DNA and protein synthesis

Question 1

genome

Answer 1

complete set of genes in a cell

Question 2

transcription

Answer 2

-the process of making pre-mRNA using part of the DNA as a template
-DNA is unwound at a certain point
-DNA helices breaks the hydrogen bonds between DNA bases
-RNA polymerase then moves along the template strand of DNA attaching activated RNA nucleotides to form the pre-mRNA strand
-a new stand is formed which acts as an intermediary template for protein synthesis
-DNA reforms its normal double helix structure behind RNA polymerase as transcription progresses
-when a stop codon is reached, RNA polymerase detaches and the completed pre-mRNA is released

Question 3

RNA splicing

Answer 3

-both DNA and pre-mRNA consist of introns and exons
-only exon sequences code for amino acids
-the pre-mRNA is therefore spliced to removed non coding introns and join exons
-this forms a mature mRNA molecule

Question 4

alternative splicing

Answer 4

-sometimes exons can be spliced in different ways, so more than 1 protein can be made form a single gene
-mutations may result in faulty splicing, leading to non functional proteins

Question 5

translation

Answer 5

-mRNA attaches to ribosomes
-tRNA anticodons bind to complimentary mRNA codons
-tRNA brings a specific amino acid
-amino acids join by peptide bonds by the use of ATP
-tRNA released after amino acid joined to polypeptide
-the ribosome moves along the mRNA to form the polypeptide