Gene Expression - questions Flashcards
Define Metabolic Pathways
A
A metabolic pathway is a sequence of enzyme controlled reactions, where one reaction is the substrate for the next
Relate enzymes to metabolic pathway
A
Explains the relationship between genes, enzymes products and metabolic pathways
M/E
In a metabolic pathway, one gene encodes one enzyme. Each enzyme can only catalyse one specific reaction due to its unique shape. The enzymes active site being correct is what allows the metabolic pathway to continue.
Describe role of an enzyme
A
An enzyme is a biological catalyst that increases the rate reaction of the cell
Describe relationship between gene and enzyme
A
One gene encodes one enzyme. Each enzyme can only catalyse one specific reaction due to its unique shape. If there is a mutation to the gene, the enzymes structure may change, causing its active site to not fit with the substrate.
Explain how a non-functional/ less functional enzyme affect the metabolic pathway
If one enzyme in the metabolic pathway is non-functioning, there is a build-up of the substrate for that reaction, and the final product cannot be made.
Describe gene mutation
A permanent change to the gene sequence
Describe Frameshift Mutation
A
a mutation in number of nucleotides by insertion or deletion so that some triplet codons are read incorrectly during genetic translation.
Describes insertion mutation
A
A base is inserted into the DNA, resulting in a frame shift and all the other bases move down one
Describes deletion mutation
A
A base is removed from the DNA and this results in a reading frame shift.
Explains how a silent mutation affects protein synthesis/ the protein.
M/E
A silent mutation is a base pair mutation caused by substitution with no impact on the sequence of the proteins produced, due to redundancy. This causes no change in the amino acids that make up the protein, so the protein is not affected
Explains how a silent mutation links to redundancy of the code
Redundancy is the fact that multiple codons code for the same amino acid. This means that if a mutation occurs where one of the codons is substituted for another that codes for the same amino acid. e.g. CCU is substituted to be CCC. They both code for proline.
Explains how a frameshift mutation affects the DNA AND mRNA produced
By adding or removing a single base, triplet from the point of the mutation is affected, which would therefore create different codons and different amino acid sequence.
Describes effect of environmental factor
An environmental factor (non-mutagenic) is a factor that affects phenotype but does not change the genotype. Effect of environmental factor can be change in hair colour, because of dye
Example of environmental factor
An example of an environmental factor would be dying your hair. If your genotype is for brown hair and you dye it blonde, you will still have the brown hair genotype but your phenotype will be blonde hair.
Explains the difference between an environmental factor and mutagen.
An environmental factor (non-mutagenic) is a factor that affects phenotype but does not change the genotype. A mutagen is a physical or chemical agents that interact with DNA increasing the chance of mutations. The main difference is that a mutagen will affect your DNA.
Define Mutagen
A mutagen is a physical or chemical agents that interact with DNA increasing the chance of mutations.
Give an example of a mutagen
An example of a mutagen is radiation (Ultra-violet light, X-rays) as it can break DNA sequences in many places, leading to chromosome rearrangement.
Explains the link between environment, genotype and phenotype related to context
genotype + environment = phenotype
The expression of genes in the genetic code results in the phenotype which has observable characteristics. However the environment can also affect the expression of the phenotype. Phenotype differences due to alleles and the influence of the environment on expressing those genes. The environment can cause genes to be increased or decreased
Define triplet
A sequence of three nucleotides that determines one amino acid
Define
Define codon
A DNA or RNA sequence of three nucleotides that codes for a particular amino acid or signals a stop codon
Define anticodon
A sequence of three nucleotides located at one end of tRNA molecule, which is complementary to a corresponding codon in a mRNA sequence.
Define protein folding
the process where a polypeptide folds into a three-dimensional structure
Define substitution
A mutation in the DNA that results in one base changed for another
Define DNA
De
