Cell Theory

The principle that all organisms are composed of cells, cells come from pre-existing cells, and the cell is the basic unit of life.

Prokaryotes

Single-celled organisms that lack a nucleus and membrane-bound organelles.

Eukaryotes

Organisms with linear DNA contained in a nucleus and multiple membrane-bound organelles.

Organic Compounds

Carbon-containing compounds derived from living organisms.

Inorganic Compounds

Compounds derived from non-living components that generally lack carbon.

Amino Acids

Monomers composed of a carboxyl group, amino group, and variable R-group that form proteins.

Condensation Reaction

The joining of amino acids that releases water and forms a peptide bond.

Hydrolysis Reaction

The breakdown of complex proteins into amino acids requiring the addition of water.

Primary Protein Structure

The specific linear sequence of amino acids in a polypeptide chain.

Secondary Protein Structure

Local folding into alpha-helices, beta-pleated sheets, or random coils stabilized by hydrogen bonds.

Tertiary Protein Structure

The stable three-dimensional folding of a single polypeptide chain essential for function.

Quaternary Protein Structure

The interaction of two or more polypeptide chains to form a single protein.

Protein Secretory Pathway

The pathway involving the rough ER, Golgi apparatus, and vesicles to export proteins via exocytosis.

Denaturation

The irreversible or reversible loss of protein function due to broken weak bonds at extreme temperatures or pH.

Nucleotide

The monomer of nucleic acids, consisting of a phosphate group, pentose sugar, and nitrogenous base.

Antiparallel DNA

The two polynucleotide chains of a DNA molecule running in opposite directions.

Histones

Proteins in eukaryotic cells that tightly package DNA into nucleosomes.

Transcription

The process of copying a DNA template strand into pre-mRNA using RNA polymerase.

RNA Splicing

The removal of non-coding introns and joining of exons during RNA processing.

Translation

The decoding of an mRNA strand by ribosomes in the cytoplasm to assemble a polypeptide chain.

Structural Genes

Genes that code for proteins involved in the structure and function of a cell.

Regulatory Genes

Genes that produce proteins to control the expression of other structural genes.

Operon

A group of structural genes in prokaryotes controlled by a single promoter and operator.

Trp Operon

An inducible operon in E. coli that regulates the synthesis of tryptophan.

Attenuation

A secondary gene regulation mechanism involving leader mRNA stem-loop structures to fine-tune transcription.

Cell Wall

Layer of cellulose surrounding the cell membrane that provides structural support and defines shape.

Smooth Endoplasmic Reticulum

Network of membranes creating channels in the cytoplasm; site of lipid synthesis and material transport.

Cell Membrane / Plasma Membrane

Double layer of phospholipids that encloses cell contents, regulates movement, and maintains shape.

Golgi Complex / Golgi Bodies

Stacks of flattened membrane sacs that package proteins into vesicles for secretion.

Nucleus

Large organelle surrounded by a double membrane containing chromosomes and nucleolus to control cellular function.

Mitochondria

Sacs with a folded inner membrane (cristae) that serve as the site for aerobic cellular respiration and energy production.

Nucleolus

Granular structure in the nucleus made of protein and nucleic acid; site of ribosomal RNA manufacture.

Chloroplasts

Organelles containing grana and stroma; the site of photosynthesis in cells.

Nuclear Membrane

Double membrane containing pores that separates the nucleoplasm from the cytoplasm and regulates material movement.

Vacuole

Membrane-bound sac containing fluid, sugars, and ions that helps maintain cell shape and stores substances.

Ribosomes

Small spherical bodies composed of RNA and protein; the site of protein synthesis.

Lysosomes

Membrane sacs containing enzymes that digest wastes and play a vital role in apoptosis.

Rough Endoplasmic Reticulum

Network of membranes studded with ribosomes that transports proteins produced by ribosomes.

Flagella or Cilia

Protruding extensions of membrane and microtubules that provide movement for the cell or surrounding fluid.

Messenger RNA (mRNA)

Carries genetic information from the DNA to the ribosomes as a single, linear strand for protein synthesis.

Transfer RNA (tRNA)

Delivers individual amino acids to the ribosome using a cloverleaf structure and an anticodon.

Ribosomal RNA (rRNA)

The main structural component of ribosomes, folding into a large and a small subunit.

Promoter Region

An upstream binding site for RNA polymerase that denotes the starting position of transcription, such as the TATA box.

Introns

Non-coding regions of DNA removed during RNA processing, found only in eukaryotes.

Exons

Regions of coding DNA that are transcribed and translated into the final protein.

Termination Sequence

A sequence of DNA that signals for the end of transcription.

Operator Region

The binding site for repressor proteins that inhibits gene expression, typically found in prokaryotes.

RNA Processing

Process in the nucleus involving the addition of a methyl-G cap and poly-A tail, and the splicing of introns and exons.

Polymerase Chain Reaction (PCR)

A technique used to amplify specific target sequences of DNA through rapid thermal cycling.

Gel Electrophoresis

A laboratory method that separates DNA fragments by size using an electrical current through an agarose gel.

Recombinant Plasmid

A plasmid vector that has had foreign target DNA inserted into it, used to produce proteins or clone genes.

Bacterial Transformation

The process by which bacterial cells take up foreign DNA, such as a recombinant plasmid, from their environment.

Restriction Endonucleases

Enzymes that cut DNA at specific recognition sites, producing sticky or blunt ends.

DNA Ligase

An enzyme that joins DNA fragments together by re-joining the sugar-phosphate backbone.

Genetically Modified Organism (GMO)

An organism with genetic material altered using genetic engineering technologies.

DNA Profiling

A technique using short tandem repeats (STRs) within satellite DNA to identify individuals or compare DNA samples.

CRISPR-Cas9

A naturally occurring bacterial defense system used to target and cleave viral DNA, adapted for genome editing.

Guide RNA (gRNA)

An RNA molecule that forms a complex with Cas9 and directs it to a specific complementary DNA sequence.

PAM Sequence (Protospacer Adjacent Motif)

A short DNA sequence (such as NGG) that Cas9 must recognize to bind and cut target DNA.

Cas1 and Cas2 Enzymes

Enzymes associated with CRISPR that cut out short sections of viral DNA to be integrated as spacers.

Bacterial CRISPR Exposure Phase

The stage where bacteriophage DNA is injected, identified as foreign, and short sections are integrated as spacers.

CRISPR-Cas9 Limitations

Current challenges include inconsistent success rates, potential off-target cuts, and ethical concerns regarding human embryo editing.