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AS OCR Biology > Unit 2.3- Nucleotides and nucleic acids > Flashcards

Unit 2.3- Nucleotides and nucleic acids Flashcards

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1
Q

Nucleotide definition:

A

Molecule consisting of a five-carbon sugar, a phosphate group and a nitrogenous group.

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2
Q

Polynucleotide definition:

A

Large molecule containing many nucleotides.

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3
Q

What are the 4 DNA bases called?

A
  • Adenine
  • Guanine
  • Cytosine
  • Thymine
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4
Q

Which DNA are purine?

A

Adenine and Guanine

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5
Q

Which DNA are pyrimidine?

A

Cytosine and Thymine

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6
Q

How many carbon nitrogen base rings do purine DNA bases have?

A

2

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7
Q

How many carbon nitrogen base rings do pyrimidine DNA bases have?

A

1

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8
Q

What type of bonds make up the backbone of DNA ?

A

Phosphodiester bonds

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9
Q

What types of bonds are there between the bases of DNA?

A

Hydrogen

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10
Q

What type of nucleotide is DNA?

A

Polynucleotide (made of 2 polynucleotide chains)

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11
Q

Whats is the structure of RNA like?

A 
-Single stranded polymer
Each RNA nucleotide consists of:
-A pentose sugar
-A phosphate group
-A base (Uracil instead of Thymine)
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12
Q

What is difference between the structure of deoxyribose and the structure of ribose?

A

On deoxyribose there is a H connected under C2, but on ribose it is an OH

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13
Q

How many hydrogen bonds are there between A and T?

A

2

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14
Q

How many hydrogen bonds are there between C and G?

A

3

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15
Q

What is the structure of AMP, ADP and ATP like?

A
  • Adenine connected to the right of a ribose molecule

- 1, 2 or 3 phosphate groups connected on the left side of the ribose molecule.

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16
Q

What do ATP, ADP and AMP all do?

A

Help to regulate many metabolic pathways.

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17
Q

What is different about the two sides of the DNA ladder?

A

They’re antiparrallel (running in different directions)

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18
Q

What does it mean by the 2 sides of the DNA ladder being antiparrallel?

A

5prime_______3prime
3prime_______5prime
This is because when one strand is upside down, it is going in the other direction compared to the first strand

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19
Q

Why does a purine have to bond with a pyrimidine?

A

Purines have 2 rings and pyrimidines have 1 so when they bond there are 3 so all the rungs of the ladder are the same size.

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20
Q

Where is RNA found?

A

The nucleus and cytoplasm

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21
Q

What are the types of RNA?

A

mRNA (messenger)
tRNA (transfer)
rRNA (ribosomal)

22
Q

How do the sizes of DNA and RNA compare?

A

RNA is generally shorter

23
Q

Why does DNA need to replicate?

A

To get an exact copy of DNA when cells divide through mitosis or meiosis

24
Q

What stage of mitosis and meiosis does DNA replicate in?

A

The interphase

25
Q

Why is DNA replication called Semi-conservative replication?

A

Because half of it stays the same and the other half is created.

26
Q

How does DNA replication happen?

A
  • DNA helicase unzips and unwinds the DNA, breaking the hydrogen bonds
  • This results in 2 single strands of DNA with exposed nucelotide bases which free floating nucleotide bases in the nucleoplasm can bond to
  • DNA polymerase causes the addition of the new nucleotide bases in the 5 prime 3 prime direction
  • The leading strand is synthesised continuously whereas the lagging strand is in fragments that are later joined
  • Hydrolysis of the activated nucleotides to release the extra phosphate groups supplies energy to make phosphodiester bonds for the backbone.
27
Q

What is the job of DNA polymerise?

A

Joins up the backbone in the 5 prime 3 prime direction by creating phosphodiester bonds

28
Q

What is the job of DNA helicase?

A

Unzips the DNA by breaking hydrogen bonds between the nucleotide bases.

29
Q

What is DNA replication?

A

Copying of DNA

30
Q

What is DNA transcription?

A

Turning DNA into RNA

31
Q

What is DNA translation?

A

Turns mRNA into proteins

32
Q

How do DNA and RNA monomers compare?

A

Both P-S-B (phosphate-sugar-base)

33
Q

How do the sugars in DNA and RNA compare?

A 
DNA= deoxyribose
RNA= ribose
34
Q

How does the location of DNA and RNA compare?

A 
DNA= nucleus only
RNA= nucleus and cytoplasm
35
Q

How does the function of DNA and RNA compare?

A 
DNA= carries/transfers genetic information
RNA= same as DNA and protein synthesis
36
Q

How does the structure of DNA and RNA compare?

A 
DNA= double strand
RNA= single strand
37
Q

How does DNA transcription happen?

A
  • DNA helicase causes DNA to unwind and unzip, breaking the hydrogen bonds between the bases
  • RNA polymerase causes free floating RNA nucleotide bases form hydrogen bonds with the complementary DNA base pairs and creates a backbone for the RNA
  • RNA helicase breaks the hydrogen bonds between the DNA and RNA bases
  • The RNA leaves through the nuclear pore
  • The DNA joins back together
38
Q

How does DNA translation happen?

A
  • mRNA leaves the nucleus through the nuclear pore
  • A ribosome attaches to the mRNA and reads the bases in codons (triplets)
  • Each codon codes for an amino acid, which are building blocks for proteins
  • tRNA codons have specific anticodons for each of the 20 amino acids
  • The complementary anticodon is attracted to the complementary codon on the mRNA and forms a weak hydrogen bond
  • The second codon on the mRNA attracts the second anti codon of tRNA and a peptide bond forms between the adjacent amino acids
  • The tRNA starts to leave as amino acids are bonded
  • The polypeptide chain has then been formed and is released into the cytoplasm
  • The tRNA molecules are activated after use by recombining with their specific amino acids
  • The protein then goes to the RER which packages the protein into a vesicle
  • The vesicle then fuses with the golgi body
39
Q

How is DNA organised in eukaryotic cells?

A
  • The majority of the DNA is in the nucleus
  • Each large molecule of DNA is tightly wound around histone proteins into the chromosomes. Each chromosome is therefore one molecule of DNA
  • There is also a loop of DNA without the histone proteins inside mitochondria and chloroplasts
40
Q

How is DNA organised in prokaryotic cells?

A
  • DNA is in a loop in the cytoplasm
  • Not wound around histone proteins
  • ‘Naked DNA’
41
Q

How is DNA organised in viruses

A

It is a loop of naked DNA

42
Q

What kind of bonds are formed between amino acids?

A

Peptide bonds

43
Q

What is the genetic code described as?

A
  • Near universal
  • Degenerate
  • Non-overlapping
44
Q

What does it mean by the genetic code being near universal?

A

In nearly all organisms, the same triplet of DNA bases codes for the same amino acids

45
Q

How many different amino acids are there that can be found in proteins?

A

20

46
Q

Proteinogenic definition:

A

Amino acids are proteinogenic if they are found in proteins

47
Q

What does it mean by the genetic code being degenerate?

A

For every amino acid apart from two there is more than one DNA triplet that codes for it

48
Q

Frame shift definition:

A

When a mutation occurs causing a base to be deleted, causing other bases to move down and different amino acids to be made

49
Q

Point mutation definition:

A

One bases changes

50
Q

Where is rRNA found?

A

Ribosomes

51
Q

What are ribosomes made of?

A

A combination of RNA and a bunch of proteins all working together

52
Q

What does the RNA in the large sub unit of a ribosome function as?

A

A ribosome and catalyses the formation of new peptide bonds during photosynthesis

AS OCR Biology (12 decks)

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