Topic 12 Flashcards
Hershey and Chase used radioactive phosphorous proteins and sulfur to?
differentially label DNA and protein
If one strand of DNA is 5’ ACTGAGCGAA 3’ then the complementary strand would be?
3’ TGACTCGCTT 5’
In Griffith’s experiment, what was the key finding when using live and heart-killed pathogenic bacteria, injected into mice?
Genetic information can be transferred from dead to living bacteria
Which of the following is NOT a component of DNA?
The Pyrimidine Uracil
The bonds found in structure of DNA are which of the following?
Phosphodiester Bonds & Hydrogen Bonds
Which of the following experiments or observations were important in understanding the structure of DNA?
Chargaff’s Rule, Franklin’s X-ray diffraction of DNA, & Watson and Crick’s proposal DNA model
The synthesis of leading vs lagging strand of DNA, differ in which of the following?
Leading strand is continuous, lagging strand is fragmented
The replication of DNA follows which of the following basic information?
Semiconservative
In DNA, complementary base-pairs formed between which of the following?
Adenine with Thymine, Guanine with Cytosine
One common feature of all DNA polymerases is that they
synthesize DNA in the 5’ to 3’ direction
Griffith’s Experiment
showed virulency was transferred, from a pathogenic S. pneumonia stain to non-pathogenic stain (transformation), by infecting lab mice in different experiments
with bacterial transformation, from nonpathogenic to pathogenic
Bacterial transformation
the transfer of free DNA released from a donor bacterium into the extracellular environment that results in assimilation and usually an expression of the newly acquired trait in a recipient bacterium. This process doesn’t require a living donor cell
Griffith’s Experiment and Avery, Macleod, and McCarty’s Experiment
Avery, Macleod, McCarty’s Experiment
identification of the transforming principle.
separated the cellular components: Proteins, lipids, and Nucleic acid, and individually added each one until the transformation occurred in Griffith’s experiment had occurred, which ultimately identified DNA as the genetic material transformation the strains.
Proteins, DNA and RNA were separated by the addition of Proteinase, RNase, DNase.
Only with the addition of DNase (causing the removal of DNA, did not transform the strain to pathogenic.
Henry and Chase Experiment
demonstrate Bacteriophage transfers genetic material is DNA not proteins, using radioactive isotopes of sulfur and phosphorus. Sulfur is incorporated into the protein coat, and Phosphorus is incorporated into the DNA
bacteriophage
any of a group of viruses that infect bacteria
Henry and Chase Experiment
Chargaff’s rule
experiments carried out by Erwin Chargaff showed that the nucleotide composition of DNA molecules were proportional A always equals that of T, and G always equal to that of C
Franklin’s x-ray diffraction experiment of DNA
using x-rays to bombard the crystal structure of DNA, the diffractions formed a pattern, that then can be analyzed to form a 3d structure, performed by Rosalinda Franklin, which allowed the understanding of the orientation of DNA fibers, and the helix structure of DNA.
Watson and Crick double helix model
DNA double helix structure via complementarity of base-pairs – deduced by Watson, and Crick using Chargaff’s rules, the proper tautomeric forms of the bases, and the diffraction experiments performed by Franklin
Semiconservative replication of DNA
The basic mechanism of DNA replication is semiconservative, DNA replication involves opening up the DNA helix, and making copies of both strands to produce two daughter helices, each consisting of one old strand and one new strand
DNA repair
photorepair, excision repair,
Then, DNA polymerase replaces the damaged region, and DNA ligase finished the process of DNA repair
Photorepair
photolyase enzyme recognizes the damage and binds to the thymine dimers, and cleaves the bonds
Photolyase
enzyme that recognizes the damage and binds to the thymine dimers, and cleaves the bonds (photorepair)
Excision Repair
Damaged DNA is recognized by the UvrABC complex, which binds to the damaged region and removes it
Reverse Transcription
Special family of viruses called Retroviruses, that are able to convert their RNA genome into a DNA copy, using an enzyme reverse transcriptase.
Retrovirus Subfamilies
Oncoretroviruses (cancer-causing retroviruses) – human T-lymphotropic viruses – causing leukemia in humans
Lentiviruses – slow viruses with long incubation periods – HIV-1 & 2, causes acquired immune deficiency syndrome (AIDS)
Endogenous retroviruses - inherited provirus DNA in animal genomes, evidence of past endogenous viruses entering host germline genome.
Non-disjunction
are caused when failure of homologues or sister chromatids to separate during meiosis, and results in a gamete developing Aneuploidy
Nondisjunction of sex chromosomes, do not generally experience severe developmental abnormalities, often reach maturity with some cases being fertile or infertile.
aneuploidy
gain or loss of a chromosome
Smaller the chromosome more likely the zygote/offspring survival
13, 15, 18, 21, and 22 being common autosomes Aneuploidy disorders.
trisomy
gain in a chromosome
monosomy
loss of a chromosome
down syndrome
trisomy 21
triple-X-females
TRISOMY X
XXX – females - Triple-X-Females
Klinefelter Syndrome
XXY – males – Klinefelter syndrome
Turner Syndrome
XO – females – Turner syndrome
Jacob Syndrome
XYY – males – Jacobs syndrome
Prader-Willi Syndrome
It is a genetic disorder that results from the absence of active genetic material in a region of chromosome 15
Restriction endonucleases
are enzymes that cleave DNA at specific sites, used by bacteria against viruses.
allows for physical mapping of DNA, by the creation of recombinant DNA molecules, that can be separated by Gel Electrophoresis.
Electrophoresis
Gel Electrophoresis, - separates DNA fragments by size through an agarose medium, when electrical current is passed through a buffer.
Larger DNA fragments move slower than smaller DNA fragments, and DNA is visualized using fluorescent dyes.
southern blot
DNA sample is cleaved by restriction enzymes and separated by gel electrophoresis
northern blot
mRNA is separated by electrophoresis
western blot
Proteins are separated by electrophoresis, and detection of specific proteins require the use of specific antibodies that can bind to proteins.
DNA fingerprint
used in criminal trials, paternity testing, and to identify remains
Restriction Fragment length Polymorphism
Restriction fragment length polymorphisms (RFLP analysis) – refers to the use of restriction enzymes, to detect differences in point and sequence mutations/duplications in short tandem repeats (STRs), in a polymorphic population.
Electrophoresis with Southern blotting, and DNA ladders can be used to compare and detect differences DNA samples.
DNA fingerprinting is used in criminal trials, paternity testing, and to identify remains.
Short tandem repeats (STRs)
common molecular biology method used to compare allele repeats at specific loci in DNA between two or more samples. A short tandem repeat is a microsatellite with repeat units that are 2 to 7 base pairs in length, with the number of repeats varying among individuals, making STRs effective for human identification purposes
Polymerase Chain Reaction (PCR)
mimics the process of DNA replication to produce millions of copies of DNA sequences, called DNA amplification, that then can be used in other molecular applications.
- Denaturation – DNA is heated to 95C, causing the double stranded DNA to separate.
- Annealing of primers – DNA primers bind to the single stranded DNA, allowing DNA polymerase to bind.
- Synthesis – DNA polymerase (Taq polymerase - is a DNA polymerase from a thermophilic bacterium, Thermus aquaticus, that is stable at typical denaturation temperatures, as the bacteria optimum temperature is 70C) makes the new DNA strand.
Cycle is repeated 25 to 30 for sufficient amplification of DNA is achieved.
Requirements for Polymerase Chain Reaction (PCR)
DNA sample for amplification
Taq DNA polymerase
Primers – initiates elongation
dNTPs – deoxyribonucleotides
Buffer solution.
DNA sequencing
slide 40 cuz there’s only pictures and no words
Transgenic organisms
are any organisms modified by the addition of one or more genes from a different species, by any alteration techniques outside conventional breeding.
Transgenic mice have been genetically modified so that they carry a green fluorescent protein
BT corn contains a gene from Bacillus thuringiensis, that produces delta endotoxins acts as an insecticide
biotechnology
slide 43 cuz there are only pictures and no words
Understand the experiments leading to the discovery of DNA as the Genetic/inheritable molecule, with Griffith’s Experiment and Avery, Macleod, and McCarty’s Experiment with bacterial transformation, and Hershey and Chase’s Experiment with Bacteriophage radioactive labeling.
Questions and Hypothesis, were formed on which molecule contained information: Proteins or Nucleotides (DNA)?
DNA was identified as the molecule of Genetic material (inheritance) due to a few main experiments performed on bacteria Streptococcus pneumoniae, which was believed to be the main cause of influenza.
Understand the experiments leading to the discovery of DNA structure, with Chargaff’s rule, Franklin X-ray diffraction experiment, Watson and Crick double helix model
Experiments from Chargaff, Franklin, and Wilkins obtained evidence for the actual structure of DNA.
DNA structure
Contains three main components:
a 5-carbon sugar (Pentose),
a Phosphate (PO4) Group,
a Nitrogen-containing base (Purine or a Pyrimidine) – Adenine, Guanine, Thymine, Cytosine, and Uracil (in RNA).
