Anti-Cancer drugs

how does dna replication keep us alive?

allows cells to replicate, replacing dead ones

when would DNA replication go wrong?

bases are copied wrong

2 scenarios where DNA replication going wrong is a problem?

• faulty cells divide and dead cells wont be replaced by healthy = tumour over time

• cells with no function accumulate

• fault in DNA causes new cells to uncontrollably replicate = tumour

cancerous cells?

cells that are created in an uncontrollable way

what causes cancerous cells to form?

faulty dna replication

treatments for cancer?

chemotherapy, radiation, surgery

drug used in chemotherapy?

cisplatin

cisplatin structure and bonding?

square planar:

transition metal complex:

central Pt, 2 Cl ligands, 2 NH3 ligands = dative covalent bond with platinum

why is the overall charge of cisplatin neutral?

2 Cl- ligands cancel out Pt 2+

transplatin structure?

ligands on opposite sides

chemotherapy?

injecting highly aggressive drugs like cisplatin to target cancer cells

process of cisplatin entering the body?

• enters - high conc. of water and low of Cl- ions

• ligand replacement: chlorine ligands are replaced by water

• ligand replacement: water ligands are replaced by DNA acting as a bidentate ligand

bidentate ligand?

a molecule or ion that can form two dative (coordinate) bonds with a central metal ion, because it has two lone pairs of electrons to donate

what base can cisplatin only bond to?

guanine, so must bond to a section with 2 adjacent guanines

how does cisplatin and guanine bond?

nitrogen closest to double bonded oxygen on guanine donates its lone pair to coordinate bond via ligand subsitution

why doesnt trasplatin work as a chemotherapy drug?

chlorine ligands can be replaced by H2O, but cannot undergo step 2 due to wrong geometry

2 ways cisplatin stops cancer?

1 triggers programmed cell death when binded with DNA = kills cancer cells

2 causes kink in DNA chain = prevents enzymes binding = no more cancerous cells can be replicated

side effects of chemotherapy?

hair loss, weight loss, headaches and vomiting

how are side effects of chemotherapy caused?

Cisplatin can bond to the DNA of regular healthy cells which can trigger death in regular cells.

Also prevent healthy cells from replicating

to create two new healthy cells.

how does cisplatin cause headaches and vomiting?

targets healthy cells in digestive system

why do we have hair loss in chemotherapy?

hair follicles replicate fast, cisplatin can bind and prevent replication

ways doctors try to reduce side effects of chemotherapy?

• target area with cancerous cells specifically

• small doses

• age is a determining factor, or other conditions

why do doctors mostly always use chemotherapy on youth and less on elderly?

youth: new cells replicate fast, so cancerous cells do

elderly: new cells created slowly, may not be most immediate

how do other medical conditions affect the decision of whether to use chemotherapy?

other conditions such as stroke can leave a patient frail, so chemo can lead to a worse quality of life and chances of success would be low

what type of people may not be deemed fit for chemo?

edlerly or those with complex conditions