Leuture 5 DNA discovery and structure

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71 Terms

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What is the Biological Function
What is the Biological Function
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Gregor Mendel (1822-1884) revealed that….
heredity is the result of discrete units of inheritance.

* Traits are not blended - can either have mom or Dad traits can be pasted down generation from generation
 heredity is the result of discrete units of inheritance.

* Traits are not blended - can either have mom or Dad traits can be pasted down generation from generation
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Wilhelm Ludvig Johannsen coined the term gene to refer the …
not or particle of inheritance

* Phenotype - Trait expressed by gene
* Genotype - collection of genes that code for phenotype
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Archibald Garred
Identifies alkaptonuria as a heritable geneticc disease that follows Mendel’s law
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Alkaptonuria
* black urine - inborn error of metabolism used of pedigree
* black urine - inborn error of metabolism used of pedigree
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What is the Biochemical basis of hereditary?
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Majority of death resulted from secondary infections of…
Streptococcus pneumoniae
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What are the two strains of streptococcus pneumoniae
* Rough Colony (R)
* Smooth Colony (S)
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What is the R strain
benign (lacks a protective capsule, recognized and destroyed by host’s immune system)
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S-strain
Is virulent (polysaccharide capsule prevents detection by host’ immune system)
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Fredirck Griffith (1928) discovered that the ..
Fredirck Griffith (1928) discovered that the ..
dead virulent strain of S. pneumonia (S-strain) could transform the harmless form (R-strain) into the virulent form.
dead virulent strain of S. pneumonia (S-strain) could transform the harmless form (R-strain) into the virulent form.
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Avery, and McCarty and Mcleod discovered that…
R-strains could be transformed with DNA extracts from dead S-strains
R-strains could be transformed with DNA extracts from dead S-strains
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Conclusion
the molecule that carries the heritable information is DNA
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Bacteriophage are?

They consist of two component
* Class of Viruses that infect bacteria
* Requires bacterial host for replication

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* DNA Genome
* Protein Capsid
* Class of Viruses that infect bacteria
* Requires bacterial host for replication

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* DNA Genome
* Protein Capsid
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Bacteriophage life cycle
The genetic information required for viral replication must be contained in either the DNA or the proteins
The genetic information required for viral replication must be contained in either the DNA or the proteins
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Hershey and chase (1952)

Labeled Bacteriophage with radioactive elements
* Phosphorous of DNA
* The sulfur of Amino Acids - Cysteine and methionine

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* Traced the transfer of those elements to the infected bacteria
* Phosphorous of DNA
* The sulfur of Amino Acids - Cysteine and methionine 

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* Traced the transfer of those elements to the infected bacteria
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Hershey and Chase confirmed What?
Experiment DNA and Protein/sulfur put in viruses that allowed to infect E.coil- blender shear off viral heads off bacter- infected bacteria contained 35P not S35
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Nucleotides
A nucleotide consist of a nitrogen-containing base, a five-carbon sugar, and one or more phosphate groups

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Carbons of the deoxyribonucleotide (monomer unit of DNA)
A nucleotide consist of a nitrogen-containing base, a five-carbon sugar, and one or more phosphate groups

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Carbons of the deoxyribonucleotide (monomer unit of DNA)
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1’
Base attached
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2’
Deoxygenated in DNA
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3’
OH - forms phosphodiester bond
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5’
Phosphate group attached
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What are the Nucleotide bases

What are Pyrimidine and Purine bases
knowt flashcard image
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DNA Polymerization
DNA Polymerization
* Hydrolysis of Phosphor anhydride bond provide energy
* Creates favorable reaction - high energy → Low energy
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Erwin Chargaff do?
Nucleotide occur in predictable ratios in living things
Nucleotide occur in predictable ratios in living things
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What is Chargaff's Rule?
A = T

G = C
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Discovery of the structure of DNA - Watson, Crick, Wilkins, and Franklin
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Discovery of structure of DNA - Watson, Crick, Franklin, and Wilkins
* Double helix with Bases pointing inward
* Complementary base-pairing between purine and pyrimidine explain Chargaff’s rule
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Complementary base-pairing of DNA makes it possible to faithfully replicate of genetic material
* Each strand serves as a template to make a new double helix - semi-conservative replication.
* Each strand serves as a template to make a new double helix - semi-conservative replication.
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Part 2 - DNA and Chromatin Structure
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DNA Structure backbone is assembled via condensation reactions forming…
Phosphodiester bonds
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Nucleotides are connected 5’ to 3’ and strands are..

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one strand and the other…
* antiparallel

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* One strand runs 5’ to 3’
* Other runs 3’ to 5’
* antiparallel

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* One strand runs 5’ to 3’
* Other runs 3’ to 5’
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DNA Structure is held together by…
Hydrogen bonds between bases
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G to C bonds are… than A to T
Stronger
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Increasing the GC content increases the … of DNA
Stability
Stability
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The DNA Helix has two grooves
* Major groove - 22 A wide - primary site of sequence specific binding of protein
* Minor groove - 12 A wide - primary non-specific binding of proteins
* Major groove - 22 A wide - primary site of sequence specific binding of protein
* Minor groove - 12 A wide - primary non-specific binding of proteins
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term image
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Major DNA sequence features (2)
* Genome
* Gene
* Genome 
* Gene
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Genome?
The complete DNA sequence of an organism
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Gene
Portion of the genome transcribed to RNA and usually translated into a protein
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Genes are read (transcribed) …..from either strand of the double helix
5’ to 3’
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Replication Origin
Special sequence where the replication of DNA begins
Special sequence where the replication of DNA begins
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Centromere
A special sequence that attaches to mitotic spindle and allows chromosome separation in mitosis
A special sequence that attaches to mitotic spindle and allows chromosome separation in mitosis
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Telomere
Repetitive sequences at the ends of Chromosomes that protect from degradation and/or fusion with other chromosomes
Repetitive sequences at the ends of Chromosomes that protect from degradation and/or fusion with other chromosomes
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The Problem with DNA is that it’s Thin and Extremely long molecule.
* Each cell in your body has 2 meters of DNA
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How does DNA fit in the cell?
DNA is packed with proteins into a complex called chromatin
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Histone proteins are major elements of…
chromatin
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Histone protein come together in an …. complex which DNA wraps around.
Octomer
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Nucleosome?
The histone + DNA Complex
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Histones proteins are…. charged and attract the …. charged DNA
Positively charged

Negatively charged
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Decondense Chromatin appears like …..

DNA wraps around nucleosome ….times …bp
Beads on a string

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1\.7 times (147 basepairs)
Beads on a string

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1\.7 times (147 basepairs)
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Another histone protein…. can …
H1 can link histones together and help condense the chromatin fibers
H1 can link histones together and help condense the chromatin fibers
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Chromatin fibers are … into loops by …
Folded

CTFC proteins
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What do CTFC do?
Pull loop through until it reaches a specific sequence

* Matches Specific DNA Sequences
* Chromosome loop-forming clamp proteins
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What is the Result of this?
Each DNA molecule has been packaged into a Mitotic chromosome that is 10,000-fold shorter than its fully extended length

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* Fully condense at Meta-phase of cell cycle
Each DNA molecule has been packaged into a Mitotic chromosome that is 10,000-fold shorter than its fully extended length

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* Fully condense at Meta-phase of cell cycle
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DNA in Eukaryote cells is organized into ..
Chromosomes
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What is a chromosome
Complex of DNA (One continuous helix) and many proteins
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In human chromosomes are paired …
Homologous chromosomes, one from each parent
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Chromosomes take on different conformations through the cell cycle
Interphase, meta phase, interphase
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In interphase, when cell is not dividing,..
different chromosomes reside in distinct territories within the nucleus.
different chromosomes reside in distinct territories within the nucleus.
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Nucleus chromatin is found in two forms
* Heterochromatin
* Euchromatin
* Heterochromatin
* Euchromatin
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Heterochromatin
That is condensed and not transcriptionally active by telomere and centromere.
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Euchromatin
That is loose and transcriptionally active
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Chromatin conformation and composition is dynamic and modified for specific biological function
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Chromatin remodeling complex (3)
* Positions nucleosomes
* Condenses and decondense
* Requires ATP
* Positions nucleosomes
* Condenses and decondense
* Requires ATP
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The Histone proteins have….terminal tails that are…
N-terminal tails that are modified to mark regions of genome for transcriptional activation or silencing
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What are the 5 Levels of DNA

1. Double helix
2. Beads on a string - DNA wraps around Histone 1.7 times 147bp creating nucleosome
3. Chromatin fibers are made with Histone HI
4. Chromatin fiber loops with CTFC - pull loop through until it reaches a specific sequence
5. Folded loops are fully condensed at meta-phase of cell cycle
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term image
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