What are the two stages of protein synthesis?
Transcription and translation.
Where does transcription take place?
Where does translation take place?
Cytoplasm when the mRNA attaches to a ribosome.
What are the two main steps of transcription?
- A section of DNA is unwound and the 2 strands separate.
2. Free complementary bases pair with the open bases on the DNA strand. (the free bases join to make complementary mRNA)
When the ribosome moves along the mRNA how many bases does it read and what are they called?
What does the mRNA pair with in the ribosome?
What do the tRNA molecules bring to the ribosome?
What does the amino acid attached to each tRNA depend on?
The order of the bases in the tRNA.
What is a chain of amino acids joined closely together called?
What are the 5 main steps of translation?
- Ribosome moves along the mRNA reading one codon at a time.
- tRNA molecules bring amino acids to the ribosome.
- Complementary bases of tRNA pair with the bases on the nRNA strand.
- The amino acids that are close together are joined to make a polypeptide.
- The tRNA is free to collect another amino acid.
What replaces thymine in RNA?
What must happen for the polypeptide to turn into a protein?
It has to fold up in a complicated 3D way.
The ______ of a protein affects the way it works.
What is meant by the word mutation?
It is a change in the sequence of bases in the genetic code.
When can a mutation sometimes be useful?
In bacteria, so that they can gain immunity or resistance to certain things.
What are examples of globular shaped proteins?
What are examples of fibrous/long shaped proteins?
- Keratin (hair, nails)
- Collagen (tendons, ligaments)
What could the 3 possible outcomes of a change in an amino be?
- No effect; it doesn’t change the shape of the protein or how it works.
- Beneficial effect; causes the protein to work better.
- Harmful effect; causes the protein to change shape sp it doesn’t work well.
Give an example of the result of harmful change in protein shape.
The allele that causes sickle cell. (The allele for sickle cell disease has one base different than the normal allele for haemoglobin).
Enzymes are biological _______.
Give examples of enzyme controlled reactions inside and outside cells.
Inside cells: Enzymes catalyse the splitting apart of the 2 DNA strands and the joining of the bases to make new strands in transcription and translation.
Outside cells: Digestive enzymes are secreted into the alimentary canal to break down large food molecules into smaller ones.
What is the ‘lock and key’ hypothesis?
Describes the way a substrate fits ,like a key, into the enzymes active site, the lock.
At optimum temperature the enzyme is working at its ________ rate.
High temperatures can cause the active site to change shape, which means the enzyme can’t hold the ________ as tightly causing the reaction to ______ _______.
Substrate, slow down.
If the temperature is too high the enzyme ________ because it’s _____ _____ breaks up.
Denatures, active site.
True or false:
As the substrate concentration increases so does the rate of reaction until all the enzyme molecules are busy.