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