biology final Flashcards
What is blending inheritance?
The hypothesis that traits are handed down from one generation to the next by the parent’s traits being blended in the offspring.
How do we know blending inheritance does not work?
Being taller than both of your parents or being shorter than both of your parents.
Who was Gregor Mendel?
An Austrian man who was born into a poor family. He wanted to go to college but he couldn’t because his family was poor. He signed up to be a monk just so he could go to college. He studied botany and physics.
Explain Gregor Mendel’s experiment.
Gregor Mendel looked at 7 different traits of pea plants and bred the plants with the same allele fro true breeding. Mendel was lucky that all traits of the pea plants followed simple dominance and were all separate chromosomes.
What plant did Mendel use for his experiments?
Pea Plants.
Why was it a good idea for Mendel to use pea plants in his experiment?
Luckily, all of the traits of the pea plants followed simple dominance and were all on separate chromosomes.
What are alleles?
One of two or more alternative versions of a particular gene. Some genes have many, each of which contains slightly different instructions for building a protein.
What are dominant alleles?
Alleles which are always expressed if present, even if the individual only has one copy.
What are recessive alleles?
Alleles which are only expressed if the individual has two copies, the individual must be homozygous for the allele.
Explain the shorthand we use to designate allele pairs.
Genotypes. Genotypes are the arrangement of alleles that a person has.
What does “homozygous” mean?
Refers to an individual which has two of the same alleles at a particular locus.
What does “heterozygous” mean?
Refers to an individual which has two different alleles at a particular locus.
What is Mendel’s Law of Segregation?
States that diploid organisms inherit 2 genes per trait during meiosis. The genes separate so there is 1 gene per section. He demonstrated this with a Punnet Square.
What is Mendel’s Law of Independent Assortment? How did he demonstrate it?
States that gene pairs segregate during gamete production independently of other gene pairs located on non-homologous chromosomes. He demonstrated this using the pea plants.
What is complete dominance?
When there are two alleles, one is dominant and the other is recessive.
How is complete dominance different from incomplete dominance?
Incomplete dominance is one dominant allele and one recessive allele and the dormant allele does not completely mask the recessive allele.
What is codominance?
A situation in which two different alleles are completely expressed in heterozygotes. The ABO blood typing system in humans is an example.
What is pleiotropy?
A situation in which one gene controls two seemingly unrelated aspects of the phenotype. EX: Sickle Cell Syndrome
What is epistasis?
A situation in which one gene pair may block the expression of a different gene pair.
Give an example of each type of inheritance.
Autosomal Recessive - Sickle Cell Syndrome, Galactosemia.
Autosomal Dominant - Achondroplasia, Huntington’s Disease.
X-Linked Recessive - Colorblindness, Hemophilia.
What is discontinuous variation?
When there are two or more separate phenotypes. Examples are tall or short plants and purple or white flowers.
What is quantitative inheritance?
A situation in which a single phenotypic trait is controlled by several gene pairs, resulting in continuous variation. Example of this would be skin color.
What are some examples of how genetic inheritance interacts with the environment?
When your skin color changes because of the sun providing more melanin to appear.
How is sex determine in humans and other mammals?
SRY gene. If SRY is found in a human, that human is a male.
What are some examples of animals in which sex is not genetically determined?
Alligators and Turtles.
What is linkage?
The property of genes located on the same chromosome, which tend to be transmitted together.
How can linkage be disrupted?
Crossing over.
What are difficulties involved in studying human genetics?
Difficulties involved in studying human genetics include small family sizes, long generation times, and privacy concerns and other ethical questions.
What is pedigree analysis?
Pedigree Analysis is when you use a family tree with known individuals to determine the traits that will be passed down.
What is the difference between an abnormality, a disorder, a syndrome, and a disease?
An abnormality refers to a genetic condition that is deviated from normal but it is not life threatening and does not cause any symptoms. A disorder refers to a genetic abnormality that causes medical symptoms. A syndrome refers to a genetic disorder that has a recognizable set of symptoms that comes with it. A disease refers to a medical problem that is caused by an infection, a toxin, or a lack of a certain nutrient. This is not a genetically caused problem.
What are the three main patterns of inheritance?
The three main patterns of inheritance are Autosomal Recessive, Autosomal Dominant, and X-Linked Recessive.
What are examples of genetic disorders that are transmitted in each pattern?
Examples of Autosomal Recessive are Sickle Cell and Galactosemia. Examples of Autosomal Dominant are Achondroplasia and Huntington’s Disease. Examples of X-Linked Recessive are Colorblindness and Hemophilia.
What are the different types of changes in chromosome structure?
The different types of changes in chromosome structure are:
- Duplication: a copied chromosome has 2 copies of itself.
- Inversion: break off part of a chromosome and when it is reassembled, it has turned itself backwards.
- Translocation: Break off part of one chromosome and attach it to part of another chromosome.
Deletion: Part of a chromosome is destroyed or lost.
What are the different types of changes in chromosome number? What are the various examples of aneuploidies in human sex chromosomes?
The different types of changes in chromosome number are called Aneuploidy. Aneuploidy is broken down into Monosomy and Trisomy.
Monosomy is if there is one chromosome.
YO – fatal
XO – survivable (Turner Syndrome)
Trisomy is if there are three chromosomes in one set.
XXY – Klinefelter Syndrome
XYY – Extra-Y Syndrome
XXX – Super Female
What did Fred Griffith discover? How did his experiment work?
Fred Griffith discovered that there was something in the bacteria that could turn R strain into S strain which was called the transforming substance. In his experiment, he took S strain, heated them up to kill them but they stayed alive and he injected them into mice. He mixed dead S strain and live R strain and injected them into the mice and that killed them.
What did Alfred Hershey discover? How did he know that the genetic substance was DNA instead of protein?
Alfred Hershey discovered the DNA, not proteins, was the genetic material of the cell. He knew that the genetic substance was DNA instead of protein because he used viruses and viruses are made of DNA and proteins. If sulfur was passed along, it would have been proteins, but since it was phosphorus passed along, Hershey knew it was DNA.
What are Chargaff’s Rules? Why are they important to the structure of DNA?
Chargaff’s Rules are that cytosine is equal to guanine and adenine is equal to thymine. Chargaff’s rules are important to the structure of DNA because of the way the nucleotides are aligned in the DNA molecule.
What did Watson and Crick discover? How was the work of Franklin and Wilkins critical to this discovery?
Watson and Crick discovered the structure of DNA. The work of Franklin and Wilkins was critical to this because of their conduction of X-ray diffraction experiments on DNA which helped to discover its basic double helix structure.
