Chapter 10: The Chemical Nature of the Gene Flashcards
What form of “coding instructions” or “genetic language” are genes made up of?
nucleic acids
What are the four important characteristics that biologists concluded all genetic material posses?
- genetic material must contain COMPLEX INFORMATION (instructions for traits and functions)
- genetic material must REPLICATE faithfully (cell division)
- genetic material must be able to be EXPRESSED (encode for phenotype)
- genetic material must have the capacity to VARY (differ in genetic makeup)
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?
nuclein (nucleic acid)
In the late 1800s, Albrecht Kossel carried out further work on the chemistry of DNA and determined that it contains four nitrogenous bases: ____, ____, ____, and ____
adenine, cytosine, guanine, and thymine (A C G T)
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 ____.
nucleotides
The incorrect hypothesis proposed that all four bases are present in DNA in a fixed sequence is called the _____ hypothesis.
tetranucleotide
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?
Chargaff’s rules
In the early 1900s, biologists used Mendel’s early ideas of heredity and concluded that genes resided on ______ which contained both DNA and protein.
chromosomes
James Watson and Francis Crick discovered what influential identification of DNA in 1953?
the double helix or three-dimensional structure
Rosalind Franklin revealed the clearest images of DNA’s three-dimensional structure by using what technique?
x-ray diffraction or x-ray crystallography
Label three parts of the nucleotide.
phosphate, sugar, and nitrogenous base
Which sugar belongs to DNA and which belongs to RNA?
DNA - deoxyribose sugar, RNA - ribose sugar
How is the length of DNA measured?
By the number of nucleotides.
When numbering sugars, what are the order of numbers based off of?
The carbon positions.
Which carbon position in sugars changes based on DNA and RNA nucleotides? What is the difference between deoxyribose sugar and ribose sugar?
2’ position
OH in ribose, H in deoxyribose
What part of the nucleotide is attached to the 1’ position on the sugar? What about the 5’ position?
1’ = nitrogenous base, 5’ = phosphate group
Purines and Pyrimidines: Which do Adenine, Thymine, Uracil, Guanine, and Cytosine belong to? Which has 1 ring and which has 2 rings?
Purines: Adenine, Guanine (2 rings)
Pyrimidines: Cytosine, Thymine, Uracil (1 ring)
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.
amine, 6’
oxygen, 6’
amine, 4’
methyl, 5’
methyl
DNA molecules have a net ___ charge due to which part of the nucleotide?
negative, phosphate group
Which two factors can neutralize a phosphate group in the DNA molecule?
positively charged valence electron proteins, metal cations
What are the full names for each deoxyribonucleotides?
dAMP, dGMP, dTMP, dCMP
Deoxyadenosine 5’-monophosphate
Deoxyguanosine 5’-monophosphate
Deoxythymine 5’-monophosphate
Deoxycytidine 5’-monophospahte
What is one kind of DNA that exists in single-stranded form?
viral genomes
What kind of bond links two nitrogenous bases?
hydrogen bonds
Which end of the DNA strand is the polar end also known as the “head”?
The 3’ end
DNA or RNA: Can wrap back on itself if long enough, and can pair with base pairs on same strand.
RNA
Name three common forms of RNA.
rRNA, tRNA, mRNA
Which kind of DNA exists in the presence of water and is the predominant form of DNA in cells?
B-DNA (stable)
Is B-DNA a right-handed helix or left-handed helix?
right-handed helix
How many base pairs does it take for DNA to complete a 360º turn?
10 bp
In B-DNA, what degree are base pairs in relation to the helical axis?
90º
What areas on a DNA double-helix often form regions of DNA-protein interaction?
Major and minor grooves
Which form of DNA is formed in the absence of water?
A-DNA
Is A-DNA a right-handed helix or a left-handed helix?
right-handed helix
True or False: Bases in A-DNA are set at a 90º angle from the helical axis?
False; Bases in A-DNA are tilted at an angle in relation to the axis
In relation to B-DNA, A-DNA is a lot more wider and ____.
shorter
Is Z-DNA a right-handed helix or a left-handed helix?
left-handed helix
How are the base pairs in Z-DNA set up in relation to the helical axis?
they are situated in zig-zag direction
Which base pairs are repeated in Z-DNA?
G-C base pairs
Why is the Central Dogma of molecular biology, not a completely true definition in relation to DNA > RNA > Proteins?
special information pathways; certain types of RNA can be translated (mRNA), certain regions cannot be translated, reverse transcription, RNA replication… etc.
What is one true statement about the Central Dogma of molecular biology by Francis Crick that deals with proteins/nucleic acids and information?
“…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.
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 ____.
stem, loop
What kind of bond connects nucleotides together on a sugar backbone? Which parts bond together?
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)
