cellular control Flashcards
what is a mutation
random changes in the genetic material (DNA) of a cell that leads to the introduction of variation
what is the function of the Lac Operon
an example of a regulatory mechanism at the transcriptional level (i.e. a regulatory mechanism that occurs during transcription)
what is a gene mutation
a random change to the base sequence of DNA
where can mutations happen
- somatic cells
- gametes
gametes (mutation in gametes)
- present in egg or sperm
- can be inherited
- causes cancer family syndrome
somatic cells (mutation in somatic cells)
- non - gamete tissue
- cannot be inherited
what are the 2 types of mutation
- point mutations/substitutions
- insertion/deletions (or indel mutations)
what is a point mutation/substitution
one base pair replaces another. Otherwise known as a substitution.
what is insertion/deletion (or indel mutations)
one or more nucleotides are inserted, or deleted from a length of DNA, this may cause a frame shift.
what is the difference between the coding and template strands in DNA
- nucleotides, add on to a template strand.
- mRNA, is the same as the coding strand.
what is translation
mRNA, is used, to put the amino acids in the correct order during protein synthesis.
what is silent mutation
a mutation where the same amino acid is coded for using a different triplet thus meaning there are no consequences.
what is a missense mutation
one base change, leads to a different amino acid being made. The impact this had, depends on the amino aid that is being made.
what is nonsense mutation
one point mutation which leads to a stop codon. Therefore, stopping the production of the polypeptide.
what is a frameshift mutation
- a deletion
what are 3 categories of mutations
- beneficial
- neutral
- harmful
what is a beneficial mutation
different alleles, e.g. paler skin enables vitamin D to be made whilst black skin has more melatonin thus protecting from skin cancer.
what is a neutral mutation
- inability to smell certain flowers
- different shaped ear lobes
what is a harmful mutation
- Duchenne muscular dystrophy (nonsense mutation)
what is an activator
starts transcription
what is a repressor
stops/prevents transcription
what does the regulatory gene do (repressor)
stops transcription
what is the function of B galactosidase
hydrolyses lactose -> glucose and galactose
what is the function of lactose permease
allows lactose to enter the bacterial cell
why is gene expression so important in eukaryotes
controlling gene expression, is important to ensure the correct proteins are being made by the correct cells.
what do transcription factors control
they control which genes, are switched on or off
what do transcription factors bind to
specific promotor region
what is post transcriptional gene regulation
splicing out non-coding intron regions of transcribed mRNA
what is alternative splicing
genes can be spliced in different ways. Therefore length of DNA can encode more than one protein, depending on how it is spliced
what is post translational gene regulation
- modifications, to the proteins or amino acids
- e.g. adding non protein groups, like lipids or phosphates, forming extra bonds, folding or shortening, modification of cAMP.
what is a homeotic gene
a large group of genes, that control anatomical development
what is a homeobox sequence
part of the gene. that codes the homeodomain
what is the homeodomain sequence
part of a protein, that is shaped in a way, that allows it to bind to DNA and act as a transcription factor.
where are homeobox genes found
in plants, animals and fungi.
what does the term ‘collinearity’ mean
hox genes, are activated during development of the embryo. They are expressed, in order, from front to back
how are the hox genes regulated
- maternally supplied mRNA, in egg cytoplasm -
