DNA and proteins Flashcards
What are proteins made of?
Amino acid chains known as polypeptide chains, coiled up forming its shape.
What are the four levels of structure of a protein?
Primary, secondary, tertiary, quaternary.
Describe the primary structure of a protein
The chain of amino acids/polypeptide chain. Considered useless at this stage.
Describe the secondary structure of a protein
Polypeptide chain begins folding as hydrogen bonds begin forming.
Still can’t do its job.
Describe the tertiary structure of a protein
Protein continues coiling further as different kinds of bonds begin forming.
Can maybe now do its job if it doesn’t require the quarternary stage.
Describe the quarternary structure of a protein
Some proteins have more than one polypeptide chain. This is where other coiled chains connect.
Haemoglobin is an example of this.
Protein can now do its job.
Define what an enzyme is
An enzyme is a biological catalyst
What are the two types of enzymes?
Anabolic - enzymes which are building larger complex molecules from simple simpler molecules.
ANTS are BUILDING nests
Catabolic - breaking down large complex molecules into smaller simpler molecules.
CATS are BREAKING things (pushing things off the edge)
Define what a gene is
A section of DNA which codes for one specific mRNA molecule
What is the active site of an enzyme?
The active site is where the job is done. Where substrates slot into the enzyme to either be broken down or built up.
What are inhibitors? and what are the two types?
Inhibitors turn the enzyme on and off as we don’t always need them on.
Inhibitors slow down a reaction, product is still made but just slower. (toxins are inhibitors).
Competitive inhibitors - Sitting in the active site stopping substrates from entering. Competing for the active site.
Non-competitive inhibitors - don’t sit in the active site, inhibitor finds the allosteric site and changes the shape of the active site. Substrate can no longer fit.
What are genetic mutations?
A mutation is any change in the codon sequence.
What are the different types of genetic mutations?
Substitution
- Nonsense
- Missense
- Silent
Frameshift
- deletion
What is a nonsense mutation?
When bond gets damaged by radiation or something else, and wrong letters get put together. Results in a stop codon in the middle of the mRNA strand.
Changes one amino acid.
What is a Missense mutation?
When wrong amino acid gets coded for. Still makes sense but the wrong sense. Can result in a change in the proteins shape.
Changes one amino acid.
What is a silent mutation?
No change, no big deal. Will change the codon (first letter) but will just change it into a degenerate, so does not actually change the amino acid coded.
Changes one amino acid.
What is a deletion mutation?
Changes everything! One letter is taken out, so changes codons all the way down stream. This is almost always bad.
Changes everything.
List three factors which increase chances in a mutation occurring.
High radiation
Mutagenic chemicals
Some viruses
Define transcription
Using a section of of DNA (gene) to build a complimentary strand of mRNA.
Happens in the nucleus.
Define translation
A strand of mRNA to provide the instructions for a ribosome to build a polypeptide chain.
Happens in the endoplasmic reticulum.
Explain the lock and key theory
The enzyme’s active site is the lock/hole, substrate is the key.
The wrong key/substrate won’t fit into the lock/active site.
Can have one lock and multiple keys and they will all work. Lock doesn’t get used up.
Eventually the lock/active site may break.
Describe protein synthesis
The process of transcribing an mRNA strand from DNA, and building a polypeptide chain/protein through the ribosome enzyme.
What is SCNT? (Somatic Cell Nuclear Transfer)
When the nucleus from a somatic cell is placed into an enucleated gamete for cell division to begin.
Explain the steps of SCNT
- Somatic cell’s nucleus is removed
- Nucleus is then injected into ovum from a second donor
- That egg can now initiate development through mitosis
