PL.8
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What are the building blocks for DNA?
Deoxyribose (a sugar), phosphate groups, and four different bases.
What are the four bases in DNA?
Adenine (A), thymine (T), cytosine (C) and guanine (G).
What two building blocks join together by condensation to form the DNA backbone?
Deoxyribose and phosphate. That’s why it is also called a sugar-phosphate backbone.
Which parts of the sugar-phosphate backbone joins to the bases by condensation?
The deoxyribose.
What shape is DNA?
Double helix.
Each sugar/phosphate/base group form a unit known as what?
Nucleotide.
What bonds are formed between base pairs which means they can only pair up with one another?
Hydrogen bonding.
What are the two base pairs for DNA?
A-T C-G
How many hydrogen bonds are formed between the base pair thymine and adenine?
2
How many hydrogen bonds are formed between the base pair cytosine and guanine?
3
Base pairing in DNA allows it to do what two things?
• Synthesis a complementary copy of itself. - Allow mRNA to synthesis a complementary copy for use in protein synthesis.
What is mRNA?
messenger RNA.
Which of the backbone building block of RNA differs from that of DNA?
It has ribose instead of deoxyribose, which is also a sugar.
Which base in DNA, T, A, C, G are not present as an RNA base?
T
Which base is present instead of T in RNA?
Uracil (U).
What is the first step of protein synthesis?
Transcription.
Describe the transcription process?
• Using an enzyme, the section of DNA related to the coding of a protein unzips, this allows the single strand to be used as a template for copying. • RNA nucleotides join up to a mRNA strand the order that the bases pairs up with the DNA template. • When the section of DNA is copied, the mRNA leaves and the double helix of the DNA reforms.
In mRNA, the sequence of bases corresponds to codings for amino acids, how many bases code for each amino acid?
3
What is the group of three bases coding for amino acids known as?
Codon.
Do each amino acid correspond to one codon?
No, because there are 64 different codons and only 20 amino acids, most amino acids have more than one codon.
Which amino acid codes for start?
Met, it is always at the start of the protein sequence.
What codon is used at the end of the synthesis?
Stop codons, there are three and they indicate the end of the synthesis.
In what structure of the cell does protein synthesis (translation) take place in?
Ribosomes.
mRNA carries the template that allows what feature of the protein to be correct?
The primary structure.