Molecular Biology Principles Flashcards

1
Q

DNA structure

A

2 polynucleotide chains, double helix, sugar phosphate back bone,

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2
Q

How are nucleotides joined together?

A

phosphodiester linkage

hydroxyl group of 3 carbon phosphate group of 5 carbon

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3
Q

What are nucleotides?

A

phosphate, sugar, base

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4
Q

What are nucleosides?

A

base and sugar

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5
Q

How are the base and sugar joined together?

A

peptidic bond

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6
Q

How many hydrogen bonds does G+C have?

A

3

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7
Q

How many hydrogen bonds does A+T have?

A

2

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8
Q

How does DNA replication occur?

A
  • ORI region (AT bases)
  • DNA gyrase and helicase make DNA unwind
  • DNA polymerase - synthesises template DNA
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9
Q

What enzymes promote the unwinding of DNA in DNA replication?

A

DNA gyrase and helicase

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10
Q

What is the core enzyme in Transcription?

A

RNA polymerase

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11
Q

What happens in transcription?

A

Coding strand is transcribed into mRNA

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12
Q

Where does transcription start?

A

At a promotor 10 bases up form start site

-10 TATAAT and -35 TTGACA

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13
Q

What is the transcriptional terminator?

A

inverted repeats forming a stem loop in the mRNA

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14
Q

What is the core enzyme in translation?

A

Ribosomes

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15
Q

What is the function of a ribosome?

A

to incorporate charged tRNA in the A site following the mRNA template

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16
Q

How are genomes organised in eukaryotes?

A

Several linear DNA molecules are present within the membrane enclosed nucleus

17
Q

How are genomes organised in prokaryotes?

A

circular chromosome is packed into a structure called nucleoid
also contain plasmids

18
Q

What does a genome contain?

A

genes, RNA, regulatory RNA regions, noncoding DNA regions

19
Q

which genome is larger; bacterial or mammals?

A

mammals

20
Q

How many genes are in 2 Mb genome?

A

2,000

21
Q

How do prokaryotes replicate DNA?

A

bidirectional replication - two replication forks

from ORI to Ter

22
Q

How is GC Skew measured?

A

GC skew = (G-C) /( G+C)

23
Q

What is the GC skew used for?

A

to identify leading and lagging strand in bacterial chromosome

24
Q

Which strand, leading or lagging, has more G+T?

A

leading

25
Q

What causes excess G+T in the leading strand?

A

hydrolytic deamination of cytosine to uracil

26
Q

what genes are encoded in the leading strand?

A

highly transcribed and essential genes