For example, true breeding seed for purple flowers would always develop into plants with purple flowers. The Mixed Inheritance Hypothesis predicted that crossing two different pure lines would result in an intermediate.
Mendel’s Seven Crosses
When seeds were developed from Mendelian crosses, he discovered that all the resulting seeds (F1) were identical in shape to one of the parents. The expressed F1 phenotype was termed the dominant phenotype, while the suppressed phenotype was termed the recessive phenotype. From his study, Mendel concluded that the physical traits (or phenotypes) he was studying (i.e., seed shape, flower color, etc.) were determined by a combination of what he called "discrete hereditary units." This concept, known as
Which of Mendel's laws is indicated by the arrows from the diploid parent to the haploid gamete.
Which of Mendel’s Laws is indicated by the arrows from the diploid parent to the haploid gamete?
What does the bringing together of parent alleles in a box represent?
What does each square represent?
Determine the genotype and phenotype ratios in the offspring for a cross between a homozygous dominant female and a homozygous recessive male. Determine the genotype and phenotype ratios in the offspring for a cross between a homozygous recessive female and a heterozygous male. Determine the genotype and phenotype ratios in the offspring for a cross between a heterozygous female and a heterozygous male.
Determine the genotype and phenotype ratios in the offspring for a cross between a heterozygous female and a homozygous dominant male. Cystic fibrosis of the pancreas is an inherited condition caused by faulty fat metabolism. If a heterozygous man marries a heterozygous woman, what is the probability that their first child will have the disease.
Allele
Alleles are alternative versions of the same gene
Definition: A dominant allele is a variation of a gene that will produce a particular phenotype, even if the individual has only one copy. The allele is dominant because one copy of the allele is all that is needed to produce enough of the protein encoded by the gene. Example: Dark hair (R) is dominant to blond or red hair (r) because having even one copy of the dark hair allele will code for enough melanin protein to make the hair appear dark*.
Definition: A recessive allele is a variant of a gene that must be homozygous if it is inherited in order to be expressed in a phenotype. Cause no. 2. The recessive allele is normal and the dominant allele is the broken version, but we need two good copies to get the job done. The normal function of the FGFR3 (a) gene is to encode a protein that prevents bone growth.
Even if a person has a normal copy of FGFR3(a), the damaged version sends a signal that is just too strong.
COMMON MISCONCEPTIONS
Recessive
Only recessive alleles cause
If you are a man, you only have one copy of each gene located on the X chromosome, because you only have one X chromosome.
Homologous Chromosomes
Noted with a capital letter for the dominant allele and a small letter for the recessive allele (Xx).
GAMETES
ZYGOTE
MALE
FEMALE
The two copies of each gene in each individual can be the same allele (homozygous) or different alleles (heterozygous).
There can be many different alleles (versions) of each gene in this
An example of a gene with multiple alleles in the population is the human blood group gene. IA = a version of the gene that codes for a type A protein on the red blood cells. IB = a version of the gene that codes for a type B protein on the red blood cells.
Even if there are more than two alleles in the population, there are at most two alleles in a single individual.
This individual person has a max of two
There are three alleles of a gene in the population, and then there are six possible allele combinations in an individual.
Codominance
Roan coat
Notation rules
ROAN
Cross a striped petunia with a red petunia
More than 2 alleles in a population (IA, IB and i), but no more than 2 alleles in one individual. They were discovered by Karl Landsteiner at the University of Vienna in 1900 and 1901 when he was trying to find out why blood.
Sex Linked Traits
Definition
Why are most sex linked traits on the X chromosome?
X Chromosome Y Chromosome
X and Y chromosomes contain short regions of homology at one end. These homologous regions allow the pairing. synapsis) of the X and Y chromosomes during prophase 1 of meiosis.
The pattern of inheritance is different with sex-linked genes dying at their sex loci.
The pattern of inheritance is different with sex-linked genes die to their location on sex
THOMAS MORGAN – elucidation of sex-linked genes with Drosophila (fruit fly) Drosophila
Sex Limited Inheritance in Drosophila” (1910), by Thomas Hunt Morgan
Morgan began breeding the white-eyed mutant fly and discovered that in one generation of flies, the trait was only present in males. Through further breeding analyses, Morgan discovered that the “genetic factor that controlled the flies' eye color was located on the same chromosome that determined sex.” Morgan then took those red-eyed females and mated them with the original white-eyed mutant male to determine whether or not the inheritance of eye color followed Mendelian inheritance.
If Mendel's patterns were applied to Morgan's flies, there would be one white-eyed fly for every three red-eyed flies in the resulting generation of flies, regardless of sex. Morgan observed one white-eyed fly for every three red flies, and that inheritance pattern was not equally distributed between males and females. After observing the inheritance pattern of white eyes, Morgan hypothesized that a factor, or gene, that controlled eye color was located on the X chromosome.
Males showed the white eye trait because the trait was present on their only X chromosome. The females did not show the white eye trait because it was only present on one of their X chromosomes. Predicted what the sex and eye color ratio of the offspring would be if his hypothesis was true.
In one mating, Morgan took a red-eyed male and mated it with a white-eyed female. He predicted and observed that half of the flies would be red-eyed females and the other half would be white-eyed males. That mating showed that the occurrence of the white-eyed trait is limited to the X chromosome, as only male offspring were able to exhibit the white-eyed trait with a single copy of the trait.
In 1911, Morgan published more details of his experiments with the white-eyed mutant, an account in which Morgan explicitly stated that chromosomes carry hereditary factors, or genes. That book contained contemporary scientific information on heredity and included the results of Morgan's white-eyed mutant experiments.
Hemophilia
After an injury, blood clots protect the body by sealing off damaged blood vessels and preventing excessive blood loss. These blood clotting problems cause continuous bleeding that is difficult to control. Female carriers have about half the normal amount of coagulation factor VIII or coagulation factor IX, which is generally sufficient for normal blood clotting.
Red-green
Red-green color blindness
Hemophilia in humans is inherited as an X linked recessive trait. A woman whose father has
Calico is a coat color found in cats and is caused by a SEX-linked CODOMINANT allele. A genetic disease is a disease caused in whole or in part by a change in DNA.
Single-gene diseases can be dominant or recessive, and autosomal or sex-linked
Most genetic diseases are caused by a recessive allele of a gene. The disease therefore only develops in
Did you know that there are truly rare people born all the time? Around 350 million people
Carriers” of genetic diseases
Sickle Cell Anemia
Signs and symptoms of sickle cell disease are caused by sickling of red blood cells. Painful episodes can occur when sealed red blood cells, which are rigid and inflexible, become stuck in small blood vessels.
Cystic Fibrosis
Over time, mucus buildup and infections result in permanent lung damage, including the formation of scar tissue (fibrosis) and cysts in the lungs. The pancreas is an organ that produces insulin (a hormone that helps control blood sugar levels).
Huntington Disease
Huntington's disease is a progressive brain disorder that causes uncontrolled movements, emotional problems and loss of thinking ability.
Phenylketonuria (PKU)
- Does the trait skip generations?
- Is the trait found much more often in
- linked Dominant RARE!!
- Linked Recessive
Before newborn screening programs could detect PKU in the first few hours after birth, PKU was one of the leading causes of intellectual and psychological problems. Today, as a result of newborn screening programs that allow almost immediate treatment of the condition, PKU has been virtually eliminated as a cause of IDD in this country. If children with the condition follow this diet at birth, they grow normally and usually show no symptoms or health problems.
A newborn screening, in which blood is taken from a heel prick and tested for multiple genetic diseases. Phenylketonuria (PKU) is a genetic condition in which a person cannot use the amino acid phenylalanine. Individuals with PKU must follow a strict diet low in phenylalanine. Suppose a man who is a carrier marries a woman with PKU. What are the chances that they will have a child with PKU? Cystic fibrosis is a chronic recessive genetic disorder that affects the respiratory and digestive systems. Jaren was diagnosed with cystic fibrosis when he presented with symptoms including a persistent cough and excessive appetite with little weight gain. Neither of his parents show symptoms of the disease. What are the genotypes of Jaren's parents? What are the chances that a future child of Jaren's parents will NOT inherit cystic fibrosis? What are the chances that a future child of Jaren's parents will inherit cystic fibrosis? Why are Jaren's parents showing no symptoms. Sickle cell anemia is a condition that exhibits codominance. Sickle cell disease is the heterozygous condition and contains both normal and sickle shaped blood cells. Sickle cell disease is when all blood cells are present. sickle-shaped and has lifelong medical implications. A man with sickle cell disease has a child with a woman without sickle cell disease. What are the chances of having a child with sickle cell disease? What are the chances of a normal offspring? What are the chances that you will have a child with sickle cell disease? The musician Woody Guthrie, who wrote This Land is Your Land, died of Huntington's disease. Huntington's disease is caused by a latent dominant gene, meaning it is not phenotypic. physically) are expressed until later in life. If one parent has the disease, the offspring that do not have the trait are heterozygous carriers.
A female who has this trait may or may not pass the gene for the disease on to her son or daughter. Mothers of males who have this trait are either heterozygous carriers or have the disease.
