Chapter 14 Flashcards
Transcription
The first step of gene expression, in which a particular segment of DNA is copied into RNA by the enzyme RNA polymerase
-Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language
Base Sequence
The order of nucleotide bases in a DNA molecule
RNA
The nucleic acid that is used in key metabolic processes for all steps of protein synthesis in all living cells and carries the genetic information of many viruses
mRNA
A large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression
tRNA
- Transfer ribonucleic acid
- a type of RNA molecule that helps decode a messenger RNA (mRNA) sequence into a protein
rRNA
A molecular component of a ribosome, the cells essential protein factory
- Ribosomal RNA
- rRNA does not make proteins, but makes polypeptides (assemblies of amino acids) that go to make up proteins
Uracil
One of the four nucleobases in the nucleic acid of RNA
RNA polymerase
An enzyme that produces primary transcript RNA
Promoter
DNA sequences that define where transcription of a gene by RNA polymerase begins
Pre-mRNA processing
- includes two different types of segments: exon and introns
- exons are segments that are retained in the final mRNA, where introns are removed in a process called splicing
Exons
Any nucleotide sequence encoded by a gene that remains present within the final mature RNA product of that gene after introns have been removed by RNA splicing
Codons
A sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
Genetic code
The set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells
Anticodon
A sequence of three bases that are complementary to a codon in the messenger RNA
-during translation, the bases of the anticodon form complementary base pairs with the bases of the codon by forming the appropriate hydrogen bonds
Amino acids
The building blocks of all biological proteins
- amino acids link together by peptide bonds in a particular order as defined by genes
- genes are translated by RNA to amino acid chains; the length and order of the amino acid chain then dictates the three-dimensional structure of a polypeptide bond
Peptide bond
- a chemical bond Formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (h2o)
- this dehydration synthesis reaction (aka a condensation reaction), and usually occurs between amino acids
Polypeptide
Chains of amino acids
-proteins are made up of one or more polypeptide molecules
Initiation
The small subunit of the ribosome binding to the 5’ end of mRNA with the help of initiation factors (IF)
Ribosome
A sphere-shaped structure within the cytoplasm of a cell that is composed of RNA and protein and is the site of protein synthesis
Elongation
The stepwise addition of amino acids to the growing protein chain
Termination
Stop of mRNA synthesis at the terminator site
Translation
The process in which cellular ribosomes create proteins
-in translation, mRNA (produced by transcription from DNA) is decided by a ribosome to produce a specific amino acid chain (polypeptide)
Gene
The molecular unit of heredity of a living organism
-it is used extensively by the scientific community as a name given to some stretches of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA) that code for a polypeptide or for an RNA chain that has a function in the organism
Alternative splicing
A regulated process during gene expression that results in a single gene coding for multiple proteins
-in this process, particular exons of a gene may be included within or excluded from the final, processed mRNA produced from that gene
