nucleic acids and their functions Flashcards

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1
Q

what is a nucleotide?

A

the basic unit which nucleic acids are formed from

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2
Q

what are nucleotides composed of?

A

a phosphate group, a pentose (five-carbon) sugar and an organic nitrogenous base

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3
Q

what is a nucleic acid?

A

polymers of nucleotides, for example DNA or RNA

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4
Q

pentose (five-carbon) sugar in DNA

A

deoxyribose

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5
Q

pentose (five-carbon) sugar in RNA and ATP

A

ribose

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6
Q

what are the possible organic bases in DNA?

A

adenine, thymine, guanine, or cytosine

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7
Q

what are the possible organic bases in RNA?

A

adenine, cytosine, guanine or uracil

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8
Q

what is the main function of DNA?

A

replication and providing the code for protein synthesis

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9
Q

what is the function of RNA?

A

transfers genetic information from DNA to ribosomes made from RNA and proteins

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10
Q

what is the function of ATP?

A

involved in the transfer of energy

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11
Q

how do nucleotides join together to form nucleic acids?

A

nucleotides join together by phosphodiester bonds formed in condensation reactions

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12
Q

describe a DNA molecule

A

a DNA molecule is a double helix composed of two polynucleotides joined together by hydrogen bonds between complementary bases

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13
Q

describe an RNA molecule

A

an RNA molecule is a short polynucleotide chain

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14
Q

why is ATP known as the universal energy currency?

A

because it is used in all energy requiring reactions in all cells in all living organisms

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15
Q

what is the nucleotide ATP made up of?

A

adenine (nitrogenous base) joined to ribose (five-carbon sugar) and three phosphate groups

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16
Q

what energy-requiring reactions is ATP involved in?

A

active transport, protein synthesis, nerve transmission and muscle contraction

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17
Q

how is ATP formed?

A

ATP is formed when phosphate is added to adenosine diphosphate (condensation reaction)

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18
Q

what is a pyrimidine base?

A

bases with a single ring structure

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19
Q

what is a purine base?

A

base with a double ring structure

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20
Q

examples of pyrimidine (single ring) bases

A

cytosine, thymine, uracil

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21
Q

examples of purine (double ring) bases

A

adenine, guanine

22
Q

what forms the backbone of a DNA strand?

A

sugar-phosphate

23
Q

what are the purine-pyrimidine complementary base pairings?

A

adenine always pairs with thymine. two hydrogen bonds form between adenine and thymine
cytosine always pairs with guanine. three hydrogen bonds pair between cytosine and guanine

24
Q

why is complementary base pairing important?

A

so that DNA replicates correctly

25
Q

what are the three different types of RNA?

A

messenger RNA
ribosomal RNA
transfer RNA

26
Q

what is the function of ribosomal RNA?

A

rRNA combines with protein to form ribosomes

27
Q

what is the function of mRNA?

A

mRNA carries the code for the polypeptide chain that will be formed in the translation stage of protein synthesis

28
Q

how is mRNA formed?

A

mRNA is formed in the nucleus by transcription of a strand of DNA

29
Q

how does the mRNA leave the nucleus after the polypeptide is formed?

A

the mRNA leaves through the nuclear pore

30
Q

what is the function of tRNA?

A

tRNA transports amino acids to the ribosome for translation

31
Q

what is tRNA made up of?

A

tRNA contains an anticodon and an amino attachment site

32
Q

what is the first step of semi-conservative DNA replication?

A

the double helix unwinds and the hydrogen bonds between the complementary bases break using the enzyme helicase therefore separating the two strands of DNA

33
Q

what is the second step of semi conservative DNA replication?

A

one of the separated strands is used as the template and complementary base pairing occurs between the template strand and free nucleotides

34
Q

what is the final step of semi conservative DNA replication?

A

adjacent nucleotides are joined by phosphodiester bonds formed in condensation reactions by the enzyme polymerase

35
Q

why is dna replication said to be semi conservative?

A

because each new replicated DNA molecule contains one original strand and one newly formed strand

36
Q

where is mRNA formed?

A

in the nucleus

37
Q

transcription

A

the first stage of protein synthesis. it is the conversion of the genetic code to a sequence of nucleotides in mRNA

38
Q

translation

A

the second stage of protein synthesis. it takes place in the ribosomes. it is the conversion of the code in mRNA to a sequence of amino acids

39
Q

where does translation occur?

A

translation occurs at the ribosome

40
Q

what is the region of the DNA that contains the code for proteins called?

A

exons

41
Q

what is the non-coding DNA between the exons called?

A

introns

42
Q

what are the two stages of protein synthesis?

A

transcription and translation

43
Q

what are the two types of organic base?

A

purine and pyrimidine

44
Q

describe the structure of an ATP nucleotide

A

an ATP nucleotide contains ribose, adenine, and three phosphate groups

45
Q

what is an endergonic reaction?

A

a non-spontaneous reaction that requires an input of energy, for example ATP formation

46
Q

what is an exergonic reaction?

A

a spontaneous reaction that overall releases energy, for example ATP hydrolysis

47
Q

describe the role of ATP

A

ATP is a universal energy currency. ATP is hydrolysed to release energy

48
Q

what is complementary base pairing?

A

complementary base pairing describes how hydrogen bonds form between complementary purine and pyrimidine bases

49
Q

describe the structure of mRNA

A

mRNA contains 2000 nucleotides, a single helix and is unstable

50
Q

describe the structure of tRNA

A

tRNA contains 80 nucleotides, a clover leaf shape, a single helix and an anticodon on one end with amino acid binding site on the other

51
Q

describe the structure of rRNA

A

rRNA contains 1800 to 5000 nucleotides and two subunits, one large one small