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Biology OCR A > 2.3 Nucleic acids > Flashcards

2.3 Nucleic acids Flashcards

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1
Q

What are nucleotides?

A

Monomers of nucleic acids, DNA and RNA.

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2
Q

What is the sugar in RNA?

A

ribose pentose sugar

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3
Q

What is the sugar in DNA?

A

deoxyribose pentose sugar

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4
Q

What is a nucleotide called when it has more than one phosphate group?

A

Phosphorylated

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5
Q

What are 2 examples of phosphorylated nucleotides?

A

ADP (adenosine diphosphate) and ATP (adenosine triphosphate). ATP is an energy-rich end-product of most energy releasing biochemical pathways and drives most energy-requiring metabolic pathways.

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6
Q

What role do nucleotides play in NADP?

A

Nucleotides are found in the coenzyme NADP (nicotinamide adenine dinucleotide phosphate) which is used during photosynthesis.

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7
Q

What other coenzymes contain nucleotides?

A

NAD and FAD, used in respiration

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8
Q

What are the 4 DNA nitrogenous bases?

A

T - Thymine
A - Adenine
C - Cytosine
G - Guanine

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8
Q

What does the structure of a nucleotide look like?

A

Refer to textbook (page 86)
A nitrogenous base is attached to the pentose sugar at Carbon 1 and a phosphate molecule attached at either carbon 3 or carbon 5

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9
Q

idk how to word this but DNA is a macromolecule in all living organisms

A

sorry

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9
Q

What is the overall structure of DNA?

A

DNA is made up of repeating monomeric units in 2 polynucleotide chains

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10
Q

What is it called when the 2 polynucleotide chains run in opposite directions?

A

antiparallel

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11
Q

What is the covalent bond between the sugar residue and the phosphate group called?

A

phosphodiester bond

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12
Q

Which bases are purine bases?

A

Adenine and Guanine

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13
Q

What are purine bases?

A

Bases with only one ring

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14
Q

What are pyrimidine bases?

A

Bases with two rings

15
Q

Which bases are pyrimidine bases?

A

Thymine and Cytosine

16
Q

How many hydrogen bonds are there between Adenine and Thymine?

A

2 hydrogen bonds

17
Q

How many hydrogen bonds are there between Cytosine and Guanine?

A

3 hydrogen bonds

18
Q

Why are the hydrogen bonds between bases useful?

A

They can unzip for transcription and replication

19
Q

What does a 5’ (5 prime) chain mean?

A

The phosphate group is attached to the 5th carbon of the deoxyribose sugar.

20
Q

What does a 3’ (3 prime) chain mean?

A

The phosphate group is attached to the 3rd carbon of the deoxyribose sugar.

21
Q

How does DNA exist within eukaryotic cells?

A
  • in the nucleus
  • wraps around histone proteins
  • one loop of DNA does not have histone proteins
22
Q

How does DNA exist within prokaryotic cells?

A
  • DNA is a loop in the cytoplasm (no nucleus)
  • not wound around histone proteins (aka naked)
23
Q

What is the process of semi-conservative replication?

A
  • unwinds (gyrase enzyme)
  • unzips (DNA helicase)
  • free phosphorylase bases attach to exposed bases
  • DNA polymerase catalyzes
  • leading strand synthesized continuously, lagging strand discontinuously
24
Q

Why is it called semi-conservative replication?

A

One strand of OG DNA is kept within each new helix of DNA.

25
Q

How often do mutations occur?

A

every 1 in 10^8. Certain enzymes can proofread and limit mutations, however not all mutations are harmful.

26
Q

How is RNA different to DNA?

A

sugar molecule is called ribose sugar
nitrogenous pyrimidine base uracil replaces thymine
polynucleotide is often single stranded
polynucleotide chain is shorter
mRNA (messenger), tRNA (transfer), rRNA (ribosomal)

27
Q

What are examples for need of specific genetic code?

A

enzymes need a specific active site
antibodies need a complementary shape to the pathogen

28
Q

Why is tRNA (messenger) needed?

A

DNA code cannot pass through the nucleus

29
Q

Why is genetic code referred to as universal?

A

In almost all living things, a DNA codon codes for the same amino acids

30
Q

Why is genetic code referred to as degenerate?

A

For most amino acids, except methionine and tryptophan, a change in the base triplet can still code for the same amino acid

31
Q

Why is genetic code referred to as non-overlapping?

A

The genetic code is only ever read from a fixed point.

32
Q

What are ribosomes made of?

A

Ribosomal RNA and proteins in almsot equal parts

33
Q

What is tRNA (transfer)?

A

Made in the nucleolus, they are single stranded polynucleotides which can twist into a hairpin shape. It has an anticodon at one end which is complementary to the codon on the mRNA.

34
Q

What do ribosomes do?

A

They catalyse the formation of polypeptides

35
Q

What energy is needed during protein synthesis?

A

ATP

36
Q

How does the polypeptide form its 3D shape?

A

chaperone proteins in the cell help form its shape into a tertiary structure.

Biology OCR A (18 decks)

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