history 4. Test matings to see if heritable |
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When do offspring express Callipyge phenotype?
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Only heterozygotes inheriting CLPG from sire
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imprinting
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expression depends on whether allele is inherited from sire or dam
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QTL
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Quantitative Trait Loci
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restriction enzyme
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Protein that recognizes specific patterns of nucleotides w/in DNA stretch and cuts the DNA @ site where those patterns occur
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Polymerases
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Proteins that synthesize DNA from individual nucleotides using one of the DNA strands as a template
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reference family
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group of related but genetically varied animals (usually 3 generations)
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Which DNA analysis is best for parentage testing and why?
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Microsatellites b/c you don't need as many as you would if you used SNPs; also more cost-effective
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Which DNA analysis is best for identity testing and why?
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SNPs b/c they are more precise and have fewer mutations
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Which DNA analysis is best for species testing and why?
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mtDNA because there is more variation between species
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Promoter
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site of RNA polymerase binding to DNA template
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What is enzymatic synthesis of RNA molecule complementary to DNA strand?
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mRNA transcription
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splicing
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excision of introns and joining of the exons
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What are represented by looping strands of nucleic acid?
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introns
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Are microsatellites well conserved between species?
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no
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What does genetic heterogenity result from?
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mutations causing the same phenotype
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genetic anticipation
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genetic mutations increasing from generation to generation
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3 steps in PCR cycle
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1. Denaturation
2. Annealing 3. Extension |
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How can SNPs be detected?
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gene sequencing
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What makes the PCR reaction specific to certain sequences?
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Primers recognize a very specific order of bases as to where to cut the DNA for replication
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What is the mechanism for silencing genes?
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methylation
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Is it possible to alter gene expression w/out changing DNA sequence?
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Yes; the environment can change genes (phenocopy)
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Possible consequence loss of imprinting?
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Bad genes may be expressed (cancer-causing; etc.)
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What is the effect of heating DNA?
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Double stranded seperates to single strands
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Which direction does DNA polymerization occur?
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5' to 3'
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What is PCR used for?
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Duplicating specific DNA segment
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Why would trinucleotide repeats be more likely found in coding sequences than dinucleotide repeats?
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Trinucleotide repeats create codons and codons code for amino acids. You are more likely to have amino acids repeated in a protein.
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What is the advantage in using microsatellites over SNPs for parentage testing?
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higher polymorphism
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Why is mtDNA used preferentially in forensic analysis?
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higher concentration of mtDNA in the cell vs. nuclear DNA
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Which parent does Maple Leaf Foods focus on genotyping?
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dam
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What is not a motivation for Maple Leaf Foods genotyping?
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tool for genetic improvement
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Name 2 reagents in PCR and explain their function
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1. Taq polymerase: Can survive at high temperatures to build complementary DNA strand
2. dNTPs: Building blocks for the polymerase (ATCG) |