Lecture 13: DNA Structure & Function

These flashcards cover key terms and concepts related to DNA structure, replication, transcription, and translation as outlined in the lecture notes.

DNA

Deoxyribonucleic acid, the molecule that carries the genetic instructions for life.

Template strand

The strand of DNA that serves as a model for RNA synthesis during transcription.

Transcription

The process of copying a segment of DNA into RNA.

Pre-mRNA

The initial form of mRNA before processing, which includes introns and exons.

Splicing

The process of removing introns from pre-mRNA and connecting exons.

Processed mRNA

The mature form of mRNA after splicing, with a 5' cap and a poly-A tail.

5' Cap

A modified guanine nucleotide added to the 5' end of mRNA for protection and recognition.

Poly-A Tail

A sequence of adenine nucleotides added to the 3' end of mRNA that aids in stability and export from the nucleus.

Semi-conservative replication

The mechanism by which DNA replicates, producing two strands, each containing one original and one new strand.

Meselson-Stahl Experiment

An experiment that demonstrated the semi-conservative nature of DNA replication.

Helicase

An enzyme that unwinds the DNA double helix during DNA replication.

Topoisomerase

An enzyme that prevents the supercoiling of DNA strands during replication.

SSB proteins

Single-stranded binding proteins that stabilize unwound DNA strands during replication.

Primase

An enzyme that synthesizes a short RNA primer to initiate DNA replication.

DNA polymerase III

The main enzyme responsible for synthesizing new DNA strands during replication.

Okazaki fragments

Short segments of DNA synthesized on the lagging strand during replication.

Ligase

An enzyme that joins DNA fragments by forming phosphodiester bonds.

Exonuclease activity

The activity of an enzyme that removes nucleotides from the ends of DNA strands.

Central Dogma

The framework describing the flow of genetic information from DNA to RNA to protein.

Transcription

The synthesis of RNA from a DNA template.

Translation

The process of synthesizing proteins based on the sequence of mRNA.

mRNA

Messenger RNA, the RNA transcript that carries genetic information from DNA for protein synthesis.

rRNA

Ribosomal RNA, a component of ribosomes essential for protein translation.

tRNA

Transfer RNA, which carries amino acids to the ribosome for protein synthesis.

Codon

A sequence of three nucleotides in mRNA that specifies an amino acid.

Redundant code

A characteristic of genetic code where multiple codons can encode the same amino acid.

Start codon

A codon that signals the start of translation, typically AUG (methionine).

Stop codon

A codon that signals the termination of translation (UAA, UAG, UGA).

RNA processing

Modifications made to pre-mRNA, including adding the 5' cap, poly-A tail, and splicing.

Transcription factors

Proteins that help regulate the transcription of genes by assisting RNA polymerase.

Gene promoter

A DNA sequence that initiates transcription of a particular gene.

Intron

A non-coding region of RNA removed during RNA processing.

Exon

A coding region of RNA that remains after RNA processing and is translated into protein.

RNA polymerase

An enzyme that synthesizes RNA strands from a DNA template during transcription.

Amino acid

The building blocks of proteins, encoded by codons in mRNA.

Polypeptide chain

A chain of amino acids linked by peptide bonds, forming a protein.

Eukaryotes

Organisms whose cells contain a nucleus and other organelles.

Prokaryotes

Single-celled organisms without a nucleus, such as bacteria.

Replication fork

The Y-shaped region where DNA is split into two strands during replication.

Transcription bubble

The region where DNA strands unwind and RNA synthesis occurs during transcription.

Nucleotide

The basic building block of DNA and RNA, consisting of a sugar, phosphate group, and base.

Base pairing rules

Rules dictating the pairs of nitrogenous bases in DNA/RNA (A-T, C-G, A-U in RNA).

Chromosome

A long DNA molecule containing many genes, found in the nucleus of eukaryotic cells.

Genome

The complete set of genetic information in an organism.

Mutation

A change in the DNA sequence that can lead to variation in genes.

Phenotype

The physical and physiological traits of an organism, determined by its genotype.

Genotype

The genetic constitution of an organism, comprising its alleles.

Allele

Different versions of a gene that can exist at a specific locus.

RNA splicing

The process of removing introns and joining exons in pre-mRNA.

5’ untranslated region (5’ UTR)

The region of mRNA that precedes the start codon; not translated into protein.

3’ untranslated region (3’ UTR)

The region of mRNA that follows the stop codon; involved in regulation of translation.