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If one base coded for only one amino acid, how many different amino acids could be coded for in total? Is this a sufficient number to make all proteins?

No because every 3 bases count for 1 amino acid

What if a group of two bases, in any order, coded for one amino acid? How many combinations?


Is three bases enough to code for twenty different amino acids?

No because with only three bases, one wouldn't get a purine or pyrimidine to connect with and it would result in a dead/disfigured organism

Difference between DNA and mRNA

DNA: Double stranded, Thymine, and Deoxyribose
RNA: Single stranded, Uracil, and Ribose

The steps of transcription

1. Helicase causes weak hydrogen bonds between the bases on the parental DNA break causing the two strands to separate, leaving the bases exposed.
2. Part of the DNA double helix containing the gene to be transcribed unwinds due to RNA polymerase binding to the promoter sequence.
3. RNA nucleotides find complementary nucleotides on the antisense strand of the parental DNA.
4. Weak hydrogen bonds form between the complementary RNA and DNA nucleotides.
5. Process continues until the terminator sequence is reached: mRNA peels off the DNA and leaves the nucleus through nuclear pores in the nuclear membrane.
6. Sugar-phosphate bonds form between the RNA nucleotides to form mRNA due to the action of RNA polymerase.

The strand of DNA that has the same base sequence at the mRNA

Sense strand


The part that does code


The part that doesn't code

Describe how introns removed from the mRNA strand before it leaves the nucleus

RNA splicing occurs: introns removed by RNA splicing SNURP (proteins) clear out unnecessaries

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