Topic 3: Gene Expression Flashcards
Gene expression involves ________________________
the transcription and translation of DNA sequences
Only a fraction of genes in a cell are ______
expressed
Transcription and translation involve ____________
3 types of RNA (mRNA, tRNA, rRNA)
RNA is ______
single stranded
RNA is composed of nucleotides containing ____________
ribose sugar, phosphate, C, G, A, and Uracil bases
mRNA carries a copy of the __________________
DNA code from the nucleus to the ribosome
mRNA is transcribed from DNA ____________
in the nucleus
mRNA is translated into proteins ____________
by the ribosomes in the cytoplasm
Each triplet of bases on the mRNA is called ______
a codon
A codon ______
codes for a specific amino acid
How does tRNA fold?
due to complementary base pairing
At one end of the tRNA molecule there is ____________
an anticodon (an exposed triplet of bases)
Each tRNA carries a specific amino acid where?
to the ribosome
What forms the ribosome?
rRNA and proteins
What happens when RNA polymerase moves along the DNA?
unwinding of the double helix and breaking Hydrogen bonds
What does RNA polymerase synthesise?
a primary transcript of mRNA from RNA nucleotides
How are RNA nucleotides matched to the DNA template?
through complementary base pairing
What is uracil complementary to?
Adenine
Cytosine is complementary to?
Guanine
How is a mature mRNA transcript formed?
RNA splicing
what are introns of the primary transcript?
non-coding regions
What are exons and what do they form?
coding regions and they are joined together to form the mature transcript
what happens to the order of exons during splicing?
unchanged
tRNA is involved in the translation of mRNA into __________
a polypeptide at a ribosome
Translation starts with _____
a start codon
translation ends with _____
a stop codon
How do anticodons bond to codons?
By complementary base pairing
What is the genetic code on the mRNA translated to?
A sequence of amino acids
How are the amino acids joined together?
Through peptide bonds to form a polypeptide
When is the polypeptide complete?
Wants to stop codon is read
What happens to a tRNA after translation?
The tRNA leaves the ribosome and it’s free to pick up another amino acid
How can different proteins be expressed from one gene?
As a result of alternative RNA splicing
What can one primary transcript produce?
Several different mature mRNA transcripts
What can alternative RNA spicing produce?
Different mature mRNA transcript depending on which exons are retained
What does alternative splicing produce?
A variety of proteins from the same gene
What are amino acids linked by?
Peptide bonds to form polypeptides
What do polypeptide chains fold to form?
A 3-D shape of a protein
How are the polypeptide chains held together?
By hydrogen bonds and other interactions between individual amino acids
How is the phenotype determined?
By proteins produced as a result of gene expression
What else can influence the phenotype?
Environmental factors
