Gene expression Flashcards
Describe the structure of RNA
RNA is a single strand made up of DNA nucleaotides
RNA nucleotides are composed of a ribose sugar a phosphate and one of the 4 bases
What is the function of mRNA
mRNA carries a copy of the DNA code from the nucleus o the ribosome in the cytoplasm
What is each triplet of bases on the mRNA molecule called
Codon
What do codon code for
a specific amino acid
Describe the function of tRNA
It brings specific amino acids to the ribosome for protein synthesis
How does tRNA fold
due to complementary base pairing
What forms the ribosome
rRNA and proteins
The role of RNA polymerase in transcription of DNA into primary mRNA transcripts
mRNA is assembled in the nucleus using a gene as its template
RNA polyemrase moves along DNA unwinding the double helix and breaking the hydrogen bonds between the bases
RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides
free RNA nucleotides join to the exposed DNA bases on one DNA strand by complementary base pairs
RNA uracil pairs with DNA adeneine RNA adenine pairs with DNA thymine and cytosine pairs with guanine
RNA polymerase joins the adjacent RNA nucleotides ribose sugar to phosphate to form the sugar phosphate backbone of single stranded mRNA Energy is required from ATP
mRNA splicing occurs to remove the introns and complete the mature mRNA
What happens as a result of alternative RNA splicing
different proteins can be expressed from one gene
different proteins can be expressed from the one gene as a result of what
alternative RNA splicing
Why does alternative RNA splicing occur
because different exons are retained
Describe translation of mRNA
tRNA is involved in the translation of mRNA into a sequence of amino acids forming a polypeptide chain
translation of mRNA occurs at a ribosome
translation begins at a start codon and ends at a stop codon
ribosome binds to mRNA at start codon
each TRNA molecule brinds its specific amino acid to the ribosome
the tRNA anticodons bond with mRNA codons by complementary base pairing
peptide bonds form between amino acids forming a polypeptide chain
ribosome moves along the mRNA strand
once peptide bonds forms each TRNA leaves the ribosome
translation ends at a stop codon
energy is required from ATP
What does the order of DNA based determine
the orger of the DNA bases determines the order of the amino acids
What are amino acids linked by
peptide bonds to form polypeptides
What do polypeptide chains do
fold to form the 3D shape of a protein held together by hydrogen bonds and other interactions between individual amino acids
What is phenotype determined by
by the proteins produced as a result of gene expression
What else can influence a phentype
environmental factors
What is gene expression controlled by
regulation of both transcription and translation
What is the RNA sugar
Ribose sugar
What is the DNA sugar
deoxyribose sugar
What strand is RNA
single stranded
What strand is DNA
Double stranded
What is the function of tRNA
Carries its specific amino acid to ribosome
What is the function of rRNA
rRNA and proteins make up the ribosome
What are introns
Non coding regions of DNA
What are exons
Coding regions of DNA
Name the regions always removed fro primary mRNA transcript
introns
Explain why it is important that non coding regions are removed from the primary transcript of this gene before translation
So the order of exons remains the same and the correct protein is made
why is RNA splicing necessary
The introns are removed fro primary transcript of the mRNA and the exons are spliced togetehr to form a mature mRNA transcript
What is the name of the bond between amino acids
Peptide bonds
What does a tRNA molecule have on either end
An anticodon oat one end and an attachnment site for a specific amino acid at the other end
Describe the process RNA splicing
The introns are removed from the primary transcript of the mRNA and the exons are spliced together to form a mature mRNA transcript
Is the order of the eoxns changed or unchanged during splicing
Unchanged
What happens ot the mature mRNA after splicing
passes out of the nucleus into the cytoplasm where it becomes translated into a sewuence of amino acids
What is mRNA transcribed from
mRNA is transcribed form DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm
Describe the structure of a tRNA molecule
Has an anticodon at one end and an attachment site for a specifc amino acid at the other end
How does alternative splicing result in the formation of many different proteins from one single gene
different exons are retained
