Questions and Answers
Which inheritance pattern is characterized by mainly affecting males, with no father-to-son transmission and all daughters of affected fathers being carriers?
In recessive epistasis, what would be the expected phenotypic ratio among the offspring?
What is the purpose of a methylase in the context of restriction enzymes?
Which cloning vector is characterized by a capacity of 100 to 500 kb?
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What is the expected phenotypic ratio when two genes work in duplicate gene action?
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What does the presence of blue bacteria indicate when using multiple cloning sequences in the lacZ gene?
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Which type of epistasis occurs when a dominant locus affects the expression of another gene, resulting in a ratio of 12:3:1?
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What is the primary function of dideoxynucleotides (ddNTPs) in DNA sequencing?
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What can be inferred if crossing two organisms produces wild-type progeny, indicating complementation?
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In the context of PCR, what is the temperature used during the primer annealing step?
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How is recombination frequency (RF) calculated?
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What is the purpose of using Southern blotting?
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What distinguishes Northern blotting from Southern blotting?
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Which method can be used to study the total mRNA and non-coding RNA in a sample?
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In a dihybrid cross showing crossing over, what are the expected parental genotype frequencies?
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During the denaturation step of PCR, DNA is heated to which temperature?
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Which type of chromosomal abnormality involves the exchange of segments between chromosomes?
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What is the chromosome number associated with Trisomy?
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Which of the following is NOT a hallmark of cancer cells?
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Which type of cancer originates from epithelial tissue?
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Which term describes a condition involving two copies of a chromosome from only one parent?
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What is the main characteristic of chromosomal abnormalities that are considered unbalanced?
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What process refers to the formation of new blood vessels by cancer cells?
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Which condition describes the presence of small adenomatous crypts in the colon?
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Which mutation results in the continuous presence of B-galactosidase due to the inability of the repressor to bind to the operator?
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What role does the TATA Binding Protein (TBP) play in transcription initiation?
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Which of the following statements about the Arabinose operon is true?
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What is the primary function of proximal control elements in transcription regulation?
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Which component is NOT considered a general transcription factor in the eukaryotic transcription process?
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Which mutation leads to the constant binding of a super repressor to LacO, resulting in no transcription?
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What type of mutation is primarily associated with the activation of oncogenes?
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Which mechanism is NOT a method by which proto-oncogenes can become activated?
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What is required for the function of a recessive mutation in tumor suppressor genes?
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Which of the following is an example of an oncogene category related to cell cycle regulation?
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What is the role of EPSP synthase in plants that have been modified for glyphosphate resistance?
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Which of the following does NOT describe how chromosomal translocation can activate proto-oncogenes?
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In the context of diacetyl detection in C.elegans, which gene is necessary for the expression of odr-10?
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Which of the following describes the function of the herbicide glyphosphate?
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Study Notes
Genetic Concepts
- X-linkage: Primarily affects males; cannot be passed from father to son; all daughters of affected fathers become carriers.
- Mitochondrial cytopathy: Inheritance follows a matrilineal pattern.
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Epistasis (gene interactions):
- Complementary Gene Action: Both genes must be present for expression; results in a 9:7 ratio of color to albino (e.g., plant color).
- Recessive Epistasis: A recessive locus impacts another gene, resulting in phenotypes A-Bb = aabb; produces a 9:3:4 ratio (e.g., mouse color).
- Dominant Epistasis: A dominant locus affects another, with phenotypes A-B- = aaB-; shows a 12:3:1 ratio (e.g., albino: color 1: color 2).
- Duplicate Gene Action: If two genes perform the same function, only aabb will result in no function; yields a 15:1 color to albino ratio.
- Complementation: Wild-type progeny from crossing indicates alleles from different genes; e.g., aa, BB + AA, bb = aA, Bb demonstrates complementation.
Cloning Techniques
- Restriction Fragment Length Polymorphism (RFLP): Mutation alters recognition site of restriction enzyme, leading to fragments of different lengths.
- Methylase: Bacterial enzyme that methylates DNA, inhibiting enzyme cuts by restriction enzymes.
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Cloning Vectors:
- Plasmids: Capacity up to 20kb.
- Bacteriophages: 25-30kb size.
- Cosmids: Modified plasmids, 30-40kb.
- Bacterial Artificial Chromosomes (BACs): Can encompass 100-500kb.
- Yeast Artificial Chromosomes (YACs): Size ranges from 200kb to 2Mb.
- Complementary DNA (cDNA): Synthesized from mRNA using reverse transcriptase, contains no introns.
DNA Sequencing & PCR
- DNA Polymerases: Utilize dNTPs; dideoxynucleotides (ddNTPs) are used to terminate replication.
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Polymerase Chain Reaction (PCR):
- Denaturation: Heat to 95°C for 30s to separate strands.
- Primer Annealing: Cool to 58°C for 30s to allow primers to bind.
- Primer Extension: Heat to 72°C for 1 minute for Taq polymerase activity.
- Southern Blot: DNA fragments are electrophoresed, denatured, and transferred to a membrane for hybridization with labeled primers.
- Northern Blot: Similar to Southern, but used for mRNA, no denaturation required.
- In Situ Hybridization: Technique used in developmental genetics.
- Transcriptome: All mRNA plus non-coding RNAs present in a cell.
Linkage & Chromosome Mapping
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Recombination Frequency (RF): Indicates physical distance between loci; closer genes experience fewer crossovers.
- RF calculated as (number of recombinants / total progeny) x 100.
- Dihybrid Cross Example in Flies: Crosses yield non-parental phenotypes indicating crossover; RF shows genes are 5 map units apart.
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Genetic Mutations:
- Euploidy: Normal chromosome number (46).
- Polyploidy: Three or more chromosome sets (e.g., triploidy = 69).
- Aneuploidy: Gain or loss of individual chromosomes (e.g., monosomy = 45, trisomy = 47).
Cancer Genetics
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Cancer Types:
- Carcinomas: Originate from epithelial cells.
- Sarcomas: Arise from mesodermal tissues.
- Adenocarcinomas: Derived from glandular tissues.
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Hallmarks of Cancer Cells:
- Rapid growth and division.
- Insensitivity to growth signals.
- Ability to evade programmed cell death (apoptosis).
- Unlimited replication potential.
- Inducing angiogenesis for nutrient supply.
- Capability of metastasis.
- Proto-oncogenes: Normal genes that, when mutated, become oncogenes leading to uncontrolled cell division; commonly dominant mutations.
- Tumor Suppressor Genes: Require mutations in both alleles to function abnormally (e.g., p53).
Eukaryotic Gene Expression Regulation
- RNA Polymerase II: Essential for transcription of protein-coding genes.
- Promoter Region: Specific sequence recruiting RNA polymerase II and transcription factors, guiding transcription initiation.
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Regulatory Regions:
- Proximal elements regulate transcription initiation.
- CAAT box and GC box facilitate the binding of regulatory proteins.
- General Transcription Factors: Prominent examples include TFIIA and TFIIB, crucial for forming pre-initiation complexes.
- TATA Binding Protein (TBP): Part of TFIID complex that binds to the DNA and modifies its structure for protein binding.
Applications of Genetics
- Insulin Production: Preproinsulin is converted to active insulin, utilizing separate plasmids for subunit production.
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Agricultural Advances:
- Selective Breeding: Enhancing traits through directional breeding.
- Herbicide Resistance: Genetic modifications enable plants to withstand herbicides like glyphosate via incorporation of viral promoters into Ti plasmids of R. radiobacter.
- Insecticide Resistance: Utilizing cry toxins for pest resistance mechanisms.
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Description
Test your understanding of key genetics concepts such as X-linkage, mitochondrial cytopathy, and gene interactions including epistasis. This quiz covers various genetic principles and ratios, providing a solid overview on the topic. Perfect for students studying genetics!