Molecular Genetics - Exam 1
What was Miescher's contribution to the early study of DNA? - extracted "nuclein" (DNA) from the
nuclei of human white blood cells
"nuclein" is weakly acidic and phosphorous- rich
What was Feulgen's contribution to the early study of DNA? - localized "nuclein" almost exclusively
within the chromosomes
What is epigenetics/"noisy development"? - environment has huge influence on gene expression
What are the three components of a nucleotide? - 1) phosphate group
2) deoxyribose
3) nitrogenous base
Which nitrogenous bases are purines and which are pyrimidines? - Purines - adenine, guanine
Pyrimidines - cytosine, thymine
Which way does B-form DNA spiral? Z-form? Which is the 'normal,' functional type usually found in
vivo? - B-form spirals to the right and is the type most often found in vivo.
Z-form spirals to the left and is found mostly in vitro.
What are the phosphodiester bonds in the DNA backbone like? - One bond is between phosphate and
the 5' carbon of a sugar;
the next bond is between phosphate and the 3' carbon of a sugar.
What are the bonds between nitrogenous bases like? - Hydrogen bonds
A has two bonds to T
C has three bonds to G
, What is a gene? - a region of DNA capable of being transcribed into a functional RNA with correct
temporal and spatial expression
What is the regulatory region of a gene? - contains specific DNA sequences that control the expression
of the gene (transcription initiation, etc.)
What is the coding region of a gene? What is it also known as? - contains information for the gene
product; also known as an exon
What is the intron region of a gene? - sequences within eukaryotic genes that separate exons
often takes up more of the DNA than exons
What is hyperchromic shift? - nitrogenous bases are freed when heated DNA denatures; they have
higher absorbance than DNA usually does
Which part of DNA is hydrophobic and which is hydrophilic? - bases are hydrophobic; phosphates are
hydrophilic
What is Tm? - melting temperature when DNA is half denatured
What kinds of DNA have higher Tm? - longer and/or C/G rich strands, because they have more
hydrogen bonds between bases
What effect does adding substances that make the phosphate groups of DNA more hydrophobic (ex.
methanol, DMSO) have on the Tm? - more strand repulsion, so Tm will decrease
What effect does adding salt have on the Tm? - shields negative charges of phosphate groups, reduces
strand repulsion, results in increased Tm
What happens to stringency if you increase temperature? - higher stringency reaction
What was Miescher's contribution to the early study of DNA? - extracted "nuclein" (DNA) from the
nuclei of human white blood cells
"nuclein" is weakly acidic and phosphorous- rich
What was Feulgen's contribution to the early study of DNA? - localized "nuclein" almost exclusively
within the chromosomes
What is epigenetics/"noisy development"? - environment has huge influence on gene expression
What are the three components of a nucleotide? - 1) phosphate group
2) deoxyribose
3) nitrogenous base
Which nitrogenous bases are purines and which are pyrimidines? - Purines - adenine, guanine
Pyrimidines - cytosine, thymine
Which way does B-form DNA spiral? Z-form? Which is the 'normal,' functional type usually found in
vivo? - B-form spirals to the right and is the type most often found in vivo.
Z-form spirals to the left and is found mostly in vitro.
What are the phosphodiester bonds in the DNA backbone like? - One bond is between phosphate and
the 5' carbon of a sugar;
the next bond is between phosphate and the 3' carbon of a sugar.
What are the bonds between nitrogenous bases like? - Hydrogen bonds
A has two bonds to T
C has three bonds to G
, What is a gene? - a region of DNA capable of being transcribed into a functional RNA with correct
temporal and spatial expression
What is the regulatory region of a gene? - contains specific DNA sequences that control the expression
of the gene (transcription initiation, etc.)
What is the coding region of a gene? What is it also known as? - contains information for the gene
product; also known as an exon
What is the intron region of a gene? - sequences within eukaryotic genes that separate exons
often takes up more of the DNA than exons
What is hyperchromic shift? - nitrogenous bases are freed when heated DNA denatures; they have
higher absorbance than DNA usually does
Which part of DNA is hydrophobic and which is hydrophilic? - bases are hydrophobic; phosphates are
hydrophilic
What is Tm? - melting temperature when DNA is half denatured
What kinds of DNA have higher Tm? - longer and/or C/G rich strands, because they have more
hydrogen bonds between bases
What effect does adding substances that make the phosphate groups of DNA more hydrophobic (ex.
methanol, DMSO) have on the Tm? - more strand repulsion, so Tm will decrease
What effect does adding salt have on the Tm? - shields negative charges of phosphate groups, reduces
strand repulsion, results in increased Tm
What happens to stringency if you increase temperature? - higher stringency reaction
