DNA Flashcards
Similarity and differences between translation and transcription
Both involve the conversion of one type of message into another type of message.
Translation reads RNA to make proteins - Transcription reads DNA to make RNA
Describe how HIV is replicated
- HIV attatches to complimentary receptors on T cell using attachment proteins
- HIV releases RNA into the T cell
- reverse transcriptase converts RNA into DNA
- virus proteins produces
- virus particles assembled and released from cell
Suggest and explain 2 other investigations that should be done before ADC is administered to humans:
- test on other mammals to check for safety/ side effects
- investigate different concentrations of ADC to find suitable dosage
Describe how HIV is replicated in a cell once (4)
- transcriptase converts RNA to DNA
- viral DNA inserted into T cell DNA
- DNA transcribes into HIV mRNA
- HIV mRNA translated into new viral proteins for assembly into viral particles
Transcription occurs differently in eukaryotic and prokaryotic cells. Explain why. (3)
- eukaryotic DNA contains introns
- therefore eukaryotic pre-mRNA contains introns
- (after transcription) pre-mRNA needs to be spliced to remove introns
Describe the process of DNA transcription (6)
- breaks hydrogen bonds betw/ strands
- DNA helix unwinds -> exposes the bases to act as template
- only one strand acts as template
- free mRNA nucleotides align by comp base pairing
- RNA polymerase forms phosphodiester bonds betw/ adjacent RNA nucleotides
- forming sugar phos backbone
- forms pre-mRNA
- gets spliced to remove introns
- mRNA leaves cell through nuclear pores
Describe the role of mRNA in protein synthesis: (4)
- (mRNA) carries the genetic code for a protein
- mRNA {binds / attaches} to ribosome
- complementary anticodon (on tRNA) will bind to codon (on mRNA)
- sequence of {bases / codons (on mRNA) determines the sequence of amino acids
Describe how one amino acid is added to a polypeptide that is being formed at the ribosome during translation. (3)
- tRNA brings specific amino acid to ribosome
- anticodon on tRNA binds to codon on mRNA
- amino acids joined by condensation reaction
Describe how mRNA is produced from an exposed template strand of DNA. (3)
Do not include splicing.
- (Free RNA) nucleotides form complementary base pairs;
- Phosphodiester bonds form;
- By (action of) RNA polymerase;
Describe how mRNA is formed by transcription in eukaryotes. (5)
- Hydrogen bonds (between DNA bases) break
- (Only) one DNA strand acts as a template;
- (Free) RNA nucleotides align by complementary base pairing;
- (In RNA) Uracil is used in place of thymine;
- RNA polymerase joins (adjacent RNA) nucleotides;
- (By) phosphodiester bonds (between adjacent nucleotides);
- pre-mRNA spliced to form mRNA
Describe how a polypeptide is formed by translation of mRNA (6)
- (mRNA attaches) to ribosomes
- ribosome moves to find start codon
- (tRNA) anticodons (bind to) comp. (mRNA) codons;
- tRNA brings specific amino acid;
- Amino acids join by pep bonds;
- (Amino acids join together) with use of ATP;
- tRNA released (after amino acid joined to polypeptide);
- ribosome moves along mRNA to next codon to form polypeptide;
what is the proteome of the cell
the full range of proteins that a cell is able to produce
Describe the structure of DNA (5)
- Polymer of nucleotides;
- Each nucleotide formed from deoxyribose, a phosphate (group) and an organic/nitrogenous base;
- Phosphodiester bonds (between nucleotides);
- Double helix/2 strands held by hydrogen bonds;
- (Hydrogen bonds/pairing) between adenine, thymine and cytosine, guanine;
replication
Describe how the seperation of strands occurs (2)
- DNA helicase
- breaks H bonds betw/ polynucleotide strands
Explain why faster rate of plasmid replication in a culture of higher amino acid concentration (2)
- amino acids used in protein synthesis
- so more DNA polymerase for replication
