Rock Hill, SC
Tuesday, December 03, 2013
We'll approach this large unit this way...
~DNA: The history of its discovery
~DNA Structure: animated (John Kyrk)
~DNA Models (yes, they're movable)
~DNA Packaging animation
DNA Replication johnkyrk
DNA Replication McGrawHill
DNA Replication bioteach
DNA Replication stolaf
DNA Replication semiconservatism
DNA Replication HHMI
(This is the best: how it really goes down)
How does a blueprint of a house become a house? How does this "code" in a nucleus become flesh and blood??? Here's how...
Proteins run everything. This is when RNA plays its role
with DNA to help produce proteins, called
which include the processes of
See the difference in the DNA and RNA sugar :
View images of different kinds of proteins below...
Protein Synthesis: Part 1: Transcription
Protein Synthesis: Part 2: Translation
Transcription and Translation (HHMI)
Choose DNA transcription (basic detail)
and Translation (advanced detail)
Protein Synthesis Transcription/Translation Movie Movie 2
Human Genome Project
Protein Data Bank (PDB.org)
on these images of Meiosis I and II to see enlarged version.
here, then click "What is Heredity?"
|Textbook reading (Modern
Chromosome Structure: 151-153
Genetics Problems (w/answers) (from class)
Textbook Reading for Honors (Modern Biology):
Mendel's work: 173-178
Punnett Squares: 182-183
Incomplete Dominance: 184
Polygenic traits: 242
Codominant/incomplete dom./X-linked traits: 244
Mutagens: The result of too much radiation (Chernobyl)
GENE THERAPY / CLONING pros and cons
Study Guide Key (from class)
|The Father of Modern
Gregor Mendel's work led to major
contributions to the understanding of how
heritable traits are passed between
generations. From his work, two major
principles were established that we still
1. Law (Principle) of Segregation (one
allele from each parent)
>During fertilization (when sperm and egg
Law (Principle) of Independent Assortment
>Genes on separate chromosomes separate
Here's a good dihybrid, X-linked trait genetics problem. Before you look below at the answer, try to figure out the solution for yourself.
A male that is heterozygous for type A blood and is a hemophiliac marries a woman who's type AB and a carrier. What are the possibilities of genotypes and phenotypes of their offspring? (Need a hint?..... Remember, hemophilia is sex linked [on the X chromosome]. So, you'll need to use X and Y for part of your Punnett square, labeling the X properly. Also, you'll need to use the alleles designated for human blood: IA, IB, i.)
An example of Codominance: Human Blood
There are more than 20 genetically determined blood group systems known today, but the ABO and Rh systems are the most important ones used for blood transfusions.
How the human bodyís immune system works:
Antigens: a molecule on a cell surface that elicits an immune response (white blood cells attacking the perceived foreign cell containing the antigen). The antigen of interest found on blood cells is two carbohydrates (A and B) that may be found on blood cell surfaces.
Antibody: a protein your
white blood cells produce to attach to antigens and
attempt to counter their effect. You may have antibodies in
you that are seeking out antigen A or B.
Rh blood types were discovered in 1940 by Karl Landsteiner and Alexander Wiener. The Rh system was named after rhesus monkeys, since they were initially used in the research to make the antiserum for typing blood samples. If the antiserum agglutinates your red cells, you are Rh+. If it doesn't, you are Rh-. People are either Rh- or Rh+. Those who are Rh+ have an Rh antigen present on the red blood cell surface. Rh- do not automatically have an Rh+ antibody, but they will develop if any Rh+ blood is introduced. Rh+ blood patients will not have any antibodies (canít have an antibody against something thatís not there: Rh- only means no Rh+ antigen)
Clinically, the Rh factor,
like ABO factors, can lead to serious medical
complications. The greatest problem with the Rh
group is not so much incompatibilities following
transfusions (though they can occur) as those
between a mother and her developing fetus.
Mother-fetus incompatibility occurs when the
mother is Rh- (dd) and the father is Rh+ (DD or
Dd). Maternal antibodies can cross the placenta
and destroy fetal red blood cells (Hemolitic
anemia, or Rh Disease). The risk
increases with each pregnancy. Europeans are
the most likely to have this problem--13% of
their newborn babies are at risk. Actually only
about Ĺ of these babies (6% of all European
births) have complications. With preventive
treatment, this number can be cut down
even further. Less than 1% of those treated
have trouble. However, Rh blood type
incompatibility is still the leading cause of
potentially fatal blood related problems of the
newborn. In the United States, 1 out of 1000
babies are born with this condition.
Genetic engineering is the process of replacing specific genes in an organism in order to ensure that the organism expresses a desired trait. Genetic engineering is accomplished by taking specific genes from one organism and placing them into another organism.
∑ Genetic engineering can only occur when scientists
know exactly where articular genes for particular
traits occur on specific chromosomes.
> A gene map shows the relative location
of each known gene on a chromosome.
> Genome refers to all the genetic material
in an organism. The Human Genome Project
that mapped the DNA sequence of human
genes is useful in identifying genes for
∑ In cloning, an identical copy of a gene or an entire
organism is produced. This may occur naturally or
may be engineered. Cloning brings benefits such as
organ transplants or saving endangered species,
but it may also result in an organism with genetic
disorders or health problems.
∑ In gene therapy, scientists insert a normal gene into
an absent or abnormal gene. Once inserted the normal
gene begins to produce the correct protein or enzyme,
eliminating the cause of the disorder. However, gene
therapy has had limited success because the host
often rejects the injected genetic material.
∑ Stem cells are undifferentiated cells that have the
potential to become specialized in structure or function.
Although primarily found in embryos, they are also
found all over the adult human body (ex: bone marrow)
but may be harder to isolate. Therapy using stem cells
can replace tissue that is deficient due to disease
∑ Results of genetic engineering may include:
>The development of plants that manufacture
natural insecticides, are higher in protein,
or spoil more slowly.
>The development of animals that are bigger,
are faster growing, or are resistant to disease.
>The development of bacteria that produce
hormones such as human insulin or human
>In humans, it is theoretically possible to
transplant copies of normal genes into the cells
of people suffering from genetically carried
diseases such a Tay-Sachs disease,
cystic fibrosis, and sickle-cell anemia.
is the method of artificially selecting and breeding only organisms
with a desired trait to produce the next generation. Almost all
domesticated animals and most crop plants are the result of
∑ The process works because in order for the
parents to show strong expression for the
trait, they must carry at least one gene
for the trait.
>Once the breeder has successfully
produced offspring with the desired
set of characteristics, inbreeding
(crossing individuals who are closely
>Over several generations, the gene for
the trait will become more and more
prevalent in the offspring.
>The drawback to this method is that
recessive gene defects often show up
more frequently after several
generations of inbreeding.
∑ Hybridization, which is another form of
selective breeding, is the choosing
and breeding organisms that show strong
expression for two different traits in order to
produce offspring that express both traits.
This occurs often between two different
(but similar) species.
The offspring are often hardier than either
of the parents.
for problem above:
THE STEPS TO SOLVING THIS (and ANY) PUNNETT PROBLEM:
1. Step one: Determine the genotypes of the parents (diploid).
The Father: Male, heterozygous for type A blood and hemophiliac = IAi Xhy
The Mother: Female, type AB and a carrier = IAIB XHXh
So, your cross will be:
2. Step two: Determine the possible gametes that each parent could form (haploid):
3. Set up and solve your Punnett
4. Determine the genotypes and phenotypes, and their ratios.
square in the Punnett below exhibits a unique genotype.
Type A carrier female
The NEW Genetics: Read these pages to discover how genes work, new roles/rules for RNA and DNA, life's genetic tree, the human genome, and 21st century genetics.
Monohybrid, Complete Dominance
Create Punnett squares for the following
parentage, and determine
phenotypes/genotypes of offspring:
b. Father: Homozygous for freckles (FF)
M2. Assume brown eyes (B) are dominant to blue (b). A brown-eyed man marries a blue-eyed woman. They have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw the Punnett square that illustrates this family. What is the man's genotype? What are the genotypes of the children?
M3. In dogs, wire hair (S) is dominant to smooth (s). In a cross of a homozygous wire-haired dog with a smooth-haired dog, what will be the phenotype of the F1 generation?
In rabbits, black fur (B) dominates white
fur (b). Perform the following
crosses. Give phen/gen. for all
Albinism is an inherited recessive condition
in skin color. The absence of the
pigment melanin causes the person to be very
pale with very light hair (a yellowish
white) and pale eye color (cloudy blue).
b. Could any of the normal skin color children eventually pass the albino gene to their children? Which ones?
D1. In Drosophila melanogaster (fruit flies), the gene for dachs (short legs, d) is recessive to the allele for normal leg length (D). The allele for hairy body (h) is recessive to the allele for normal body (H). Determine the genotypes of the F1 for the following crosses:
a. DdHh x DDhh
b. DDHh x Ddhh
c. DdHh x ddhh
In guinea pigs, black hair is dominant to
a. A fully homozygous black, long
In peas, the allele for tall (T) plants
dominate the dwarf allele (t).
a. TtRR x TtRr
Incomplete Dominance / Codominance
IC1. Explain the difference between incomplete dominance and codominance.
In some chickens, the gene for feather color
is controlled by codominance.
The allele for black is B and the allele for
white is W.
If two erminette chickens were crossed,
A black chicken is crossed with a white.
In snapdragons, flower color is controlled
by incomplete dominance.
A pink is crossed with a white.
What cross will produce the most pink
Cross someone with type AB blood with a
heterozygous type A person.
IC9. Mrs. Smith and Mrs. Jones had babies at the same maternity hospital at the same time. Mrs. Smith took home a girl and named her Sue. Mrs. Jones took home a boy and named him Jim. However, Mrs. Jones was sure she had a girl and brought suit against the hospital. Blood tests showed that Mr. Jones had blood type O, Mrs. Jones was type AB. Both Mr. and Mrs. Smith were type B, Sue was type A, and Jim was type O. Had a swap occurred?
In radishes, red and white are
pure-breeding colors, while long and
round are pure-breeding shapes.
The hybrids are purple and oval.
Note: When working with sex linked (or X linked) traits, use the sex chromosome symbols X and y for the alleles in your problems.
S1. Are these statements about sex-linked traits TRUE or FALSE? Prove or disprove with Punnetts and explain.
a. A girl cannot have hemophilia unless mom
S2. In colorblindness, the normal male genotype is XCy, whereby the colorblind male genotype is Xcy.
a. What is the genotype of a normal female?
S3. Cross a colorblind male with a carrier. What might their children be?
Can a couple who sees color normally have a
colorblind son? Daughter?
Cross a colorblind male with a perfectly
normal homozygous female.
S5. A hemophiliac male, whose mother and father both had normally clotting blood, marries and has 4 children with a lady who has normally clotting blood, but whose father was a hemophiliac. Can you determine the possible genotypes and phenotypes of all the individuals boldfaced?
MA1. Coat color in rabbits is determined by a single gene that has at least four different alleles. Different combinations of alleles result in four colors: Full color (brown), Chinchilla (gray), Himalayan (black and white), and Albino (white). Using the following information, complete the Punnett squares and answer the questions.
C = full color, dominant to everything else
a. What are the possible genotypes for an
e. C cch x
MA2. Human hair color is controlled by one gene with four alleles (with some incomplete dominance):
HBr = brown HBd = blonde hR = red hbk = black
So, possible genotypes and phenotypes can be:
HBdHBd or HBdhbk = blonde HBdhR = strawberry blonde
HBdHBr = mousy brown HBrHBr or HBrhbk = brown
HBrhR = auburn hRhR or hRhbk = red hbkhbk = black
If someone with auburn hair has children with someone with red hair (but whose mother had black hair), what are the genotype and phenotype probabilities for their children?
Sex Linked / Dihybrid
SD1. Find out the F1's phenotypes and genotypes.
N - Dominant gene for normal skin color (autosomal)
H - Dominant gene for normal blood clotting
factors (X chrom)
Problem: Cross an albino male bleeder with a normal skinned carrier.
Images of some proteins:
All have a different shape.
Don't forget: form and function go hand in hand.
They're shaped like they are because of what they do.
You'll recognize 4hhb, 2hiu, 1igt, 1i6h, 1bkv, and others.
(Hint, zoom your screen to 200X to read it better)
Can two medium toned people have a white or black baby?
Because three sets of alleles determine skin color
- yes -
though the chances are 1/64...
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