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biology > D1.1 - DNA replication > Flashcards

D1.1 - DNA replication Flashcards

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1
Q

anode

A

positively charged terminal

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2
Q

binary fission

A

asexual reproduction in bacteria

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3
Q

DNA profiling

A

matching an unknown sample of DNA to see if they correspond

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4
Q

in vitro

A

translates to in glass meaning that procedures occur outside of a living organism in lab conditions

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5
Q

marker

A

region of repetitive DNA sequence in a genome location which varies in number of repeats for each person

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6
Q

DNA replication

A

process that produces exact copies of DNA with identical base sequences

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7
Q

DNA ladders

A

contain fragments of known sizes measured in kilobases to estimate absolute fragment length

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8
Q

what is DNA replication required for?

A
  • reproduction - precedes binary fission and mitosis (asexual) and meiosis (sexual)
  • tissue replacement - produce new cells to replace worn out or damaged cells in tissues
  • growth - production of more cells by mitosis
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9
Q

semi - conservative replication

A

process by which two strands of DNA are separated and each is used as a template to guide the formation of a new strand using complementary base pairing

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10
Q

what does semi-conservative replication result in?

A

leads to a pair of DNA molecules with identical base sequences each consisting of one original and one new strand

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11
Q

what is the role of complementary base pairing in DNA replication?

A

allows freely floating DNA nucleotides to base pair with unmatched nucleotides on the separated strands to form hydrogen bonds

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12
Q

DNA polymerase

A

joins nucleotides by making covalent bonds between them on each template strand to form a double stranded DNA molecule that are exact copies of the original DNA molecule

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13
Q

helicase

A

unwinds the DNA double helix and breaks the hydrogen bonds between bases to separate the DNA strands

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14
Q

what is the process of DNA replication?

A
  1. helicase unwinds the double helix structure and separates the two strands
  2. free DNA nucleotides are added using the existing strand as a template according to complementary base pairing
  3. on each strand, DNA polymerase links nucleotides to form a new strand
  4. the products are two DNA molecules that are identical to each other and the original DNA molecule
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15
Q

What is DNA replication?

A

Process that produces exact copies of DNA with identical base sequences

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16
Q

What is DNA replication required for?

A
  • replication
  • growth
  • tissue replacement
17
Q

What are 2 ways in which the process of DNA replication allows a high degree of accuracy in copying base sequences?

A

semi-conservative nature of DNA - new pair of DNA molecules each has 1 strand from the original model
complementary base pairing - free nucleotide join with unmatched nucleotide, forming hydrogen bonds and DNA polymerase joins the nucleotides into a new strand on each template strand, this forms two new double stranded DNA molecules that are exact copies of the original DNA molecule.

18
Q

What is a PCR?

A

polymerase chain reaction used to amplify DNA samples by making many copies

19
Q

What are the 3 steps involved in PCR testing?

A
  1. Melting (denaturation) - mixture is heated to 90C, breaking the bonds between the two strands of DNA
  2. Annealing - temperature is lowered to 60C to allow the primers to bind to target DNA sequence
  3. Extending - optimum temperature for Taq polymerase (72C) allows it to form double-stranded DNA though complementary base pairing on a template strand
20
Q

What are the parts of a PCR test?

A
  • DNA that needs to be amplified
  • Primers
  • Free nucleotides - create new DNA molecules
  • Taq polymerase - used as it doesn’t denature at high temperatures
21
Q

What are primers?

A

short lengths of single stranded DNA with complementary bases which provide a starting point for Taq polymerase to synthesis a new strand of DNA

22
Q

Why is cycling needed in PCR?

A

to make large amounts of DNA copies

23
Q

Why is PCR heated to a high temperature?

A

to separate DNA strands by breaking hydrogen bonds

24
Q

Why is the temperature then lowered?

A

to allow primers to bind to target DNA sequence

25
Q

How are new strands formed in PCR?

A

complementary base pairing using Taq polymerase - used as it can withstand high temperatures and won’t be denatured

26
Q

What is gel electrophoresis?

A

tool for DNA fragment separation based on size

27
Q

How is gel electrophoresis carried out?

A

amplified DNA samples are fragmented using endonuclease restriction enzymes which cut DNA molecules at specific base sequences
- when comparing two samples, they must be fragmented using the same endonuclease restriction enzyme

28
Q

How are DNA fragments separated?

A

samples are loaded into wells in an agarose gel and an electrical current is applied, causing the negative DNA to travel towards the positive anode

29
Q

What is the relationship between DNA fragment size and movement?

A

smaller DNA fragments move faster and further through the agaorse gel than larger fragments which are hindered by the gel matrix

30
Q

Why must the gel be stained?

A

DNA must be stained to see the patterns of the bands produced

31
Q

What is the process of DNA profiling?

A
  1. DNA samples are collected
  2. PCR is used to amplify DNA of particular markers to produce more copies
  3. Gel electrophoresis is used to separate DNA fragments according to their length which is dependent on the number of repeats
  4. Gel electrophoresis generates a unique pattern of bands which is called a DNA profile
32
Q

How is DNA profiling used in forensics?

A

DNA is collected from the crime scene and other supsects and if they were taken from the same person, the pattern must be identical between two samples

33
Q

What are the uses of DNA profiling?

A
  • forensic testing
  • paternity testing
  • detecting mutations
  • diagnosing diseases by identifying the pathogen that has the person’s cells
  • prepare DNA for use in biotechnological techniques
  • force genetic changes through recombination PCR
34
Q

How is DNA testing used in paternity testing?

A

DNA sample is collected from both the child and possible parents and all the bands in the child’s profile must be in one of the parents’ profiles, because the child contains a combination of both parents’ alleles

biology (28 decks)

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