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Topic 1: biological molecules > 1.4 DNA and protein synthesis > Flashcards

1.4 DNA and protein synthesis Flashcards

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Organic Chemistry 101 flashcards
1
Q

what are the three parts of a nucleotide?

A

-5 carbon pentose sugar
-nitrogenous base
-phosphate group

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2
Q

what is the difference bwtween DNA and RNA?

A

the pentose sugar in DNA is deoxyribose and the sugar in RNA is ribosewha

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3
Q

what are the two types of bases in neucleotides?

A

-purine
-pyrimidine

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4
Q

what is the difference between purines and pyrimidines?

A

-purines: two nitrogen containing rings
-pyrimidines: one nitrogen containing rings

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5
Q

what are the five types of bases?

A

-adenine
-thymine
-cytosine
-guanine
-uracil

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6
Q

which bases are purines?

A

adenine and guanine

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7
Q

which bases are pyrimidines?

A

cytosine, thymine and uracil

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8
Q

why do nucleotides carry a negative charge?

A

because the phosphate group in the cytoplasm of cells joins and makes the molecule acidic

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9
Q

how are the three elements of nucleotides joined together?

A

condensation reaction

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10
Q

what does ATP stand for

A

adenosine triphosphate

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11
Q

what is the structure of ATP?

A

a nucleotide with 3 phosphate groups

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12
Q

what happens when energy is needed?

A

-the third phosphate bond in the molecule is broken in a hydrolysis reaction which is catalysed by ATPase

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13
Q

what is the monomer unit for nucleic acids?

A

nucleotide monomer units

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14
Q

what is the difference in the storage of DNA in eukaryotic cells and prokaryotic cells?

A

in eukaryotic cells it’s stored in chromosomes in the nucleus and in prokaryotic cells it floats freely in strands in the cytoplasm

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15
Q

what bonds hold together nucleotides?

A

phosphodiester bons between sugars on one nucleotide and the phosphate group on the next, this forms a sugar-phosphate backbone

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16
Q

what shape is DNA?

A

double helix held by hydrogen bonds between complimentary base pairs

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17
Q

what shape is RNA?

A

-complex shapes held by hydrogen bonds or remain long and thread like

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18
Q

how many hydrogen bonds are between C and G?

A

3

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19
Q

how many hydrogen bonds are between A and T?

A

2

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20
Q

how does semi-conservative replication work?

A

-DNA helicase ‘unzips’ the two strands of DNA along the line of hydrogen bonds and unravels them and these go on to act as templates
- the exposed bases attract free neucleotides and new hydrogen bonds are formed between matching pair bases
-DNA polymerase lines up and catalyses the linking up of the neucleotides along the template strand
-DNA ligase catalyses the formation of phosphodiester bonds between the two strands of DNA

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21
Q

what is the definition of a gene?

A

a sequence of bases on a DNA molecule coding for a sequene of amino acids in a polypeptide chain

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22
Q

what is a codon?

A

a sequence of three bases on the DNA or RNA

23
Q

what are the differences between DNA and RNA?

A
  • different sugar (ribose)
  • different base (uracil instead of thymine)
  • single helix not double
24
Q

what functions does RNA carry out?

A
  • carries instructions for a polypeptide from the DNA in the nucleus to the ribosome where proteins are made
  • it picks up specific amino acids from the protoplasm and carries them to the surface of the ribosomes
  • it makes up the bulk of the ribosome themselves
25
Q

what are the three types of RNA?

A
  • mRNA
  • tRNA
  • rRNA
26
Q

how many polypeptides can one piece of mRNA make?

A

1

27
Q

what strand of the DNA does mRNA use?

A

antisense strand

28
Q

what strand of the DNA does mRNA not use?

A

sense strand

29
Q

what does RNA polymerase do?

A

enzyme that polymerises nucleotide units to form RNA in a sequence determined by the antisense strand of DNA

30
Q

what initially holds the complimentary RNA bases in place?

A

hydrogen bonds

31
Q

what type of bond is catalysed by RNA polymerase?

A

phosphodiester bonds between the sugars and phosphate groups of the bases to form the strand of mRNA

32
Q

what is tRNA?

A

small units of RNA that pick up particular amino acids from the cytoplasm and transport them to the surface of the ribosome to align with the mRNA

33
Q

what is the shape of tRNA described as?

A

clover leaf

34
Q

what is this shape due to?

A

hydrogen bondign between different bases

35
Q

what is an anticodon?

A

a sequence of three bases on tRNA that are complimentary to the bases in the mRNA codon

36
Q

what is a binding site?

A

where the tRNA picks up amino acids

37
Q

what bonds form between amino acids once they are lined up on the surface of the ribosome?

A

peptide bonds

38
Q

what are the two stages to protein synthesis?

A

transcription and translation

39
Q

what is the process of transcription?

A

1- hydrogen bonds between comnplimentary bases in the DNA strand break and the double helix uncoils
2- the antisense strand is used as a template to make an mRNA molecule using free mRNA neucleotides
3- these free nucleotides line up by complimentary base pairing and are joined by phosphodiester bonds catalysed by RNA polymerase
4- the mRNA strand leaves the nucleus through a nuclear pore to a ribosome in the cytoplasm

40
Q

what is the process of translation?

A

1- tRNA binds to a specific amino acid from the cytoplasm depending on it’s anticodon
2- complimentary anticodons of tRNA bind to mRNA and is held in place by hydrogen bonds
3- amino acids that are lined up join by peptide bonds and the tRNA molecules detach from the amino acids leaving a polypeptide chain

41
Q

what are two known facts about the genetic code?

A
  • non-overlapping (each triplet is only read once and no sharing of bases): the effect of a mutation would only affect one amino acid
  • degenerate (more than one triplet codes for the same amino acids): protects organisms from the effects of mutations
42
Q

what are start stop codons?

A

they start and stop protein synthesis

43
Q

what are non-coding sections of DNA called?

A

introns

44
Q

what are the coding sections of DNA called?

A

exons

45
Q

what is a point mutation?

A

a change in one or a small number of neucleotides affecting a single gene

46
Q

what are the three types of point mutation?

A
  • substitutions
  • deletions
  • insertions
47
Q

what is a substituion mutation?

A

when one base substitues another

48
Q

what is a deletion mutation?

A

base is completely lost from a sequence

49
Q

what is an insertion mutation?

A

when an extra base is added

50
Q

what are chromosomal mutations?

A

changes in the positions of the genes within the chromosome

51
Q

what are whole-chromosome mutations?

A

an entire chromosome is either lost during meiosis or duplicated in one cell by error (Down’s syndrome)

52
Q

what effects do mutations have?

A
  • some have no effect
  • can result in a new superior protein that gives the organism an advantage
  • some cause damage and disrupt the biochemistry of the entire organism (changing the active sites of enzymes)
53
Q

what is an example of the result of a point mutation?

A

sickle cell anemia

54
Q

sickle cell anemia

A
  • genetic disease that affects the protein chains making up the heamoglobin in the red blood cells
  • heamoglobin molecules stick together to form rigid rods that give the red blood cells a sickle shape
  • they do not carry oxygen efficiently

Topic 1: biological molecules (7 decks)

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