1.3 - Gene Expression Flashcards
What proportion of genes in a cell are expressed?
a small number
Gene expression involves what two main processes on DNA sequences?
Transcription and translation
What types of RNA are involved in gene expression?
mRNA, tRNA, rRNA
RNA contains what 3 distinct features from DNA?
single stranded, uracil instead of thymine, ribose sugar
The m in mRNA stands for what?
messenger
What is mRNA’s role in gene expression?
to carry a copy of the DNA code to from the nucleus to the ribosome
What happens to mRNA in the nucleus?
it is transcribed from DNA
What happens to mRNA in the ribosome?
it is translated into proteins
Where are ribosomes located?
the cytoplasm
What is a codon?
a triplet of bases on mRNA
What does a codon do?
codes for a specific amino acid
What does the t in tRNA stand for?
transfer
What is special about tRNA’s structure and why is it this way?
it is folded due to complementary base pairing(hydrogen bonds)
What is tRNA’s role in transcription?
to carry its specific amino acid to the ribosome
What are the main features of tRNA?
anticodon, specific amino acid attachment site
What does the r in rRNA stand for?
ribosomal
What does rRNA do?
forms a ribosome along with proteins
What does RNA polymerase do to DNA?
it moves along DNA, unwinding it and breaking the hydrogen bonds between bases
What does RNA polymerase synthesise?
a primary transcript of mRNA
How does RNA polymerase synthesise a primary transcript of mRNA?
using RNA nucleotides by complementary base pairing
What process creates a mature transcript of mRNA?
RNA splicing
What are introns and are they retained?
non-coding regions (for proteins) - no
What are exons and are they retained?
coding region(for proteins) - yes
What is notable about the order of retained exons?
it is unchanged
What is the function of translation?
to “translate” a mature transcript of mRNA into a polypeptide
How is translation commenced and ceased?
a start and stop codon
How do codons and anticodons bond?
by complementary base pairing
synonym of this: “mature mRNA transcript –> polypeptide”
genetic code –> sequence of amino acids/protein
What links amino acids and what does this form?
peptide bonds - polypeptide/protein
What is the fate of tRNA after translation?
leaves the ribosome to be reused
What process means different proteins can be expressed from one gene?
alternative RNA splicing
Different mature transcripts of mRNA are dependant on what?
which exons are retained
What difference in structure is there between a polypeptide and a protein?
proteins are 3D shapes
What holds proteins in their 3D shape?
hydrogen bonds and other interactions between individual amino acids
A protein’s shape determines what?
its function
What determines phenotype?
proteins produced from gene expression and environmental factors(influences)
