cellular control 6.1

Question 1

types of mutations

Answer 1

-substitution= one base pair is replaced for another
-insertion or deletion = one or more nucleotide is added or removed from DNA. can cause frameshift= disrupts triplet code readings
Can lead to a shorter and longer protein as well

Question 2

effects of mutations

Answer 2

• can be positive or negative
  -silent= no effect (degenerate)
  -missense= change in the base sequence that leads to change in the amino acid sequence
  -nonsense mutation= codes for a stop codon. not developed protein will not function
• function may be lost or better

Question 3

the regulatory mechanisms that control gene
expression at the transcriptional level

Answer 3

• transcription factors controls the rate of transcription of genes

in eukaryotes:
- heterchromatin (tightly wound DNA in histones) needs to be converted to euchromatin to allow the gene for RNA polymerase to bind to. Can be done by phosphorlynation or aceylation decreasing positive charge of DNA so its less likely to bind to gene.

in prokaryotes:
- they respire using glucose but when not present can use lactose
-genes needed to respire lactose are found on the lac operan such as B-galactosidase and lactose permease.
- lac operan is arranged in order of LACI (regulator gene and codes for repressor proteins), promotor region, operator region,and structural genes which codes for the proteins B-galactosidase and lactose permease. (lacZ,lacY,lacA.

• when glucose is present LacI is expressed. to make a repressor protein which binds to the operator region blocking RNA polymerase from binding to the promotor region so structual genes are not transcribed.
  -when lactose is present it binds to the repressor protein causing a conformational change hence repressor can no longer bind too the operator region. so RNA polymerase bind to the promotor and codes for the structural proteins
  -

Question 4

post-transcriptional level

Answer 4

• After translation the MRNA formed is called primary MRNA. which contains both introns and extrons
  introns= do not code for proteins
  extrons=codes for proteins
• introns are removed during splicing
  -RNA is further modified to create mature RNA

Question 5

homobox genes

Answer 5

• regulatory genes that control the body developments plan
• they are highly conserved over time in animals,plants and fungi. (same over the years)
  -regulates mitosis and apoptosis (programmed cell death) which responds to intrnal stimuli e.g. DNA damage and external stimulus such as stress
  -apoptosis prevents us from having connected tissues

Question 6

post-translational

Answer 6

• some proteins need to ctivated before they are functional
• they can be activated by cyclic AMP.
• binding of protein activates the g protein which in turn activates adenyl cyclase to catalyses the formation of Camp from ATP
  -Camp activates PKA (protein kinase A)
  -Activated PKA catalyses phosphorylation which can activate many enzymes