chapter 07

Genome

The complete set of genetic material in an organism, including all of its genes and nucleic acid sequences

Gene

A segment of DNA that codes for a specific polypeptide or functional RNA molecule

Genotype

The genetic composition of an organism, representing its specific set of genes

Phenotype

The observable physical traits and functions of an organism, determined by its genotype

Central Dogma

The flow of genetic information from DNA to RNA to protein

DNA Replication

The process of making an exact copy of DNA, ensuring genetic information is passed during cell division

Semiconservative Replication

Each new DNA molecule consists of one original (parental) strand and one newly synthesized strand

Helicase

An enzyme that unwinds the DNA double helix during replication

DNA Polymerase

The enzyme that synthesizes new DNA strands by adding nucleotides complementary to the template strand

Okazaki Fragments

Short DNA fragments synthesized discontinuously on the lagging strand during replication

Primase

An enzyme that synthesizes RNA primers needed to start DNA synthesis

Ligase

An enzyme that joins Okazaki fragments together to form a continuous DNA strand

mRNA

Messenger RNA; carries genetic information from DNA to the ribosome for protein synthesis

tRNA

Transfer RNA; brings the correct amino acid to the ribosome during translation

rRNA

Ribosomal RNA; structural and enzymatic component of the ribosome involved in assembling proteins

Codon

A three-nucleotide sequence in mRNA that specifies an amino acid or stop signal

Anticodon

A three-nucleotide sequence in tRNA complementary to the codon in mRNA

Operon

A group of genes transcribed together along with their regulatory elements in prokaryotes

Promoter

A DNA sequence where RNA polymerase binds to start transcription

Operator

A DNA region within the operon where regulatory proteins can bind to control gene expression

Repressor

A protein that binds to the operator to halt transcription in an operon

Inducer

A molecule that inactivates a repressor, allowing gene expression in an inducible operon

Mutation

A change in the nucleotide sequence of DNA, which can affect gene function

Point Mutation

A mutation affecting a single nucleotide pair in DNA

Frameshift Mutation

A genetic mutation caused by insertions or deletions that change the reading frame of the gene

Missense Mutation

A point mutation resulting in a codon that codes for a different amino acid

Nonsense Mutation

A mutation that turns a codon into a stop codon, prematurely ending translation

Silent Mutation

A mutation that does not change the amino acid sequence of the resulting protein

Mutagen

An agent, physical or chemical, that increases the rate of mutations

Transformation

The uptake and incorporation of naked DNA fragments from the environment by a bacterial cell

Transduction

The transfer of genetic material from one bacterium to another via a bacteriophage

Conjugation

The direct transfer of DNA from one bacterial cell to another via cell-to-cell contact, usually by a pilus

Plasmid

A small, circular, independently replicating DNA molecule found in bacteria

Transposon

A segment of DNA that can move from one location to another within or between DNA molecules

Horizontal Gene Transfer

The movement of genetic material between organisms other than by vertical transmission from parent to offspring&

Spliceosome

prokaryotic mRNA

Polycystronic: codes for many proteins

Eukaryotic mRNA

Monocystronic: each mRNA codes for one region