Quiz 2 Flashcards
True breeding
An organism that produces offspring identical in appearance to itself, generation after generation
Trait
A specific characteristic exhibited by an organism
Cross fertilization
The fertilization of a female gamete from one organism with the male gamete of another
Parent generation
Organisms that are initially crossed an usually true breeding
First filial generation
The offspring of a cross of P Generation
Second filial generation
The offspring of a cross between the F1 generation
Hybrid
Offspring that result from crossing 2 true breeding varieties of the same species
Monohybrid
The offspring produces from parents that differ in just 1 trait
Monohybrid cross
A cross of 2 individuals that differ by just 1 trait
Allele
A specific form of a gene
Dominant
A form of a trait that always appears when an individual has an allele for it (Y)
Recessive
The form of a trait that only appears when an individual has 2 alleles for it (y).
Homozygous
Having 2 identical alleles for a trait (YY or yy)
Heterozygous
Having 2 different alleles for a trait. Dominant allele over powers recessive allele. (Yy)
Genotype
The combination of alleles for any given trait or the genetic makeup for an organism
Phenotype
The physical traits of an organism
Punnett square
A grid used to illustrate all possible genotype a and phenotype a of offspring from genetic crosses. Developed by Reginald Punnett.
Test cross
A cross between a parent of an unknown genotype and a homozygous recessive parent
Dihybrid
The offspring produced from parents that differ in 2 traits
Dihybrid cross
The cross of 2 individuals that differ in 2 traits due to 2 different genes
The law of segregation
Mendel’s first law: traits are determined by pairs of alleles that separate during meiosis so that each gamete receives one allele
The form of a trait expressed in the offspring depends on what?
Depends on whether dominant or recessive alleles are inherited
Mendel’s 2nd Law
The law of independent assortment. States that if genes are located on separate chromosomes, they will be inherited independently of one another.
Pedigree
A type of flowchart that uses symbols to show inheritance patterns of traits in a family over many generations. Used to show how traits, controlled by a single gene or multiple genes, run through a family. Useful for predicting diseases within a family line.
Incomplete dominance
A situation where neither allele dominant a each other and both have an influence on the individual, resulting in a blending of the traits; called partial expression
Codominance
A situation where both alleles are expressed fully to produce offspring with a third phenotype
What are the 4 blood types?
A, B, AB, O
What are the genotypes for blood types?
A) I^AI^A or I^Ai
B) I^BI^B or I^Bi
AB) I^AI^B
O) ii
What blood types are dominant/recessive and which ones are co dominant?
AB is codominant and the rest are dominant/ recessive
What are the 3 possible alleles for the blood type gene?
I^A, I^B, and i
Linked genes
The genes that cause traits to be inherited together. They are found on the same chromosome and do not sort independently (an exception to Mendel’s 2nd law)
How can unlinking in occur?
If crossing over occurs during gamete formation
Sex-linked gene
Any gene located on the X or Y chromosome (sex chromosome). For humans, most sex-linked genes are found on the X chromosome since it’s much larger than the Y’s.
Sex-linked traits
Traits controlled by X-linked and Y-linked genes. Many sex-linked traits are also genetic disorders. Ex) red-green colour blindness
Genome
The sequence of DNA for all the chromosomes of an organism.
How many base pairs are there in the human genome?
3 billion
How much of our DNA is made up of DNA that codes for specific traits?
only 2%
What was the human genome project?
Launched in 1990, completed in 2003, a worldwide project which involved the sequencing of the human genome.
Genomics
The study of genomes and how genes work together to control phenotypes
Plasmid
Small circular pieces of DNA that can exit and enter bacterial cells.
Restriction enzymes
Molecules that have the ability to cut DNA at a specific site; different restriction enzymes recognize and cut different sites
Recombinant DNA
A fragment of DNA consisting of nucleotide sequences from at least two different sources
How is recombinant DNA done?
Can be made from any 2 pieces of DNA that have been cut with the same restriction enzyme
Give an example of recombinant DNA
Geneticists can use this technique to transfer a piece of DNA with a gene of interest from one species to another. Ex) putting omega in a banana
Describe spider silk, a product of engineering
Spider silk, dragline fibre, is at least 5 times as strong as steel and twice as strong as the material in bulletproof vests, waterproof, and ductile. Using recombinant DNA scientists can make spider silk outside a spider’s body to put in other organisms such as goats to produce milk with the protein from spider silk. Also used for manufacturing, parachutes, and outerwear
Describe Bt corn, a product of genetic engineering
A bacterium found in soil, produces a natural pesticide of crystal proteins that are lethal to certain insects but harmless to humans. These genes have been inserted into corn using recombinant DNA to produce its own pesticides against insects
Gene therapy
The process by which defective genes in a genome are corrected with a normal copy of the gene.
The three basic steps of gene therapy
1) scientists remove/alter viral DNA so that the viruses cannot harm the cells they enter
2) copies of the DNA that include the normal human gene are placed inside each virus and incorporated into the virus’ DNA
3) large numbers of these viruses are used to infect the target cells in an attempt to insert the normal human DNA into the cells genome
Setbacks to gene therapy
Jesse Gelsinger died due to severe immune system response in 1999
In 2003, 2 children developed leukaemia a few years after the gene therapy was completed (it activated the gene that causes leukaemia)
Gene therapy successes
1) restoration of vision in patients with an inherited retinal disease
2) repairing a gene that causes Duchenne muscular dystrophy
3) restoring hearing after hairs in the inner ear are damaged
