Genetics P1
Chapter 9
9.1; Identification of DNA as genetic material.
4 criteria for genetic material
1. Information; the material must contain info to construct the entire organism.
2. Transmission; the material must be passed on
3. Replication; must be copied
4. Variation; must have variety that accounts for different phenotypes.
August Weismann and Carl Nägeli; ´ćhemical substance within living cells are responsible
for transmission of traits P-F1´´
Griffith´s research
Griffiths research with bacteria and mice proved that bacterial cells are capable of
transformation, calling the transforming substance transforming principle.
Found that non-infecting bacteria mixed with dead infective bacteria transformed
non-infective bacteria into infective.
Transformation; when a bacterial cell takes up a plasmid or vector segment of
chromosomal DNA from the environment. 2) when a normal cell is converted into a
malignant cell.
Macleod, Avery & McCarty´s research
The researchers were wondering what substance was changing the R bacteria. They found
that only DNA was able to transform.
Solution (strain R and dead strain S) + protease (enzym that decrates proteins) = mouse
dies
- So protease killed the protein and mouse still died so proteins are not responsible
Solution + DNAse= mouse doesn't die
- DNase killed dna and mouse did not die so DNA is responsible.
proves; When DNA is destroyed by dnase it doesn't kill the mouse, so DNA is responsible.
,9.2; Overview of DNA and RNA structures.
Primer; primes the synthesis of DNA.
● Base+ sugar= nucleoside
● Base+ sugar + phosphate= Nucleotide
Bases pair through hydrogen bonds
A&T have 2 hydrogen bonds
C&G have 3 hydrogen bonds.
- C&G- rich DNA is more stable because of the higher count of hydrogen bonds.
DNA can form alternative types of double helices.
● Most dominant form is B-DNA
● at some .;.. A-DNA, Z-DNA
Different levels of complexicty
1. Nucleosides form the repeating structural unit of nucleic acids.
a. Nucleotides are linked together in a linear manner to form a strand of DNA or
RNA.
2. Two DNA-strands form double helix.
3. Dimensional structure of DNA fis result of bending.
,9.3; Nucleotide structure
Nucleotide= (at least) one phosphorus group + a pentose sugar + nitrogen base
● There are two types of sugars; desoxyribose (in DNA) and ribose (in RNA)
● The nitrogen bases are divided into 2 categories
9.4; STructure of a DNA-strand
● Phosphate group connects two sugar molecules
via two ester bonds. Linkage in strands =
phosphodiester bond
● phosphates+sugar make up th e´backbone;; of
the strand
● phosphodiester linkage involves attachment of
phosphate to 3´ carbon of
one nucleotide and to the
5´ carbon of the next
nucleotide
, 9.5; Discovery of the double helix
James Watson and Francis Crick, used models to interpret the structure of DNA. Rosalind
Franklin found that DNA produced a well defined diffraction pattern when exposed to x-rays
which proves that the structure had a repeating pattern. Results found that the pattern
looked like a helix.
9.6; Structure of the DNA double helix
● the double twisted strand structure is stabilized by base pairs between the opposite
strands that are hydrogen bonds. if you count the basis of
one strand you have gone 360* around the axis of the
helix.
● Purines only bond with pyrimidines.
● The bases have flat structures that lay on top of each other
within a single dna strand---this also stabilizes the DNA
structure.
● Grooves= the indentations where atoms of the bases are in
contact with the environment.
9.7; RNA structure
Sometimes Double strands of RNA can form between more strands
which causes unusual shapes.
Chapter 12
12.1; Overview of transcription
● Protein encoding genes carry info for the amino-acid
sequence in a polypeptide.
DNA
Regulatory sequence: site fot the binding
of regulatory proteins; role of these
proteins is to regulate the rate of
transcription
Promoter; provides a site for the
beginning of transcription.
Terminator; provides a site for end of
transcription.
Chapter 9
9.1; Identification of DNA as genetic material.
4 criteria for genetic material
1. Information; the material must contain info to construct the entire organism.
2. Transmission; the material must be passed on
3. Replication; must be copied
4. Variation; must have variety that accounts for different phenotypes.
August Weismann and Carl Nägeli; ´ćhemical substance within living cells are responsible
for transmission of traits P-F1´´
Griffith´s research
Griffiths research with bacteria and mice proved that bacterial cells are capable of
transformation, calling the transforming substance transforming principle.
Found that non-infecting bacteria mixed with dead infective bacteria transformed
non-infective bacteria into infective.
Transformation; when a bacterial cell takes up a plasmid or vector segment of
chromosomal DNA from the environment. 2) when a normal cell is converted into a
malignant cell.
Macleod, Avery & McCarty´s research
The researchers were wondering what substance was changing the R bacteria. They found
that only DNA was able to transform.
Solution (strain R and dead strain S) + protease (enzym that decrates proteins) = mouse
dies
- So protease killed the protein and mouse still died so proteins are not responsible
Solution + DNAse= mouse doesn't die
- DNase killed dna and mouse did not die so DNA is responsible.
proves; When DNA is destroyed by dnase it doesn't kill the mouse, so DNA is responsible.
,9.2; Overview of DNA and RNA structures.
Primer; primes the synthesis of DNA.
● Base+ sugar= nucleoside
● Base+ sugar + phosphate= Nucleotide
Bases pair through hydrogen bonds
A&T have 2 hydrogen bonds
C&G have 3 hydrogen bonds.
- C&G- rich DNA is more stable because of the higher count of hydrogen bonds.
DNA can form alternative types of double helices.
● Most dominant form is B-DNA
● at some .;.. A-DNA, Z-DNA
Different levels of complexicty
1. Nucleosides form the repeating structural unit of nucleic acids.
a. Nucleotides are linked together in a linear manner to form a strand of DNA or
RNA.
2. Two DNA-strands form double helix.
3. Dimensional structure of DNA fis result of bending.
,9.3; Nucleotide structure
Nucleotide= (at least) one phosphorus group + a pentose sugar + nitrogen base
● There are two types of sugars; desoxyribose (in DNA) and ribose (in RNA)
● The nitrogen bases are divided into 2 categories
9.4; STructure of a DNA-strand
● Phosphate group connects two sugar molecules
via two ester bonds. Linkage in strands =
phosphodiester bond
● phosphates+sugar make up th e´backbone;; of
the strand
● phosphodiester linkage involves attachment of
phosphate to 3´ carbon of
one nucleotide and to the
5´ carbon of the next
nucleotide
, 9.5; Discovery of the double helix
James Watson and Francis Crick, used models to interpret the structure of DNA. Rosalind
Franklin found that DNA produced a well defined diffraction pattern when exposed to x-rays
which proves that the structure had a repeating pattern. Results found that the pattern
looked like a helix.
9.6; Structure of the DNA double helix
● the double twisted strand structure is stabilized by base pairs between the opposite
strands that are hydrogen bonds. if you count the basis of
one strand you have gone 360* around the axis of the
helix.
● Purines only bond with pyrimidines.
● The bases have flat structures that lay on top of each other
within a single dna strand---this also stabilizes the DNA
structure.
● Grooves= the indentations where atoms of the bases are in
contact with the environment.
9.7; RNA structure
Sometimes Double strands of RNA can form between more strands
which causes unusual shapes.
Chapter 12
12.1; Overview of transcription
● Protein encoding genes carry info for the amino-acid
sequence in a polypeptide.
DNA
Regulatory sequence: site fot the binding
of regulatory proteins; role of these
proteins is to regulate the rate of
transcription
Promoter; provides a site for the
beginning of transcription.
Terminator; provides a site for end of
transcription.
