Biology Lecture Notes: Molecular Biology, Biochemistry, and Cell Cycles

Flashcards covering DNA/RNA structure, replication, gene expression, biochemistry, cell transport, and the cell cycle based on lecture notes.

Purines

Nitrogenous bases with a double ring structure, including Guanine (G) and Adenine (A).

Pyrimidines

Nitrogenous bases with a single ring structure, including Cytosine (C), Thymine (T), and Uracil (U).

Semiconservative process

DNA replication where each daughter molecule consists of one original parent strand and one newly replicated strand.

Helicase

An enzyme that unwinds the DNA strands during replication.

Topoisomerase

An enzyme that relaxes coiling in front of the replication fork.

DNA Polymerase III

The enzyme that creates new DNA strands by adding nucleotides to the 3' end of an existing template.

Okazaki fragments

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

Ligase

An enzyme that joins Okazaki fragments on the lagging strand together.

Alternative Splicing

An mRNA modification process that can result in different versions of the final mRNA molecule.

Reverse transcriptase

An enzyme that copies the viral RNA genome into DNA, allowing it to integrate with the host cell.

Inducible operon

A system, such as the lac operon, where gene transcription is normally off but can be turned on by an inducer.

Repressible operon

A system, such as the trp operon, where genes are normally transcribed but can be turned off when resources are abundant.

Surface tension

A property of water resulting from hydrogen bonds at the surface of the liquid that resist stretching.

Dehydration Synthesis

A chemical reaction that removes a water molecule to bond monomers together into a polymer.

Hydrolysis

A chemical reaction that adds a water molecule to cleave a bond between monomers.

Primary Structure

The specific sequence and order of amino acids in a protein chain.

Endosymbiosis

The theory that membrane-bound organelles like mitochondria and chloroplasts evolved from free-living prokaryotic cells.

Aquaporin

A specific transmembrane protein that facilitates the diffusion of water across the cell membrane.

Hypotonic

A solution where the concentration of solute outside the cell is lower than inside, causing the cell to take in water and potentially burst.

Water potential equation

Represented by the formula $\Psi = \Psi_s + \Psi_p$.

Solute potential formula

Calculated using the equation $\Psi_s = -iCRT$ where $i$ is the ionization constant, $C$ is molar concentration, $R$ is the pressure constant ($0.0831$), and $T$ is temperature in Kelvin.

Quorum Sensing

A bacterial communication process using chemical messengers to coordinate responses based on the density of the population.

Negative Feedback

A feedback mechanism that maintains homeostasis by returning a physiological process to its set point.

Positive Feedback

A mechanism that amplifies a response, moving the stimulus further away from the set point, such as in blood clotting.

Go Phase

A non-dividing state where cells can exit the cell cycle, though some may re-enter in response to specific signals.

Cyclin-dependent kinase (Cdk)

An enzyme that, when joined with cyclin, helps the cell move past checkpoints in the cell cycle.