Mendelian Genetics Quiz

Study Notes

Law of Segregation: Each organism carries two alleles for each trait, which segregate during gamete formation.
Law of Independent Assortment: Genes for different traits assort independently during meiosis, although gene linkage can affect this.

Monoecious organisms possess both male and female reproductive structures (hermaphrodites).
Dioecious organisms are distinctly male or female.
Monoecious reproduction involves meiosis in stamen producing haploid pollen grains, while pistil forms haploid nuclei that develop into an embryo.
Dioecious sexual determination in mammals follows XY/XX and in birds follows ZW/ZZ systems.
Klinefelter syndrome (47, XXY) and Turner syndrome (45, X) are examples of chromosomal anomalies affecting sex characteristics.
SRY gene encodes for testis determining factor (TDF), crucial for male gonad formation.
X chromosome has X-inactivation center (Xic) with Xist gene, leading to Barr body formation (inactive X chromosome).

Loss of function mutations can be amorphic (no protein function) or hypomorphic (reduced function).
Gain of function mutations may be hypermorphic (increased function), antomorphic (disturbed function), or neomorphic (new function).
X-linkage affects mostly males; affected males do not pass traits to sons.
Mitochondrial diseases follow maternal inheritance.
Epistasis types include:
- Complementary gene action: both genes needed (9:7 ratio).
- Recessive epistasis: a recessive allele masks another (9:3:4 ratio).
- Dominant epistasis: a dominant allele masks another gene (12:3:1 ratio).
- Duplicate gene action: both genes can produce a phenotype unless both are absent (15:1 ratio).

RFLP detects mutations by analyzing fragment lengths after restriction enzyme digestion.
Cloning vectors vary in size: Plasmids (<20kb), Bacteriophages (25-30kb), Cosmids (30-40kb), BACs (100-500kb), YACs (200kb-2Mb).
cDNA is synthesized from mRNA using reverse transcriptase, representing only expressed genes.

dideoxynucleotides (ddNTPs) terminate DNA strand elongation during sequencing.
PCR consists of denaturation, primer annealing, and primer extension.
Southern blot identifies specific DNA sequences, while Northern blot targets mRNA.
In situ hybridization is utilized in developmental genetics.

Recombination Frequency (RF) indicates centromere distance; closer genes exhibit fewer crossover events.
RF calculation: (number of recombinants / total progeny) x 100%.
Dihybrid and trihybrid crosses analyze linkage and distances between multiple loci through product ratios.

Bacteria grow in nutrient broth or minimal media; E. coli divides every 20 minutes.
Phases of growth: lag phase (adaptation), log phase (rapid growth), stationary phase (nutrient depletion).
Transformation, transduction, and conjugation describe mechanisms for genetic exchange among bacteria.

Constitutive expression involves constant transcription; regulated expression relies on environmental factors.
Control mechanisms include negative repression and positive activation.
The lac operon, induced by lactose, illustrates regulatory gene expression through repressor and activator binding.

RNA polymerase II drives protein-coding transcription.
Enhancer regions regulate gene expression; promoter and proximal control elements initiate transcription.
Chromatin structure is modulated by histone acetylation (promoting transcription) and DNA methylation (suppressing transcription).

Types of base pair mutations: silent, missense (functional changes), nonsense (premature stop codons).
Mutations can be induced (from environmental agents) or spontaneous (replication errors).
DNA repair mechanisms exist, including photoreactivation and various excision repair pathways.

Allele frequencies are influenced by natural selection, mutations, migration, genetic drift, founder effects, and bottlenecks.
The evolutionary clock measures time elapsed through the mutation rate.

Chromosomal structure includes p and q arms, centromeres, kinetochore, and telomeres.
Chromosome abnormalities can be numerical (aneuploidy, polyploidy) or structural (deletions, duplications, translocations).
Uniparental disomy results from inheriting two copies of a chromosome from one parent.

Cancer arises from accumulated mutations affecting cell proliferation and regulation.
Types of cancer include carcinomas, sarcomas, and adenocarcinomas.
Hallmarks of cancer include rapid growth, evasion of apoptosis, limitless replication, and metastasis.
Oncogenes promote cell division; tumor suppressor genes inhibit it. Mutations activate proto-oncogenes or inactivate tumor suppressors.

Insulin production involves using recombinant DNA technology to produce active insulin from separate subunits.
Genetic engineering enhances agriculture through selective breeding, herbicide resistance, and insecticide incorporation.