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Biology Module 2: Foundations in Biology > 2.1.3 Nucleotides and nucleic acids > Flashcards

2.1.3 Nucleotides and nucleic acids Flashcards

1
Q

what is a nucleotide

A

a monomer from which nucleic acids are made of

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2
Q

what is a nucleic acid

A

the functional molecule made of one or more polynucleotide chains
eg DNA, RNA

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3
Q

what is the structure of nucleotide

A

made of three components
- a pentose sugar - contains 5 carbon atoms
- a nitrogenous base - contains carbon and nitrogen
- a phosphate group - contains phosphate

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4
Q

what is the difference between RNA and DNA nucleotides

A

-DNA has a deoxyribose sugar and RNA has a ribose sugar
-DNA has the bases A,T,C,G
-RNA has the bases A,U,G,C
-DNA is long and RNA is relatively short
-DNA has 2 strands RNA has 1 strand

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5
Q

what is a purine

A
  • a class of nitrogenous bases which are made up of two rings.
  • adenine and guanine
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6
Q

what is a pyrimidine

A

a class of nitrogen bases which are made up of a single ring
- cytosine, thymine and uracil

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7
Q

describe the complementary base pairings between the different bases

A

always a pyrimidine with a purine
adenine pairs with thymine via 2 hydrogen bonds A-T
cytosine pairs with guanine via 3 hydrogen bonds C-G

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8
Q

what is RNA

A

it is a type of nucleic acid that uses information from DNA to synthesis proteins

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9
Q

describe the synthesis and breakdown of polynucleotides

A
  • nucleotides are joined together via condensation reactions to form polynucleotides
  • the phosphate group of one nucleotide forms a covalent bond with the sugar of another nucleotide
  • this forms a phosphodiester bond
  • many nucleotides can join this way to create a chain of phosphates and sugars known as the sugar-phosphate backbone
  • phosphodiester bonds can be broken via hydrolysis reactions
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10
Q

what is DNA

A

a type of nucleic acid that contains instructions needed to make proteins

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11
Q

what are some features of DNA

A
  1. sugar-phosphate backbone - protect the coding bases on the inside of the helix
  2. double stranded - allows strands to act as templates in DNA replication
  3. Large molecule - it stores lots of information
  4. double helix - makes the molecule more compact
  5. complementary base pairing - allows accurate DNA replication
  6. Weak hydrogen bonds- allows strands to separate in DNA replication
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12
Q

what is ATP

A

it is a phosphorylated nucleotide that provides energy for many process inside living cells

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13
Q

what is the structure of ATP

A
  • ATP contains ribose, adenine and three phosphate groups
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14
Q

how does ATP go to form ADP

A

when ATP is hydrolysed it forms ADP and one phosphate molecule
- the process is catalysed by ATP

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15
Q

what is the structure of ADP

A
  • ADP contains a ribose sugar adenine and 2 phosphate groups
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16
Q

what is the structure of DNA (deoxyribonucleic acid)

A
  • contains deoxyribose ( a pentose sugar)
  • A,T,C,G base
  • a phosphate group
  • hydrogen bonding between the complimentary base pairs on two antiparallel DNA nucleotides forms a DNA molecule
  • the twisting of DNA produces the double-helix shape
17
Q

how is DNA copied

A

a process called semi-conservative replication

18
Q

explain the process of DNA replication

A
  1. DNA is unwounded by the gyrase enzyme
  2. The bonds between the DNA strands are pulled apart by the enzyme helicase, to break the hydrogen bonds
  3. Both strands act as a template for DNA replication
  4. free nucleotides pairs with the template strands complementary bases
  5. the enzyme DNA polymerase joins the free nucleotides together via condensation reaction in the 5’ to 3’ direction.
  6. the other strand known as the lagging strand is done after the first strands is replicated and is replicated in the 3’ to 5’ direction by the DNA polymerase enzyme
  7. two identical copies of DNA are made, each copy is made of one original DNA strand and one new DNA strand
19
Q

what is a mutation

A
  • changes to the DNA base sequence
20
Q

what are some errors during DNA replication which leads to mutations

A
  • bases inserted into the complimentary strand in the wrong order
  • an extra base being inserted
  • a base being left out
    these mistakes occur at random and are spontaneous ( they do not have any particular case)
21
Q

explain the importance of conserving genetic information with accuracy

A
  • retaining one original DNA strand maximise accuracy during DNA replication as each DNA strand is created from an existing template
  • each new cell will contain the same genetic information as its parent so genetic continuity is ensured between generations of cells.
  • this is important as cells in our body is replaced regularly and the new cells needs to carry out the same roles as the parent cells
22
Q

what is genetic code

A
  • the order of bases on DNA consisting of triplets/codons of bases.
  • each triplet codes for a particular amino acid known as a codon
23
Q

what are the features of genetic code

A
  1. universal - each DNA triplet codes for the same amino acid in all organisms
    2.non-overlapping - each base in the DNA is only read once
    - degenerate - most amino acids are coded for by more than one triplet
24
Q

what is a gene

A

a short section of DNA that codes for a polypeptide ( a protein)

25
Q

how does a gene determine the sequence in a polypeptide ( primary structure of a protein)

A
  • a codon codes for an amino acid
  • the amino acids in a polypeptide chain are bonded by peptide bonds.
  • the gene is a sequence of bases on a DNA molecule which forms multiple amino acids to make a polypeptide chain/ protein.
26
Q

what is the non-codon section of DNA

A
  • a section of DNA which doesn’t code for a protein
27
Q

what is the two stages of protein synthesis

A
  • transcription
  • translation
28
Q

where does transcription and translation occur

A

transcription - nucleus
translation - cytoplasm

29
Q

explain the process of transcription

A
  • in the nucleus, the gyrase enzyme uncoils the DNA strand and helicase enzyme breaks the hydrogen bonds
  • RNA polymerase enzyme allows for the nucleotides to bind weakly to the complementary DNA nucleotides on template strand to form the messenger RNA
  • the mRNA is an exact copy of the coding strand and has the bases (A,U,C,G)
  • mRNA leaves the nucleus via nuclear pores into the cytoplasm and bind to ribsome
30
Q

explain the process of translation

A
  • ribosome moves along mRNA three bases at a time
  • at each mRNA codon, a transfer RNA (tRNA - made in the nucleolus) with complementary anti-codon lines up and carries an amino acid.
  • the amino acids join by peptide ponds to for a polypeptide and this folds into a 3D protein

Biology Module 2: Foundations in Biology (6 decks)

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