Genes And Protein Synthesis

Question 1

What are genes?

Answer 1

A gene is a section of DNA that contains the sequence of codons that codes for a protein. The sequence of amino acids in a polypeptide forms the primary structure of a protein.

Each acid is coded for by a triplet (sequence of three bases). Different sequences of bases code for different amino acids.

Question 2

Purpose of mRNA

Answer 2

• is a single polynucleotide strand
• its made in the nucleus during transcription
• mRNA carries the genetic code from the DNA in he nucleus to the ribosomes in the cytoplasm for translation

Question 3

Purpose of tRNA (transfer RNA)

Answer 3

• a single polynucleotide strand folded into a clover shape
• each tRNA molecule has a specific sequence of three bases at one end called an anticodon
• they also have an amino acid binding site at the other end
• tRNA is found in the cytoplasm where its involved in translation of mRNA
• tRNA carries the amino acids that are used to make proteins to the ribosomes

Question 4

Purpose of rRNA (ribosomal RNA)

Answer 4

-rRNA forms the two subunits (large subunit and small subunit) in a ribosome, along with proteins
The rRNA in the ribosome helps catalyse the formation of peptide bonds between the amino acids

Question 5

What is the genetic code?

3 word to describe it?

Answer 5

The sequence of base triplets (codons) in DNA or mRNA which codes for specific amino acids

• non-overlapping: in the genetic code each base triplet is read in sequence separate from the droplet before and after it (base triplets don’t share their bases)
• degenerate: some amino acids are coded for by more than one codon
  Not all triplets code for amino acids though, some triplets are used as stop codons to tell the cell when to stop the production of a protein
• universal: the same specific codons code for the same amino acids in all living organisms (so all organisms use this code)