Genetics and Molecular Biology: Core Concepts and Key Terms

Central Dogma

The flow of genetic information: DNA → RNA → Protein.

DNA

The molecule that stores genetic instructions.

mRNA

A copy of DNA that carries instructions to make a protein.

Transcription

Process of making RNA from DNA.

Translation

Process of making a protein from mRNA.

Protein

A molecule made of amino acids that performs functions in the body.

Gene

A section of DNA that codes for a protein or trait.

Allele

Different versions of the same gene.

Genome

The complete set of DNA in an organism.

Heterogeneous

Made of different parts or elements.

Homogeneous

All the same or uniform.

Structural Gene

A gene that codes for a protein.

Regulatory Gene

A gene that controls when and how other genes work.

RNA Polymerase

The enzyme that makes RNA from DNA.

Chromatin

DNA wrapped around proteins (histones), like loose packing of DNA.

Chromosome

Tightly packed DNA, visible during cell division.

Histones

Proteins that DNA wraps around.

Phosphate Group

A chemical part of DNA/RNA that links nucleotides together.

Arginine/Lysine

Amino acids (positively charged) that bind tightly to DNA.

Amino acid

Building block of proteins.

GFP (Green Fluorescent Protein)

A protein that glows green, often used in labs.

Mutation

A change in DNA.

Phenotype

The physical trait you can see (e.g., eye color).

Epigenetics

Changes in gene activity without changing DNA sequence.

Gene expression

The process of turning a gene 'on' to make RNA/protein.

Sex Chromosome

Chromosome that determines sex (X and Y).

Haploid number (n)

Half the total chromosome set (in gametes, e.g., 23 in humans).

Diploid (2n)

Full set of chromosomes (in body cells, e.g., 46 in humans).

Ploidy

The number of sets of chromosomes.

Eukaryotes

Organisms with cells that have a nucleus.

Homologs

Matching chromosomes (one from each parent).

Dominant trait

Trait that shows up if at least one allele is present.

Recessive trait

Trait that only shows up if two copies are present.

Sex linkage

Traits linked to the X or Y chromosome.

Polygenic traits

Traits controlled by many genes (e.g., height, skin color).

Polygenic model

The idea that multiple genes together influence a trait.

Recessive allele

The version of a gene that is hidden if a dominant allele is present.

Dominant allele

The version of a gene that shows its effect even with one copy.

Nucleosome

DNA wrapped around histone proteins, like 'beads on a string.'