Lecture 2 - Building Blocks: Nucleotides and Amino Acids

Question 1

What does the central dogma state?

Answer 1

The flow of information is from DNA to RNA to proteins.

Question 2

Which process converts information from DNA to RNA?

Answer 2

Transcription

Question 3

Which process converts information from RNA to proteins?

Answer 3

Translation

Question 4

What are the four base pairs found in DNA? Which pairs pair to each other?

Answer 4

A, T, C, G (A-T, C-G)

Question 5

What monomer makes up proteins?

Answer 5

Amino Acids

Question 6

Who discovered nucleic acids? When?

Answer 6

Friedrich Miescher discovered nucleic acids in 1869.

Question 7

How were nucleic acids discovered?

Answer 7

Nucleic acids were discovered by isolating an acidic compound from the nuclei of white blood cells collected from puss on discarded surgical bandages.

Question 8

What does DNA stand for?

Answer 8

Deoxyribonucleic Acid

Question 9

What does RNA stand for?

Answer 9

Ribonucleic Acid

Question 10

How long can DNA be?

Answer 10

DNA can be as long as hundreds of millions of nucleotides.

Question 11

How long is RNA typically?

Answer 11

RNA is usually hundreds to thousands of nucleotides long.

Question 12

What are nucleic acids composed of?

Answer 12

Nucleic acids are composed of a phosphate group, pentose sugar (ribose or deoxyribose), and a nitrogenous base (A, T, C, G, U).

Question 13

What are the two categories of nitrogenous bases?

Answer 13

Purines and Pyrimidines

Question 14

How many rings do purines have?

Answer 14

2

Question 15

How many rings do pyrimidines have?

Answer 15

1

Question 16

Which bases are purines?

Answer 16

Adenine and Guanine

Question 17

Which bases are pyrimidines?

Answer 17

Uracil, Thymine, and Cytosine

Question 18

Which nitrogenous base is pictured below?

Answer 18

Adenine

Question 19

Which nitrogenous base is pictured below?

Answer 19

Guanine

Question 20

Which nitrogenous base is pictured below?

Answer 20

Uracil

Question 21

Which nitrogenous base is pictured below?

Answer 21

Thymine

Question 22

Which nitrogenous base is pictured below?

Answer 22

Cytosine

Question 23

What is the difference between a nucleotide and a nucleoside?

Answer 23

Nucleosides don’t have a phosphate group.

Question 24

What is the repeated phosphate-pentose chain in a sequence of nucleotides known as?

Answer 24

The “Backbone”

Question 25

What type of bond links nucleotides together? Where are they formed?

Answer 25

Phosphodiester Bonds

They are formed between the 3’ hydroxyl on the pentose and the 5’ phosphate.

Question 26

In which direction do we write nucleic acid sequences? Why?

Answer 26

Nucleic acid sequences are written in a 5’ to 3’ direction because this is the direction they are synthesized in.

Question 27

Who discovered the double helix structure? Who was awarded the Nobel prize for it? Who generated the high-resolution diagrams but was not recognized due to their passing.

Answer 27

James Watson and Francis Crick discovered the double helix. They were awarded the Nobel prize, along with Maurice Wilkins. Rosalind Franklin generated the diagrams but passed away before the prize was awarded and was not recognized.

Question 28

What information is stored in the DNA backbone?

Answer 28

Absolutely None

Question 29

In which direction do polynucleotide chains exist in DNA double helices.

Answer 29

Antiparallel (to eachother)

Question 30

How many hydrogen bonds exist between paired adenine and thymine?

Answer 30

2

Question 31

How many hydrogen bonds exist between paired cytosine and guanine?

Answer 31

3

Question 32

What is the most prevalent form of DNA found in cells?

Answer 32

B Form

Question 33

How do the helical grooves differ in B form DNA?

Answer 33

In B form DNA, one groove is bigger than the other groove. These are named the major and minor grooves.

Question 34

How does A-DNA compare to B-DNA?

Answer 34

A-DNA is shorter and wider than B-DNA.

Question 35

How does Z-DNA compare to B-DNA?

Answer 35

B-DNA is right-handed while Z-DNA is left-handed. Z-DNA is longer and narrower.

Question 36

Is A-DNA right-handed or left-handed?

Answer 36

Right-Handed

Question 37

What happens to B-DNA (in vitro) in very low humidity?

Answer 37

B-DNA changes to A-DNA.

Question 38

Which type of DNA can form DNA-RNA hybrids and RNA-RNA double helices in vivo.

Answer 38

A-DNA

Question 39

When does Z-DNA form?

Answer 39

Z-DNA forms when short DNA molecules are in a regularly alternating purine-pyrmidine sequence, leading to the zig-zag left-handed Z-form helix.

Question 40

How can Z-DNA be used as a tag for which parts of the genome are transcribed?

Answer 40

There is a possiblity that an RNA-DNA hybrid will form shortly after genes are transcribed. This hybrid takes on the Z-form.

Question 41

What can DNA binding proteins do to the shape of the DNA helix while reading it?

Answer 41

DNA binding proteins can distort the shape of the DNA helix.

Question 42

What causes DNA denaturation?

Answer 42

Heat

Question 43

What is the T_m of double stranded DNA?

Answer 43

T_m is the temperature at which the sample is halfway denatured.

Question 44

Why is T_m a function of G-C content?

Answer 44

T_m is a function of G-C content because they form three hydrogen bonds (instead of two like A-T) and therefore require more energy to break the bonds and be denatured.

Question 45

What are the two main secondary structures of RNA? What do they look like?

Answer 45

Question 46

What is the structure of the RNA pseudoknot?

Answer 46

The RNA pseudoknot is one polynucleotide chain of RNA holding on to itself in two subsequent loops

Question 47

What is the importance of the RNA pseudoknot?

Answer 47

The RNA pseudoknot is cruicial to the function of a RNA molecule. The pase pairing holds the RNA together and the bonds cannot be disrupted without transforming RNA’s original function.