transcription and translation Flashcards
What is the purpose of transcription?
Converts message in a gene into a single stranded RNA molecule
where within a eukaryotic cell does transcription take place
nucleus
Describe the structure of RNA
single stranded, single nucleobases on the strand (no base pair), backbone held by covalent bonds
RNA monomer
nucleotides
what makes up RNA nucleotides
ribose sugar, phosphate group, nitrogenous base (Adenine, uracil, cytosine, guanine)
DNA sugar vs RNA sugar
DNA- deoxyribose, RNA- ribose
DNA # of strand vs RNA
DNA- double stranded, RNA- single stranded
Base pairing rules for RNA compared to DNA
DNA- adenine pairs with thymine and cytosine with guanine, RNA-adenine pairs with uracil and cytosine still with guanine
3 types of RNA
mRNA, tRNA, rRNA
what is mRNA function
messenger RNA, carries the instructions from DNA out of nucleus and into cyto, hold the code for building proteins
tRNA function
transfer RNA, brings and ensures correct amino acids from the cytoplasm to a ribosome to build proteins
rRNA function
ribosomal RNA, forms part of ribosomes where proteins are made,bond amino acids together resulting in the release of polypeptide
what is the first step of transcription
Initiation: RNA polymerase is attached and aligned to DNA w/ the help of other proteins, forming a transcription complex, the start of a gene is located on the DNA molecule and transcription complex rna polymerase unwinds and unzips segment of DNA (about 10-20 nucleotides)
what is 2nd step of transcription
Elongation: RNA polymerase binds complementary free floating RNA nucleotides to one strand of the DNA template, forming a strand of RNA. Newly formed RNA peels away (5’-3’) from DNA template strand as it is made, RNA polymerase only synthesizes RNA in the 5’ to 3’ direction
what is the 3rd step of transcription
Termination: A sequence in DNA signals the end of a gene, the RNA strand detaches completely. DNA winds back up, RNA polymerase is released and transcription complex disassembles.
direction transcription occurs
5’-3’
end result of transcription
A single stranded of RNA molecule
What happens to end product of transcription?
mRNA carries the genetic info from DNA to ribosomes for protein synthesis
What enzyme(s) are involved, and what do they do?
RNA polymerase- unwinds and unzips DNA double helix, signals start of the gene, binds free floating RNA nucleotides to DNA template, releases newly formed RNA molecule and detaches from DNA,
purpose of translation
synthesizing proteins, Converting an mRNA message into a polypeptide (protein)
where within a eukaryotic cell does translation take place
cytoplasm
Describe how the correct amino acids are brought to the ribosome in the correct order in translation
The codons give a specific order to which the matching anti-codons will match up, the tRNA with the matching codon will have the corresponding amino acid, so the sequence of codons ensure the correct order
describe the role of tRNA in translation
tRNA- transfer RNA, carries AA from cytoplasm to ribosome for protein synthesis, responsible for the anti codons and carrying the corresponding amino acids
describe the role of mRNA in translation
mRNA- acts as a template for the tRNA to build amino acids on, has the sequence of codons that the tRNA needs
describe the role of rRNA in translation and describe its large subunit and small subunit
rRNA - site of protein synthesis, large subunit has 3 binding sites for tRNA , small subunit binds to mRNA
first step of translation
initiation- small ribosomal subunit moves along mRNa to find start codon, the matching anticodon forms a hydrogen bond, large subunit ensures that it is in the middle of binding site (P)
3rd step of translation
once the stop codon is reached, ribosome releases the polypeptide and the complex dissasembles
2nd step of translation
Elongation- the next tRNA with anticodons matches with the next set of codons (codon set= 3 letters) in the A site, ribosome catalyzes peptide bond formed between amino acids, tRNA in P site is shifted to E (exit) and detaches, tRNA in A site is shifted to P site opening up the spot in A site and repeats this process, tRNa is reused and leaves ribosome to go to cytoplasm to pick up another AA
what structure acts as an enzyme in translation
The rRNa acts as an enzyme as it catalyzes the formation of peptide bonds between the amino acids to form a polypeptide chain
what enzymes are in translation
there are no actual enzymes in translation
direction of AA being added in translation
5’-3’
end result of translation
a polypeptide chain (protein)
why are hydrogen bonds between the anti codons and codons important
it ensures the correct amino acid
what is confirmation
bending and binding of itself forming a unique 3D shape
