AP Bio Vocab Unit 6

Vocabulary flashcards for key terms in molecular biology.

Activator

A substance that initiates a physiological activity.

Alternative splicing

A process that results in a single gene coding for multiple proteins.

Anticodon

A sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA.

Antiparallel

A structural arrangement in which two strands of a DNA molecule are aligned parallel to each other, but running in opposite directions.

Bacteria

Single-celled microorganisms that have cell walls but lack organelles and an organized nucleus.

Bacterial transformation

The genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material (DNA) from its surroundings through the cell membrane(s).

Bacteriophage virus

A virus that infects and replicates within bacteria and archaea.

Biotechnology

The exploitation of biological processes for industrial and other purposes, especially the genetic manipulation of microorganisms for the production of antibiotics, hormones, etc.

Central dogma

The process by which the instructions in DNA are converted into a functional product, such as a protein.

Chargaff's rule (base pair rule)

In DNA, the proportion of adenine equals that of thymine and the proportion of guanine equals that of cytosine.

Chromatin

The material of which chromosomes are made other than DNA.

Circular chromosome

A chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a circle.

Cloning

The production of identical copies of DNA, cells, or organisms.

Coding strand (sense/complementary)

The DNA strand that has the same sequence as the mRNA, except that thymine is substituted for uracil in DNA.

Codon

A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

Conjugation

The process by which one bacterium transfers genetic material to another through direct contact.

CRISPR-Cas9 system

A revolutionary gene editing technology.

Deletion (frameshift)

A mutation in which one or more nucleotides are removed from a DNA sequence.

Differential gene expression

The process by which cells selectively activate specific genes, leading to cell specialization.

Directionality

The direction in which DNA and RNA are synthesized, conventionally expressed as 5' to 3'.

DNA

Deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main component of chromosomes. It is the carrier of genetic information.

DNA microarray

A collection of microscopic DNA spots attached to a solid surface.

DNA polymerase

An enzyme that synthesizes DNA molecules from deoxyribonucleotides, using a DNA template.

DNA replication

The process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.

DNA sequencing

The process of determining the precise order of nucleotides within a DNA molecule.

Double helix

The structure formed by double-stranded molecules of nucleic acids such as DNA.

Elongation

The lengthening of a polypeptide chain during translation.

Enhancer region

A short region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur.

Epigenetics

The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.

Euchromatin

A lightly packed form of chromatin that is rich in genes, and is often under active transcription.

Evo-devo

A field of biological research that compares the developmental processes of different organisms to infer the ancestral relationships between them and to understand how developmental processes evolve.

Exon

A segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence.

Frameshift mutation

A mutation in which one or more nucleotides are inserted or deleted from a DNA sequence, resulting in a shift in the reading frame.

Gel electrophoresis

A laboratory method used to separate mixtures of DNA, RNA, or proteins according to their size and charge.

Gene expression

The process by which information from a gene is used in the synthesis of a functional gene product.

Genetic engineering

The direct manipulation of an organism's genes using biotechnology.

Genetic modification

A process that alters the genetic material of an organism.

Genetically modified organism (GMO)

An organism whose genetic material has been altered using genetic engineering techniques.

Genome

The complete set of genes or genetic material present in a cell or organism.

Genotype

The genetic constitution of an individual organism.

GTP cap

A modified guanine nucleotide that is added to the 5' end of a messenger RNA molecule.

Helicase

An enzyme that unwinds the DNA double helix during replication.

Heterochromatin

A tightly packed form of chromatin that is generally not transcribed.

Histone

Proteins around which DNA can wind for compaction and gene regulation.

Histone acetylation

The attachment of acetyl groups to histone proteins, resulting in a more open chromatin structure and increased gene expression.

Histone methylation

The addition of methyl groups to histone proteins, resulting in a more condensed chromatin structure and decreased gene expression.

Homeotic genes

Genes that regulate the development of anatomical structures in various organisms.

Horizontal gene transfer

The transfer of genetic material between organisms other than by descent.

Hox genes

A subset of homeotic genes, which are a group of related genes that control the body plan of an embryo along the anterior-posterior (head-tail) axis.

Inducer

A molecule that initiates gene expression.

Inducible operon (lac)

A gene system that is normally 'off' but can be 'turned on' when a specific molecule is present.

Insertion (frameshift)

A mutation in which one or more nucleotides are inserted into a DNA sequence.

Intron

A segment of a DNA or RNA molecule that does not code for proteins and interrupts the sequence of genes.

Lagging strand

The DNA strand that is synthesized discontinuously during replication, away from the replication fork.

Leading strand

The DNA strand that is synthesized continuously during replication, towards the replication fork.

Ligase

An enzyme that joins DNA fragments together.

Linear chromosome

A chromosome with a structure that consists of a continuous line.

micro RNAs

Small non-coding RNA molecules that regulate gene expression by binding to mRNA molecules.

Missense mutation (substitution)

A point mutation in which a single nucleotide change results in a codon that codes for a different amino acid.

Morphogenesis

The biological process that results in the shape of an organism or part of an organism.

mRNA

Messenger RNA, a type of RNA that carries genetic information from DNA to ribosomes for protein synthesis.

Mutagen

A physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level.

Mutation (positive, negative, neutral)

A change in the nucleotide sequence of a gene or DNA molecule.

Nonsense mutation (substitution)

A point mutation in which a codon that codes for an amino acid is changed to a stop codon.

Nucleoid region

A region within bacteria visible in electron micrographs that contains the cell's DNA.

Nucleosome

A structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones.

Nucleus

A membrane-bound organelle in eukaryotic cells that contains the cell's chromosomes.

Okazaki fragments

Short DNA fragments synthesized on the lagging strand during DNA replication.

Operator region

A region of DNA that controls the expression of a gene or group of genes.

Origin of replication

The site where DNA replication begins.

Phenotype

The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Plasmid

A small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA.

Point mutation

A mutation affecting only one or very few nucleotides in a gene sequence.

Poly-A tail

A sequence of adenine nucleotides added to the 3' end of mRNA molecules during RNA processing.

Polymerase Chain Reaction (PCR)

A laboratory technique used to amplify specific DNA sequences.

Promoter region

A region of DNA where RNA polymerase begins transcription.

Protein synthesis

The synthesis of proteins from mRNA.

Reading frame

The order in which nucleotides are read during translation.

Regulatory protein

A protein that controls the rate of gene transcription by binding to specific DNA sequences.

Replication bubble

The process of copying a double-stranded DNA molecule to produce two identical DNA molecules.

Replication fork

A structure that forms during DNA replication, where the DNA is unwound and the new strands are synthesized.

Repressible operon (trp)

A gene system that is normally 'on' but can be 'turned off' when a specific molecule is present.

Repressor

A protein that binds to the operator and blocks the attachment of RNA polymerase to the promoter, preventing transcription of the genes.

Restriction enzymes

Enzymes that cut DNA molecules at specific nucleotide sequences.

Restriction site

A specific sequence on a DNA molecule where a restriction enzyme cuts.

Retrovirus

A virus that contains RNA as its genetic material and uses reverse transcriptase to synthesize DNA.

Reverse transcriptase

An enzyme that synthesizes DNA from an RNA template.

RNA modifications

The modification of RNA after transcription.

RNA polymerase

An enzyme that synthesizes RNA from a DNA template.

RNA primers (primase)

Short RNA sequences that initiate DNA replication.

RNAi

RNA interference, a biological process in which RNA molecules inhibit gene expression or translation, by neutralizing targeted mRNA molecules.

rRNA

Ribosomal RNA, a type of RNA that is a component of ribosomes.

Semiconservative replication

The process of DNA replication in which each of the two original DNA strands serves as a template for a new strand, resulting in two DNA molecules, each with one original and one new strand.

Silent mutation (substitution)

A mutation that does not significantly alter the phenotype of the organism in which it occurs.

Spliceosome

A complex of proteins and RNA that splices pre-mRNA.

Sticky end

An end of a DNA molecule with unpaired nucleotides that can form hydrogen bonds with a complementary sticky end.

Structural genes

Genes that code for proteins that are not involved in regulation.

Subsitution

A type of mutation in which one nucleotide is replaced by another.

Sugar-phosphate backbone

The backbone of a DNA or RNA molecule, consisting of alternating sugar and phosphate groups.

TATA box

A DNA sequence within the promoter region that is the binding site for a transcription factor called TATA-binding protein (TBP).