Genetics Chapter 10: DNA - The Chemical Nature of the Gene

1. it must carry complex information

2. it must replicate faithfully

3. it must encode the phenotype

4. it must have the capacity to very

what are the four characteristics that genetic material was hypothesized to have?

nuclei

___ contain the genetic material

nuclear material is slightly acidic and high in phosphorus

what did Johann Friedrich Miescher show?

nucleic acid and protein

what was chromatin shown to contain?

DNA contains four nitrogenous bases

what did Albrecht Kossel show?

adenine, cytosine, guanine, and thymine

what are the four nitrogenous bases in DNA?

A=T and C=G

what are Chargaff's Rules?

a repeating unit of DNA or RNA made up of a sugar, a phosphate, and a nitrogenous base

what is a nucleotide?

DNA, protein

it was known that ___ and ___ was in the nucleus, but it was unclear if either compound satisfied the four necessary characteristics

a phenomenon observed by Fred Griffith, found that Streptococcus pneumoniae bacteria could be transformed from nonvirulent to virulent strains

what is transformation?

Streptococcus pneumoniae, virulent (IIIS) strains and nonvirulent (IIR) strains

what bacteria was studied in the transforming principle?

killed the mice

what did virulent strains of bacteria do in Fred Griffith's experiments?

did not kill mice

what did nonvirulent strains of bacteria do in Fred Griffith's experiments?

did not kill mice

what did heat killed virulent strains of bacteria do in Fred Griffith's experiments?

killed the mice

In Griffith's experiments, what happened when a heat killed virulent strain was mixed with a live nonvirulent strain?

substance responsible for transformation, DNA

what is the transforming principle?

samples were treated with protease, RNase, and DNase enzymes, only the DNase treated material lost the transforming material

how was the transforming principle identified?

the T2 bacteriophage

what did Hershey and Chase study?

DNA was labeled with P32 and protein was labeled with S35

in Hershey and Chase's experiment, what was labeled and what was used?

by attaching to the outer wall of a bacterial cell and injecting its DNA into the cell

how does a phage reproduce?

the DNA replicates and directs the production of phage coat proteins

what happens after a phage injects its DNA?

protein, DNA

a T2 page is approximately 50% ___ and 50% ___

infected a batch of E. coli with phages with P32 labeled DNA and infected a separate batch with phages with S35 labeled proteins

how did Hershey and Chase set up there experiment?

bacteria infected by P32 phages was radioactive, confirmed that DNA, not protein, is the genetic material of phages

what did Hershey and Chase discover?

collect X-ray diffraction data of DNA

what did Maurice Wilkins and Rosalind Franklin do?

X-ray diffraction data, Chargaff's rules, and observations by other scientists

what did Watson and Crick use to develop a 3D model of DNA?

2 antiparallel strands of nucleotides, right-handed helix, sugars and phosphates on the outside, bases on the interior

what is the structure of DNA?

studied the tobacco mosaic virus, showed some viruses use RNA as their genetic material

what did Fraenkel-Conrat and Singer study/show?

created hybrid viruses by mixing RNA and protein from different strains of TMV, new viral progeny where identical tot he strain in which RNA had been isolate

how did Fraenkel-Conrat and Singer show that RNA is the genetic material in tobacco mosaic virus?

RNA isolated from TMV is sufficient to infect tobacco plants alone

what did Gierer and Schramm show?

monomer, polymer

nucleotides are the ___, while nucleic acids are the ___

a sugar, phosphate, and nitrogenous base

what do nucleotides contain?

only contains a sugar and nitrogenous base, no phosphate group

what is a nucleoside?

5

how many carbon atoms do pentose sugars contain?

ribose: contains hydroxyl (OH) on 2' carbon

deoxyribose: contains an H on 2' carbon

what is the difference between ribose and deoxyribose?

ribose

what is shown?

deoxyribose

what is shown?

additional oxygen makes it more reactive and unstable

how does the hydroxyl group at the 2' carbon in RNA affect it?

it is less reactive and more chemically stable than RNA (due to lack of oxygen on 2' C)

why is DNA better suited to serve as the long-term carrier of genetic information?

covalently linked within the sugar-phosphate backbone or with the nitrogenous base

what are the hydroxyl groups in DNA linked to and how?

purine and pyrimidine

what are the two types of nitrogenous bases?

six-member ring attached to a five-member ring

what is a purine base?

adenine and guanine

what nitrogenous bases are purines?

only a six-member ring

what is a pyrimidine base?

cytosine, uracil (RNA), and thymine (DNA)

what nitrogenous bases are pyrimidines?

a phosphorous atom bonded to four oxygen atoms

what does a phosphate group consist of?

acidity (negative charge)

what property does the phosphate group give nucleic acids?

5' carbon of the sugar

what is the phosphate group always bonded to in a nucleotide?

1' carbon of the sugar

what are nitrogenous bases linked to in a nucleotide?

deoxyribonucleotides

what are DNA nucleotides known as?

ribonucleotides

what are RNA nucleotides known as?

phosphodiester linkages

what are the bonds that connect nucleotides?

a strong covalent bond that joins the 5' phosphate group of one nucleotide to the 3′ hydroxyl group of the next nucleotide in a polynucleotide strand

what are phosphodiester linkages?

a free phosphate group attached to the 5' carbon

what is on the 5' end of a polynucleotide strand

a free hydroxyl group attached to the 3' carbon

what is on the 3' end of a polynucleotide strand

5' to 3'

what is the polymer polarity of a polynucleotide

hydrogen bonds

how are bases on opposite strands of DNA connected?

the covalent phosphodiester bonds that link sugars and phosphate groups

what bonds are stronger in DNA?

because they are complimentary

why do the two strands of DNA base pair?

single strand

RNA usually exists as a ___ ___

helical

DNA secondary structure is typically ___

hydrophobic bases are on the interior, protected from the aqueous environment, which interacts with the sugar-phosphate hydrophilic backbone

how is DNA's double helix structure advantageous in an aqueous environment?

2

how many hydrogen bonds do A-T base pairs have?

3

how many hydrogen bonds do G-C base pairs have?

they are more stable

what is true about G-C rich DNA sequences?

adjacent bases are aligned so that their rings are parallel and stack on top of one another

what is stacking in DNA?

stabilize the DNA molecule but do not require that any particular base follow another, therefore the base sequence of the DNA molecule is free to vary

what does stacking do in DNA?

right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells.

what is B-DNA?

proteins interact with the DNA and sequence independent interactions (like with transcription factors) occur

what happens in the major groove of DNA?

is less water is present

when does A-DNA exist?

if the molecule contains particular base sequences

when can Z-DNA exist?

with transcription

how does information flow from DNA to RNA?

with translation

how does information flow from RNA to protein?

genotype, phenotype

information flow from DNA-->RNA-->protein takes genetic information from ___ to ___

fold into special secondary structures

what can single stranded nucleic acids do?

secondary structure formed when sequences of nucleotides on the same polynucleotide strand are complementary and pair with each other

what is a hairpin?

play important roles in mRNA regulation, rRNA forming ribonucleoproteins complexes, and more

what do nucleic acid secondary structures do?