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Biochem > RNA Replication Mutation > Flashcards

RNA Replication Mutation Flashcards

1
Q

What is Codon?

A

Base triplets of mRNA

mRNA transports genetic information for protein synthesis

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2
Q

What is Anticodon?

A

Base triplets of tRNA

(tRNA transports amino acids to ribosomes for protein synthesis)

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3
Q

What is Translation?

A

= Protein synthesis -> coded amino acids are built in the protein chain

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4
Q

What happens during replication?

A

DNA double helix splits into two single strands, serving as a Template (pattern) for the formation of the new strand by base pairing

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5
Q

What does it mean that the Replication is semiconservative?

A

= the produced new double helix is composed of one “parental” (derived from the original cell) and one newly synthesised strand

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6
Q

What are the 3 phases of DNA replication?

A
  • Initiation (1)
  • Elongation (2)
  • Termination (3)
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7
Q

Initiation of replication in Prokaryotes:

A

Begins at the Startpoint = Replication Origo (composed of consensus sequences: similar sequences in all living organisms)

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8
Q

Function of dnaA proteins?

A

They recognice replication origo and bind to dnaA binding sites (in inititation of replication in Prokaryotes)

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9
Q

Function of dnaB and dnaC proteins?

A
  • They bind to dnaA protein
  • They have helicase activity
    (initiation of replication in prokaryotes)
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10
Q

What does it mean that dnaB and dnaC has helicase activity?

Prokaryotes

A

H-bonds between complementary base pairs get split -> double helix opens at replication origo and “replication bubble” (also called “replication fork”) is formed.
(inititation of replication in prokaryotes)

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11
Q

What is the function of Single Strand Binding Proteins (SSB-proteins)
(Prokaryotes)

A

They keep the two strands separate from each other (when complemetary base pairs are not allowed to match again)

(inititaion of replication in prkaryotes)

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12
Q

What is a Primer?

Prokaryotes

A

A short RNA sequence with free 3´-OH-group

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13
Q

How do synthesis of primers happen?

Prokaryotes

A

By Primosomes

- Primosome is a protein complex where the most important component is primase enzyme, synthesising primer.

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14
Q

Continous synthesis happens in?

Prokaryotes

A

Leading strand.

Only one primer is needed

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15
Q

What is Lagging strand?

Prokaryotes

A

Discontinous synthesis happens, several short fragments are formed.

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16
Q

What is Okazaki-fragment?

Prokaryotes

A

One primer is needed for each single fragments (in lagging strand)
-> primer + DNA together are called Okazaki-fragment

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17
Q

What is responsible for the synthesis of the new DNA strand?

Prokaryotes

A

DNA polymerase III (DNA-dependent polymerase III)

- Direction of synthesis is 5´-> 3´

18
Q

How is the building of nucleotides in the new strands?

Prokaryotes

A

Deoxyribonukleoside triphosphate (dNTP) -> Deoxyribonukleoside monophosphate (dNMP) are built in + inorganic pyrophosphate is released.

19
Q

Elongation of replication in Prokaryotes?

A

DNA polymerase III builds new nucleotides in new strands -> continous synthesis on leading strand, while discontinous synthesis on lagging strand (okazaki-fragments)

20
Q

At the end of replication (at terminus sequence)?

A

DNA polymerase III dissociates

21
Q

DNA polymerase I:

A
  • Primers are hydrolysed and cut out by DNA polymerase I.

- Fills space between separate DNA fragments by building appropriate nucleotides in the chain.

22
Q

What is DNA ligase?

A

Ligation of newly synthesised DNA fragments at sugar-phosphate backbone (uses ATP for the formation of phosphodiester bonds)

23
Q

Termination of replication in Prokaryotes:

A
  • DNA polymerase I. hydrolyses and removes primers, then completes the strand with newly synthesised DNA fragments.
  • DNA ligase ligates the backbone of DNA fragments.
24
Q

Functions of DNA ligase?

A
  1. DNA ligase hydrolyses one ATP to AMP and PPin -> the activated AMP molecules binds to enzyme
  2. The 5´-end of DNA fragments forms phosphodiester bond with the 3´-end of the neighboring DNA fragment
  3. AMP dissociates from the enzyme
25
Q

Function of Topoisomerases?

A

Tenseness and twist of DNA strands during replication

26
Q

Proteins needed for replication are organised in?

A

Replisome

27
Q

DNA polymerase operates as a dimer, which means?

A

-> replication of two DNA strands happens simultaneously.

28
Q

Which one of Eukaryotes or Prokaryotes has numerous origos?

A

Eukaryotes

29
Q

What does numerous replication mean?

A

Numerous replisomes -> replication happens at different places at the same time.

30
Q

DNA polymerase alpha?

A

Synthesis of new DNA strand

(Eukaryotes)

(equals with DNA plymerase III of Prokaryotes)

31
Q

DNA polymerase beta?

A

Repair of DNA during replication
(Eukaryotes)

(Equals with DNA polymerase II of Prokaryotes)

32
Q

DNA polymerase gamma

?

A

Replication of mitochindrial DNA

33
Q

DNA polymerase delta?

A

Synthesis of new DNa strand (further from primer)

- Needs PCNA (proliferating cell nuclear antigen) protein for operation

34
Q

What is a Telomere?

A

Extra sequence attached to the 3´end of chromosome, rich in G-bases

(only eukaryote)

35
Q

Containes no genetic information, so loss of these sequences during replication causes no problem?

A

Telomere

36
Q

What is Telomerase?

A

Enzymes synthesise telomeric sequences (even more active in gametes and tumor cells -> more cell division is possible than normally)

37
Q

What is mutation?

A

Changes in the structure of DNA that result in heritable changes in the coded genetic formation

38
Q

Mutations results in?

A
  • genetic diseases
  • cancer
  • evolution
39
Q

Types of Mutations?

A 
Type 1:
- Spontaneous
- Induced (UV/radiation/chemicals)
Type 2: 
- gametic
- Somatic
Type 3:
- Chromosme
- gene/point
40
Q

Types of Point mutations?

A
  1. Substitution
    - Missense (code other amino acid)
    - Nonsense (code STOP)
    - Silent or samesense (code the same amino acid)
  2. Insertion
    - Frame shift mutation
  3. Deletion
    - Frame shift mutation
41
Q

Types of Mutagenesis?

A

Nitrites, nitrates, oxidative deamination, UV radiation, Timin dimers (covalent bonds between two pyrimidine base), Malignus melanoma, Repair by deletion

Biochem (14 decks)

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