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BIOL 1210 Lab Exam > DNA Isolation > Flashcards

DNA Isolation Flashcards

1
Q

Name the bond found between paired bases of the DNA double helix

A

Hydrogen bond

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2
Q

What is DNA soluble in?

A

Water

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3
Q

What is DNA insoluble in?

A

ethanol

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4
Q

What is the purpose of using NaCl in the lab?

A

NaCl helps to mask the negative charge of the DNA molecule, allowing the DNA to clump together

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5
Q

What is the purpose of using detergent in the lab?

A

To break down the phospholipid bilayer in the cell membranes and release the contents of the cell

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6
Q

What material is used to breakdown the phospholipid bilayer?

A

Detergent

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7
Q

What are monomers of DNA called?

A

Nucleotides

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8
Q

What inhibits the breakdown of DNA during precipitation?

A

Cold temperatures

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9
Q

What is an enzyme that degrades DNA?

A

DNase

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10
Q

List the materials used to isolate DNA

A

120 mL soft fruit (strawberries)

resealable sandwich bag/ziploc bag

10 mL liquid dish detergent

60 mL ice-cold 99% isopropanol

3.75 mL NaCl

120 mL warm water

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11
Q

What organism was the DNA isolated from? give latin and common names

A

strawberries

Fragaria ananassa

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12
Q

Why were the strawberries broken down by hand first?

A

To mechanically break down the rigid plant cell walls

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13
Q

What was the purpose of adding the NaCl and warm water solution to the strawberries?

A

To dissociate the DNA from the histone proteins

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14
Q

What are 3 reasons why the strawberry/NaCl/water mixture was placed in hot water for 15 minutes?

A

To denature the proteins

To dissolve the lipids in the cells

To inhibit the enzymes

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15
Q

What was the purpose of putting the strawberry/NaCl/water mixture into ice-cold water for 10 minutes?

A

To precipitate the proteins and lipids out

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16
Q

Why was the solution filtered through a cheese cloth?

A

To filter out the proteins, lipids, and cell walls

17
Q

What occurred when the isopropanol was poured slowly over the fruit filtrate? What is the purpose of this?

A

A clear layer of isopropanol formed on top of the fruit filtrate

DNA will diffuse into the alcohol/precipitate out because alcohol is less polar than water

18
Q

What happened when the fruit filtrate was mixed with the isopropanol?

A

The DNA precipitated onto the stir stick and the isolated DNA became visible

19
Q

Briefly explain the procedure of this experiment

A
  1. put 120 mL of fruit in plastic bag and remove all air
  2. macerate fruit in plastic bag with hands (2 mins)
  3. prepare 3% NaCl solution by dissolving 3/4 tsp of NaCl in 120 mL of warm water
  4. add 60 mL of NaCl solution to fruit bag
  5. Add 10 mL of liquid detergent to fruit solution
  6. squeeze solution for 1 minute
  7. Heat 1 L of water to ~60 degrees C
  8. place sealed fruit bag into hot water, cover for 15 mins
  9. put fruit bag into bowl of ice cubes and water for 5-10 mins
  10. strain fruit solution through cheese cloth into clean cup
  11. transfer fruit filtrate into clear cup
  12. tilt cup and pour ice cold isopropanol into cup to form layer
  13. gently mix at the interface using a stir stick
20
Q

What % NaCl was the solution with warm water?

A

3% NaCl

21
Q

How does a cell package ~6 feet of DNA into the nucleus?

A

The structure of DNA allows it to be packaged tightly

It is a double helix that is coiled into small beads by histone proteins

22
Q

Is the white sticky precipitate you isolated pure DNA? What else could be present? Why?

A

No, it is not pure DNA because there may still be proteins BUT the two big contaminants are: RNA and sodium

RNA will be present because it is isolated by the same method as DNA

Positively charged Na is still attracted to the negatively charged DNA

23
Q

Define DNA

A

It is the macromolecule that carries genetic information required for the growth, development, function and reproduction of living organisms

24
Q

Describe the structure of DNA

A

DNA is made up of nucleotides that pair to form a double-stranded molecule

25
Q

What does each eukaryotic chromosome consist of?

A

a single linear double-stranded DNA molecule wrapped around proteins called histones

26
Q

Describe a chromatin

A

the DNA-protein complex consisting of a single linear double-stranded DNA molecule and histone proteins

27
Q

What do chromosomes look life for most of the cell cycle?

A

A diffuse mass of long thing chromatin fibres

28
Q

When a cell prepares to divide (mitosis or meiosis), what happens to the chromatin?

A

It condenses to form distinct chromosomes

29
Q

T or F: DNA is present in the cells of only some organisms

A

False. DNA is present in the cells of ALL organisms

30
Q

Many food plants are ___ploid

A

Polyploid

31
Q

What does polyploid mean?

A

the organism has more than two copies of their genome in each cell

32
Q

What makes food plants ideal for DNA extraction?

A

Each cell contains a lot of DNA because food plants are polyploids = they have more than 2 copies of their genome in each cell

33
Q

What ploidy are strawberries?

A

octoploid (8n)

34
Q

Why is it better to use a soft fruit like strawberry or kiwi for this experiment?

A

It is easier to release the DNA from the nucleus without breaking it

BIOL 1210 Lab Exam (6 decks)

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