BIO I - EXAM IV

Directionality

The principle that indicates the orientation in which nucleic acids are read and built: Polymerases read 3' to 5', build 5' to 3', and ribosomes read mRNA 5' to 3'.

Base pairing in DNA

Adenine (A) pairs with Thymine (T) and Guanine (G) pairs with Cytosine (C).

Base pairing in RNA

Adenine (A) pairs with Uracil (U) and Guanine (G) pairs with Cytosine (C).

DNA replication

The process by which DNA makes a copy of itself, resulting in one old strand and one new strand (semi-conservative).

Leading strand

The DNA strand that is synthesized continuously in the same direction as the replication fork.

Lagging strand

The DNA strand that is synthesized discontinuously in small fragments known as Okazaki fragments.

Promoter

The DNA sequence that determines the template strand and direction of transcription; it is NOT transcribed.

Codon

A sequence of three nucleotides on mRNA that corresponds to a specific amino acid.

Anticodon

A sequence of three nucleotides on tRNA that is complementary to a codon on mRNA.

Types of mutations

Silent (no change), Missense (different amino acid), Nonsense (premature stop), Frameshift (causes shift in reading frame).

Central Dogma of Molecular Biology

The flow of genetic information from DNA to RNA to Protein.

Eukaryotic transcription location

Transcription occurs in the nucleus.

Prokaryotic transcription location

Transcription occurs in the cytoplasm.

Frameshift mutation

A mutation that causes a shift in the reading frame of the genetic sequence, often resulting in a severely altered protein.

Redundant genetic code

The property of the genetic code where multiple codons can code for the same amino acid.

Unambiguous genetic code

The property of the genetic code where each codon corresponds to only one amino acid.

Gene expression

The process of making a functional product, such as RNA or protein, from a gene.

Okazaki fragments

Short sequences of DNA synthesized on the lagging strand during DNA replication.

Semiconservative replication

The method of DNA replication in which each daughter molecule consists of one old strand and one newly synthesized strand.