6.1: DNA and RNA Structure

Question 1

In the year __, ________ _______ performed ______ _____ of DNA.

Answer 1

• 1950
• Rosalind Franklin
• X-ray crystallography

Question 2

What did Rosalind Franklin’s work reveal for DNA?

Answer 2

• a pattern that was regular and repetitive

Question 3

During the same time as Franklin, who analyzed DNA samples from different species? What rule held true for all species? (3)

Answer 3

• Edwin Chargaff
  - The amount of adenine equals the amount of Thymine
• The amount of cytosine equals the amount of guanine

Question 4

Nucleotide Structure: what is the structure of a purine? Which base pairs are included in purines?

Answer 4

• double ring structure

- A, G

Question 5

Nucleotide Structure: What is the structure of pyrimidines? What bases are included?

Answer 5

• single ring structure

- C, U, T

Question 6

What type of bonds hold base pairs together, and are they strong?

Answer 6

• hydrogen bonds

- weak, easily breakable

Question 7

How many hydrogen bonds do adenine and thymine have?

Answer 7

2

Question 8

How many hydrogen bonds do cytosine and guanine have?

Answer 8

3

Question 9

How do hydrogen bonds aid in DNA replication?

Answer 9

• hydrogen bonds allow for the DNA strands to be easily separated during the replication process

Question 10

Who combined the findings of Franklin (Helix shape) and Chargaff (base pairing) to create the first 3D, double helix model of DNA?

Answer 10

Watson and crick

Question 11

What are the key features of DNA? (2)

Answer 11

• double stranded helix

- DNA strands are anti parallel

Question 12

What is the structure of DNA’s double-stranded helix? (2)

Answer 12

• sugar-phosphate (deoxyribose) backbone

- centre has nucleotides pairing

Question 13

DNA strands are anti parallel. What does this mean in terms of strand direction? (2)

Answer 13

• one strand runs 5’ to 3’

- other strand runs opposite, upside down direction 3’ to 5’

Question 14

What free group is located at DNA strand’s 5’ end?

Answer 14

Phosphate group

Question 15

What free group is located at a DNA strand’s 3’ ends?

Answer 15

Hydroxyl group (OH)

Question 16

What is the key function of DNA? (2)

Answer 16

• primary source of heritable information

- genetic information is stored in and passed from one generation to the next through DNA

Question 17

What is the exception to how DNA is the primary source of heritable information?

Answer 17

• RNA is the primary source of heritable information in some viruses

Question 18

How does DNA look like in Eukaryotic cells? (2)

Answer 18

• found in nucleus

- Linear chromosomes

Question 19

How does DNA look like in prokaryotic cells?

Answer 19

• located in the nucleotide region

- chromosomes are circular

Question 20

Prokaryotes and some eukaryotes contain plasmids. What are plasmids? (2)

Answer 20

• accessory DNA (ex. Bacteria)

- small, circular DNA molecules that separate from the chromosomes

Question 21

How do plasmids replicate? Which organisms are they mostly found in?

Answer 21

• independently from the chromosomal DNA

- prokaryotes

Question 22

What do plasmids contain that are very important?

Answer 22

• genes that may be useful to the prokaryote when it is in a particular environment, but may not be required for survival

Question 23

Plasmids can be manipulated in laboratories. Generally, how can labs form recombinant plasmid DNA? (1)

Answer 23

• plasmids can be removed from bacteria, then a gene of interest can be inserted into the plasmid to form recombinant plasmid DNA

Question 24

Give an in-depth explanation of how labs can form recombinant plasmid DNA.

Answer 24

1. When the recombinant plasmid is inserted back into the bacteria, the gene will be expressed
2. Bacteria can exchange genes found on plasmids with neighbouring bacteria
3. Once DNA is exchanged, the bacteria can express the gene acquired. This helps with survival of prokaryotes

Question 25

What does RNA stand for? How many strands? What base pairs and what quantities are they?

Answer 25

• ribonucleic acid
• single-stranded
• A=U
• C=G

Question 26

What does DNA stand for? How many strands, and what nucleotides are included in what quantities?

Answer 26

• deoxyribonucleic acid
  - double stranded
• A=T
• C=G

Question 27

What is a key difference between RNA and DNA that we have not mentioned in other cards?

Answer 27

• RNA has ribose sugar (pentose)

- DNA had deoxyribose (pentose with one less oxygen atom)