Structure and replication of DNA Flashcards

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1
Q

What are the main FLS concepts?

A

The central dogma

Changes in gene expression results in cell specialisation

Cell structure and function is entirely dependent upon energy

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2
Q

What is the central dogma?

A

The idea of the two-step process of transcription and translation
Information resides in NDA which goes to RNA which in turn transmits information. The proteins then act based upon this information.

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3
Q

what is DNA?

A

A macromolecule of a nucleic acid

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4
Q

What is DNA made of?

A

Two polynucleotide chains

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5
Q

What is each polynucleotide made up of?

A

Many nucleotides

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6
Q

What does a nucleotide consist of?

A

5-carbon sugar (deoxyribose)
Nitrogen containing base
Phosphate group

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7
Q

Name the four bases

A

Adenine
Thymine
Cytosine
Guanine

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8
Q

What is a nucleoside?

A

Sugar + base

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9
Q

What is the bond between the sugar and the base?

A

A glycosidic bond

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10
Q

What is the bond between the sugar and the phosphate?

A

A phosphodiester bond

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11
Q

Why is DNA described as anti-parallel?

A

The two strands run parallel to each other but in opposite directions

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12
Q

How many hydrogen bonds are there between adenine and thymine?

A

Two

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13
Q

How many hydrogen bonds are there between cytosine and guanine?

A

Three

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14
Q

Which two bases are purine?

A

Adenine

Guanine

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15
Q

Which two bases are pyramidine?

A

Cytosine

Thymine

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16
Q

How does a purine base differ from a pyramidine base?

A

Purine bases have two rings

Pyramidine bases have one ring

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17
Q

What is the major groove?

A

The space between two turns of the double helix

18
Q

What is the minor groove?

A

The space between two strands of DNA

19
Q

What is meant by the 5 prime end?

A

The 5 carbon sugars are asymmetrical

The side the 5th carbon is found is the 5 prime end

20
Q

Describe asexual reproduction in prokaryote

A
Entire genome in one circular chromosome
The chromosome replicates once 
Two chromosomes migrate to opposite ends of the cell 
Cell divides 
Daughter cells have 1 chromosome each
21
Q

Describe asexual reproduction in eukaryotes

A

DNA replicates during S phase
Gene expression occurs in G1 and 2
Nuclear division occurs in mitosis
Cell division occurs at the end of mitosis

22
Q

Why is DNA replication described as semi-conservative?

A

The strands separate

A new strand is made using an old strand as a template

23
Q

Which is the first enzyme involved in DNA replication?

A

Helicase unwinds the double helix DNA

24
Q

Which is the second enzyme involved in DNA replication?

A

Single-strand binding protein binds to and stabilises the single strand to keep DNA unwound

25
Q

Which is the third enzyme involved in DNA replication?

A

DNA primase adds ribonuceloside triphosphate to synthesise and RNA primer

26
Q

What is the fourth enzyme involved in DNA replication?

A

DNA polymerase proceeds in a 5’ to 3’ direction

27
Q

What rate does DNA polymerase work at?

A

1000 bases a second

28
Q

What 3 things does DNA polymerase rely on?

A

Template
Primer
All 4 nucleotides

29
Q

What is the fifth enzyme involved in DNA replication?

A

Exonuclease removes nucleotides from the end of a DNA strand

Has a 5’ to 3’ and 3’ to 5’ version

30
Q

What is the sixth enzyme involved in DNA replication?

A

Ligase joins ends of single DNA strands by making new phosphate bonds

31
Q

How does RNA differ from DNA?

A

Single stranded

Uracil instead of thymine

32
Q

What is the name given to the adding of nucleotides by DNA polymerase?

A

Elongation

33
Q

What does exonuclease remove?

A

The RNA primer

34
Q

What names are given to the two strands?

A

Leading and lagging

35
Q

What causes differences in the two strands?

A

DNA polymerase has to work 5’ to 3’

36
Q

What happens to the lagging strand?

A

It is fragmented

These fragments are called Okazaki fragments

37
Q

How many origins of replication are there in prokaryotes and eukaryotes?

A

Prokaryotes have one

Eukaryotes have many

38
Q

What is the seventh enzyme involved in DNA replication?

A

Gyrase relaxes supercoils produced when the molecule is twisted during replication
Also facilitates unwinding at the beginning

39
Q

What is the eight enzyme involved in DNA replication?

A

Telomerase uses a short RNA template to add short DNA repeats to the short ends of linear chromosomes when the last primer is removed using RNA template to protect the genetic information

40
Q

What is the name given to the point at which the double strand splits?

A

Replication fork