Week 10 BIO1011

Reading frame

the correct grouping of mRNA nucleotides into consecutive non-overlapping codons from a start codon.

Translation

the process by which a cell reads a mature mRNA sequence to form a polypeptide.

Central dogma

the flow of genetic information from DNA to RNA to protein.

Transcription

the process of using DNA as a template to make a complementary RNA molecule.

mRNA

messenger RNA that carries the codon sequence used to specify amino acid order.

Codon

a group of three adjacent nucleotides in mRNA that specifies an amino acid or stop signal.

Genetic code

the correspondence between codons and amino acids.

Redundant code

the fact that more than one codon can specify the same amino acid.

Degenerate code

another term for the genetic code being redundant.

Start codon

the codon that begins translation

Stop codon

a codon that ends translation and releases the polypeptide

AUG

the start codon and codon for methionine.

UAA

a stop codon.

UAG

a stop codon.

UGA

a stop codon.

Ribosome

the cellular structure that reads mRNA and builds a polypeptide.

Small ribosomal subunit

the ribosomal subunit that binds mRNA first.

Large ribosomal subunit

the ribosomal subunit that contains the A

A site

the aminoacyl site where a charged tRNA enters the ribosome.

P site

the peptidyl site where the growing polypeptide is held.

E site

the exit site where spent tRNA leaves the ribosome.

tRNA

transfer RNA that matches an anticodon to an mRNA codon and brings the correct amino acid.

Anticodon

the three-nucleotide sequence on tRNA that base-pairs with an mRNA codon.

Charged tRNA

a tRNA molecule with its amino acid attached.

Uncharged tRNA

a tRNA molecule without an amino acid attached.

Charging

the process of attaching the correct amino acid to the 3' end of a tRNA.

Aminoacyl-tRNA synthetase

the enzyme that attaches the correct amino acid to the correct tRNA.

CCA end

the three-base sequence at the 3' end of tRNA where the amino acid is attached.

Polypeptide

a chain of amino acids joined together during translation.

Protein folding

the process by which a polypeptide forms its functional shape.

Quaternary protein structure

the arrangement of multiple polypeptide subunits in one protein.

3D structure

the folded tertiary shape of a protein.

2D structure

the linear amino acid sequence or simple representation of protein structure.

Eukaryotic ribosome

a larger ribosome found in eukaryotic cells.

Prokaryotic ribosome

a smaller ribosome found in bacteria.

Open reading frame

the continuous stretch of codons from start codon to stop codon.

mRNA processing

the steps that produce mature mRNA before translation in eukaryotes.

Endomembrane system

the membrane network involved in making

Rough endoplasmic reticulum

the organelle where ribosomes make proteins destined for secretion or membranes.

Golgi apparatus

the organelle that modifies

Vesicle

a small membrane-bound sac that transports proteins between organelles.

Functional protein

a protein that has been correctly made

Translation initiation

the stage of protein synthesis where the ribosome assembles on mRNA at the start codon.

Translation elongation

the stage where amino acids are added one by one to the growing polypeptide.

Translation termination

the stage where a stop codon ends protein synthesis.

Point mutation

a mutation where one base pair is replaced by another.

Nucleotide substitution

another term for a point mutation.

Silent mutation

a point mutation that changes a codon but not the amino acid.

Missense mutation

a point mutation that changes one amino acid to another.

Nonsense mutation

a point mutation that creates a stop codon.

Insertion mutation

a mutation where one or more nucleotides are added to DNA.

Deletion mutation

a mutation where one or more nucleotides are removed from DNA.

Frameshift mutation

an insertion or deletion that shifts the reading frame.

In-frame insertion

an insertion of nucleotides in multiples of three that adds amino acids without shifting the reading frame.

In-frame deletion

a deletion of nucleotides in multiples of three that removes amino acids without shifting the reading frame.

Non-coding DNA

DNA that does not code for protein and is usually less affected by coding-region mutations.

Coding DNA

DNA sequence that is transcribed and translated into protein.

Mutation

a change in the nucleotide sequence of a genome.

Somatic cell mutation

a mutation in body cells that is not passed to offspring.

Germ cell mutation

a mutation in reproductive cells that can be passed to offspring.

Mutation repair

cellular mechanisms that detect and correct DNA damage or replication errors.

Transposable element

a movable DNA sequence that can insert into or near genes.

Transposon

another term for a transposable element.

Tertiary structure

the overall 3D folding of a single polypeptide chain.

Binding site mutation

a mutation that alters a protein’s ability to bind a substrate

Truncation

shortening of a protein due to an early stop codon.

Phenotype effect

the visible or functional outcome of a mutation in a cell or organism.

Single-nucleotide polymorphism

a DNA site where a nucleotide differs among individuals in a population.

PCR

polymerase chain reaction

Denaturation

the PCR step where DNA strands are separated by heating.

Annealing

the PCR step where primers bind to the template DNA.

Extension

the PCR step where DNA polymerase builds new DNA strands.

Primer

a short DNA sequence that starts DNA synthesis in PCR.

DNA polymerase

the enzyme that synthesizes new DNA strands.

Exponential amplification

the rapid doubling of DNA amount during PCR.

Gel electrophoresis

a method used to separate DNA fragments by size.

Restriction enzyme

an enzyme that cuts DNA at a specific recognition sequence.

EcoRI

a commonly used restriction enzyme.

Restriction site

the specific DNA sequence recognized and cut by a restriction enzyme.

Sticky ends

short single-stranded overhangs created by some restriction enzymes.

DNA ligase

the enzyme that joins DNA fragments together.

Recombinant DNA

DNA formed by combining genetic material from different sources.

Molecular cloning

the process of making many copies of a DNA fragment using a vector and host cell.

Cloning vector

a DNA molecule used to carry and replicate foreign DNA.

Plasmid

a circular DNA molecule used as a common cloning vector in bacteria.

E. coli

a bacterium commonly used as a host for cloning and DNA amplification.

Bacterial transformation

the process of introducing foreign DNA into bacteria.

Gene cloning

the production of many copies of a specific gene or DNA fragment.

Complementary DNA

cDNA made from mRNA using reverse transcriptase.

Reverse transcriptase

the enzyme that makes DNA from an RNA template.

Dideoxynucleotides

chain-terminating nucleotides used in DNA sequencing.

DNA sequencing

determining the order of nucleotides in a DNA molecule.

CRISPR/Cas9

a gene-editing system that allows targeted DNA modification.

Genetic engineering

the direct manipulation of DNA for research or practical use.

Recombinant insulin

insulin produced using genetically engineered organisms.