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38 Cards in this Set

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What was the classic assumption about heredity called constancy of species?
All species have been maintained and relatively unchanged since the time of creation.
What was the classical assumption about heredity concerning trait transmission? What was wrong with this theory?
Traits are transmitted directly and independently. If it were true, all organisms in a species would eventually be the same.
What were some of the advantages of Mendel choosing the garden pea for his expirements?
Many hybrids had been previously produced, large variety of true-breeding specimens, small and easy to grow, and the sexual organs were enclosed in a flower.
Why did Mendel allow his peas to self-fertilize for several generations before doing his expirement?
To assure their pure-breeding traits.
What is the F1 generation?
The generation of organisms produced after crossing two known genotype organisms. (First Filial)
What is the F2 generation?
The generation of organisms prodeuced after crossing organisms from the F1 generation. (Second Filial)
What is the phenotypic ratio present in the F2 generation? What is this ratio called? What is it a disguised ratio of?
3:1, Mendelian Ration, 1:2:1 (genotypic ration)
Mendel proposed that parents transmitted _______, different forms of the same trait, to their offspring.
Alleles
What is homozygous? What is heterozygous?
Having the same two alleles for a trait. Having two different alleles for a trait.
What is genotype? What is phenotype?
The sum of an organism's alleles that express for a trait. The physical expression of a trait.
If an allele is always expressed in the phenotype when it is in the genotype, it is __________.
Dominant
What tool is used to examine genotypes among generations of organisms?
Punnett squares
What is Mendel's Law of Segregation?
Alleles for a trait in an organism remain distinct from one another.
What is a test cross?
The crossing of an organism with unknown genotype with a homozygous recessive organsim to determine the unknown's genotype.
What is Mendel's Law of Independent Assortment?
Genes coded on different chromosomes are inhereted independently of one another.
How is the law of independent assortment tested?
A dihybrid cross
What are some ways that Mendelian inheritance is obscured?
Continious variation (multiple genes, same trait), Pleiotropic effects (single alle, multiple traits), Incomplete dominance (Pp is not the same phenotype as PP), Environmental Effects (environment determines intensity of trait), Epistalsis (one gene interferes with another)
What is a genetic disorder?
Detrimental effects caused by harmful allele. (Allele is not always recessive i.e. Huntingdon's Disease)
What is codominance?
The situation where no allele is dominant, and each has its own effect. (i.e. ABO blood antigens)
What are pedigrees?
Family trees that track genetic disorders or information.
What are mutations?
Accidental, random, and rare changes in genes. They usually occur on recessive alleles.
Describe hemophilia.
Hemophilia is a genetic disorder where the blood is slow to clot or doesn't at all. It is sex linked on the X chromosome and is recessive.
Describe sickle-cell anemia.
It is a genetic disorder where red blood cells take on irregular shapes and have defective hemoglobin. Those who are homozygotes for it have the disease. Heterozygotes usually do not and are resistant to malaria.
Describe cystic fibrosis.
It is a disease that causes body cells to secrete a thick mucus that clogs airways. It is caused by a defect of the cf gene.
How have researchers been trying to correct genetic disorders like cystic fibrosis?
By using adeno-viruses to insert functional copies of the defective gene into a cell.
Because of negative side effects of using adeno-viruses, what are researchers attempting to use now?
Adeno-associated viruses
What is a trait that is determined by a gene on a sex chromosome called?
Sex-linked
How many chromosome pairs do humans have? How many groups are they divided into based on size and shape?
Twenty-three, Seven
What are autosomes?
Chromosomes that do not determine sex.
What is a Barr body?
The inactivated x chromosome attached to the nuclear membrande in an embryonic female.
What is aneuploidy? What is primary nondisjunction?
Gametes with the gain or loss of a chromosome. The failure of chromosomes correctly in meiosis I or meiosis II.
What gene is Down Syndrome caused by?
Trisomy 21.
What is the genotype of Klinefelter's syndrome? What are its symptoms?
XXX or XXY. Sterile female with two Barr bodies and otherwise normal, or sterile male with female body characteristics and low mental capacity.
What is the genotype of Turner's syndrome? What are its symptoms?
XO. Sterile female, low mental capacity.
What is the genotype of Jacob's syndrome? What are its symptoms? What is interesting about its distribution?
XYY. Fertile, normal appearing male. It occurs 20x more frequently in prison and mental institutions.
What is genetic counseling? What are some of the methods they use?
A process of identifying parents at high risk of producing children with genetic defects. Amniocenesis (extract amniotic fluid) and Chorionic Villi Sampling (extract part of the chorion)
What are the three things genetic counselors can identify?
Aneuploidy or Gross Alterations, Proper Enzyme Function, and Association with Known Genetic Markers
Who made these flashcards?
Robert Fromm