Unit 6 & 7 Genetics, Gene Expression and Biotechnology Flashcards
Define: Genetics
The scientific study of heredity.
Define: Gene
The set of information that controls a trait; code in the DNA.
Define: Allele
The different forms of a gene.
Define: Dominant
An allele thats trait always shows up in an organism when present.
Define: Recessive
An allele that is masked when a dominant allele is present.
Define: Monohybrid
The crossing of parents that are both heterozygous to a trait.
Define: Dihybrid
The crossing of parent that are both heterozygous to 2 traits.
Define: P generation
The first generation in a cross.
Define: F1 generation
The second generation.
Define: F2 generation
The third generation.
Define: Homozygous
Having 2 identical alleles for a trait.
Define: Heterozygous
Having 2 different alleles for a trait.
Define: Genotype
An organisms genetic makeup or allele combinations.
Define: Phenotype
An organisms physical appearance or visible traits.
Define: Test cross
Breeding a homozygous recessive individual with a dominant individual to find out if its hetero or homozygous.
Autosome
A chromosome with a that’s the same as its homologous pair and similar in males and females.
Sex chromosome
A chromosome that is different in males and females.
Genetics used in primitive civilizations
- Domestication of plants and animals
- Important demonstration or early genetic engineering lead to agricultural development
Gregor Mendel
- Laid down the foundation for the field of genetics (1800)
Morgan
Used fruit flies to identify chromosomes as a region of the cell where genes are stored.
Modern genetics
- Population genetics ~ evolution
- Oncology, oncogenes and cancer
- Genetic disease and gene therapy
- Recombinant technology (ex: crop resistance, animal breeding)
- DNA finger printing
Inheritance
The transmission of traits from one generation to the next.
Mendel’s experiments
- He performed controlled breeding experiments
- Ex: experimented with monohybrid crosses following inheritance in 2 heterozygous parents.
The principal of dominance mendel said
Some factors for a trait show up when present (dominant). Other factors are overpowered by the dominant and only show up when the dominant factor isn’t present.
Dominance today:
Factors are alleles of the same gene.
Dominance correction
Many traits do not follow dominant and recessive inheritance. These are called non-Mendelian traits.
The Principal of Segregation, Mendel said:
Factors for the same trait are separated from each other during the formation of gametes and get rearranged after fertilization.
Segregation today:
Alleles for the same gene get separated during meiosis (haploid cells form) and get paired up again during fertilization.
Correction segregation:
None
The Principal of Independent Assortment, Mendel said:
- Factors for different traits separate from each other during the formation of gametes and get rearranged again during fertilization.
Independent Assortment today:
- Genes for different traits separate from each other during meiosis and get rearranged again during fertilization.
Independent Assortment correction:
- It is chromosomes not genes that separate from each other, so if 2 genes are on the same chromosome they do not independently assort, they are said to be linked genes and are inherited together.
Chi squared test proves:
If a null hypothesis is supported by the data or not.
Null hypothesis:
A hypothesis that states that the examined independent variable does not influence the dependent variable.
Null hypothesis in genetic problems:
States mode of inheritance and possible outcomes of a cross.
Rules of chi squared:
- Only counted values
- At least 20 counted values
- Must have null hypothesis
- Must be able to calculate expected values
Incomplete dominance
A form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele; this results in a combined phenotype.
Example: red + white = pink
Codominance
It transpires when both of the contributors of both alleles are visible and do not overpower each other in the phenotype.
Lethal alleles
Some genotypic combinations are deadly and will not be counted in the live offspring ratio. With today’s medicine many of these traits are not necessarily deadly.
Polygenic inheritance
- A simple phenotypic characteristic is inherited by the interaction of at least 2 genes.
Example: Skin color in humans. - The frequency of the traits that follow polygenic inheritance are in a bell curve shape.
Locus
The position of a gene on a chromosome.
Epistasis
The phenotypic expression of one gene at one locus that alters that of a gene at a second locus.
Epigenetics
- The study of changes in inheritance that is not caused by changes in the DNA
- Genes can be activated or inactivated
- Chromosomes can be tightly packed or loosened
Chromosomal Theory of Inheritance
Genes occupy specific loci on chromosomes and it is the chromosomes that undergo segregation and independent assortment during meiosis.
People
Sutton - came up with the theory
Morgan - Proved it with experimentation on fruit flies
Traits located on the autosomes…
follow autosomal inheritance.
Sex chromosomes
Chromosomes that are responsible for the determination of the gender.
Other organisms have different system of chromosomes:
Sometimes
Sex-linked
Genes on the x and y chromosome.
Genetic disorders on x chromosome show up more in males:
Genetic disordeson y chromosome on it show up in males.
Human pedigrees
Chart that follows certain traits over several generations.
Autosomal dominant
Don’t skip generations the same in males and females.
Autosomal recessive
Can skip generations the same in males and females.
X-Linked dominant
Determined by trial and error doesn’t skip generations.
X-Linked recessive
Can skip generations, usually more males.
Y-Linked
Every male in the family has the trait.
X-Linked recessive vs. Autosomal recessive
Look for a daughter with a trait that father does not have to look for clues like that.
Biotechnology
The use of living systems and organisms to develop useful products.
Today, biotechnology is used for…
- New medical cures
- Increase agricultural yields
- To find new fuel sources
- Address various environmental problems
Genetically modified organisms (abbreviated as GMOs)
Organisms that have had the process of using DNA tools to modify the DNA or organisms to produce useful products.
We can genetically modify organisms by…
- Altering the DNA of existing genes to modify proteins coded from the genes
- Adding a foreign gene to an organism
- Deleting or turning off existing genes
Transgenic organisms
Organisms with a foreign gene inserted in the term.
Research methods for biotechnology
A. DNA sequencing
B. Restriction enzymes
C. Ligation
D. Gel electrophoresis
E. Polymerase chain reaction
DNA sequencing is used to determine…
The nucleotide sequence of a given gene or an entire organism.
DNA sequencing can be used to study (real life example):
- DNA of entire organisms
- Paternity cases
- Genetic testing
- Evolutionary research
DNA sequencing steps
- DNA molecules are cut into fragments.
- Fragments are copied many times.
- Copies are single strand DNA molecules, so complementary nucleotides are added one at a time.
- And electronic monitors detect when which nucleotide was added at each time.
Restriction enzymes
Special enzymes originally found in bacteria that cut DNA at certain sequences (restriction sites).
Sticky ends/Sticky cut
When enzymes cut between the base pairs and the nucleotides to make sticky ends.
Blunt ends
When across the double helix.
What can restriction enzymes be utilized for?:
Cuts “gaps” in large DNA molecules and new genes are inserted into the DNA.
Sticky ends vs. Blunt ends
Sticky ends are easier for attaching DNA together.
Ligation
The process of reassembling DNA fragments by utilizing DNA ligase enzymes.
Recombinant DNA
The process when DNA from different organisms or sources is assembled by ligation.
Gel electrophoresis
Method that separates large molecules, such as nucleic acids and proteins, on the basis of their size, electric charge and other properties.
Process of gel electrophoresis:
- DNA is cut by restriction enzymes, then injected into gel
- Electric current is run through the gel
- Molecules are dragged along the gel by the current
Polymerase chain reaction (abbreviated as PCR)
- This method is used to amplify genes that scientists are interested in studying.
- Very fast process
Benefits of biotechnology:
- Insert genes into bacteria for cheese and insulin
- Plants can become, herbicide resistant, bug resistant, grow faster, bigger yields
- Golden rice has good nutrition
Threats of biotechnology:
- Super bugs
- Disrupts food chain
- Indigestible material in crops or livestock
- Ethical issue