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Year 1 > Nucleic acids + DNA replication > Flashcards

Nucleic acids + DNA replication Flashcards

1
Q

DNA functions

A
  • stores genetic information
  • directs own replication
  • directs transcription of complementary molecule of mRNA
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2
Q

mRNA functions

A
  • carries genetic information
  • directs translation of genetic information into proteins
  • copied from DNA and used as template for protein synthesis
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3
Q

tRNA functions

A
  • translator of genetic information

- deliver amino acids to ribosomes in protein synthesis

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4
Q

rRNA functions

A
  • components of ribosomes
  • structural + functional roles
  • involved in binding mRNA and tRNA in protein synthesis
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5
Q

Purine bases

A
  • adenine + guanine

- 2 rings

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6
Q

Pyrimidine bases

A
  • cytosine + thymine + uracil

- 1 ring

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7
Q

Nucleoside

A

bases + 5-carbon (pentose) sugar

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8
Q

Nucleotide

A

phosphorylated nucleosides (5’ position of sugar)

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9
Q

Watson-Crick base pairing

A
  • Adenine + thymine = 2 hydrogen bonds
  • Guanine + cytosine = 3 hydrogen bonds
    (guanine/cytosine rich regions more stable)
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10
Q

Anti-parallel

A

strands run in opposite directions

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11
Q

DNA primary structure

A

chains of nucleotides held together by phosphodiester bonds attaching the phosphates

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12
Q

DNA secondary structure

A

2 strands of DNA held together by hydrogen bonds between complementary bases

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13
Q

DNA tertiary structure

A

DNA wrapped around histones, forming chromatin
chromatin is then packaged into nucleosomes
then supercoiled into a chromosome

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14
Q

Describe process of transcription

A
  • double-stranded DNA separated into coding + template strand
  • template strand complementary to RNA transcript
  • complementary nucleotides added by RNA polymerase to growing RNA molecule
  • template strand read from 3’-5’
  • RNA synthesised from 5’-3’
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15
Q

What are the different types of RNA polymerase?

A

generally, RNA polymerases synthesise RNA molecules

RNA polymerase 1 = directs synthesis of rRNA
RNA polymerase 2 = directs synthesis of mRNA
RNA polymerase 3 = directs synthesis of tRNA

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16
Q

mRNA structure (prokaryotic)

A

polycistronic (encode multiple proteins)
no chemical modifications
no splicing

17
Q

mRNA structure (eukaryotic)

A

monocistronic (encode a single protein)
chemical modifications = 5’ methylated guanine nucleotide cap, 3’ = polyA tail
splicing (removal of introns + ligation of exons)
consists of introns and exons

18
Q

tRNA structure

A 
trinucleotide anticodon (on anticodon loop) = directs specific interaction with appropriate codon in mRNA
variable loop
acceptor stem = amino acid can join here
clover leaf secondary structure
19
Q

Describe the ribosomes and rRNAs in prokaryotic cells

A

70s ribosomes
large and small subunits
sizes = 50s +30s
rRNA = 23s, 5s, 16s

20
Q

Describe the ribosomes and rRNAs in eukaryotic cells

A

80s ribosomes
large and small subunits
sizes = 60s + 40s
rRNA = 28s, 5.8s, 5s, 18s

21
Q

Which antibiotics are ribosome-inhibiting and what ribosomes do they target?

A 
streptomycin = 30s subunit
erythromycin = 50s subunit
tetracycline = 30s subunit
chloramphenicol = 50s subunit
22
Q

What is the type of DNA replication?

A

semi-conservative
2 parental DNA strands act as template for new DNA and after replication each double-stranded DNA contains one strand from the parental DNA and one new (daughter) strand

23
Q

Which experiment proved the semi-conservative method of DNA replication?

A

Meselson and Stahl
used E.Coli DNA made with 2 nitrogen isotopes (14 +15)
and density gradient centrifugation

24
Q

Describe DNA replication in eukaryotes

A

initiation = proteins bind to origin of replication and helicase unwinds DNA helix - 2 replication forks formed at origin of replication
elongation = primer sequence added with complementary RNA nucleotides which are then replaced with DNA nucleotides
during elongation, leading strand is made continuously, lagging strand made in pieces (Okazaki fragments)
termination = primers removed and replaced with new DNA nucleotides and backbone sealed by DNA ligase

25
Q

Define lagging strand

A

strand of the template DNA double helix that is oriented so that the replication fork moves along it 5’-3’

26
Q

Define leading strand

A

strand of the template DNA double helix that is oriented so that the replication fork moves along it 3’-5’

Year 1 (41 decks)

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