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BIOLOGY OCR > Nucleic Acids > Flashcards

Nucleic Acids Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

How many rings do purines have?

A

2 rings

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2
Q

How many rings do pyrimidines have?

A

1 ring

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3
Q

What are the 5 bases?

A 
Adenine
Guanine
Thymine
Cytosine
Uracil
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4
Q

Which bases are pyrimidines?

A

Cytosine
Thymine
Uracil

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5
Q

Which bases are purines?

A

Adenine

Guanine

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6
Q

What are phophorylated nucleotides?

A

Nucleotides with extra phosphate groups attached

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7
Q

Give 2 examples of phophorylated nucleotides

A

ATP - Adenosine triphosphate (3 phosphate groups attached)

ADP - Adenosine diphosphate (2 phosphate groups attached)

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8
Q

What type of reaction bonds nucleotides together?

A

condensation reaction

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9
Q

What are phosphodiester bonds?

A

Covalent bonds which hold the polynucleotide together at carbon 5 and carbon 3

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10
Q

What does it mean when 2 polynucleotide chains are running in antiparallel?

A

Parallel but pointing in opposite directions. One strand runs from 3’ to 5’ and the other from 5’ to 3’.

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11
Q

What is the process of DNA purification?

A
  1. Break up the DNA containing tissue (e.g. cheek cells from a swab) to break it up into cells
  2. Add a detergent – detergents break apart lipids, like those found in the plasma membrane
  3. Shake with ethanol to precipitate the DNA out of solution
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12
Q

What are the steps in DNA replication?

A
  1. DNA double helix unwinds and “unzips”; the hydrogen bonds between base pairs are broken. The unzipping of the hydrogen bonds is catalysed by an enzyme called
    DNA helicase.
  2. The exposed nucleotide bases act as a template for assembly of the new DNA strand.
  3. Free nucleotides move towards these exposed bases according to the base pair rule.
  4. An enzyme called DNA polymerase binds the nucleotides together with covalent bonds, forming the new sugar-phosphate backbone. (travels from 5’ to 3’)
  5. The leading strand is replicated continuously, and the lagging strand is synthesised in fragments (discontinuously) that are then joined by ligase enzymes.
  6. This results in 2 daughter DNA strands
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13
Q

What does DNA Helicase do?

A

Catalyses the unzipping of hydrogen bonds

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14
Q

Why do we call it semi-conservative replication?

A

one of the original/parental strands is conserved on each daughter DNA molecule.

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15
Q

What does DNA polymerase do?

A

binds the nucleotides together

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16
Q

What does ligase do?

A

Joins the fragments of the lagging strand together

17
Q

What does degenerate mean?

A

Several/lots of different triplets can code for the same amino acid

18
Q

What does universal mean?

A

the genetic code is the same for all living organisms

19
Q

What does non-overlapping mean?

A

One triplet is coded for, one after another

20
Q

What is a gene?

A

A sequence of DNA nucleotides that codes for a protein

21
Q

Define transcription

A

the process of copying RNA from DNA

22
Q

What are the steps in transcription?

A
  1. DNA strand unwinds and unzips by DNA helicase
  2. RNA nucleotides pair up with the exposed bases on one strand of DNA – called the template strand
  3. The new nucleotides form the coding strand, which is complementary to the template strand
  4. DNA rezips and rewinds after the coding strand of mRNA detaches
  5. mRNA migrates/leaves through nuclear pores to the ribosomes for translation into a protein
23
Q

Define translation

A

the process of creating polypeptides based off mRNA

24
Q

What are the steps in translation?

A
  1. mRNA attaches to a ribosome on the RER
  2. Transfer RNA (tRNA) carries the corresponding amino acid to each codon on the mRNA
  3. The anti-codon is a triplet of bases that form part of a tRNA molecule which is complementary to the codons on the mRNA strand
  4. The mRNA has a start codon at the beginning and a stop codon (that doesn’t code for an amino acid) at the end
  5. One by one amino acids are added as the tRNA anti-codons temporarily pair with the codons on the mRNA strand.
  6. Adjacent amino acids are joined together by peptide bonds, creating a polypeptide chain
  7. This process continues until the ribosome reaches the stop codon. At this point, the polypeptide breaks loose from the ribosome and is free
25
Q

Is translation an active or passive process?

A

Active process - requires ATP

26
Q

What are the differences between DNA and RNA?

A 
DNA = Double stranded
RNA = Single stranded

DNA - Found in Nucleus only
RNA - Nucleus + Cytoplasm

Only 1 form of DNA
3 forms of RNA (tRNA mRNA rRNA)

DNA - Deoxyribose sugar
RNA - Ribose sugar

DNA - Thymine
RNA - No Thymine it has Uracil instead

27
Q

How many hydrogen bonds form between bases A and T?

A

2 Hydrogen bonds

28
Q

How many hydrogen bonds form between bases G and C?

A

3 Hydrogen bonds

29
Q

How many proteins does mRNA code for?

A

1 protein

30
Q

What is the structure of a nucleotide?

A

Pentose sugar
Phosphate group
Nitrogenous base

31
Q

What are the 3 types of RNA?

A

mRNA - messenger RNA
tRNA - transfer RNA
rRNA - ribosomal RNA

BIOLOGY OCR (12 decks)

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