DNA Structure and Function Lecture Notes

These flashcards cover key terms and concepts related to the structure and function of DNA, mechanisms of replication and transcription, and processes of protein synthesis.

DNA

A double helix consisting of two antiparallel strands.

Nucleotides

The basic building blocks of DNA made of a sugar, a phosphate group, and a nitrogenous base.

Mutations

Changes in DNA sequences that can be deleterious and are not allowed to accumulate in germ cells.

Germ Cells

Cells that contribute to the formation of a new generation of organisms, distinct from somatic cells.

DNA Replication Models

Three proposed models are: conservative replication, semi-conservative replication, and dispersive replication.

Meselson-Stahl Experiment

An experiment that demonstrated semi-conservative DNA replication using isotopes of nitrogen to label DNA.

Replication Fork

The Y-shaped region where the parental DNA strands are separated during DNA replication.

Leading Strand

The DNA strand that is synthesized continuously in the 5'-to-3' direction.

Lagging Strand

The DNA strand synthesized in short segments that are later joined together.

Helicase

An enzyme that unwinds the double-stranded DNA during replication.

Topoisomerase

An enzyme that relieves the strain caused by supercoiling ahead of the replication fork.

Primase

An enzyme that synthesizes RNA primers to initiate DNA replication on the lagging strand.

Sliding Clamp

A protein that enhances the processivity of DNA polymerase during DNA replication.

Exonucleolytic Proofreading

A mechanism that removes incorrectly paired nucleotides from the DNA strand during replication.

Origin of Replication

The specific site where DNA replication begins.

Operon

A cluster of genes under the control of a single promoter, transcribed together.

RNA Polymerase

The enzyme responsible for synthesizing RNA from a DNA template during transcription.

cAMP

Cyclic adenosine monophosphate, a signaling molecule that regulates gene expression in response to glucose levels.

Transcription Factors

Proteins that play a role in the regulation of gene expression by binding to specific DNA sequences.

Riboswitches

Segments of RNA that regulate gene expression by binding to small molecules, leading to conformational changes.

Translation Termination

The process by which the ribosome recognizes a stop codon and releases the newly synthesized protein.

Polyribosomes

Multiple ribosomes translating a single mRNA molecule simultaneously.

Secretory Pathway

The process by which proteins are transported within and out of the cell, involving the endoplasmic reticulum and Golgi apparatus.