Protein Synthesis Flashcards
What is the essential idea of translation and transcription?
Translation + transcription -> physical traits
Define genes in RNA translation
Instructions on the synthesis of proteins
Give the purpose of ribosomes
codon/gene sequences -> polypeptides
Central Dogma of Genetics Locations
Nucleus (DNA) - transcription -> mRNA - translation -> polypeptides
How does the genetic sequences affect the protein synthesis
Determines which amino acid to use
Purpose of mRNA
- a transcript copy of DNA
- to determine the types of a.a.
Define the purpose of tRNA
Clover-leaf shaped sequence that carries an a.a.
Define the purpose of rRNA
- primary component of ribosomes
What enzyme does DNA transcription use
RNA polymerase
Outline the steps of transcription
1.) RNA polymerase binds to promoter of DNA @ the start of a gene
2.) Separation of DNA strands (not fully unwound), copy from anti-sense DNA.
3.) RNA polymerase reaches terminator site
4.) mRNA -> cytoplasm for translation
Define anti-sense DNA
- The template DNA strand for DNA transcription
Define promoter
- The part of DNA where transcription starts
How does RNA polymerase create the RNA strand
- ribonulceic triphosphate (rNTP)/free nucleotides binds to the complementary partner in anti-sense
- A-U: RNA
- energy from phosphate used for binding
Describe the time when RNA polym/ reaches the terminator site
- RNA polym. detaches from DNA
- double helix reforms
Explain transcription [7]
Explain how polypeptides are produced by the process of translation [8]
- mRNA translated;
- mRNA binds with small subunit of ribosome;
- ## Aminoacyl enzymes tRNA synthetases attach specific amino acid to tRNA;
What is each ribosome subunit composed of?
rRNA molecules and proteins
Which ribosomal subunit binds to the mRNA?
The small subunit
Whats does the large ribosomal unit do?
has binding sites for tRNAS and also catalyzes peptide bonds between amino acids
Define transcription
synthesis of mRNA copied from the DNA base sequence by RNA polymerase
How are the amino acid sequences of polypeptides is determined?
by mRNA according to genetic sequences
What are the factors of gene expression? / What will make certain genes necessary to be expressed?
- cell specialization
- environment
Why does the length of mRNA molecules vary?
(guessing) Because of the gene expression
- not all genes are transcribed and translated
What does a cell need to do in order to produce a lot of a certain protein?
Make more copies of mRNA
What makes DNA stable?
- The DNA polymerase’s ability to proofread
- hydrogen and phosphodiester bonds
Why should transcription and translation happen?
To produce proteins for:
- bilogical processes
- enzymes
- structural
- storage of energy
- transport proteins
- hormones
- immunoglobulin
Define origin
The starting point of DNA replication
Describe intron splicing
- Within eukaryotic genes are non-coding sequences called introns, which must be removed (via splicing) prior to forming mature mRNA
- The coding regions are called exons and these are fused together when introns are removed to form a continuous sequence
- In other words, introns are intruding sequences whereas exons are expressing sequences
Define premature mRNA
mRNA with introns
Define introns
Genes that do not code proteins
Define exons
Genes that code proteins
Describe the process of intron splicing
- Spliciosomes
- 5’ of mRNA capped
- 3’ end of mRNA w/ poly-A tail
At what point we can say that mRNA has matured
- after intron splicing
Describe the process of DNA transcription
What is the start codon in translation?
AUG
Describe the process of translation
1.) Small unit ribosome binds to AUG (start protein)
2.) tRNA complementary base pairing to codons via anti-codons and carries a.a.
3.)
4.) Large ribosomal subunit attaches and makes translation complex
5.) Corresponding tRNA binds to anti-codons to codons (A -> P -> E)
- A: anti-codon attached to condon
- P: A.a. attaches
- E: uncharged tRNA exits
-> tRNA of AUG at P
Describe the process of translation
1.) Small unit ribosome binds to AUG (start protein)
2.) tRNA complementary base pairing to codons via anti-codons and carries a.a.
3.)
4.) Large ribosomal subunit attaches and makes translation complex
5.) Corresponding tRNA binds to anti-codons to codons (A -> P -> E)
- A: anti-codon attached to condon
- P: A.a. attaches
- E: uncharged tRNA exits
6.) @ STOP codon, A release factor binds to the A binding site.
How ling does RNA translation go?
Until it reaches the stop codon
What are the possible STOP codons?
UAA, UAG, UGA
Define anti-codon
nitrogenous bases in tRNA that binds to complementary codon
What do ribosomes do during translation
- binding site for mRNA and tRNA
- ctalyze the peptide bonds of the polypeptide
Describe the translation complex
Outline translation
- mRNA binds to the small ribosome
- mRNA has codons
- tRNA has anti-codons, comp base pairing to codons
- tRNA molecules bond to a specific amino acid according to the codon
- large subunit binds to small subunit — 3 binding sites but 2 tRNA at a time
- Ribosome moves along mRNA 5’ to 3’ until a stop codon
- anti-codons and codons actually bind (b4 was just an explanation)
- peptide bond formed between 2 a.a.
-tRNA at third binding site (E) and detaches - another tRNA to first site (A)
- until STOP codon
Which genetic process/central dogma process affects gene expression? [1]
Transcription
Define gene (bioninja)
egment of double-stranded DNA that codes for an RNA sequence is called a gene
Describe capping
- a methyl group to the 5’-end of the transcribed RNA
- The methylated cap provides protection against degradation by exonucleases and also allows the transcript to be recognised by the cell’s translational machinery (nuclear export proteins and ribosome)
- LIKE AN OFFICE ID
Describe polyadenylation
- Polyadenylation describes the addition of a long chain of adenine nucleotides (a poly-A tail) to the 3’-end of the transcript
- The poly-A tail improves the stability of the RNA transcript and facilitates its export from the nucleus
Point mutation
The mutation/change in a single nitro base in DNA
ACG -> ATG
Define telomerase [FIND MARKSCHEME]
An enzyme in transcription that caps and adds adenine nucleotides to the mRNA
