How can we help?

You can also find more resources in our Help Center.

Biology Chapter 6, 7, 8

STUDY
PLAY
Transcription
DNA is copied into a complementary mRNA, then the mRNA IS delivered to the ribosomes in the cytoplasm
Translation
Ribosomes translate the message in the mRNA into polypeptide chains, then into proteins
mRNA (messenger RNA)
Intermediary between DNA and ribosomes, translated into proteins by ribosomes
tRNA (transfer RNA)
Transfers appropriate amino acids to ribosomes as they synthesize proteins
rRNA (ribosomal RNA)
Binds with proteins to form ribosomes
Transcription includes
Initiation, elongation, and termination.
Promoter regions
Areas of the DNA located "upstream" from the gene that is to be copied
Transcription initiation
RNA polymerase binds to the promoter region at the TATA box and begins uncoiling
TATA box
Promoter region that enables binding of RNA polymerase
RNA polymerase
An enzyme that reads a DNA strand and creates a complementary RNA strand
Transcription elongation
RNA polymerase makes a copy of the template strand in the 5 prime to 3 prime direction
Template strand
The DNA strand that is copied into an mRNA molecule during gene transcription
Coding Strand
The DNA strand that is not being copied, but contains the same sequence as the new RNA molecule
Transcription termination
Transcription is terminated when the RNA polymerase recognizes a termination sequence
Termination in prokaryotes
Transcription may be stopped by a protein binding the mRNA, or by the mRNA twisting itself into a loop
Termination in eukaryotes
A termination sequence may be a string of adenines, which will bind to the proteins and transcription stops
Capping & tailing
Poly-A tail is added to the 3 prime end of the mRNA to protect it from being digested or damaged. The 5 prime cap is also added.
Poly-A tail
A chain of adenine nucleotides
5 prime cap
A chain of seven guanines used at the initial site for attachment of mRNA's and the ribosomes
Splicosomes
An enzyme-protein complex that removes the introns from the mRNA
Introns
Non-coding sections of the mRNA
Exons
Coding sections of the mRNA
Alternative splicing
A process that produces different mRNA's from the removal of introns and combining of exons. This allows more than one polypeptide to be made from one gene.
Anticodon
The complementary sequence of base pairs on a tRNA that corresponds to the codons of the mRNA.
Pre-mRNA
Precursor mRNA are made of exons and introns. Are the immature and vulnerable single strand mRNA
Codon
A group of three base pairs that code for an individual amino acid
Wobble hypothesis
States that the rules of base pairing are relaxed at the third position, so that a base can pair with more than one complementary base
Start codon
A codon that initiates translation by signalling the start of a polypeptide.
Stop codon
A codon that causes the ribosome to terminate translation by signalling the end of a polypeptide
Translation
During translation amino acids are linked together to form a polypeptide chain which will later be folded into a protein.
Ribosome
Consists of the A site, P site, E site and two subunits
A site
Where the incoming aminoacyl-tRNA binds to the mRNA
Aminoacyl-tRNA
tRNA together with its amino acid
P site
Where the growing polypeptide chain is bound
E site
Where the empty tRNA exits and released
Aminoacylation
Process where the tRNA is bound to its corresponding amino acid
Translation initiation
Ribosomes bind to the mRNA, recognizing the 5 prime cap. Meth-tRNA starts the translation by joining the small ribosomal subunit and scanning the mRNA until it reaches the start codon. Large ribosomal subunits then bind to complete the ribosome
Translation elongation
A new tRNA+amino acid enters the ribosome, at the next codon downstream of the current codon. If the anticodon matches the mRNA codon, base pairs and the ribosome can link the two amino acids together. The empty tRNA moves to the E site and is released.
Translation termination
Termination of a polypeptide chain occurs when the ribosome encounters a stop codon at the A site. Polypeptide is released and ribosomal subunits separate.
Release factor
Protein that aids in the releasing of the polypeptide chain
Polysome
A complex formed when multiple ribosomes attach to the same mRNA to facilitate rapid translation
Housekeeping genes
Genes that are constantly needed in the cell
Transcription factors
Proteins which activate genes when required
Gene regulation
Turning off and on of genes depending on their requirements
Operon
A cluster of genes on a bacterial chromosome that is connected by one promoter and one operator
Negative feedback
The result of the process influences the operation at the process itself
Promoter
Where DNA transcription begins
Operator
Sequence of bases that controls transcription
Lac operon
Operon required for the transport and metabolism of lactose
Metabolic genes
LacZ, LacY, LacA
LacZ
Gene that codes for the enzyme that breaks down lactose
LacY and LacA
Genes that code for the uptake of lactose in the cell
Repressor protein
Binds to the operator and blocking the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes
Trp operon
A group of genes that code for the components for production of tryptophan