bsc2010 ch 16 & 17 transcription

central dogma

dna → mrna via transcription, mrna → protein via translation

genetic code

this is made up of pyrimidines and purines linked by proteins

codon

mRNA, made 5’→3’, follows base-pairing rules (GC, UT, TA)

RNA polymerase

enzyme that performs transcription, attaches to the 3’ end; allows for the lack of a primer (like DNA replication needs)

transcription factors

in eukaryotic cells, these are used to recognize and bind to the promoter

sigma

in prokaryotic cells, this is used to recognize and bind to the promoter

promoter

signals the start point for transcription of a gene, made of a specific base pair

• TATA box - several AT base pairs

promoter vs start codon

promoters are regions of DNA where transcription starts (ex. the 5’ end), while start codons are the first bases to be translated on an mRNA (ex. start codon AUG)

terminator

at the end of a gene, these cause transcription to stop

template strand

directs sequence of RNA by providing complementary bases to match with the new RNA nucleotides, with it’s opposite being the coding strand

3’ end

when RNA is transcribed, nucleotides are added to the ___________

• this is also where the poly-a tail goes

5’ cap

this end receives a modified nucleotide

poly-a tail

at the 3’ end of the mRNA molecule, this is a structure made of many amino acids stacked together

splicing

removing introns and joining exons to mature mRNA

• mRNA → continous coding sequence

introns

when mRNA is matured/spliced, these are taken out

exons

when mRNA is spliced, these are kept and joined together

tRNA

transfer RNA, aids the cell’s ability to translate an mRNA message into a protein

• each one of these has an anticodon on the other end, with anticoding having a complementary codon on the mRNA

• they also connect the right amino acid to the right codon on mRNA

• tRNA anti-codon ←→mRNA codon

anticodon

base-pairs with complementary codons on mRNA

• every __________ pairs with a codon on the mRNA

amino-acyl tRNA synthetase

links the right amino acids with the right tRNA

ribosomes

__________ are made out of ______________ RNA and proteins, consisting of a larger and smaller subunit

• brings tRNAs with mRNA codons together → protein synthesis

• the large subunits contain 3 binding sites for tRNA (APE)

translation

mRNA → proteins

a-site

this location in the ribosome’s large subunit holds the tRNA that carries the next amino acid to be added to the chain

p-site

this location in the ribosome’s large subunit holds the tRNA that carries the growing polypeptide chain

e-site

this location in the ribosome’s large subunit is where the tRNAs leave the ribosome

APE

abbreviation for a-site, p-site, e-site

start codon

the methionine tRNA attaches at the _______________

• consistent codon that initiates translation and sets the reading frame

stop codon

termination occurs when a ________________ in the mRNA reaches the A site of the ribosome

peptide bond

during elongation on translation, this type of bond is formed

point mutations

changes in just one base pair of a gene

nonsense

a _____________ mutation is where one of the amino acids are changed into a stop codon, and nearly always leads to a nonfunctional protein

silent

a __________ mutation is where there’s no effect on the amino acids produced by a codon due to the redundancy in the genetic code

• as a product, the code is different but you still get the same amino acids as if it were normal

missense

a ___________ mutation is where amino acids are still coded for, but it’s not the right one

insertions

a type of frameshift mutation that often has the most disastrous effect on the resulting protein more than substitutions

• adds a base-pair

deletions

a type of frameshift mutation that often has the most disastrous effect on the resulting protein more than substitutions

• removes a base-pair

frameshift mutation

insertion or deletion of nucleotides may alter the reading frame and thus causing the most disaster in the proteins, being known as a _____________________

prokaryotes

in ____________, translation and transcription happen simultaneously

spliceosomes

enzyme that carries out most RNA splicing, with some RNA splicing happening spontaneously

UTR

untranslated region of the mRNA molecule, acts as a buffer to protect the coding region

coding strand

the complementary base strand for the template strand

initiation

the first stage of translation; methionine tRNA binds to the start codon (AUG)

elongation

the second stage of translation; amino acids are joined together

• amino acids are added one by one to the last AA placed down

  1. tRNA binds to A-site

  2. peptide bond forms at P-site

  3. tRNA moves from A-P-E

termination

the last stage of translation; stop codon is reached and the release factor binds

release factor

during the termination of translation, the A site accepts a protein

• instead of an amino acid being joined to the chain, a water molecule is joined instead

not

mutations may ___ cause disease or disorder in these locations

• a non-coding region of DNA (UCR) aka buffer

• in an intron

• mutations that cause no change in the amino acids

• mutations in body cells cannot be passed to offspring

• mutations in sex cells can be passed to offspring