Topic 6 - DNA Structure and Protein Synthesis Flashcards
What are the monomers that make up DNA strands?
Nucleotides
What are the four bases?
A & T
C & G
What are the two components that form the backbone of a DNA strand?
Sugar and Phosphate backbones.
What are the symbols for bases, sugar and phosphates?
Bases - Square
Sugar - Pentagon
Phosphate - Circle
What is a gene?
A small section of DNA found on a chromosome.
How many bases are there in a gene?
Three
A section of protein contains 25 amino acids. Calculate the number of bases in a gene which coded for this amino acid sequence.
75
How is the code from a gene transferred to ribosomes? (2 marks)
A molecule of mRNA (messenger ribonucleic acid) is made by copying the code from the DNA in the gene.
The mRNA molecule carries the code for the ribosome in the cytoplasm to be made into an amino acid which is the folded to make a protein.
After a protein chain forms what happens to it which allows it to carry out a specific job?
The protein folds into a unique shape to carry out a function in the body.
Explain the two stage process of protein synthesis.
Transcription:
- Takes place in the nucleus
- The base sequence of a gene is copied into mRNA (messenger ribonucleic acid) which is a single stranded molecule
- The mRNA now passes out of the nucleus and into the cytoplasm
Translation
- Takes place in the cytoplasm
- The mRNA molecule then attaches to a ribosome
- Amino acids are now brought to the ribosome on tRNA (transfer ribonucleic acid)
- The ribosome now reads the triplet of bases on the mRNA
- These are used to join together the correct amino acids in the correct order
- Once the protein chain is complete, it now folds into its unique shape
- The shape enables the protein to carry out its specific function
