Biotechnology, Microscopy & Fundamental Biological Theories

Vocabulary flashcards covering fundamental biological theories and a range of biotechnology and microscopy techniques mentioned in the lecture notes.

Cell Theory

States that all living organisms are composed of one or more cells, the cell is the basic unit of structure and function, all cells arise from pre-existing cells, and cells carry hereditary information.

RNA World Hypothesis

Proposes that self-replicating RNA molecules preceded modern life, serving both as genetic material and as catalytic molecules.

Central Dogma of Biology

Describes the general flow of genetic information—DNA is transcribed to RNA, which is translated into protein.

Light Microscope

Uses visible light to view thin samples; suitable for overall cell morphology at moderate magnification.

Scanning Electron Microscope (SEM)

Produces high-resolution images of the surface of 3-D objects by scanning them with an electron beam.

Transmission Electron Microscope (TEM)

Generates highly magnified images of thin cross-sections, revealing internal ultrastructure of specimens.

Confocal Laser Scanning / Fluorescence Microscope

Uses lasers and fluorescent tags (e.g., antibodies) to visualize specific cellular components such as chromosomes during mitosis.

Polymerase Chain Reaction (PCR)

In vitro technique that exponentially amplifies a target DNA segment through repeating cycles of denaturation, annealing, and elongation.

Denaturation (PCR Step)

High heat (~95 °C) separates double-stranded DNA into single strands.

Annealing (PCR Step)

Cooling phase that allows primers to bind (hybridize) to complementary sequences on single-stranded DNA.

Elongation (PCR Step)

DNA polymerase extends primers, synthesizing new complementary DNA strands.

Reverse Transcriptase

Enzyme that synthesizes complementary DNA (cDNA) from an RNA template; naturally used by viruses and in labs to remove introns from mRNA.

Centrifugation

Separates components of a liquid sample by rapid spinning; densest materials form a pellet at the bottom.

Cell Fractionation Order

Typical sedimentation sequence: nuclei → mitochondria/chloroplasts → ribosomes.

DNA Sequencing

Determines the precise order of nucleotides in a DNA (or RNA) molecule.

Dideoxy Chain Termination Method (Sanger Sequencing)

Uses dideoxynucleotides lacking a 3′-OH to terminate DNA synthesis at specific bases, enabling sequence determination.

Southern Blot

Blotting technique that identifies specific DNA fragments.

Northern Blot

Blotting technique that detects specific RNA molecules.

Western Blot

Blotting technique employed to identify particular proteins.

Blotting Methodology

Sample separation by electrophoresis → transfer to nitrocellulose membrane → hybridization or antibody probing to reveal target fragment.

Gel Electrophoresis

Separates DNA fragments by size and charge through an agarose or polyacrylamide matrix; smaller fragments travel farther.

Microarray Assay

Screens expression levels of thousands of genes simultaneously across a genome.

Recombinant DNA

DNA molecule formed by combining sequences from different sources using molecular cloning techniques.

Restriction Endonuclease (Restriction Enzyme)

Cuts DNA at specific nucleotide sequences called restriction sites, generating sticky or blunt ends.

Restriction Site

Short, palindromic DNA sequence recognized and cleaved by a restriction enzyme.

Sticky Ends

Single-stranded overhangs produced by staggered restriction enzyme cuts; facilitate ligation with complementary DNA.

DNA Ligase

Enzyme that covalently joins the sugar-phosphate backbones of DNA fragments.

Vector (Molecular Biology)

Vehicle—such as a plasmid or bacteriophage—used to carry foreign DNA into host cells.

Plasmid

Circular, double-stranded bacterial DNA molecule often used as a cloning vector; can carry antibiotic-resistance genes for selection.

Bacteriophage

Virus that infects bacteria; sometimes employed as a vector to deliver recombinant DNA.

Transformation (Bacterial)

Process by which bacteria uptake extracellular DNA, enabling introduction of recombinant plasmids.

Gene Library (Gene Bank)

Collection of DNA fragments representing an organism’s genome, stored in vectors for later study or retrieval.