Gene expression Flashcards
State how introns and exons differ
Introns (non-coding regions) and exons (coding regions)
How much of a gene is expressed ?
Only a fraction
How is gene expression controlled?
Its controlled by regulation of transcription and translation
What are genes expressed to do?
To produce proteins
What does gene expression result in?
The phenotype of an individual human
What does RNA polymerase do in transcription?
It moves along DNA, unwinding the double helix and aligning RNA nucleotides by complementary base pairing
Which codons code for an amino acid?
Start and stop codons, which start and stop translation
Describe transcription of DNA
DNA polymerase unzips and unwinds DNA
RNA polymerase adds complementary RNA nucleotides
To make mature RNA, introns are removed and exons are spliced together
Describe translation of mature RNA
mRNA goes to the ribosomes
mRNA has a triplet of bases called a codon which codes for a specific amino acid
tRNA carries a specific amino acid
Anticodons on tRNA align with codons on mRNA
Amino acids align in the correct sequence
Amino acids are linked by peptide bonds
There’s a start and stop codon which indicates when to start and stop translation
Describe the structure of RNA
It is single stranded
The base pairs are Uracil-Adenine, Guanine-Cytosine
It is composed of nucleotides containing ribose sugar and phosphate
rRNA and proteins form the ribosome
tRNA folds due to complementary base pairing
What is an anticodon?
It’s an exposed triplet of bases.
At one end and an attachment site for a specific amino acid at the other end
What is gene expression
Transcription and translation of a gene to synthesise proteins
One ways by which the expression of a single gene can result in different proteins being produced
Alternative RNA splicing
Explain the importance of the regulation of gene expression
Energy and resources are conserved
What does tRNA do?
Picks up a specific amino acid from the cytoplasm and brings it to the ribosome. It also folds due to complementary base pairing
What does mRNA do?
Carries the genetic code from the nucleus to the ribosome
What does rRNA do?
Along with protein it gives structure to the ribsome
What happens after anticodons bond to codons by complementary base pairing?
It translates the genetic code into a sequence of amino acids
Where is mRNA transcribed and then translated?
It’s transcribe from the DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm
What is a triplet of bases and what does it code for?
A codon and it codes for a specific amino acid
What does RNA polymerase synthesis?
A primary transcript of mRNA from RNA nucleotides by complementary base pairing
Where does translation begin?
At a start and stop codon and ends at a stop codon
What does anticodons bond to?
Codons by complementary base pairing, translating the genetic code into a sequence of amino acids
What happens when different proteins is expressed from one gene
Alternative RNA splicing
What is a gene
A gene is a section of DNA which carries the code for the [production of one protein
what are the requirements for transcription?
Free RNA nucleotides
Enzymes including RNA polymerase
Energy in the form of ATP
Template is DNA
How is the sugar phosphate backbone formed?
By strong chemical bonds between the deoxyribose of one nucleotide and the phosphate of another. it’s controlled by DNA polymerase
What is the function of DNA polymerase in replication?
It joins nucleotides together to the 3’ end
Why is a primer needed in DNA replication?
DNA polymerase can only add nucleotides to a pre-existing chain
Describe the structure of tRNA
single stranded with some double stranded parts
