Biochemistry - Nucleic Acids Flashcards
What are Nucleic acids?
Molecules for storing cell information and determining inherited characteristics in organisms.
What does the structure of a nucleotide encode?
Information needed to synthesise all proteins in organisms.
What are polynucleotides?
Polymer chains made from repeating nucleotide units.
Structure of a nucleotide?
Consists of a phosphate group attached to a nucleotide.
Also consists of a nitrogenous organic base attached to a sugar residue.
What are the two types of nucleic acid?
Deoxyribonucleic acid
Ribonucleic acid
What is the different residue between ribonucleic acids and deoxyribonucleic acids?
DNA has deoxyribose
RNA has ribose.
What is DNA’s 4 different nitrogenous bases?
Adenine, Guanine, Cytosine, Thymine.
What replaces thymine in RNA?
Uracil.
What are pyramidines? With examples?
Single nitrogen containing ring structure - Cytosine, thymine uracil.
What are purines? With examples?
Two fused nitrogen containing ring structure - Adenine, guanine.
What’s the DNA structure?
Two polynucleotide chains twisted into a double helix.
What is the DNA backbone?
Nucleic acids have a backbone of alternating phosphate and sugar groups from which nitrogenous bases protect.
What makes a nucleoside?
Nitrogenous base + sugar
What makes a nucleotide?
Nucleoside and phosphate.
Why does A bind to T and C bind to G? What is the term for the reason?
Due to shapes and partial charges on molecules.
This restriction is called complimentary base pairing.
What’s the structure of DNA?
2 strands of a polynucleotide chain held together by hydrogen bonds between complementary bases. Result in a double helix.
How is hereditary information passed onto the next generation?
DNA makes exact copies of itself.
When are copies of DNA made?
During cell division.
What’s the genome?
Genetic code of an organism.
Where is genetic info stored?
Stored in DNA as base pairs.
Where is DNA packaged?
In chromosomes.
Where are chromosomes?
In nucleus of each cell.
True or false? Sections of genetic code are switched on or off depending on the type and function of the cells?
True.
How does complimentary base pairing allow replication to take place?
Double helix of DNA unzips, revealing unpaired bases.
Free nucleotides in the cell then pair with these bases forming an identical to the original.
What are nitrogenous bases joined by?
Hydrogen bonds.
Define RNA.
Single stranded molecule that is formed from transcription of DNA.
What’s the difference between nucleotides in DNA replication and transcription?
replication - Deoxyribonucleotides involved.
transcription - Ribonucleotides involved.
Where does the messanger RNA go and to do what?
Messanger RNA moves out of the nucleus and attaches to a ribosome.
When are proteins assembled?
During translation.
What is RNA’s code deciphered into? By what?
Peptide chain (proteins primary structure). By tRNA molecules,
What is the basic structure of a protein?
Amino acid chain linked by peptide bonds.
How many naturally occurring amino acids?
Around 20 naturally occurring amino acids.
What is an amino acid codon?
A three base sequence.
How many triplet codes can be made from 4 bases?
64 triplet codes. (Just 4 to the power of 3)
True or false? Amino acids can’t be encoded for by more then one triplet codon.
False. They can and this is why we call genetic code the term ‘degenerate’.
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How many codons act as stop signals for protein - synthesis?
3
Protein synthesis = translation
Codon = triplet codon.
They’re the same thing.
What is the process of protein synthesis?
- One end of mRNA attaches to a ribososme
- Ribosome moves along mRNA three bases at a time.
- tRNA binds to free amino acids in the cytoplasm.
- tRNA molecules each carry a specific amino acid.
- They also have their own triplet code which bonds to the corresponding triplet code.
- mRNA determines the order of the amino acids.
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