DNA and RNA Structure and Function

Vocabulary flashcards related to DNA and RNA structure, function, and related molecular biology concepts.

DNA

A double-stranded helical molecule composed of nucleotide monomers that serves as the molecule of heredity.

RNA

Involved in information transfer related to protein synthesis. Can also be the hereditary molecule in some viruses.

Nitrogenous Base Pairing

Adenine (A) binds with Thymine (T), and Guanine (G) binds with Cytosine (C).

Antiparallel Strands

The two strands of DNA run in opposite directions (5' to 3').

Replication

The process by which DNA is copied, using each strand as a template for synthesizing a complementary strand.

Mutation

A change in the DNA sequence that can lead to evolution.

Semiconservative Replication

Each daughter DNA double helix consists of one conserved strand from the parent molecule and one newly synthesized strand.

Helicase

Enzyme that unwinds the double-stranded DNA at the origin of replication.

DNA Polymerase

Enzyme that adds new nucleotides to the 3' end of a growing strand during replication.

Primase

Enzyme that synthesizes RNA primers to provide an existing strand for DNA polymerase to start adding nucleotides.

RNA Primers

Short sequences of RNA that are complementary to the template strand, used to initiate DNA synthesis.

Single-Strand Binding Proteins

Proteins that prevent the DNA double helix from rewinding during replication.

Leading Strand

The strand of DNA that is continuously synthesized during replication.

Lagging Strand

The strand of DNA that is discontinuously synthesized in segments known as Okazaki fragments.

Okazaki Fragments

Short sequences of DNA that are discontinuously synthesized on the lagging strand.

DNA Ligase

Enzyme that seals the gaps between DNA fragments with sugar-phosphate bonds.

Central Dogma of Molecular Genetics

The flow of genetic information: DNA → RNA → Protein.

Gene

A sequence of DNA nucleotides that codes for RNA, which in turn codes for protein.

mRNA (messenger RNA)

Carries instructions from DNA to ribosomes.

rRNA (ribosomal RNA)

Forms the catalytic part of ribosomes and binds amino acids during protein synthesis.

tRNA (transfer RNA)

Brings specific amino acids to ribosomes for protein synthesis.

RNA Polymerase

Enzyme that transcribes DNA into RNA.

Template Strand

The strand of DNA that is transcribed into RNA.

Coding Strand

The strand of DNA that has the same nucleotide sequence as the mRNA (except T is replaced by U).

Polysomes

Multiple ribosomes reading the same RNA strand in prokaryotes.

Codon

A group of three RNA nucleotides that code for one amino acid.

Anticodon

A sequence of three nucleotides in tRNA that binds to a complementary codon in mRNA.

Ribosome

The site of protein synthesis, where mRNA is translated into a sequence of amino acids.

Operon

A prokaryotic system of gene regulation with control elements that allow for gene regulation.

Promoter

A DNA sequence where RNA polymerase binds to initiate transcription.

Operator

A DNA sequence where a repressor protein binds to regulate the operon.

Regulatory Gene

A gene that codes for a regulatory protein, often a repressor protein.

Inducible Operon

An operon that is usually off but can be turned on (e.g., lac operon).

Repressible Operon

An operon that is usually on but can be turned off (e.g., trp operon).

Epigenetics

Changes in DNA expression involving reversible chemical modifications of DNA or modifications in DNA packaging without altering the nucleotide sequence.

Introns

Intervening sequences of DNA within genes that are transcribed into pre-mRNA but not translated into protein.

Exons

DNA sequences that become RNA and are ultimately translated into protein.

Alternative Splicing

A process where exons are spliced together in different ways to produce multiple protein versions from a single pre-mRNA transcript.

MicroRNA (miRNA)

Small RNAs involved in post-transcriptional control of gene expression through RNA silencing.

Point Mutation

A change in a single nucleotide.

Silent Mutation

A mutation that results in the same amino acid being coded for.

Missense Mutation

A mutation that changes one amino acid to another.

Nonsense Mutation

A mutation that inserts a stop codon instead of an amino acid.

Frameshift Mutation

Occurs when a deletion or insertion alters the reading frame of codons.

Germline Mutation

A mutation in cells that produce gametes (sperm/egg) and can be inherited.

Somatic Mutation

A mutation that emerges in some tissue during the course of development or adult life and is not passed on to future generations.

Horizontal Gene Transfer

A process where one organism transfers genetic material to another organism that is not its offspring.

Bacterial Conjugation

Transfer of a plasmid from one bacterium to another via a pilus.

Viral Transduction

Transfer of genes between organisms via viruses.

Recombinant DNA

DNA that has been artificially combined from more than one source.

Restriction Enzymes

Enzymes that cut DNA at specific sequences called restriction sites.

Gel Electrophoresis

A technique used to sort molecules by size and/or electrical charge.

PCR (Polymerase Chain Reaction)

A cell-free technique for cloning DNA in a test tube.

Reverse Transcriptase

An enzyme that creates a DNA copy of RNA.

What is the lactose inducible operon?

The lactose inducible operon, also known as the lac operon, is a set of genes in bacteria that are regulated together, allowing the organism to metabolize lactose when it is present in the environment. It includes structural genes that encode enzymes needed for lactose utilization, and it is activated in the presence of lactose.

What is the trp operon?

The trp operon is a group of genes in bacteria that are responsible for the biosynthesis of tryptophan. It is a negative feedback system that is normally active, and it is regulated such that if tryptophan levels are high, the operon is turned off to prevent the overproduction of tryptophan

What is the effect of mutations in sickle cell anemia?

Mutations in sickle cell anemia result in a change in the hemoglobin protein, leading to the production of abnormal hemoglobin (HbS). This causes red blood cells to take on a sickle shape, which can block blood flow, cause pain, increase risk of infection, and lead to various complications such as anemia and organ damage