Science Olympiad Designer Genes 26

Vocab from Science Olympiad's event Designer Genes. Made for school year 25-26.

Purine

Thes have a two-ringed structure consisting of a nine-membered molecule with four nitrogen atoms. Ex. adenine + guanine

Pyrimidine

These have one single ring, which has just six members and two nitrogen atoms.

Ex. cytosine, thymine, uracil

Law of Segregation

The two alleles for each gene separate during gamete (sperm/egg) formation, so each gamete receives only one allele. This aligns with meiosis, where homologous chromosomes (carrying the alleles) split.

In other words: Organisms have 2 forms of a gene (each is an allele) that separate such that each resultant gamete has only 1 of the alleles. This happens in Anaphase I.

Law of Independent Assortment

Alleles for different genes (on different chromosomes) are distributed to gametes independently of one another. The inheritance of seed shape is separate from the inheritance of seed color. This holds true unless genes are physically linked on the same chromosome.

Epistasis

A circumstance where the expression of one gene is modified (e.g., masked, inhibited or suppressed) by the expression of one or more other genes.

Haploid

These cells contain a single set of chromosomes (n).

Diploid

These cells contain two sets, one from each parent (2n).

Tetrad

This is a structure formed during Prophase I, consisting of four chromatids (two homologous chromosomes paired together) that undergo synapsis and crossing over. This paired structure is crucial for genetic recombination and ensures proper chromosome separation into four genetically unique haploid gametes

DNA vs RNA

DNA is double stranded, RNA single stranded

DNA has deoxyribose sugar and RNA has ribose

DNA has thymine and RNA has uracil

Introns

These are non-coding segments of DNA within genes that are transcribed into pre-mRNA but removed during RNA splicing, leaving only protein-coding exons. They enable alternative splicing to generate protein diversity, regulate gene expression, and are found in eukaryotic genomes.

Exons

These are the protein-coding sequences of a gene that remain in mature mRNA after splicing, acting as the "expressed" regions used to create proteins. They represent specific, functional genetic instructions (e.g., coding for amino acids in actin or myosin)

Transcription

This is the first step of gene expression where a specific DNA sequence is copied into a complementary RNA molecule (mRNA) by the enzyme RNA polymerase. Its purpose is to transfer genetic information from DNA to the cytoplasm for protein synthesis. The three main steps are initiation, elongation, and termination, creating a portable RNA copy.

Translation

This is the biological process where ribosomes in the cytoplasm or rough ER synthesize proteins by decoding messenger RNA (mRNA) sequences into amino acid chains (polypeptides). It is the second step of gene expression, converting the mRNA genetic code into functional proteins using transfer RNA (tRNA) to add specific amino acids.

Transfer RNA

This translates genetic information from mRNA into proteins by delivering specific amino acids to the ribosome.

Ribosomal RNA

This is a major component of ribosome which allows mRNA and tRNA to connect so amino acids can connect.

Messenger RNA

Carries blueprint into the cytoplasm and serves as the template for protein synthesis

AUG

The codon for amino acid Methionine, a start codon.

Codon

This is a sequence of three consecutive nucleotides on mRNA that encodes a specific amino acid or signals the start/stop of protein synthesis.

Prokaryotic DNA Replication

This is a fast, simple process occurring in the cytoplasm with one origin. These organisms have small, circular, naked DNA.

Eukaryotic DNA Replication

This is a slower and more complex process that occurs in the nucleus with multiple origins during the S-Phase. It uses large, linear DNA wrapped around histone proteins.

Leading Strand

This is produced continuously (5’ to 3’) towards the replication fork.

Lagging Strand

This is produced discontinuously (5' to 3') away from the fork in short Okazaki fragments.

Helicase

Enzyme in the DNA replication process that separates the two strands of DNA. They use energy from ATP hydrolysis.

Primase

These are an essential enzyme in DNA replication that synthesizes short RNA primers (typically 5–15 nucleotides long) on single-stranded DNA templates.

DNA Polymerase

This synthesizes new DNA molecules by adding nucleotides—the building blocks of DNA—to a growing strand during replication. It works by reading existing template strands and ensuring accurate pairing (A-T, C-G) to create two identical DNA copies from one, while also providing proofreading to correct mistakes

DNA ligase

This repairs and connects DNA strands by catalyzing the formation of phosphodiester bonds between adjacent 3′-hydroxyl and 5′-phosphate ends. It acts as a "molecular glue" to seal nicks in the backbone, crucial for DNA replication (joining Okazaki fragments), repair, and genetic recombination.