Genetics and Molecular Biology

A comprehensive set of vocabulary flashcards covering key concepts in genetics and molecular biology.

DNA

A double-helix molecule containing the genetic instructions used in the development, functioning, and reproduction of all living organisms.

Gene

A specific sequence of DNA nucleotides that serves as the blueprint for building proteins and determining individual traits.

Allele

One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Chromosome

A tightly coiled structure of DNA and protein that carries genomic information from one generation to the next during cell division.

Genotype

Specific combination of alleles inherited from parents, often represented by letter pairs.

Phenotype

The set of observable physical traits or biochemical characteristics of an organism determined by its unique genetic makeup and environment.

Homozygous

A genetic condition where an individual inherits two identical alleles for a particular gene from both biological parents.

Heterozygous

A genetic condition where an individual inherits two different alleles for a particular gene, such as one dominant and one recessive.

Dominant

An allele that is always expressed in the phenotype, even if only one copy is present in the genotype.

Recessive

An allele that is only expressed in the phenotype when an individual possesses two copies of that specific version.

Codominance

A pattern of inheritance where both alleles in a heterozygote are fully and separately expressed, such as in AB blood types.

Incomplete Dominance

An inheritance pattern where the heterozygous phenotype is a blend or intermediate between the two homozygous parent phenotypes.

Sex-linked Inheritance

Traits or disorders controlled by genes located on the sex chromosomes, most commonly found on the larger X chromosome.

Haploid/Diploid

Diploid cells contain two complete sets of chromosomes (2n), while haploid gametes contain only one single set (n).

Gamete

Specialized haploid reproductive cells, such as sperm or eggs, that unite during fertilization to form a new organism.

Zygote

The diploid cell resulting from the fusion of two haploid gametes, representing the very first stage of a new individual.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis, which increases genetic variety in the resulting gametes.

Mutation

A permanent alteration in the DNA sequence that makes up a gene, which may result in a change to the protein produced.

Transcription

The first step of gene expression where a specific segment of DNA is copied into a complementary strand of messenger RNA.

Translation

The process where ribosomes decode the information carried by mRNA to assemble a specific sequence of amino acids into a protein.

mRNA

A single-stranded RNA molecule that carries the genetic 'message' from the DNA in the nucleus to the ribosome for synthesis.

tRNA

Small RNA molecules that carry specific amino acids to the ribosome and match them to the coded mRNA message.

Ribosome

A complex cellular machine, located in the cytoplasm or on the rough ER, that serves as the site for protein synthesis.

Codon

A three-nucleotide sequence on a messenger RNA molecule that codes for a specific acid or a signal to stop.

Anticodon

A three-nucleotide sequence on a tRNA molecule that is perfectly complementary to a specific codon found on the mRNA strand.

Amino Acid

Organic compounds that serve as the fundamental building blocks of proteins, with twenty different types existing in nature.

Nucleotide Bases

The nitrogenous building blocks of DNA (A, T, C, G) and RNA (A, U, C, G) that carry the genetic code.

RNA Polymerase

The primary enzyme responsible for reading a DNA template and synthesizing a complementary strand of messenger RNA (mRNA) during transcription.

Helicase

A specialized 'unzipping' enzyme that breaks the hydrogen bonds between nucleotide bases to unwind the DNA double helix during replication or transcription.

DNA Polymerase

An essential enzyme that builds new DNA strands by assembling nucleotides in the correct sequence, using an existing strand as a template during replication.

Replication

The biological process of producing two identical replicas of DNA from one original DNA molecule, ensuring genetic information is passed to new cells.