Chapter 4: Nucleic Acids and Information Flow Flashcards

Vocabulary flashcards covering the key terms, historical experiments, structures, and processes of nucleic acids and transcription from Chapter 4.

Genome

The entirety of an organism's genetic material or DNA contained within its cells.

F. Griffith Experiment (1928)

Demonstrated that genetic information can be transferred between bacterial strains, showing that heat-killed virulent bacteria contain genetic material capable of transforming live nonvirulent bacteria into virulent ones.

Avery, MacLeod, and McCarty Experiment (1944)

Identified DNA as the transforming molecule by degrading DNA, RNA, or protein components from heat-killed virulent bacteria and showing that transformation failed only when DNA was destroyed by DNase.

Hershey and Chase Experiment (1952)

Confirmed that DNA, not protein, is the genetic material by radioactively labeling DNA and protein in bacteriophages and observing that only labeled DNA entered host bacteria upon infection.

Photograph 51

An iconic X-ray diffraction image of B-form DNA taken by Rosalind Franklin in 1952 that revealed the double helical structure of DNA.

Nucleoside

A molecule consisting of a five-carbon sugar (ribose or deoxyribose) covalently bonded to a nitrogenous base, lacking phosphate groups.

Nucleotide

The monomeric building block of nucleic acids, composed of a nucleoside (sugar and nitrogenous base) attached to one or more phosphate groups.

Purines

Double-ring nitrogenous bases found in nucleic acids, consisting of Adenine (A) and Guanine (G).

Pyrimidines

Single-ring nitrogenous bases found in nucleic acids, consisting of Cytosine (C), Thymine (T), and Uracil (U).

Phosphodiester Bond

A strong covalent bond linking adjacent nucleotides in a nucleic acid chain between the $3'$ hydroxyl group of one sugar and the $5'$ phosphate group of another.

Chargaff's Rule

The principle stating that in DNA, the concentration of Cytosine equals Guanine ($\%C = \%G$) and the concentration of Adenine equals Thymine ($\%A = \%T$).

Base Stacking

Interactions between adjacent base pairs stacked vertically along the same strand of DNA that stabilize the double helix structure.

Central Dogma

The fundamental model describing the direction of genetic information flow: DNA is transcribed into RNA, which is translated into protein.

Ribose

The five-carbon sugar present in RNA nucleotides, characterized by having a hydroxyl ($\text{-OH}$) group attached to its $2'$ carbon.

Uracil

A pyrimidine base present in RNA instead of Thymine, characterized by having a hydrogen ($\text{-H}$) atom where Thymine has a methyl ($\text{-CH}_3$) group.

RNA World Hypothesis

The hypothesis proposing that RNA was the original genetic material in early life because it can store information and possesses catalytic properties.

Template Strand

The specific DNA strand read by RNA polymerase to synthesize a complementary RNA transcript during transcription.

Nontemplate Strand

The DNA strand complementary to the template strand, whose nucleotide sequence matches the synthesized RNA transcript (with Uracil substituted for Thymine); also called the coding strand.

Promoter Region

A DNA sequence located upstream of a gene (such as the eukaryotic TATA box, $5'\text{-TATAAA-}3'$) that serves as the binding site for transcription factors and RNA polymerase.

Transcription Factors

Proteins that recognize specific promoter DNA sequences and direct RNA polymerase to initiate transcription.

RNA Polymerase

An enzyme that unwinds DNA strands and synthesizes an RNA polymer complementary to the DNA template strand in the $5'$ to $3'$ direction.

Transcription Bubble

A localized unwound region of double-stranded DNA (~$14$ base pairs in length) inside RNA polymerase where transcription actively occurs.

Coupled Transcription and Translation

A phenomenon in prokaryotes where ribosomes begin translating an mRNA transcript into protein while RNA polymerase is still synthesizing it.

$5'$ Cap

A modified guanosine nucleotide ($7\text{-methylguanosine}$) added to the $5'$ end of eukaryotic primary RNA transcripts to provide mRNA stability and permit ribosome recognition.

Poly(A) Tail

A chain of adenine nucleotides added to the $3'$ end of eukaryotic pre-mRNA during polyadenylation to protect against exonucleases and facilitate transport out of the nucleus.

Introns

Non-coding regions of eukaryotic primary RNA transcripts that are removed during RNA splicing.

Exons

Coding regions of eukaryotic RNA transcripts that remain after splicing and are joined together to form the final functional mRNA.

Alternative Splicing

A process during eukaryotic RNA processing where different combinations of exons from a single primary transcript are joined together to produce distinct protein isoforms.