Download DNA Ligase Joke (insert laughter here)

DNA Ligase Joke (insert laughter here)
Mendel
• The inheritance of biological characteristics
are determined by genes.
• For two or more forms of a gene, dominance
and recessive forms may exist.
• Most sexually reproductive organisms have
two sets of genes that separate during gamete
formation.
• Alleles segregate independently.
Mendelian Ratio
• 3-1 review
• Review concept of F1, F2, Dom, Rec, Hetero,
Homo, genotype, phenotype, allele
Beyond Dom and Rec
• Incomplete Dominance – One allele is not
completely dominant over the other. White
flower crosses with a red = pink flower.
• Codominance – Both alleles contribute to the
phenotype. Red cow X White Cow = Roan
Cow.
• Multiple Alleles – More than two alleles
control the phenotype. Coat color of rabbits.
• Polygenic traits – Several genes control the
trait. Skin color in humans
Dihybrid Cross RrYy: 9:3:3:1
He then performed a dihybrid cross (two factor cross) .He crossed two pea plants that differed in
• two traits .( Shape and colour).
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His results - F1
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all had round yellow seeds.The offspring were heterozygous for both traits.
• R- round r - wrinkled
• Y- yellow y- green
• RrYy - round and yellow
Then Mendel allowed the F1
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generation of his dihybrid cross to self pollinate.
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Of 551 plants in the F2
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generation the results were :
• 320 round yellow
• 104 round green
• 101 wrinkled yellow
• 26 wrinkled green
• This represented a ratio of 9:3:3:1
The Law of independent assortment :
• The inheritance of one pair of alleles does not affect the inheritance of alleles of another trait.
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Let’s TRY!!
36.What are Mendel’s unit characters known as today?
(A) chromosomes
(B) genes
(C) genotypes
(D) phenotypes
37. What are all possible gametes that would be produced
from parent 1 with genotype TtRr and parent 2 with genotype
Ttrr?
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38. In fruit flies, long wing is dominant to short wing. A cross between
heterozygous long winged flies produces 1000 offspring. According to Mendelian
ratios, how many of the offspring would be heterozygous long winged?
(A) 0
(B) 250
(C) 500
(D) 1000
39. Purple flowers are dominant to white flowers in pea plants. If a homozygous
dominant plant is crossed with a recessive plant, what is the phenotypic ratio in
the offspring?
(A) ½ purple, ½ white
(B) ¾ purple, ¼ white
(C) all purple
(D) all white
• 40. An organism has genotype Xx Yy zz. How many gamete combinations
can be produced from this organism?
• (A) 2
• (B) 4
• (C) 8
• (D) 16
• 41. Why would a single-trait test cross produce offspring that all have the
dominant
• phenotype?
• (A) Alleles are co-dominant.
• (B) Both parents are heterozygous.
• (C) Parent with the dominant phenotype is heterozygous.
• (D) Parent with the dominant phenotype is
• If a mother is a carrier for the recessive sexlinked disorder hemophilia, and her husband
has the normal dominant allele, what
percentage of their children will have
hemophilia?
• (A) 50% of daughters
• (B) 50% of sons
• (C) 100% of daughters
• (D) 100% of sons
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42. Flower colour in snap dragons is an example of incomplete dominance. The
heterozygous condition results in pink colour. What is the phenotypic ratio resulting
from a cross between two pink flowers?
(A) 50% pink, 25% red, 25% white
(B) 50% red, 50% white
(C) 75% red, 25% white
(D) 100% red
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43. A man with type O blood and a woman with type A blood are expecting a child. Both the
man and the woman’s fathers have type B blood. What is the probability of the child
having type O blood?
(A) 0%
(B) 25%
(C) 50%
(D) 100%
Figure 14-3 A Pedigree
Section 14-1
Pedigree
A circle represents
a female.
A horizontal line connecting
a male and female
represents a marriage.
A half-shaded circle
or square indicates
that a person is a
carrier of the trait.
A completely
shaded circle or
square indicates
that a person
expresses the
trait.
A square represents
a male.
A vertical line and a
bracket connect the
parents to their children.
A circle or square
that is not shaded
indicates that a
person neither
expresses the trait
nor is a carrier of
the trait.
Karyotype
Safe transfusion
Phenotype
Blood Type
genotype
Antigen
To
From
DNA Structure ( W and C)
– Thread-like and made up of two anti-parallel
strands
– Sugar-phosphate groups form “rails”
– Nitrogenous bases form the “rungs”
– 4 bases- A, G (purines), C, T (pyrimidines)
– Complementary base pairings (“Chargaff’s Rule”)
DNA Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Sugar
(deoxyribose)
C3
C2
Nitrogenous base
(A, G, C, or T)
DNA Double Helix
5
O
3
3
P
5
O
O
C
G
1
P
5
3
2
4
4
2
3
P
1
T
5
A
P
3
O
O
P
5
O
3
5
P
4 bases- A, G (purines), C, T (pyrimidines)
DNA vs RNA
• Differs in three major ways:
– RNA has ribose vs deoxyribose in DNA
– RNA has Uracil in place of Thymine
– RNA is single stranded
DNA Replication
• 4 Step Process
– Initiation
– Elongation
– Termination
– Proofreading
• Occurs during the s-phase in interphase in mitosis
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DNA Replication – Initiation
• Helicases
– Enzymes that cleave and unravel segments of
DNA, forming Replication Forks.
– This may occur at hundreds of places along the
DNA strand in Replication Bubbles.
5’
Parental DNA Molecule
3’
Replication
Fork
3’
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Helicase
5’
DNA Polymerase (diagram in textbook)
Attaches new nucleotides using the parent strands as templates
2 limitations (1)Can only attach nucleotides to the 3’ end
(2)Needs a RNA “primer” to get started
Termination
Strands re-wind automatically
following replication-both strands are
identical—recall semi-conservative:—
each new DNA double-helix has one
parental strand and one newly-formed
strand
No enzyme activity necessary
Proofreading
• DNA polymerase detects the correct complementary
base to add
– This would still result in a 1 in 10000 to 1 in
100000 error rate
• Has another function: detects whether or not
hydrogen bonds form
• If not, “knows” there’s a mistake and replaces the
wrong base
– This makes the error rate less than 1 in one billion
base pairs
ENZYME SUMMARY
• That led to the understanding that DNA is the genetic material
– T.H. Morgan (1908)
• Genes are located on chromosomes.
– Frederick Griffith (1928)
• a Transforming Factor can change an observable trait (phenotype)
– Avery, McCarty & MacLeod (1944)
• Transforming Factor is DNA
– Erwin Chargaff (1947)
• Chargaff rules: A = T, C = G
– Hershey & Chase (1952)
• confirmation that DNA is genetic material
– Watson & Crick (1953) – awarded Nobel Prize (1962)
• determined double helix model of DNA
– Rosalind Franklin (1953)
• X-ray crystallography – revealed that DNA is a Double Helix ( structure)
Mental
picture,
Write
the
blueprint,
THE CENTwAL DOGMA
build the house…central dogma
DNA
RNA
PROTEIN
TRANSCRIPTION (DNAmRNA)
Translation
Translate into protein
tRNA
Can’t read this ‘book’ without your
mRNA glasses on
Mutations
• 1. CHROMOSOMAL MUTATIONS
- Deletions and insertions of segments
- Translocations/Non-Disjunction (sections are flipped
around)
• 2. GENE MUTATIONS
- Silent mutations (point mutations - same protein is coded
for)
- Mis-sense mutations (point mutations/substitutions – a
different protein is made)…mistake
- Nonsense mutations (insertions and deletions/frameshift
mutations – too disrupted, no protein)
Mutations drive Variation ( evolution!)
• Mutation
– random changes to DNA
• errors in mitosis & meiosis
• environmental damage
• Sex
– mixing of alleles
• recombination of alleles
– new arrangements in every offspring
• new combinations = new phenotypes
– spreads variation
• offspring inherit traits from parent
• What type of mutation occurs if the DNA
sequence CCG TTT CGG changes to
• CCG TTC CGG?
• (A) deletion
• (B) frameshift
• (C) insertion
• (D) substitution
Biotechnology
• Stem cell research
• Prenatal diagnosis (chorionic villi sampling,
amniocentesis, invitro fertilization)
• Cancer research (mutations, carcinogens)
• GMOs (eg golden rice)
• DNA microarrays (identification of gene
expression)
• DNA fingerprinting and gel electrophoresis
• Gene therapy (gene transformations)
• Cloning of organisms (eg Dolly the sheep)
Techniques ( parentage/CSI)
• Restriction Enzymes/ recombinant DNA
• Amplification: millions=vector, billions=PCR
• Sorting: gel electro ( CSI/Paternity)
HGP( Genome Project)
 identify your risk of disease ( Angie J)
Prevent a genetic disorder ( gene therapy)
 Who can access your info?
( employer/insurance)
 Who OWNS your info?
• 78.(b) Current court cases have centered
around ownership of individuals’ DNA.
• i) State two arguments against a company’s
right to sell an individual’s DNA.
GMO/GMF
• Herb resistant crops ( 2001 cornflakes in Can)
• Insulin
• PCB eating Bacteria ( bioremediation)
– Other Bioremediation: bacteria to clean up oil
spills, air pollution, heavy metals
Pros/Cons GMO/GMF
•  Health:
– improved nutrition=reduced disease
– No info on the long term effects
•  Environmental:
– more herbicides? Non target organisms? No LTE
– Cross breeding ( super weeds/super bugs)
•  Social/Economical:
– Manipulation of life/living things
– Large companies may control too much ( food
distribution etc)
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The Newfoundland population is an excellent example of this phenomenon, as researchers estimate 90% are descendants
from just 20,000 - 30,000 people who migrated from south west England and Southern Ireland and settled in isolated
communities along the coast. These descendants settled in distinct settlements on the island of Newfoundland. Certain
genetic disorders have been found in increased numbers in isolated communities--much more than a larger, less isolated
population. This has created an advantage for genetic researchers. Researchers have constructed pedigree charts indicating
family relationships and genetic disorders.
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This historical pattern of migration and isolation has resulted in Newfoundland being recognized as a unique founder
population. Features that make it unique and well suited for genetic research include:
Coastal settlements (outports)
Large family sizes
Descendants living in the same area
Religious segregation and geographic isolation
Cultural and environmental homogeneity
Genetic Causes of Sudden Cardiac Arrest
“In many cases sudden cardiac death is because of one gene mutation in the gene known as TMEM43 that has been passed
through the generations, which causes the electrical system of the heart to malfunction,” explained Dr. Hodgkinson. “This mutation
has caused the deaths of many Newfoundlanders, some named and remembered, some forgotten, the resting places of whom can
be found in the graveyards of isolated communities across the province. This is the genetic burden that has been faced by many
Newfoundland families. “
These families provided the samples that allowed the gene mutation causing this disease in TMEM43 to be found in Dr. Young’s
laboratory. “This made it possible to determine the way the mutation affects individuals across a lifespan and which diagnostic
tests are most effective,” said Dr. Hodgkinson. “From this research we know that the Holter Monitor – a 24 hour assessment of
each heart beat – can detect early signs of this disease. We have also been able to show that treatment with a cardioverter
defibrillator, implanted by Dr. Sean Connors, the elecrophysiologist responsible for the cardiac clinical care of these patients,
shocks the heart back to a normal rhythm and leads to fewer deaths.”