• 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. 

ZorseZorse

Liger

Human Heredity 14-1Human Heredity 14-1

A Picture of chromosome arranged in rows is a A Picture of chromosome arranged in rows is a karyotypekaryotype

Humans have 23 pairs (46) chromosomesHumans have 23 pairs (46) chromosomes

Two of the 46 chromosomes are called sex Two of the 46 chromosomes are called sex chromosomes because they determine an chromosomes because they determine an individual’s sexindividual’s sex

Females have two copies of a large X Females have two copies of a large X chromosome. Males have one X and one small Y chromosome. Males have one X and one small Y chromosomechromosome

Human Heredity 14-1Human Heredity 14-1

The remaining 44 chromosomes are known as The remaining 44 chromosomes are known as autosomal chromosomes or autosomal chromosomes or autosomesautosomes..

All human egg cells carry a single X All human egg cells carry a single X chromosome (23, X). chromosome (23, X).

However, half of all sperm cells carry an X However, half of all sperm cells carry an X chromosome (23,X) and half carry a Y chromosome (23,X) and half carry a Y chromosome (23,Y). chromosome (23,Y).

This ensures that just about half the zygotes will This ensures that just about half the zygotes will be 46XX and half will be 46XYbe 46XX and half will be 46XY

Is this a male or female’s Is this a male or female’s karyotype?karyotype?

Human Heredity 14-1Human Heredity 14-1

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

A pedigree chart shows relationships A pedigree chart shows relationships within a family.within a family.

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

Human Heredity 14-1

Female Male

Vertical lines and a bracket connect parents to their children

Horizontal line connecting a male and a female represents a marriage

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.

wwWW or Ww?

White forelock trait = Dominant trait

Human Heredity 14-1Human Heredity 14-1

Some traits, such as the shape of eyes or Some traits, such as the shape of eyes or ears are actually polygenetic, controlled by ears are actually polygenetic, controlled by many genes.many genes.

Of course, many personal traits are also Of course, many personal traits are also governed by environmental factors.governed by environmental factors.

The human genome The human genome – our complete set of – our complete set of genetic information- includes tens of genetic information- includes tens of thousands of genes.thousands of genes.

Blood TypeBlood TypeSome of the very first human genes to beSome of the very first human genes to beidentified were those that control blood type.identified were those that control blood type.

The best known genes that determine human The best known genes that determine human blood types are the ABO blood groups and Rh blood types are the ABO blood groups and Rh blood groups.blood groups.

The Rh blood group is determined by a single The Rh blood group is determined by a single gene with two alleles- positive & negative. The gene with two alleles- positive & negative. The positive (Rh+) allele is dominant, so persons positive (Rh+) allele is dominant, so persons who are Rh+/Rh+ or Rh+/Rh- are said to be who are Rh+/Rh+ or Rh+/Rh- are said to be Rh positive! Individuals with Rh-/Rh- alleles Rh positive! Individuals with Rh-/Rh- alleles are Rh negative!are Rh negative!

Blood Type Blood Type

There are 3 alleles for the ABO blood group There are 3 alleles for the ABO blood group gene: Igene: IA A IIBB and i and i

Alleles IAlleles IAA and I and IBB are codominant. The alleles are codominant. The alleles produce molecules known as antigens on the produce molecules known as antigens on the surface of red blood cellssurface of red blood cells

Individuals with alleles IIndividuals with alleles IA A and Iand IBB produce both A produce both A and B antigens, making them blood type ABand B antigens, making them blood type AB

The i allele is recessive.The i allele is recessive.

Blood Type Blood Type

Persons with IPersons with IAAIIAA or I or IAAi produce only the A i produce only the A antigen, so they are blood type A.antigen, so they are blood type A.

Those with IThose with IBBIIBB or I or IBBi produce only the B i produce only the B antigen, so they are blood type Bantigen, so they are blood type B

Those persons who are homozygous for the i Those persons who are homozygous for the i allele (ii) produce no antigen, and have blood allele (ii) produce no antigen, and have blood type Otype O

Human DisordersHuman Disorders• Some genetic disorders are caused Some genetic disorders are caused

by autosomal recessive alleles by autosomal recessive alleles carried on chromosomes.carried on chromosomes.

• Examples: albinism, cystic fibrosis, Examples: albinism, cystic fibrosis, galactosemia, phenylketonuria, Tay-galactosemia, phenylketonuria, Tay-Sachs disease.Sachs disease.

Human DisordersHuman Disorders

• Other genetic disorders are caused by the Other genetic disorders are caused by the dominant alleles, that are expressed even dominant alleles, that are expressed even if a recessive allele is present. if a recessive allele is present.

• Examples: achondroplasia, Huntington’s Examples: achondroplasia, Huntington’s disease, hypercholesterolemiadisease, hypercholesterolemia

• Co-dominant alleles (2 dominant alleles) Co-dominant alleles (2 dominant alleles) cause other disorders. cause other disorders.

• Example Sickle Cell Anemia Example Sickle Cell Anemia • Go over all the disorders in your textbook.Go over all the disorders in your textbook.

Human Chromosomes 14-2Human Chromosomes 14-2

**Chromosomes 21 and 22 were the first human **Chromosomes 21 and 22 were the first human chromosomes whose sequences were chromosomes whose sequences were determined. determined.

**Chromosome 22 contains as many as 545 **Chromosome 22 contains as many as 545 different genesdifferent genes

**Chromosome 21 has about 225 genes.**Chromosome 21 has about 225 genes.

• Genes located close together on the same Genes located close together on the same chromosomes are linked, meaning they tend to be chromosomes are linked, meaning they tend to be inherited together.inherited together.

• Sex-linked genes are those with a special pattern of Sex-linked genes are those with a special pattern of inheritance located on the X or Y chromosomes.inheritance located on the X or Y chromosomes.

More than 100 genes have been found on the X More than 100 genes have been found on the X chromosome. (Only a few have been found on the chromosome. (Only a few have been found on the Y)Y)

Colorblindness – three human genes associated Colorblindness – three human genes associated with color-blindness are located on the X with color-blindness are located on the X chromosome.chromosome.

Sex cell inheritance patterns for male and female children

Sex LinkedSex LinkedMales have just ONE X chromosome. All sex-linked Males have just ONE X chromosome. All sex-linked

alleles are expressed in males, EVEN if they are alleles are expressed in males, EVEN if they are recessive. So, if a male receives a recessive allele recessive. So, if a male receives a recessive allele on the X chromosomes, the trait WILL be expressed.on the X chromosomes, the trait WILL be expressed.

For a female to show the sex-linked recessive trait For a female to show the sex-linked recessive trait (such as color-blindness), she MUST receive 2 (such as color-blindness), she MUST receive 2 copies of the recessive allele, one on each of her X copies of the recessive allele, one on each of her X chromosomes.chromosomes.

Hemophilia is another example of a sex-linked Hemophilia is another example of a sex-linked disorder. (2 genes for blood clotting on X disorder. (2 genes for blood clotting on X chromosome)chromosome)

MaleThe "a" recessive allele will beexpressed in his phenotype 

FemaleThe "a" recessive allele will notbe expressed in her phenotype

CHROMOSOME DISORDERS!!CHROMOSOME DISORDERS!!**There is a common error in meiosis called **There is a common error in meiosis called

nondisjunction this means that chromosomes do not nondisjunction this means that chromosomes do not separate properly. Abnormal number of separate properly. Abnormal number of chromosomes may end up in gametes.chromosomes may end up in gametes.

Sometimes individuals may have 3 copies of a Sometimes individuals may have 3 copies of a chromosome (trisomy)chromosome (trisomy)

Down Syndrome – 3 copies of chromosome 21Down Syndrome – 3 copies of chromosome 21

Edward’s syndrome – 3 copies of 18 (trisomy 18)Edward’s syndrome – 3 copies of 18 (trisomy 18)

Klinefelter Syndrome – XXXY XXXXYKlinefelter Syndrome – XXXY XXXXY

Turner Syndrome – Females with only one XTurner Syndrome – Females with only one X

Molecular Genetics 14-3Molecular Genetics 14-3

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

**No individual is exactly like another, **No individual is exactly like another, except identical twins.except identical twins.

**DNA fingerprinting analyzes sections of **DNA fingerprinting analyzes sections of DNA that have little or no known function DNA that have little or no known function but vary widely from one individual to but vary widely from one individual to another.another.

DNA FINGERPRINTING!!DNA FINGERPRINTING!!

How it works:How it works:1.1. Small samples of DNA are cut with a restriction Small samples of DNA are cut with a restriction

enzyme.enzyme.

2.2. Separated by size with gel electrophoresisSeparated by size with gel electrophoresis

3.3. Fragments containing high variable regions are Fragments containing high variable regions are detected with a DNA probe, revealing a series detected with a DNA probe, revealing a series of DNA bands of various sizesof DNA bands of various sizes

4.4. If enough combinations of restriction enzymes If enough combinations of restriction enzymes are used, a pattern of bands is produced that are used, a pattern of bands is produced that is different from the pattern of anyone else in is different from the pattern of anyone else in the world.the world.

Human Genome Project: How Human Genome Project: How was it done?was it done?

videovideo