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level: 2.1 Structure of RNA and DNA

Questions and Answers List

level questions: 2.1 Structure of RNA and DNA

QuestionAnswer
RNA meaning- Ribonucleic acid
DNA meaning- Deoxyribonucleic acid
What monomers make up DNA- Nucleotides
Nucleotide structure- A pentose sugar (as it has 5 carbons) - A phosphate group - A nitrogen-containing organic base
Mononucleotides- One nucleotide
Dinucleotides- Two nucleotides - Bonded together through the joining of the deoxyribose sugar of one and the phosphate group of the other
Polynucleotides- Long chain of nucleotides
Phosphodiester bond- Condensation reaction between a pentose sugar, a phosphate group and an organic base - Bonding them together
Types of nitrogen-containing organic bases- Cytosine C - Thymine T - Uracil U - Adenine A - Guanine G
Ribonucleic acid (RNA) structure- Polymer - Single, short polynucleotide chain - Pentose sugar is always ribose - Organic bases are cytosine, uracil, adenine, guanine
Different functions of different types of RNA- Transfers genetic information from DNA to the ribosomes - Ribosomes are made up of proteins and another type of RNA - Involved in protein synthesis
DNA structure- Polymer - Made up of two strands of nucleotides forming a double helix - Pentose sugar is always deoxyribose - Organic bases are cytosine, thymine, adenine, guanine
Strands of nucleotides (DNA structure)- Each of the two strands is very long - Joined together by hydrogen bonds formed between certain bases
Base pairing- Adenine always pairs with thymine - Guanine always pairs with cytosine - They are complementary to one another
The double helix- Two polynucleotide strands that are anti-parallel - Strong phosphodiester bonds joining the backbone - Hydrogen bonds joining nucleotides between base parings
The stability of DNA- The phosphodiester backbone protects the more chemically reactive organic bases - Hydrogen bonds link organic base pairs - There are 3 hydrogen bonds between cytosine and guanine, the higher the proportion of C-G pairings the more stable the DNA molecule
Function of DNA- Carries genetic code - Has instructions to make proteins
How DNA is adapted for its function- Very stable structure, most mutations are repaired - Strands joined by hydrogen bonds, allows them to separate during DNA replication + protein synthesis - Large, carries more genetic information
RNA (differences between DNA and RNA)- Single stranded - Smaller - Uracil present - Has a ribose sugar - Leaves the nucleus
DNA (differences between DNA and RNA)- Double stranded - Larger - Thymine present - Has a deoxyribose sugar - Stays in the nucleus
Explain how a change in the DNA base sequence for a protein may result in a change in the structure of the protein- A change in the sequence of amino acids means bonds in different places - This results in a different tertiary structure of proteins and that alters the function of the protein.
What is a codon- A sequence of three nucleotides which forms genetic code - Anticodon complementary to codon