Beefalo is a cross between Bison (buffalo) and domestic or exotic cattle of any breed. The purpose of the species cross was to blend the outstanding qualities of the Bison with outstanding qualities of the bovine breeds of the world.
The cross between the Bison and beef breeds combined the superior hardiness, foraging ability, calving ease, and meat quality of the Bison with the fertility, milking ability, and ease of handling from the bovine.

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**A Picture of chromosome arranged in rows is a karyotype
Humans have 23 pairs (46) chromosomes
Two of the 46 chromosomes are called sex chromosomes because they determine an individual’s sex
Females have two copies of a large X chromosome. Males have one X and one small Y chromosome

The remaining 44 chromosomes are known as autosomal chromosomes or autosomes .
All human egg cells carry a single X chromosome (23, X). However, half of all sperm cells cells carry an X chromosome
(23,X) and half carry a Y chromosome
(23,Y). This ensures that just about half the zygotes will be 46XX and half will be
46XY

*** Human genes are inherited according to
Mendel’s principles. However, in order to apply Mendelian genetics to humans, biologists must identify an inherited trait controlled by a single gene. First they must establish that the trait is actually inherited and not the result of environmental influences. Then, they have to study how the trait is passed from one generation to the next.

A pedigree chart shows relationships within a family.
If a trait is dominant, then all family members who lack the trait must have homozygous recessive (aa, bb, ff, etc.) alleles.

White forelock trait = Dominant trait
Female
Horizontal line connecting a male and a female represents a marriage
WW or Ww?
ww
Male
Vertical lines and a bracket connect parents to their children
A shaded circle or square indicates that a person expresses the trait
A circle or square that is not shaded indicates that a person does not express the trait.

Some traits, such as the shape of eyes or ears are actually polygenetic, controlled by many genes.
Of course, many personal traits are also governed by environmental factors.
**The human genome – our complete set of genetic information- includes tens of thousands of genes.

**Some of the very first human genes to be identified were those that control blood type.
The best known genes that determine human blood types are the ABO blood groups and Rh blood groups.
The Rh blood group is determined by a single gene with two alleles- positive & negative. The positive (Rh+) allele is dominant, so persons who are Rh+/Rh+ or Rh+/Rh- are said to be Rh positive!
Individuals with Rh-/Rh- alleles are Rh negative!

There are 3 alleles for the ABO blood group gene: I A I B and i
Alleles I A and I B are codominant. The alleles produce molecules known as antigens on the surface of red blood cells
Individuals with alleles I A and I B produce both A and B antigens, making them blood type AB
The i allele is recessive.
Persons with I A I A or I A i produce only the A antigen, so they are blood type A.

Those with I B I B or I B i produce only the B antigen, so they are blood type B
Those persons who are homozygous for the i allele (ii) produce no antigen, and have blood type O

**Some genetic disorders are caused by autosomal recessive alleles carried on chromosomes.
Examples: albinism, cystic fibrosis, galactosemia, phenylketonuria, Tay-
Sachs disease.

***Other genetic disorders are caused by the dominant alleles, that are expressed even if a recessive allele is present.
Examples: achondroplasia, Huntington’s disease, hypercholesterolemia
*** Codominant alleles (2 dominant alleles) cause other disorders.
Example Sickle Cell Anemia

*** Cystic Fibrosis and Sickle Cell Disease, a small change in the DNA of a single gene affects the structure of a protein causing a serious genetic disorder.
**Cystic Fibrosis (CF) is caused by a a recessive allele on Chromosome 7.
There is a deletion of 3 bases (for the missing amino acid, phyenylalanine) in the middle of a sequence for a protein called CFTR. Normal
CFTR is chloride ion (Cl ) channel through cell membranes. WITHOUT the protein CFTR, Cl ions CANNOT pass across biological membranes.

**Sickle Cell Disease is a common genetic disorder in African-Americans. It is characterized by the bent & twisted shape of red blood cells.
These misshapen cells are rigid and get stuck in capillaries so that oxygen cannot get to cells and tissues.
*Just ONE DNA base is changed to cause this disease. Valine is substituted for glutamic acid. This results in abnormal hemoglobin that sticks together, producing the sickle-shaped cells.

Sickle Cell Disease These red blood cells contain the abnormal hemoglobin characteristic of sickle cell disease.

B C
A

** Chromosomes 21 and 22 were the first human chromosomes whose sequences were determined.
**Chromosome 22 contains as many as 545 different genes, some of which are important for health.
One allele may cause a form of leukemia
Another may cause neurofibromatosis
Long stretches of DNA may be repetitive and not code for proteins -unstable- rearrangements can occur.
**Chromosome 21 has about 225 genes.
One is associated with amyotrophic lateral sclerosis
Also has long regions with no genes

***Genes located close together on the same chromosomes are linked, meaning they tend to be inherited together.
***Sex-linked genes are those with a special pattern of inheritance located on the X or Y chromosomes.
More than 100 genes have been found on the X chromosome. (Only a few have been found on the Y)
Colorblindness – three human genes associated with color-blindness are located on the X chromosome.

Sex cell inheritance patterns for male and female children

Males have just ONE X chromosome. All sex-linked alleles are expressed in males,
EVEN if they are recessive. So, if a male receives a recessive allele on the X chromosomes, the trait WILL be expressed!!!!
For a female to show the sex-linked recessive trait (such as color-blindness), she
MUST receive 2 copies of the recessive allele, one on each of her X chromosomes.
Hemophilia is another example of a sexlinked disorder. (2 genes for blood clotting on
X chromosome)

Female
The "a" recessive allele will not be expressed in her phenotype
Male
The "a" recessive allele will be expressed in his phenotype

Duchenne Muscular Dystrophy – sex – linked gene is defective in that it doesn’t code properly for a muscle protein.

**Females have 2 X chromosomes! Males have just one!
**ONE X CHROMOSOME is enough for males. It is also enough for females,
Sooooo in female cells, one X chromosome is randomly “switched off.”
The turned off chromosome forms a dense region in the nucleus called a Barr Body!!!

** In cats, a gene that controls coat spot colors is located on the X chromosomes.
One X may have alleles for orange spots.
The other X may have alleles for black spots. The cat’s cells may randomly
“switch-off” one chromosome or another in different parts of cat’s body. As a result, female cats may have a mixture of orange and black spots. Male cats have spots of only one color.

If a cat’s fur has three colors (orange, white, black….calico), then the cat is most likely female!!!!
Calico Cat This cat's fur color is controlled by a gene on the X chromosome.

**There is a common error in meiosis called nondisjunction this means that chromosomes do not separate properly. Abnormal number of chromosomes may end up in gametes.
Sometimes individuals may have 3 copies of a chromosome (trisomy)
Down Syndrome – 3 copies of chromosome 21
Edward’s syndrome – 3 copies of 18 (trisomy
18)
Klinefelter Syndrome – XXXY XXXXY
Turner Syndrome – Females with only one X

**Certain disease-causing alleles have slightly different DNA sequences from their normal counterparts. There are tests that can spot these differences.
Labeled DNA probes are specific DNA base sequences that detect the complementary base sequences found in the disease-causing alleles.
There are tests that search for changes in restriction enzymes cutting sites.
Tests detect differences between lengths of normal and abnormal DNA

**No individual is exactly like another, except identical twins.
**DNA fingerprinting analyzes sections of
DNA that have little or no known function but vary widely from one individual to another.

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Small samples of DNA are cut with a restriction enzyme.
Separated by size with gel electrophoresis
Fragments containing high variable regions are detected with a DNA probe, revealing a series of DNA bands of various sizes
If enough combinations of restriction enzymes are used, a pattern of bands is produced that is different from the pattern of anyone else in the world.

Completed in 2003!!

Sequences were determined in widely spaced regions – markers
“shot gun sequencing” – cut DNA into random fragments, find and link overlapping areas
There are relatively FEW genes in a human DNA molecule
Genes are found by locating promotors (DNA sites known for being bonding sites for RNA polymerase) Promoters indicate the start of a gene
Locate introns and exons

Absent or faulty gene is replaced by a normal , working gene. (This way, the body can make the correct protein or enzyme it needs, which eliminates the cause of the disorder.)
Viruses are often used in gene therapy, because they have the ability to enter a cell’s DNA
Virus particles are modified so they do not cause diseases. Then a DNA fragment containing a replacement gene is spliced to viral DNA. The patient is then infected with the modified gene particles, which should carry the gene into cell to correct genetic defects.