Chapter 10: The Chemical Nature of the Gene

Question 1

What form of “coding instructions” or “genetic language” are genes made up of?

Answer 1

nucleic acids

Question 2

What are the four important characteristics that biologists concluded all genetic material posses?

Answer 2

1. genetic material must contain COMPLEX INFORMATION (instructions for traits and functions)
2. genetic material must REPLICATE faithfully (cell division)
3. genetic material must be able to be EXPRESSED (encode for phenotype)
4. genetic material must have the capacity to VARY (differ in genetic makeup)

Question 3

Johann Friedrich Miescher turned to the chemistry of pus. This pus contained white blood cells with clear liquid he was able to extract and study. He found this liquid to be highly acidic and contained phosphorus. What is the original name he gave this substance, which was later renamed by one of his students?

Answer 3

nuclein (nucleic acid)

Question 4

In the late 1800s, Albrecht Kossel carried out further work on the chemistry of DNA and determined that it contains four nitrogenous bases: ____, ____, ____, and ____

Answer 4

adenine, cytosine, guanine, and thymine (A C G T)

Question 5

Phoebus Aaron Levene was a researcher of the Rockefeller Institute in New York and studied the chemistry of DNA for 40 years. He discovered that DNA consists of a large number of linked, repeating units called ____.

Answer 5

nucleotides

Question 6

The incorrect hypothesis proposed that all four bases are present in DNA in a fixed sequence is called the _____ hypothesis.

Answer 6

tetranucleotide

Question 7

Erwin Chargaff and his colleagues determined that adenine and thymine were found in equal amounts in DNA samples as well as guanine and cytosine. What did these findings become known as?

Answer 7

Chargaff’s rules

Question 8

In the early 1900s, biologists used Mendel’s early ideas of heredity and concluded that genes resided on ______ which contained both DNA and protein.

Answer 8

chromosomes

Question 9

James Watson and Francis Crick discovered what influential identification of DNA in 1953?

Answer 9

the double helix or three-dimensional structure

Question 10

Rosalind Franklin revealed the clearest images of DNA’s three-dimensional structure by using what technique?

Answer 10

x-ray diffraction or x-ray crystallography

Question 11

Label three parts of the nucleotide.

Answer 11

phosphate, sugar, and nitrogenous base

Question 12

Which sugar belongs to DNA and which belongs to RNA?

Answer 12

DNA - deoxyribose sugar, RNA - ribose sugar

Question 13

How is the length of DNA measured?

Answer 13

By the number of nucleotides.

Question 14

When numbering sugars, what are the order of numbers based off of?

Answer 14

The carbon positions.

Question 15

Which carbon position in sugars changes based on DNA and RNA nucleotides? What is the difference between deoxyribose sugar and ribose sugar?

Answer 15

2’ position
OH in ribose, H in deoxyribose

Question 16

What part of the nucleotide is attached to the 1’ position on the sugar? What about the 5’ position?

Answer 16

1’ = nitrogenous base, 5’ = phosphate group

Question 17

Purines and Pyrimidines: Which do Adenine, Thymine, Uracil, Guanine, and Cytosine belong to? Which has 1 ring and which has 2 rings?

Answer 17

Purines: Adenine, Guanine (2 rings)
Pyrimidines: Cytosine, Thymine, Uracil (1 ring)

Question 18

Adenine has a/an ____ group attached to the __ carbon.
Guanine has a/an ____ atom attached to the __ carbon.
Cytosine has a/an ____ group attached to the __ carbon.
Thymine has a/an ____ group attached to the __ carbon.
Uracil, like thymine, lacks the ___ group.

Answer 18

amine, 6’
oxygen, 6’
amine, 4’
methyl, 5’
methyl

Question 19

DNA molecules have a net ___ charge due to which part of the nucleotide?

Answer 19

negative, phosphate group

Question 20

Which two factors can neutralize a phosphate group in the DNA molecule?

Answer 20

positively charged valence electron proteins, metal cations

Question 21

What are the full names for each deoxyribonucleotides?
dAMP, dGMP, dTMP, dCMP

Answer 21

Deoxyadenosine 5’-monophosphate
Deoxyguanosine 5’-monophosphate
Deoxythymine 5’-monophosphate
Deoxycytidine 5’-monophospahte

Question 22

What is one kind of DNA that exists in single-stranded form?

Answer 22

viral genomes

Question 23

What kind of bond links two nitrogenous bases?

Answer 23

hydrogen bonds

Question 24

Which end of the DNA strand is the polar end also known as the “head”?

Answer 24

The 3’ end

Question 25

DNA or RNA: Can wrap back on itself if long enough, and can pair with base pairs on same strand.

Answer 25

RNA

Question 26

Name three common forms of RNA.

Answer 26

rRNA, tRNA, mRNA

Question 27

Which kind of DNA exists in the presence of water and is the predominant form of DNA in cells?

Answer 27

B-DNA (stable)

Question 28

Is B-DNA a right-handed helix or left-handed helix?

Answer 28

right-handed helix

Question 29

How many base pairs does it take for DNA to complete a 360º turn?

Answer 29

10 bp

Question 30

In B-DNA, what degree are base pairs in relation to the helical axis?

Answer 30

90º

Question 31

What areas on a DNA double-helix often form regions of DNA-protein interaction?

Answer 31

Major and minor grooves

Question 32

Which form of DNA is formed in the absence of water?

Answer 32

A-DNA

Question 33

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

Answer 33

right-handed helix

Question 34

True or False: Bases in A-DNA are set at a 90º angle from the helical axis?

Answer 34

False; Bases in A-DNA are tilted at an angle in relation to the axis

Question 35

In relation to B-DNA, A-DNA is a lot more wider and ____.

Answer 35

shorter

Question 36

Is Z-DNA a right-handed helix or a left-handed helix?

Answer 36

left-handed helix

Question 37

How are the base pairs in Z-DNA set up in relation to the helical axis?

Answer 37

they are situated in zig-zag direction

Question 38

Which base pairs are repeated in Z-DNA?

Answer 38

G-C base pairs

Question 39

Why is the Central Dogma of molecular biology, not a completely true definition in relation to DNA > RNA > Proteins?

Answer 39

special information pathways; certain types of RNA can be translated (mRNA), certain regions cannot be translated, reverse transcription, RNA replication… etc.

Question 40

What is one true statement about the Central Dogma of molecular biology by Francis Crick that deals with proteins/nucleic acids and information?

Answer 40

“…such information cannot be transferred back from protein to either protein or nucleic acid.” In other words, once RNA is transferred to proteins, it cannot be transferred back.

Question 41

Special (secondary) structures can form in single-stranded DNA & RNA. The long series of base pairs connecting with one another in these structures is called a ____. The top of these series of base pairs that do not connect with one another and form a circle is called a ____.

Answer 41

stem, loop

Question 42

What kind of bond connects nucleotides together on a sugar backbone? Which parts bond together?

Answer 42

phosphodiester bonds
The phosphate group at the 5’ position is added to the 3’ position on the sugar (this is why new DNA is synthesized in the 5’>3’ direction)