Hey guys i need help with a few dotpoints on this topic (1 Viewer)

[yr12yr12]

firstly I have no understanding what so ever with beadle and tantum's experiment that lead it to one gene one polypeptide instead of one gene one protien

anddd


how DNA controls the production of polypeptides ( mRNA, rNA included)

much appreciated if you guys help

 

[memo15]

George Beadle and Edward Tatum performed experiments by using a fungus called pink bread mould, they found that this mould would thrive on a minimal medium containing nothing but minerals, sucrose and vitamin biotin. They reasoned that these substances must be converted into amino acids and that enzymes are responsible for this. They exposed the fungus to X-rays causing mutations in some of its genes. As a result of these mutations the fungus was unable to synthesise particular amino acids needed for growth. They tried to grow the mould again on a minimal medium- if it failed to grow they tried to grow it on a variety of media, each containing different amino acids. They suggested that the mutant strain had lost its ability to produce one amino acid- this was because they lacked a particular enzyme. They suggested that the enzyme responsible for for the synthesis of the amino acid is controlled by a single gene. Therefore hypothesised that a single gene controls the production of a single enzyme, the one gene one enzyme hypothesis

 

[memo15]

and how DNA controls the production of polypeptides:
it occurs in two steps : Transcription and Translation:
A. transcription is the synthesis of RNA from DNA. It occurs in the nucleus.
1. The 2 strands of DNA separate
2. The free floating RNA nucleotides in pair up to their complimentary bases (ie A-U and C-G)
3. The newly formed strand of mRNA leaves the nucleus and enters the cytoplasm for translation
B:TRANSLATION- is the synthesis of proteins from mRNA and it occurs in the cytoplasm
1. The mRNA binds to a ribosome
2. tRNA molecules in the cytoplasm each carry a specific amino acid to the ribosome. The amino acid is determined by the anti-codon at one end of the tRNA molecule
3. Starting at one end the complimentary anti-codon attaches to the first codon of mRNA
4. A second tRNA attaches to the next codon of mRNA
5. The 2 adjacent amino acids are joined together by a peptide bond
6. The first tRNA is released and the process is repeated until the polypeptide is complete and the ribosome reaches a stop codon.

I hope that helped you

 

[yr12yr12]

thank you for your help.

Is your name Mehmet btw?

 

[memo15]

looll noo

 

[Nah_f_u_studies]

George Beadle and Edward Tatum performed experiments by using a fungus called pink bread mould, they found that this mould would thrive on a minimal medium containing nothing but minerals, sucrose and vitamin biotin. They reasoned that these substances must be converted into amino acids and that enzymes are responsible for this. They exposed the fungus to X-rays causing mutations in some of its genes. As a result of these mutations the fungus was unable to synthesise particular amino acids needed for growth. They tried to grow the mould again on a minimal medium- if it failed to grow they tried to grow it on a variety of media, each containing different amino acids. They suggested that the mutant strain had lost its ability to produce one amino acid- this was because they lacked a particular enzyme. They suggested that the enzyme responsible for for the synthesis of the amino acid is controlled by a single gene. Therefore hypothesised that a single gene controls the production of a single enzyme, the one gene one enzyme hypothesis

maybe a bit late buhh ..

it was originally th one gene: one proteins hypothesis because all enzymes are proteins buhh it was later changed because although all enzymes are proteins , not all proteins are enzyme e.g. haemoglobin and then was changed to one gene : one polypeptide ..

 

[SpreadTheWord]

and how DNA controls the production of polypeptides:
it occurs in two steps : Transcription and Translation:
A. transcription is the synthesis of RNA from DNA. It occurs in the nucleus.
1. The 2 strands of DNA separate
2. The free floating RNA nucleotides in pair up to their complimentary bases (ie A-U and C-G)
3. The newly formed strand of mRNA leaves the nucleus and enters the cytoplasm for translation

As the dotpoint says outline. In my own words i'll simplify it in a few sentences. The DNA code (Codons) are transcribed into the mRNA and leave the nucleus. THe mRNA will then go to the Ribosomes (Polypeptide synthesise occurs here). Meanwhile, the tRNA carries amino acids in the cytoplasm, and will also travel to the ribosomes, where it will link up the amino acids with the mRNA to create a sequence of nucleotides.