Unit 3 - Gene Expression Flashcards
in a cell, how many genes are expressed
a fraction of the genes in a cell are expressed
what does gene expression involve
gene expression involves the transcription and translation of DNA sequences
what is an RNA composed of
RNA is single stranded and is composed of nucleotides containing ribose sugar, phosphate and one of four bases: Cytosine, Guanine, Adenine and Uracil.
what three types of RNA are involved in gene translation and gene transcription
mRNA - messenger RNA
tRNA - transfer RNA
rRNA - ribosomal RNA
what is the function of mRNA
mRNA carries a copy of the DNA code from the nucleus to the ribosome, mRNA is transcribed from DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm. lastly every three bases (triplet of bases) on the mRNA molecule is called a codon and codes for a specific amino acid.
what is the function of tRNA
tRNA folds due to complementary base pairings, each tRNA molecule carries its specific amino acid to the ribosome. A tRNA molecule has an anti-codon (an exposed triplet of bases) at one end and an attachment site for a specific amino acid at the other.
what is the function of rRNA
rRNA and proteins form the ribosome
what is the function of RNA polymerase
RNA polymerase moves along the DNA unwinding the double stranded helix and breaking the weak hydrogen bonds between the bases. RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairings.
in RNA what is the complementary base pairing to Adenine
Uracil
what is formed in RNA splicing
RNA splicing forms mature mRNA transcript
What are Introns
Introns are noncoding regions of the primary transcript which are removed
what are Exons
Exons are coding regions and are joined together to make the mature transcript
In RNA splicing what remains unchanged
the order of Exons
where does translation begin and end
it begins at a start codon and ends at a stop codon
how do anticodons bond to codons
they bond via complementary base pairings translating the genetic code into a sequence of amino acids
what join amino acids together
peptide bonds
what happens to each tRNA in the ribosome
the tRNA leaves the ribosome as the polypeptide is formed
how are different mature mRNA transcripts produced
different mature mRNA transcripts are produced from the same primary transcript depending on which exons have been retained
how are different proteins expressed from one gene
different proteins can be expressed from one gene as a result of alternative RNA splicing
how are proteins formed
proteins are formed by polypeptide chains which fold and form a three-dimensional shape of a protein which is held together by hydrogen bonds and other interactions between individual amino acids
what determines a proteins function
proteins have a large variety of shapes which determine their function.
what is determined by by proteins as a result of gene expression.
phenotypes are determined by proteins produced as the result of gene expression
what also has an influence on phenotype
environmental factors also have an influence of phenotype
