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LQB381 > DNA and RNA > Flashcards

DNA and RNA Flashcards

1
Q

The Levels of Sturcture in DNA:

A
  • Primary Structure
  • Secondary Structure
  • Tertiary Structure
  • Quaternary Structure
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2
Q

Primary Structure of DNA:

A
  • the order of bases on the polynecleotide sequence (specifies genetic code)
  • 3 letters (bases) = 1 amino acid
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3
Q

Chargaff’s Rules

A

[Pyrimindines]-[Purines]

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4
Q

Base Pairing & H-Bonds:

A
  • DNA formed by two complementary antiparrallel strands
  • base pairing & H-Bonds are very important to gold strands together
  • [A]-[T] (2 H-Bonds)
  • [G]-[C] (3 H-Bonds)
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5
Q

Secondary Structure: Helical

A
  • Nitrogen base (steps in the ladder) where info is protected
  • Pentose sugar (handrails) for structure
  • Phosphate group (exposed negative side) for structure
  • Two strand antiparallel
  • Small groove & large groove & complete turn
  • Basic connection (via H-Bonds)
    Diameter is about 20A
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6
Q

The other Secondary Structure - also Helical but not so popular: A-Form
[insert photo?]

A
  • Thicker, shorter distance

- Presents in DNA-RNA duplexes

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7
Q

The other Secondary Structure - also Helical but not so popular: B-Form
[insert photo?]

A
  • The most common in genomic DNA

- The most stable under physiological conditions

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8
Q

The other Secondary Structure - also Helical but not so popular: Z-Form
[insert photo?]

A
  • Left-handed

- less common

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9
Q

Tertiary Structure:

A
  • DNA Supercoiling

- cellular DNA is extermely compacted (helix is super coiled) to save space

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10
Q

Quanternary Structure:

A
  • DNA wrapping up proteins
    In eukaryotes DNA is complexed with positively-charged proteins to form chromatin
  • Histones (positive proteins)
  • Nucleosome: DNA (negative wrapped around 8 histones (positive)
  • 150 base pairs are in contact with the proteins
    Packaged into chromosomes and safely located inside the nucleus
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11
Q

Why is DNA structure important?

A

structure allows function

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12
Q

DNA as a template:

A
  • DNA helix is denatured to allow replication
  • Each strand of DNA helix acts as a template for new complementary strand
  • Semiconservative replication (i.e. Each daughter molecule has one old strand & one new strand)
    Dependent on complementary bas pairing
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13
Q

DNA Replication:

A
  1. Helicase: unwinds helix to form replication fork
  2. Primase: Synthesises short RNA primers, complementary to template
  3. DNA polymerase: reds strand being copied and links complementary nucleotides to form new strand
  4. leading strand and lagging strand
  5. leading strand is synthesised continuously from template
  6. lagging strand is synthesised with fragments (Okazaki fragments)
  7. DNA ligase joins Okazaki fragments and seals the gaps in the newly sythesised short strands
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14
Q

DNA vs RNA: Pentose

A

DNA: Deoxyribose
RNA: Ribose

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15
Q

DNA vs RNA: n Base

A

DNA: Thymine
RNA: Uracyl

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16
Q

DNA vs RNA: Structure

A

DNA: Double Helix
RNA: (mostly single-strand)

17
Q

DNA vs RNA: Variety

A

DNA: One type
RNA: Several types

18
Q

DNA vs RNA: Location

A

DNA: Nucleolus
RNA: Nucleolus & cytoplasm

19
Q

DNA vs RNA: Stability

A

DNA: Chemically stable
RNA: Chemically unstable

20
Q

DNA Transcription: to get to mRNA

A
  • The information encoded in the genes is copied into a RNA molecule: messenger RNA (mRNA)
  • Obtained by transcription of complementary section of DNA catalysed by RNA polymerase
  • Occurs in the nucleus
  • Carries the information specifying a particular protein
    It varies in length
21
Q

mRNA

A
  • messeneger between DNA & Proteins
  • it serves as genetic template, as DNA cannot leave the nucleolus
  • the pre-mRNA transcripts contain non-coding RNA (introns) and coding RNA (exons)
  • mature mRNA has the coding regions
  • mRNA moves to the cytoplasm
  • Info encoded by the mRNA is converted into an amino acid sequence
22
Q

rRNA - Supporting Ribosomes:

A
  • 2 submits, in the cytoplasm

- subunits join at the initation of protein synthesis

23
Q

rRNA - as part of the ribosomal structure:

A
  • Structural component of ribosomes
  • rRNA combines with special proteins to form ribosomes
  • Helps align ribosomes and mRNA
  • Helps reading the mRNA
    Catalyses peptide bond formation
24
Q

tRNA

A
  • transferring amino acids
  • RNA is generally single stranded, but tRNA folds into a ‘t’ shape
  • has a recognition aite (anticodon loop)
  • binds to specific codon on mRNA
  • binds to the respective amino acid
25
Q

mRNA Vaccines:

A
  • use mRNA transcript from a part of the spike protein at surface of virus
  • mRNA injected in pt is translated into a harmless portion of the spike protein & will trigger the immune system to produce antibodies that recognise that spike protein
  • when infected with virus, the antibodies target teh virus to be destroyed by our immune system
26
Q

Traditional vaccines:

A
  • use inactivated virsu/bacterium to induce our immune system in producing antibodies

LQB381 (11 decks)

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