5 Genetics and Molecular Biology Free Online FlashCards

What does semiconservative DNA replication produce?

Each DNA molecule contains one original strand and one newly made complementary strand.

Which bases pair in DNA?

A pairs with T, and C pairs with G.

What happens during transcription?

RNA polymerase uses one DNA strand as a template to produce a complementary RNA molecule. RNA uses uracil instead of thymine.

How do ribosomes and tRNAs work together in translation?

A ribosome reads mRNA codons, while tRNAs pair their anticodons with those codons and deliver amino acids for a polypeptide.

What are three possible effects of a base substitution?

A substitution may be silent, missense, or nonsense: it may leave the amino acid unchanged, change it, or create a premature stop codon.

Which mutations may be passed to offspring?

A mutation in a cell that contributes to eggs or sperm may be inherited; a mutation in an ordinary body cell generally is not passed to offspring.

How do genotype and phenotype differ?

Genotype is an individual's allele combination; phenotype is an observable characteristic that can reflect genes and environment.

What allele combinations can result from an Aa × Aa cross?

Each parent can pass either allele. The combinations AA, Aa, aA, and aa each have a one-in-four probability under the simple model.

Why are short DNA fragments made at a replication fork?

DNA polymerase builds DNA only in the 5′-to-3′ direction, so one strand is copied in short fragments that ligase joins.

How is an initial eukaryotic RNA transcript processed?

Introns are removed, exons are joined, and protective end modifications are added before mature mRNA leaves the nucleus.

What does the mRNA codon AUG signal?

AUG is a start codon and specifies the amino acid methionine.

When can an insertion or deletion cause a frameshift?

An insertion or deletion not divisible by three shifts the reading frame, changing many downstream codons.