aboyliketim

Ah, thanks cypress, the image is really useful! I think I will be able to explore more on the different patterns and relationships. Thank you very much for your time, you've been a great help!! Regards Tim

Hi cypress, thanks for your reply! I am still slightly confused though... If ionic charge is the biggest influence, why then does Cs+ have a larger ionic diameter than F-?

Hi, given that Cs+ has 55 protons and electronic configuration of 2.8.18.18.8, and Cl- has 17 protons and electronic configuration of 2.8.8, why is the ionic radii of Cl- (0.181nm) > ionic radii of Cs+ (0.167nm)? I know that Cs+ has many more protons than Cl-, which means that the pulling force on the electrons in Cs+ is much greater than that on those in Cl-, but what about Cs+ having many more layers of electrons than Cl-? Which has more significance in determining ionic radii, the pulling force on electrons, or the number of layers of electrons? Is there a 'sure' way to determine whether Cs+ or Cl- (or any two ions in different groups and periods, for the matter), has the higher ionic radius? Thanks in advance

Any reliable source/news on this that can be provided? I know it is probably not true, but it does sound interesting. I'm sorry if 'bringing up an old thread' is frowned upon here too!

Hi I think I can try helping you with this, we learnt this in school last year! So in eukaryotes, various proteins fold and condense into fine DNA thread. There's a multilevel packing system, and finally you get a highly compact linear chromosome. There're 5 stages in general: 1. Short region of DNA double helix 2. Nucleosomes: "beads on a string", 10nm chromatin fibre 3. Solenoid of packed nucleosomes: 30-nm fibre 4. Looped domains: 300nm chromatin fibre 5. Entire mitotic chromosome So generally 1 'winds around' nucleosomes to form beads on a string. The 'beads on a string' are then packed into a solenoid, which is then folded into long loops. The long loops are then attached to a network of nonhistone scaffolding proteins, and later condenses further into the entire mitotic chromosome. If you still need help with this, feel free to tell me/pm me, I can send you a scan of my notes on this! Its not the best handwriting, but legible, with illustrations and more details, done while I was revising for my exams last year. Cheers!

Hi, I'm doing some biology homework on genetic variation, and I'm kinda stuck! Well so the case is this: Maize plants that were grown from purple grains had cobs that had all purple grains. When fully grown, the resultant plants were self pollinated, giving these results in the cobs produced: Purple grains: 1836 Red grains 578 White grains 772 I have been given a hint that the alleles are: R - red, r - colourless, E - purple, e - colourless, and am supposed to draw a genetic diagram to show the cross described... From the ratio of purple:red:white grains, I'm pretty sure it is recessive epistasis, yet i'm not sure of the relationship between the alleles given in the hints. Could someone point me in the right direction, please? Thanks in advance! Cheers.

Hi, I'm Timothy from Singapore and will be sitting for my A level exams at the end of the year! *shudder* Anyway, I read Biology, Chemistry, Math and Economics in school... To be honest I came here for homework help, but seems like an interesting place, hope to stay around here!! See you all around!