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Biology Year 1 > 2.1.3- Nucleotides + Nucleic Acids > Flashcards

2.1.3- Nucleotides + Nucleic Acids Flashcards

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1
Q

what is a nucleotide?

A

a monomer from which nucleic acids are made?

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2
Q

what are the 5 elements are nucleic acids made from?

A
  • carbon
  • oxygen
  • hydrogen
  • nitrogen
  • phosphorus
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3
Q

what are nucleotides made up of?

A
  • phosphate group
  • sugar
  • base
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4
Q

what are the two different types of nucleic acids?

A
  • DNA

- RNA

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5
Q

what are the 4 differences between DNA + mRNA?

A
  • DNA=double-stranded, while mRNA= single-stranded
  • dna contains deoxyribose, while mrna contains ribose
  • dna contains thymine, whereas mrna contains uracil
  • mrna is less stable than dna due to having exposed bases + the fact that uracil is easier to degrade.
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6
Q

what type of pentose sugar is found in DNA + mRNA?

A
  • DNA= deoxyribose

- mRNA= ribose

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7
Q

what is a purine?

A

a class of nitrogenous bases that are made up of 2 rings that Adenine + Guanine are members of.

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8
Q

what is a pyramidine?

A

a class of nitrogenous bases made up of a single ring, cytosine, thymine and uracil are members.

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9
Q

what bond is formed between 2 nucleotides (polynucleotides)?

A
  • PHOSPHODIESTER BOND
  • between the phosphate group (5th carbon) +the hydroxyl group (3rd carbon)
  • condensation reaction builds, while hydrolysis reaction breaks them down.
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10
Q

how do you write the numbers of a phosphodiester bond?

A

5”,3”

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11
Q

what is a phosphorylated nucleotide?

A

The process of introducing one or more phosphate groups into a nucleotide to produce a phosphorylated nucleoside.

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12
Q

what are the 2 examples of phosphorylated nucleotides?

A
  • ADP

- ATP

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13
Q

what is the structure of ATP?

A
  • adenine base
  • ribose sugar
  • 3 phosphate groups
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14
Q

what does ATP do?

A
  • provides energy, so that cells can synthesise, transport + move
  • it is released through hydrolysis
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15
Q

what does ATP break down into?

A
  • inorganic phosphate ion
  • ADP
  • energy
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16
Q

what is the structure of ADP?

A
  • base
  • sugar
  • two phosphate groups
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17
Q

what is the structure of DNA like?

A
  • very long, so can store increased amounts of info
  • base-pairing rules, easy to replicate info
  • double helix, stable molecule, where info is stored safely.
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18
Q

how is DNA formed?

A

-hydrogen bonding between complementary base pairs on 2 anti-parallel DNA polynucleotides

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19
Q

what are the two complementary base pairs in DNA, and how many hydrogen bonds do they form?

A
  • Adenine + Thymine = forms 2 hydrogen bonds

- Cytosine + Guanine = forms 3 hydrogen bonds

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20
Q

what bases are purines?

A
  • adenine

- guanine

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21
Q

what bases are pyramidines?

A
  • cytosine

- thymine

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22
Q

what is a double-stranded/double helix DNA?

A
  • 2 single strands of DNA twist around each other forming a double-helix
  • this helix is held by hydrogen bonds between nitrogenous bases on different strands
  • it is anti-parallel
23
Q

how many bases are in DNA and how many codons does this then make?

A
  • 4 bases = A-T, C-G

- makes 64 different codons

24
Q

what is the function of DNA?

A
  • holds genetic info
  • codes for the primary structure of proteins
  • store these codes, called genes
25
Q

what is the definition of GENES?

A

a sequence of nucleotides that code for a polypeptide.

26
Q

what is single-stranded DNA?

A

a long chain of nucleotides

27
Q

what is SEMI-CONSERVATIVE DNA REPLICATION?

A

when half of the parent strand is conserved

28
Q

what is the first stage of semi-conservative replication?

A
  • DNA helicase unzips DNA by breaking hydrogen bonds between complementary bases.
  • helicase = enzyme
29
Q

what is the second stage of semi-conservative replication?

A
  • the free DNA nucleotides become attracted to the exposed bases by complementary base pairing
  • the free strands act as templates
30
Q

what is the third stage of semi-conservative replication?

A

-free nucleotides join by phosphodiester bonds by DNA polymerase (enzyme) to form a phosphate sugar backbone.

31
Q

what is the fourth stage of semi-conservative replication?

A

-each DNA molecule is then made up of one OLD strand, and one NEW strand of DNA.

32
Q

what is the importance of semi-conservative replication?

A
  • it conserves genetic information with accuracy.

- prepares cells for mitosis

33
Q

what are the 3 types of mutations in the base sequence?

A
  • base deletion (the loss of genetic material)
  • insertion (the addition of genetic material)
  • substitution (where one base pair is replaced with another base pair)
34
Q

what does generate coding mean?

A

when amino acids have more than one corresponding codon

35
Q

what does degenerate coding mean?

A

when amino acids have more than one corresponding codon

36
Q

what are INTRONS?

A

the non-coding sections of DNA

37
Q

what are EXONS?

A

the coding regions of DNA.

38
Q

what are the 3 features of the genetic code?

A

-it is non-overlapping (each triplet is read only once, with triplets not sharing bases)
-it is degenerate (more than one triplet codes for the
same amino acids, reducing phenotypic effect of mutations).
-contains start and stop codons (which start/stop protein synthesis).

39
Q

what can mutations cause?

A

phenotypic effects

40
Q

what can mutations cause?

A

phenotypic effects

  • production of sticky mucus and causes cystic fibrosis
  • sickle cell anaemia
41
Q

what do mutations of the base sequence of DNA cause?

A
  • alters the amino acid sequence

- alters the proteins, so has many effects.

42
Q

what is nucleic acid transcription?

A

the process of copying + transporting genes out of the nucleus and into the ribosomes, to produce RNA

43
Q

what is the first stage of transcription?

A

-part of the DNA that contains the genes unzips when hydrogen bonds between two strands break

44
Q

what are the 2nd and 3rd stages of transcription

A
  • complementary free RNA nucleotides line up opposite the anti-sense strand, acting as a template.
  • these then join by phosphodiester bonds to create a single-stranded mRNA
45
Q

what is the last stage of transcription?

A
  • it stops at the end of the gene, with mRNA then moving out of the nucleus through a pore and attaching to a ribosome in the cytoplasm
  • double helix reforms
46
Q

what is an anti-sense strand?

A

a complementary copy of the sense strand that doesn’t code for a protein but acts as a template.

47
Q

what happens during translation?

A

amino acids join together to form polypeptide chains

48
Q

what is the first stage of translation?

A

-mRNA attaches to a ribosome and tRNA collects amino acids from the cytoplasm and carries them to the ribosome.

49
Q

what is the second stage of translation?

A
  • tRNA attaches itself to mRNA by complementary base pairing
  • two molecules attach to mRNA at a time
50
Q

what is the third stage of translation?

A

-the amino acids attached to two tRNA molecules join by a peptide bond and then tRNA molecules detach themselves from the amino acids, leaving them behind

51
Q

what is the last stage of translation?

A

-this process is repeated, leading to the formation of a polypeptide chain until a stop codon is reached on mRNA and ends the process of protein synthesis

52
Q

what is a sense strand?

A

a strand that contains a code for protein to be synthesised.

53
Q

what does the condensation of nucleotides form?

A
  • a long/strong phosphate-sugar backbone

- base that is attached to sugars

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