Genetics Principles and Concepts

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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?

Mitochondrial inheritance

X-linkage inheritance (correct)

Autosomal recessive inheritance

Autosomal dominant inheritance

In recessive epistasis, what would be the expected phenotypic ratio among the offspring?

15:1

12:3:1

9:7

9:3:4 (correct)

What is the purpose of a methylase in the context of restriction enzymes?

To add methyl groups to DNA, preventing cuts (correct)

To clone fragments of DNA

To recognize mutations in DNA

To cut DNA at specific sequences

Which cloning vector is characterized by a capacity of 100 to 500 kb?

Bacterial artificial chromosomes Signup and view all the answers

What is the expected phenotypic ratio when two genes work in duplicate gene action?

15:1 Signup and view all the answers

What does the presence of blue bacteria indicate when using multiple cloning sequences in the lacZ gene?

Cloning was unsuccessful Signup and view all the answers

Which type of epistasis occurs when a dominant locus affects the expression of another gene, resulting in a ratio of 12:3:1?

Dominant epistasis Signup and view all the answers

What is the primary function of dideoxynucleotides (ddNTPs) in DNA sequencing?

To terminate DNA replication Signup and view all the answers

What can be inferred if crossing two organisms produces wild-type progeny, indicating complementation?

The alleles from each parent are on different genes Signup and view all the answers

In the context of PCR, what is the temperature used during the primer annealing step?

58˚C Signup and view all the answers

How is recombination frequency (RF) calculated?

Number of recombinants divided by total number of progeny Signup and view all the answers

What is the purpose of using Southern blotting?

To detect specific DNA sequences Signup and view all the answers

What distinguishes Northern blotting from Southern blotting?

Northern blotting involves RNA, while Southern blotting involves DNA. Signup and view all the answers

Which method can be used to study the total mRNA and non-coding RNA in a sample?

Transcriptome analysis Signup and view all the answers

In a dihybrid cross showing crossing over, what are the expected parental genotype frequencies?

50% for both parental types Signup and view all the answers

During the denaturation step of PCR, DNA is heated to which temperature?

95˚C Signup and view all the answers

Which type of chromosomal abnormality involves the exchange of segments between chromosomes?

Translocation Signup and view all the answers

What is the chromosome number associated with Trisomy?

47 Signup and view all the answers

Which of the following is NOT a hallmark of cancer cells?

Sensitivity to anti-growth signals Signup and view all the answers

Which type of cancer originates from epithelial tissue?

Carcinomas Signup and view all the answers

Which term describes a condition involving two copies of a chromosome from only one parent?

Uniparental disomy Signup and view all the answers

What is the main characteristic of chromosomal abnormalities that are considered unbalanced?

Net loss or gain of chromatin Signup and view all the answers

What process refers to the formation of new blood vessels by cancer cells?

Angiogenesis Signup and view all the answers

Which condition describes the presence of small adenomatous crypts in the colon?

Hyperplasia Signup and view all the answers

Which mutation results in the continuous presence of B-galactosidase due to the inability of the repressor to bind to the operator?

LacO^c^ mutation Signup and view all the answers

What role does the TATA Binding Protein (TBP) play in transcription initiation?

It binds to the DNA minor groove and bends it Signup and view all the answers

Which of the following statements about the Arabinose operon is true?

Arabinose is necessary to break the DNA loop preventing transcription Signup and view all the answers

What is the primary function of proximal control elements in transcription regulation?

They regulate the start of transcription Signup and view all the answers

Which component is NOT considered a general transcription factor in the eukaryotic transcription process?

SP1 Signup and view all the answers

Which mutation leads to the constant binding of a super repressor to LacO, resulting in no transcription?

Lacl^s^ mutation Signup and view all the answers

What type of mutation is primarily associated with the activation of oncogenes?

Dominant mutation Signup and view all the answers

Which mechanism is NOT a method by which proto-oncogenes can become activated?

Nonsense mutation Signup and view all the answers

What is required for the function of a recessive mutation in tumor suppressor genes?

Both copies of the gene must be turned off Signup and view all the answers

Which of the following is an example of an oncogene category related to cell cycle regulation?

Myc Signup and view all the answers

What is the role of EPSP synthase in plants that have been modified for glyphosphate resistance?

Facilitates amino acid synthesis Signup and view all the answers

Which of the following does NOT describe how chromosomal translocation can activate proto-oncogenes?

Interfering with tumor suppressor function Signup and view all the answers

In the context of diacetyl detection in C.elegans, which gene is necessary for the expression of odr-10?

odr-7 Signup and view all the answers

Which of the following describes the function of the herbicide glyphosphate?

Inhibits EPSP synthase Signup and view all the answers

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.
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.
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.
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

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.
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

Cancer Types:
- Carcinomas: Originate from epithelial cells.
- Sarcomas: Arise from mesodermal tissues.
- Adenocarcinomas: Derived from glandular tissues.
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.
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.
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!