cellular control Flashcards
what is a mutation
any change to base sequence of DNa
what are the types of mutations
substitution: one or more bass are swapped for another base
deletion: one or more basses are removed
insertion: one or more bases are added
what effect could mutations have
as the order of bases determine the order and type of amino acids, completely different proteins could be made as the primary structure of the protein could change
what is frameshift mutation
when an insertion or deletion changes the way the rest of the base sequence is read. the earlier the frameshift mutation the greater the effect it will have on the protein.
what is the effect of neutral mutation
the protein function is not affects as the amino acids not change or amino acid is similar chemically or mutated triplet code not involved with protein function
what can be the effects of beneficial mutation
increase chance of survival as the organism now has an advantage.
natural selection ensure this mutation is passed onto future generations
what can be the effects of harmful mutation
decreases chance of survival as organism now have a disadvantage
can also affect protein production with can lead to genetic disorder
why do the function and structure of cells differ
despite carrying the same genes different cells will have different expressed genes
what are transcription factors
proteins that bind to DNA and switch genes on or off by increasing or decreasing the rate of transcription
their shape determine whether or not they can bind to DNA
what are the two types of transcription factors
activators ( start transcription)
repressors ( stop transcription)
where do transcription factors bind to in eukaryotes and prokaryotes
eukaryotes: specific dna does near the start of their target genes
prokaryotes: the factors bind to operons
what is an operon
a section of DnA that contains a cluster of structural genes, control elements and sometimes a regulatory gene
what are structural genes
genes that code for useful proteins e.g enzymes
what are the control elements
a promoter ( DnA sequence located before structural genes that RNA polymerase bind to) and an operon ( DNa sequence that factors bind to)
what are regulatory genes
genes that code for activators and repressors
what is E.coli
a bacterium that respires glucose but can use lactose in the absence of glucose
what is the lac operon
the section of DNA that code for the enzyme needed to respire glucose
what are the 3 structural genes found on the lac operon and what is the function of the protein they produce
lacZ lacY lacA
the proteins they produce help bacteria digest lactose
lac operon what happens when lactose is not present
- regulatory gene lacl produce the lac repressors which binds to the operator site
- transcription is blocked as RnA polymerase cannot bind to the promoter
lac operon what happens when lactose is present
- lactose binds to the lac repressors and changes it shape
- the repression can no longer bind to the operator site so move off
- RNa polymerase can now begin transcription of the structural genes
what are intro and exons
introns- section of DNA that don’t code for amino acids
exon- the rest of DNA that code for amino acids
how is gene expression controlled at post - transcriptional level
primary transcripts ( mRNA strands contain introns and exons) are edited to remove the introns by a process called splicing. the exons are then jokes together to form mature MRNA strands
the mature mRNA then leaves the nucleus to be translated
how is gene expression controlled at post- translational level
molecules that control protein activiaton work by binding to cell membranes and triggering the production of cAMP
this activates proteins inside the cell by altering their 3D structure
what is a body plan
the general structure of an organism
what are Hox genes
genes that code for proteins which control body plan development
what are homeobox sequence
regions on hox genes which are highly conserved
(these sequences have changed very little during the evolution of the organisms)
how do hox genes control development
homeobox sewage code for a part of the protein called homeodomain which binds to sites on DNA enabling the protein to work as transcription factors. the protein binds to DNA and activates or repress transcription
what is apoptosis
a highly controlled process where cells die and breakdown as part of normal development
what are the steps of apoptosis
- enzymes inside the cell break down cell components
- the cell begins to shrink and break down into fragments
- phagocytes engulf and digest the cell fragments
what role do mitosis and apoptosis play in development
mitosis and differentiation create the bulk of body parts and apoptosis refined the body parts by removing unwanted structures
genes that control mitosis are switches in and off in appropriate cells so correct body plan develop
