Molecular Biology: DNA and Genetic Code

A specific segment of DNA containing instructions for building a protein.

The order of nitrogenous bases (A, T, G, C) in DNA.

Rules determining how codons in mRNA specify amino acids in a protein.

A group of three nucleotides in mRNA that codes for one amino acid.

The process of assembling amino acids into a protein based on the mRNA code.

The flow of genetic information: DNA to mRNA to protein.

Different version of a gene.

DNA sequence copied into mRNA.

Failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

Aneuploidy, which is the gain or loss of a chromosome.

Loss of one chromosome, resulting in only one copy instead of a pair.

Gain of an extra chromosome, resulting in three copies instead of two.

A genetic condition caused by trisomy 21, resulting in an extra copy of chromosome 21.

A genetic condition in females caused by having three X chromosomes, often leading to learning disabilities.

A genetic condition in males caused by having an extra X chromosome (XXY), resulting in sterility and overlong limbs.

A genetic condition in females caused by having only one X chromosome (XO), resulting in shorter stature and infertility.

A genetic condition in males caused by having an extra Y chromosome (XYY), sometimes associated with learning and behavioral problems.

Neither allele is fully dominant; heterozygotes exhibit a blended phenotype.

DNA serves as the blueprint that dictates the order of amino acids in a protein, ultimately determining its structure and function.

The two main steps are Transcription and Translation. Transcription copies the DNA sequence into mRNA. Translation uses mRNA to build a protein.

Transcription occurs within the nucleus of eukaryotic cells.

RNA polymerase is an enzyme that catalyzes the process of Transcription, creating mRNA from DNA.

mRNA carries the genetic code from the DNA to the ribosomes in the cytoplasm, providing the instructions for building a protein.

Translation occurs in the cytoplasm, specifically at the ribosomes.

Codons are groups of three bases on the mRNA molecule that specify which amino acid to add to the protein chain.

tRNA molecules carry specific amino acids to the ribosome and bind to the corresponding codons on the mRNA, bringing the correct amino acids for protein synthesis.

Errors in protein synthesis can lead to mutations, which can potentially alter traits and cause diseases.

Accurate DNA replication ensures the faithful transmission of genetic information between generations and the correct synthesis of proteins.

The exchange of genetic material between homologous chromosomes during prophase I of meiosis, resulting in new combinations of alleles.

The random union of any sperm with any egg, contributing to the diversity of offspring.

The random separation of homologous chromosomes during meiosis I, resulting in different combinations of chromosomes in gametes.

The combination of alleles an individual has for a trait.

The observable physical expression of a trait.

Having two identical alleles for a particular trait.

The typical developmental trajectory that results in a female phenotype, meaning that male development requires the activation of specific genes.

Genetic disorders more common in males because they inherit only one X chromosome, so one copy of the recessive gene can cause the trait.

When chromosomes fail to separate correctly during cell division, leading to abnormal numbers of chromosomes (like an extra X or Y).

A female with three X chromosomes, often with learning disabilities but usually no major physical anomalies.

Males with an extra X chromosome, resulting in sterility and abnormal limb length.

Females with only one X chromosome, having shorter stature and infertility.

Males with an extra Y chromosome, sometimes associated with learning and behavioral difficulties.

A zygote lacking an X chromosome, which is not viable (cannot survive).

One allele (gene version) can mask the expression of another allele, determining the trait.

Each parent contributes one allele for a trait to their offspring, and these alleles are passed on independently.