1.3 - Gene Expression Flashcards
Genotype
A cells genotype is determined by the sequence of bases in its genes
Phenotype
Phenotype is described by the proteins that are synthesised when these genes are expressed
Structure of proteins
Contains elements C, H, O and N
Made from chains of amino acids, which are held together by peptide bonds
Hydrogen bonds form between certain amino acids and cause the polypeptide to coil or fold which give the protein it’s 3D shape and function
What is different between DNA molecules and RNA molecules
DNA contains the base Thymine whereas RNA contains the base Uracil.
DNA contains a deoxyribose sugar whereas RNA has a ribose sugar.
DNA is double stranded whereas RNA is single stranded.
Transcription of DNA to RNA
RNA polymerase moves along the DNA unwinding and unzipping the double helix, and synthesising a primary mRNA strand from free RNA nucleotides in the nucleus by complementary base pairing.
What are Introns?
Non coding sequences of DNA that aren’t involved in making a protein.
What are exons?
Sequence of bases that code for proteins
What is RNA splicing
RNA splicing is the process where introns are removed from the primary transcript of mRNA, forming a mature transcript of mRNA.
What is the function of ribosomes
Protein synthesis
To bring mRNA into contact with tRNA
Translation of mRNA
A ribosome attaches at the 5’ end of the mRNA at the start codon
The anticodons on the tRNA form weak hydrogen bonds with the codons on the mRNA and bring the amino acids in line
What is the type of bond between amino acids
Strong peptide bonds
What is alternative mRNA splicing
Alternative RNA splicing is when different mature strands of mRNA can be produced from the same primary transcript depending on which regions are treated as exons and introns
Post Translational Modification
Cleavage - protein may be cut by enzymes to become active
Molecular addition - proteins structure may be altered by addition of a carbohydrate or a phosphate group
