Genetics
Watson and Crick
(1953) Were the first to publish the structure of DNA
DNA Polymerase
-only extends nucleic acid chain -cannot start from scratch so, RNA primase synthesizes RNA primers
DNA Replication
-the copying of double stranded DNA -necessary for cell reproduction prior to cell division
direction of replication
5'>3'
Describe Purine
A 6 membered ring attached to a 5 member ring
Nucleotide
A building block of DNA, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group.
Trait of a Sex Linked Disorder
A higher enrichment of expression in one gender
deoxyribonucleic acid
A nucleic acid molecule, usually a double stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases A T C G; capable of being replicated and determining the inherited structure of cell's proteins.
Codon
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
Chargaff Rule
A=T => C=G
Homozygote
AA or aa
Heterozygote
Aa =
Helicase
An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.
Hershey & Chase
Blender Experiment Radio-actively labeled sulfur in proteins and radio-actively labeled phosphorus in a second experiment the virus and allowed to infect bacteria. Showing it was the DNA that entered the bacteria and not the protein
Trait of a Dominant Disorder
Cannot skip a generation
DNA Structure
Deoxyribonucleic acid
Haploinsuffucuency
Dominant Mutation- one copy dominant genes leads to mutation
DNA Polymerase
Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule
Mendel's first law
Equal segregation 1:3:1, and 1:2:1 Ratios are diagnostic of single-gene inheritance and based on equal segregation.
Phenotype vs Genotype
Genotype is the complement of genes Phenotype is the determined by genotype and it the expression of thoses genes
Meiosis
Making a Diploid parent cell into four Haploid daughter cells
Mitosis
Making a Diploid parent cell into two diploid daughter cells
Sex Linked Genes
Male=XY => Female=XX
X-linked repressive disorders
More prevalent in males as the only have set of X chromosomes
Autosomal chromosomes
None are sex linked chromosomes
Elements of DNA
Phosphate, Sugar Back-bone, Nitrogenous base (A,T,G and C)
Transcription
Process by which the DNA molecule in the nucleus makes a copy of itself using mRNA, then leaves nucleus of cell to go to protein synthesis [ribosomes] in cytoplasm.
Null Alleles
Proteins that have no activity
Watson and Crick
Published the first structure of DNA, 1953
rRNA
Ribosomal RNA. A nucleic acid found in all living cells. Transfers information from mRNA to the protein-forming Ribosomes system of the cell.
RNA Primer
Sequence of RNA nucleotides bound to a region of single-stranded DNA to initiate DNA replication.
Replication Origin
Specific sequence of DNA where DNA synthesis begins.
Elongation
Taq polymerase adds NTPs
Zygote
Two Haploid gametes combine to produce one Zygote
Topoisomerase
Uncoils overly coiled DNA Labeld as #3
Fredrich Griffith
Used "S" and "R" strains of bacteria to show the DNA held the genetic information as well as that bacteria can take up genetic materials
Franklin and Wilkins
Used x-ray crystalography to show two helical strands
Allele
Version of a gene, usually with fundamental implications
Gregor Mendal
Worked on Pea Plants showed gene Factor
Polymerase
add the base pairs on to the ssDNA
Denaturing
at 95 degrees
Sliding Clamp
binds polymerase to the ssDNA
DNA is a stranded
double helix
Proteins Involved in DNA replication
helicase, SSB, primase, DNA polymerase, RNase H, Ligase
Annealing
primers anneal at specific sites
DNA Replication
the process of making identical copies of DNA before cell division
Describe Thomas Morgan's work
(1913)Worked on Fruit Flies and was able to show that the genetic information was stored on chromosomes and knew that chromosomes are made up of DNA and Protein. He did not show if the information was stored on the DNA or the proteins
Describe Alfred Hershey and Martha Chase's work
(1952) "Blender Experiment" Viruses (bacterial phages) were radioactively labeled with one group having Proteins with radioactive sulfur and another group with radioactive phosphorus in the DNA. The viruses were allowed to infect bacteria and then then the phages were knocked off the bacteria. The infected bacteria were then tested for radio active P or S and it showed that it was the DNA that was passed to the bacteria as genetic material as there was no S detected but there was P detected.
Basic make-up of DNA
1. Phosphate 2. Sugar Back-bone 3. Nitrogenous base (Adenine, Thymine, Guanine, Cytosine)
Requirements of hereditary Material
1. Stable =>Storage of Information 2. Accurate but Variable => Able to pass on Information 3. Mutations => Variability
Describe Oswald Avery, Colin Macleod and Maclyn McCarthy's work
(1944) They took a pathogenic "S" strain bacteria and individually inactivated each component of the bacteria separately. The RNA, DNA, Carbohydrates, Lipids, or Proteins and then infected mice. Only the bacteria with the inactive DNA allowed the mice to survive. This showed more specifically that the DNA was the only material able to pass on the pathogenic properties
Semi Conservative
Each half of an original DNA molecule serves as a templete for a new strand, and the two new DNA molecules each have one old and one new strand.
phenylketonuria
Enzyme deficit. A deficiency where the phenylalanine is not able to be converted to Tyrosine
Thomas Morgan
Fruit Flies showed genes are on chromosomes made of DNA and Protein
Traits of a Recessive disorder
Often skip a generation
Haplosufficientcy
Only one gene copy is active but it is enough to produce sufficient enzymes. Aa Heterozygotic
Chargaff's rule
The concentration of Adenine=Thymine and Guanine=Cytosine. [A]=[T], [G]=[C]
Translation
The process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm.
Oswald Avery
Showed it was the DNA that indeed what held the genetic information by deactivating all other materials individually
SSBP
Single Strand Binding Proteins keep the replication bubble open
Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
Describe how Rosalind Franklin and Maurice Wilkins work helped show the structure of DNA
Through X-ray crystallography it was able to be seen that the structure was double stranded, helical and the that the distance between the strands were consistent and anti-parallel
Describe Gregor Mendals work
Worked on Pea plants and showed there is a "genetic factor" or "gene" involved in heritability. Did not show where information was stored
Describe pyrimidines
a 6 membered ring
Replication Fork
a Y-shaped point that results when the two strands of a DNA double helix separate so that the DNA molecule can be replicated
DNA ligase
enzyme which connects the individual okazaki fragments on the lagging strand by forming covalent bonds
the leading strand
the strand of DNA that is continuously synthesized during replication
Describe Fredrick Griffith's work
(1928) He took rough edged "R" strain (non-pathogenic) and smooth edged, "S" strain (pathogenic) and tested them on mice. The "S" strain was then boiled and destroyed the proteins but allowed for the DNA to reform. The "S" strain DNA was then injected into "R" strain bacterium and allowed to infect mice. The mice lived using the pure "R" strain but died using the "S" strain DNA. This showed that bacteria can take up genetic material and reproduce from it and that DNA must be the cause of the pathogenic properties.
Three requirements of Hereditary Material
1. Stable - Able to store information 2. Accurate - Replicable and able to be passed on 3. Variability - Some mutations are allowed to prevent cloning
DNA REPLICATION
Before the lagging-strand DNA exits the replication factory, its RNA primers must be removed and the Okazaki fragments must be joined together to create a continuous DNA strand. The first step is the removal of the RNA primer. RNAse H, which recognizes RNA-DNA hybrid helices, degrades the RNA by hydrolyzing its phosphodiester bonds. Next, the sequence gap created by RNAse H is then filled in by DNA polymerase which extends the 3' end of the neighboring Okazaki fragment. Finally, the Okazaki fragments are joined together by DNA ligase that hooks together the 3' end of one fragment to the 5' phosphate group of the neighboring fragment in an ATP- or NAD+-dependent reaction. REPLICATION IN ACTION We are now ready to review the steps of DNA replication. The process begins when the helicase enzyme unwinds the double helix to expose two single DNA strands and create two replication forks. DNA replication takes place simultaneously at each fork. The mechanism of replication is identical at each fork. Remember that the proteins involved in replication are clustered together and anchored in the cell. Thus, the replication proteins do not travel down the length of the DNA. Instead, the DNA helix is fed through a stationary replication factory like film is fed through a projector. Single-strand binding proteins, or SSBs, coat the single DNA strands to prevent them from snapping back together. SSBs are easily displaced by DNA polymerase. The primase enzyme uses the original DNA sequence as a template to synthesize a short RNA primer. Primers are necessary because DNA polymerase can only extend a nucleotide chain, not start one. DNA polymerase begins to synthesize a new DNA strand by extending an RNA primer in the 5' to 3' direction. Each parental DNA strand is copied by one DNA polymerase. Remember, both template strands move through the replication factory in the same direction, and DNA polymerase can only synthesize DNA from the 5' end to the 3' end. Due to these two factors, one of the DNA strands must be made discontinuously in short pieces which are later joined together. As replication proceeds, RNAse H recognizes RNA primers bound to the DNA template and removes the primers by hydrolyzing the RNA. DNA polymerase can then fill in the gap left by RNase H. The DNA replication process is completed when the ligase enzyme joins the short DNA pieces together into one continuous strand.
ribonucleic acid
Consist of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses.
Leaky Mutations
Has some activity but lower than normal.
mRNA
Messenger RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
Double Helix
The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
"F1" Daughter plants
The mixed second generation of the "P" plants
"P" Parental Mendal model
The original homozygotic parent plants
the lagging strand
The strand that is synthesized in fragments using individual sections called Okazaki fragments
tRNA
Transfer RNA. An RNA molecule that functions as a translator between nucleic acid and protein languages by carrying specific amino acids to the ribosome, where they recognize the appropriate codons in the mRNA.
Primase
synthesizes RNA primers for start of elongation
