Download Gregor Mendel - father of Genetics and 18th century Austrian monk

Gregor Mendel
- father of Genetics and 18th century
Austrian monk
-studied pea plants, developed idea of traits and inheritance
Genetics - The study of heredity.
Heredity - The passing on of traits from an
organism to its offspring.
Trait - characteristics of an organism
Genes – (allele) Units of heredity.
One set from each parent.
Dominant - One gene dominates another.
- ex: Brown eyes dominate blue eyes.
Recessive - Weaker trait; Ex.blue eyed genes are dominated by Brown eyed genes.
Purebred - Genes that are the same for a given traits. Ex. - 2 Brown eyed genes. BB
BB or Bb
bb
Hybrid – Two different types of genes for a given trait. Example one (B) brown
eyed gene and one blue (b) eyed gene. Bb
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Incomplete Dominance - Neither gene in an allele masks the other.
Ex : Red rose and white rose have pink offspring.
WW
RW
RR
Law of Segregation - One gene (chromosome) from each pair of
parent’s genes goes to egg or sperm cell.
Independent Assortment - Each set of genes is independently
inherited.
- random sorting
- Ex. Tallness gene is randomly assorted from eye color
gene.
*** Some genes that are close to each other on a DNA molecule do not follow this rule.
Principles of Modern Genetics
-
Traits, or characteristics, are passed on from one
generation to offspring.
-
An organism inherits genes in pairs, one from each parent.
-
Some genes are dominant and some are recessive.
-
Dominant genes hide recessive genes.
-
Some genes are not dominant or recessive; they blend
traits, incomplete dominance.
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Genetics and Probability
-Probability is the chance or likelihood that something will happen.
Punnett Squares - A chart showing the possible gene
combinations (or chromosomes) in a cross between two
organisms.
Phenotype - What the organism looks like. Ex. Brown Dog
Genotype - Gene makeup of organism.
Ex. Bb - A brown dog with one brown gene
and one white gene.
BB - A brown dog with 2 brown genes.
bb – A white dog with 2 white genes
Question : Cross a white dog (bb) with a black dog (Bb).
B
b
Phenotype = 50% Bb
b
Bb
bb
50% bb
Genotype = 50% Brown
b
Bb
50% white
bb
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Chromosomes
Chromosomes
- rod-like shaped structures made of coiled DNA
Walther Flemming - (1882 , German)
- discovered chromosomes
Walter Sutton - American 1902 : Discovered that chromosomes come in pairs.
- Sperm and egg cells have half the normal number of chromosomes.
Theory of Heredity
- Genes are carried from parents to their
offspring on chromosomes.
Meiosis - process of cell division producing sex cells
- each cell has a haploid amount of chromosomes
Haploid - 1/2 the number of chromosomes (sex cells)
Diploid
- normal number of chromosomes ( somatic or body cells )
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Thomas Hunt Morgan
- American Zoologist discovered sex
chromosomes in fruit flies.
Sex Chromosomes - X and Y chromosomes determine sex.
- X is larger than Y
Male = XY
Female
XX
Hugo De Vries
- Dutch Botanist discovered mutations in primroses.
Mutation - A change in a gene or a chromosome.
A mutation in a somatic cell only affects that organism.
A mutation in a sex cell affects its offspring.
Most mutations are harmful or neutral.
Mutations happen when DNA is damaged.
Causes (Mutagens) - X rays, UV rays,
Pollutants, toxic chemicals, old age
Beneficial - Some mutations help an organism
survive in an environment.
A mutation in a plant that can produce a toxin
that protects it from insects.
A major force behind evolution.
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Human Genetics
Y chromosome
- Triggers the production of the male hormone testosterone.
- Testosterone is a hormone that controls male secondary
sexual characteristics. i.e. deep voice, Adam’s apple
Multiple Alleles
- Some characteristics are control by more than two alleles.
- example - blue, brown and green eyed genes
Blood Surface Proteins
- Two alleles A , B ( O is lacking in all three )
- codominant - all are expressed
Mom- AB
A
A
AA
B
AB
50% = AA
50% = AB
A
Dad - AA
AA
AB
Inherited Diseases - A mutation in a gene that codes for an important protein.
- example : Sickle Cell Anemia- A mutation in the gene for
hemoglobin. Cause red blood cell to have a sickle shape.
S = gene mutation (sickle cell)
A = Normal gene
A
S
25%=Normal
A
AA
AS
50%= Carriers
S
AS
SS
25%= Sickle cell
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Genetic Diseases - Mutations can hide in hybrids.
- Some have benefits.
Sickle cell- Carriers have some protection from malaria.
Cystic Fibrosis - May have offered some resistance to typhoid.
Genetic Engineering - Future of modern medicine.
- Actually correcting the problem “gene” that causes the disease.
Nature Vs Nurture- Heredity Vs Environment
-
Twin studies suggest a 40% nature
and 60% nurture.
Sex-linked Traits- Traits that are on X chromosome.
- color blindness, hemophilia
Pedigree - A family tree showing the frequency of a
trait.
males
females
Human Genetic Disorders
Nondisjunction - The failure of a chromosome pair to separate during meiosis.
- Body (somatic) cells may have more or less than normal amount of
chromosomes, usually lethal.
Karyotype - Shows the size, shape and number of chromosomes in an organism.
Down Syndrome: An extra chromosome
(trisomy) on the 21 chromosome.
Have various physical and developmental
problems, and mental retardation.
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DNA
Deoxyribonucleic Acid
- “ The Blueprints of Life” contains all the information to make an organism.
- DNA stores and passes on genetic information from one generation to the next.
- DNA is a large molecule.
James Watson and Francis Crick
- Nobel prize winners for their discovery of the structure of DNA.
Rosalind Franklin and Maurice Wilkins
- Used X rays to discover the shape of DNA.
Structure of DNA
- Double helix, looks like a twisted ladder.
- Each rung (step) is made of two nitrogen bases connected
to each other.
Nitrogen bases
- Adenine (A), Thymine (T), Guanine (G), and Cytosine ( C )
Rules for Connection
A (adenine) only combines with T (thymine)
G ( guanine ) only combines with C ( cytosine )
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Reading Strand - Only one side of the ladder is read, the reading strand.
Complimentary strand
- Opposite strand of reading strand. A copy incase reading is damaged.
DNA is read like a book.
The words are codons.
Codons are 3 nitrogen bases long. Ex: ATT or GTC
Each codon codes for an amino acid.
These amino acids made in ribosome make up
proteins.
Genes code
for Proteins
DNA Replication:
Replication: The DNA molecule unzips itself and
is both sides are copied.
In interphase stage of Mitosis a complete copy
is made.
RNA - Ribonucleic Acid
RNA is an opposite copy of DNA
RNA is a messenger. It takes information out of nucleus to ribosomes.
Does not contain thymine, uracil ( U ) connects with Adenine ( A )
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Applied Genetics
Plant and Animal Breeding
Selective Breeding - crossing plants or animals with desirable traits
to produce offspring with those traits.
Hybridization -Crossing two organisms (usually from the same or
close species) with different variations of a trait.
Examples - corn, rice, mules, dogs.
+
=
Inbreeding - Crossing animals or plants with similar
genes.
- Used to keeps animals or plants purebreds.
Genetic Engineering -The process in which genes
are transferred from one organism to
another or designed.
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Recombinant DNA
- Inserting a gene into another genome.
Plasmid - Free floating circular pieces of bacterial DNA.
Bacterial Transformation;
1) Cut Plasmid with a restriction enzyme.
Break the circular DNA. Leaving two sticky ends.
2) Insert a gene.
Human gene for insulin.
Inserted into a plasmid
3) Force plasmid into bacteria cell.
Placed in a bacteria.
4) Plasmid forces bacteria to make gene product.
Bacteria produce insulin.
Products of Genetic Engineering
Medical - Using bacteria to make drugs, hormones, and enzymes.
- Correcting genetic diseases.
- Designing genes to combat disease.
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Agriculture - Genetically altering plants for
better produce.
- Genetically altering plants for disease
prevention. Many plants that you buy in stores
are genetically modified.
- ex: tomatoes , corn, and wheat
Gel Electrophoresis - Running cut pieces of
DNA on an agarose gel for analysis.
Restriction Enzymes - Enzymes that cut DNA at specific sites.
- Identifies an organism through its genes, used in forensics.
ex: crime scenes, food analyses, and endangered species protection
PCR- Polymerase Chain Reaction
- Making multiple copies of a segment of DNA.
- forensics and the study of genes
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Types of Gene Therapy
in vivo - “ in life ” - placing good genes in cells
invitro - “ in glass ” - correcting the genetic disease inside a test tube
in situ - “ in position ” - correcting the disease inside a cell in the
body
Future of Genetics
Gene Therapy :
- inserting “good” genes in a virus
virus infects human cell , inserts good gene
- inserting corrected genes into an actual cell
- finishing of the Human Genome Project
The Secret Code of Life
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