basic of mendelian gentics Flashcards
What is the structure of an operon?
an operon includes:
Promoter: Binding site for RNA polymerase.
Operator: Binding site for regulatory proteins.
Structural Genes: Encode related proteins, often in a polycistronic mRNA.
What is polycistronic mRNA?
A single mRNA molecule that encodes multiple proteins, each with its own Ribosome Binding Site (RBS).
What is coupled transcription and translation in bacteria?
Transcription and translation occur simultaneously in the cytoplasm.
Ribosomes begin translating mRNA while it is still being transcribed by RNA polymerase.
What is the difference between positive and negative gene regulation?
Positive Regulation: Activator proteins enhance RNA polymerase binding to weak promoters.
Negative Regulation: Repressor proteins block RNA polymerase from transcribing genes (e.g., Lac operon).
What is a true-breeding line?
A population of organisms that consistently produce offspring with the same phenotype when self-crossed.
Define genotype and phenotype.
Genotype: The genetic makeup of an organism (e.g., TT, Tt, or tt).
Phenotype: Observable characteristics resulting from the genotype (e.g., tall or dwarf plants).
What are the genotypic and phenotypic ratios in a monohybrid cross?
Genotypic Ratio: 1:2:1 (TT:Tt:tt).
Phenotypic Ratio: 3:1 (Tall:Dwarf).
What is a dihybrid cross?
A genetic cross studying the inheritance of two traits (e.g., plant height and flower color).
What is the phenotypic ratio of a dihybrid cross (F2 generation)?
9:3:3:1 (Tall & Purple : Tall & White : Dwarf & Purple : Dwarf & White).
What is the difference between homozygous and heterozygous?
Homozygous: Two identical alleles for a trait (e.g., TT or tt).
Heterozygous: Two different alleles for a trait (e.g., Tt).
What are Mendel’s key observations?
Traits are inherited as discrete units (alleles).
Dominant traits mask recessive traits in heterozygotes.
Traits segregate independently when genes are on different chromosomes.
What is the Punnett Square?
A diagram used to predict the genotypes and phenotypes of offspring based on parental crosses.
