ST.3 Gene Expression H (DNAG) Flashcards
(31 cards)
What is gene expression?
Gene expression is the process where DNA is copied and then used as a template
How much of the DNA from a cell is actually expressed?
Only a fraction
What are the two steps in gene expression called?
Transcription, translation
What is RNA?
Ribonucleic acid
Whats the difference between an RNA nucleotide and a DNA nucleotide?
What does mRNA do?
Carries a copy of the DNA code from the nucleus to the ribosome
Is mRNA transcribed? Where?
Yes, from the DNA in the nucleus
Is mRNA translated? Where?
Yes, into proteins by ribosomes in the cytoplasm
What is a triplet of its bases called and what does it do? (mRNA)
Codon, it codes for a specific amino acid
What does tRNA do?
Carries its specific amino acid to the ribosome and folds due to the complementary base pairing
Is tRNA transcribed? Where?
Yes, at the ribosome
Is tRNA translated? Where?
NO!
What is a triplet of its bases called and what does it do
Anticodon, binds briefly to the mRNA codon
Why does tRNA have so many folds?
Due to complementary base pairing
What does rRNA form with at the ribosome?
Proteins
What are the 3 differences between DNA and RNA
DNA - Double stranded, deoxyribose sugar, thymine
RNA - Single stranded, ribose sugar, uracil
Process of transcription
- RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between bases
- RNA polymerase enzyme synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing by adding nucleotides onto the 3’ end of the growing mRNA
- The molecule formed is called the primary mRNA transcript
Process of translation
-mRNa attaches to the ribosome
- Translation begins at a start codon and ends at a stop codon
- tRNA has an anticodon at one end and an attachment site for a specific amino acid at the other end
- The mRNA codons bond to tRNA anticodons by complementary base pairing
- The genetic code is translated into a sequence of amino acids
- Peptide bonds join the amino acids together
- Each tRNA then leaves the ribosome as the polypeptide is formed
- The last codon on the mRNA is called a stop codon and this ends the translation process
Non-coding regions are called..?
Introns
Coding regions are called..?
Exons
What is translation?
Translation is the part of gene expression where the mature mRNA transcript is used to synthesise a polypeptide chain at the ribosome
What happens after primary mRNA transcript? What is it called?
Introns are removed, the remaining exons are spliced together to form a continuous sequence. This is called the mature transcript
What does the mature mRNA transcript do?
Leaves the nucleus and goes to the cytoplasm
The order of exons is…….during splicing
Unchanged
