Genetics: RNA Processing and Translation Lecture

Vocabulary flashcards covering chromosome biology, telomeres, hnRNA processing steps, and translation mechanisms from the lecture.

Roslyn Franklin

The scientist who actually discovered the structure of DNA around $1952$-$1953$, although Watson and Crick took the credit.

Leonard Hayflick

The scientist who first noted cellular aging limits in $1960$.

Telomerase

An enzyme that adds DNA sequences to the ends of chromosomes so they do not shorten; it creates DNA but does not contain DNA itself.

Alternate lengthening of telomeres (ALT)

A specific non-telomerase mechanism used by cancer cells to lengthen their telomeres.

Antitelomerase drugs

Therapeutic medicines investigated to treat cancer by specifically turning off telomerase so chromosomes fail to lengthen and tumors burn out.

Stress

The number one driver for aging and cancer that scientists believe is linked to accelerated telomere loss.

hnRNA (heteronuclear RNA)

A very long, newly transcribed precursor RNA strand that must undergo post-transcriptional processing to become mature messenger RNA.

Seven methylguanosine (7mg cap)

A specialized cap added to protect the $5'$ end of hnRNA during the first step of RNA processing.

Poly-A tail

A tract of adenosine bases added to protect the $3'$ end of an RNA strand after the terminal nucleotides are removed.

Introns

Noncoding, intervening sequences within a gene that are cut out and removed during RNA processing; potentially function as histone binding sites for DNA packaging.

Exons

The expressed, protein-coding regions of a gene that remain and are spliced together after introns are removed.

Ligase

The enzyme responsible for gluing together DNA and RNA fragments, such as joining exons during RNA splicing.

Ligating

The technical term referring to adhering, attaching, or gluing molecular strands together.

Cleave

A biochemical term meaning to cut away, chop, or excise nucleic acid segments.

Mature messenger RNA (mRNA)

The shortened, fully processed RNA strand with a $5'$ 7mg cap, a poly-A tail, and spliced exons that exits the nuclear membrane to serve as a recipe card for ribosomes.

Translation

The biological process in which mRNA is decoded by ribosomes in the cytoplasm to synthesize a protein.

Transfer RNA (tRNA)

An RNA molecule featuring three loops, an amino acid binding site, an anticodon, and localized double-stranded regions.

Amino acid binding site

The specific region located at the terminal end of a tRNA molecule where an amino acid is attached.

Anticodon

The three-nucleotide sequence on the middle loop of a tRNA molecule that base-pairs with a complementary mRNA codon.

Codon

A sequence of three consecutive nucleotides on an mRNA molecule that specifies a particular amino acid during protein synthesis.

Aminoacyl tRNA synthase

The enzyme responsible for charging a tRNA molecule by attaching its corresponding, correct amino acid.

AUG

The universal start codon located at the beginning of every mRNA molecule, which sets the reading frame and codes for methionine.

Methionine

The initial amino acid incorporated into every newly translated protein, corresponding to the start codon AUG.

Lysine

An essential amino acid that pigs cannot synthesize, making it the most limiting amino acid in swine diets.