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IB HL Biology I > Unit 5 > Flashcards

Unit 5 Flashcards

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1
Q

Polymerase chain reaction (PCR)

A

artificial method of replicating DNA

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2
Q

What does PCR involve?

A

repeated cycling through high and lower temperatures

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3
Q

What are the 4 steps of PCR?

A

1) Denaturation
2) Annealing
3) Elongation
4) Steps 1-3 are repeated

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4
Q

Denaturation

A

DNA is heated to break hydrogen bonds/separate it into single strands

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5
Q

Annealing

A

DNA primers attach to the 5’ ends of target sequence at low temps

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6
Q

Elongation

A

Taq DNA polymerase adds nucleotides

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7
Q

What do primers allow?

A

the selective copying of a DNA region, bind on either side of the target sequence (on opposite strands)

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8
Q

Taq DNA Polymerase

A

heat tolerant enzyme

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9
Q

Restriction endonucleases

A

enzymes that cut DNA into fragments based on recognition of certain sequences

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10
Q

What do restriction endonucleases in DNA?

A

cut sugar-phosphate

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11
Q

What does an restriction endonucleases generate?

A

sticky or blunt ends

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12
Q

Sticky ends are…

A

complementary and single stranded

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13
Q

Gel Electrophoresis

A

A laboratory technique used to separate and isolate protein or DNA fragments based on size

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14
Q

How are fragments in gel electrophoresis made?

A

by restriction endonucleases

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15
Q

How does gel electrophoresis work (5)?

A
  • Samples of DNA or protein are placed in a porous gel
  • Placed in a chamber and covered with a salt solution, conducts electricity
  • The chamber has a negative electrode, where DNA is placed, and a positive
  • Power supply generates current that moves samples to positive end
  • Small samples move faster than large ones through the gel’s small holes
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16
Q

Genomics

A

the study of an organism’s complete set of genes and their interactions

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17
Q

Human Genome Project (HGP)

A

an international effort to determine the complete sequence of DNA bases in the human genome

18
Q

What were the results of the HGP?

A
  • Humans have 21,000 genes in 3.2 billion nucleotide pairs
  • Only 1-2% of the DNA codes for proteins (genes)
19
Q

DNA Sequencing

A

process by which the nitrogenous base order of a nucleotide sequence is explained

20
Q

What does DNA sequencing use?

A
  • PCR (with dideoxynucleotides)
  • electrophoresis
21
Q

Dideoxynucleotides (ddNTPs)

A

nucleotides that lack the 3’-hydroxyl group necessary for forming phosphodiester bonds; terminate replication

22
Q

What is the difference between regular PCR and PCR for DNA sequencing?

A

fluorescently labeled dideoxyribonucleotides are included with normal nucleotides in the PCR solutions

23
Q

What is different about DNA strands coming from PCRs using ddNTPs?

A

they differ in length

24
Q

What does the length of a DNA strand indicate?

A

the position where a ddNTP was incorporated

25
Q

What does reading the dideoxyribonucleotides from the shortest to longest fragment do?

A

it gives the base sequence of the original molecule in the 3’ to 5’ direction

26
Q

How are fluorescently labeled DNA fragments separated?

A

based on size using gel electrophoresis

27
Q

What happens as each DNA fragment reaches the end of the gel?

A

a laser excites its fluorescent base and a camera detects the color and therefore the base

28
Q

DNA profiling (2)

A
  • the analysis of DNA fragments to determine whether they come from an individual
  • compares sequences from noncoding DNA regions that show variation between individuals
29
Q

Where is DNA profiling used?

A

paternity and forensic investigations

30
Q

Why aren’t genes used in DNA profiling?

A

they are too similar between individuals

31
Q

short tandem repeats (STRs)

A

long stretches of DNA in non-coding regions made up of repeating elements

32
Q

Who founded the technique of DNA sequencing?

A

Fred Sanger

33
Q

Why are STRs useful (2)?

A
  • Every person has several locations were STR repeats are present in their DNA (same locations across different people)
  • Each person has a unique number of STR repeats at each location in their genome
34
Q

How can STRs be cut out?

A

using restriction endonucleases

35
Q

What about STR fragments help with identification?

A

their length

36
Q

What is needed for there to be a match between crime scene and suspect DNA?

A

DNA fragments of suspects should be a complete match with the DNA fragments from crime scene

37
Q

What are the steps of DNA profiling (4)?

A
  • Polymerase chain reaction (PCR) is used to amplify a DNA sample collected from an individual
  • Restriction endonucleases are used to cut out short tandem repeats from DNA
  • Gel electrophoresis separates the fragments of DNA
  • DNA fragments are analyzed
38
Q

How are DNA fragments analyzed for forensic investigations?

A

DNA of suspect compared to DNA from a crime scene

39
Q

How are DNA fragments analyzed for paternity investigations?

A

child’s DNA fragments are compared to its suspected parents

40
Q

What must be seen for someone to be considered the biological father of a child on a paternity test?

A

The DNA that is not covered by the mother must be made up for by the father

IB HL Biology I (10 decks)

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