2.1 Structure of RNA and DNA Flashcards

(19 cards)

1
Q

Describe the basic function of DNA and RNA in all living cells

A

DNA: Holds genetic information which codes for polypeptides (proteins)

RNA: Transfers genetic information from DNA to ribosomes

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2
Q

Name the types of molecules from which a ribosome is made

A

RNA and Proteins

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3
Q

What is the monomer that makes up DNA

A

A nucleotide

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4
Q

What are the 4 nitrogenous bases in DNA

A

Guanine
Cytosine
Adenine
Thymine

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5
Q

Describe how nucleotides join together to form polynucleotides (3)

A
  • Condensation reactions, removing water molecules
    ● Between phosphate group of one nucleotide and deoxyribose / ribose of another
    ● Forming phosphodiester bonds
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6
Q

How is the polynucelotide held together

A

Strong covalent bonds called phosphodiester bonds

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7
Q

How are the DNA polymer pairs joined together

A

Hydrogen bonds between the Nitrogenous bases

This is how the double helix strcutre is created as the two chains twist

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8
Q

What is the only condition through which hydrogen bonds form in polynucelotides

A

They can only form between complimentary base pairs
Cytosine—Guanine 3
Adenosine–Thymine 2
Guanine—Cytosine 3
Thymine–Adenine 2

Number of ‘-‘ represent the number of h bond bwteen the bases

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9
Q

What is RNA (3)

A

*A polymer of a nucleotide formed of a:
- Ribose
-Nitrogenous base
- Phosphate group
*Relatively short
*Single Stranded

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10
Q

Name the 4 nitrogenous bases in RNA

A

Adenine
Uracil
Guanine
Cytosine

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11
Q

What are the differences between the DNA and RNA monomers

A
  • DNA contains the base Thymine whereas RNA has Uracil instead of Thymine
  • DNA contains the pentose suagr deoxyribose whilst RNA contains Ribose
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12
Q

What are the two differences between the polymers of DNA and RNA

Length

A
  • DNA is much longer as it contains 23,000 genes whereas RNA is shorter as it only contains 1
  • DNA is double stranded whilst RNA is single stranded
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13
Q

Which Nitrogenous bases are Purine

A

Adenine and Guanine
They both have two rings
Guanine has a double bond to O

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14
Q

Which Nitrogenous bases are pyrimidine

A

Thymine Cytosine and Uracil
Has one ring

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15
Q

Why can Adenine and Cytosine not bond

A

Adenine would form 2 hydrogen bonds whereas Cytosine would form 3 hydrogen bonds

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16
Q

What is the differnece between Deoxyribose and Ribose

A

Deoxyribose chemical formula-C5 H10 O4
Ribose has the same but one more oxygen
Strcture of Deoxyribose is more stable so it has a sotrnger covalent bonds as the C3 bond will be bonded directly oto the phosphate group

17
Q

How are polynucleotides formed

A

When DNA contains a second antiparallel chain that runs in the opposite direction

E.g. 5’ prime and 3’ prime end

18
Q

Why is DNA stable

A
  • The phosphodiester backbone protects the more chemically reactive organic bases inside the double helix
  • Hydrogen bonds link the organic base pairs forming bridges
19
Q

Suggest how you can use incomplete information about the frequency of bases on DNA strands to find the frequency of other bases (3)

A
  1. % of adenine in strand 1 = % of thymine in strand 2 (and vice versa)
  2. % of guanine in strand 1 = % of cytosine in strand 2 (and vice versa)
    * Because of specific complementary base pairing between 2 strands