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GENETICS
1. Gregor Mendel—Father of Genetics
2. Genetics– the scientific study of heredity
3. Heredity—passing of traits from parents to offspring
4. Traits—physical or behavioral characteristics studied in genetics. Examples: eye color, hair color, short , tall, etc.
http://learn.genetics.utah.edu/content/begin/tour/
P generationpurebred tall & purebred short
1st experiment (height):
F1 generation- ALL plants were
tall
F2 generation: ¾ tall, ¼ short.
F1 generation plants then crossed:
P generation plants crossed:
5. Genes are the sections of DNA on chromosomes that control traits.
6. Alleles are different forms of a gene pair. Each one of the pair is an allele.Each organism inherits a combination of twoalleles - one from each parent.
**Individual alleles control the inheritance of traits. Some are dominant and others are recessive.
7. A dominant allele is one whosetrait always shows up in theorganism when the allele is present. It blocks another geneticfactor. Ex. Brown eyes8. A recessive allele is blocked ,or covered up, whenever the dominant allele is present. Ex. Blue eyes
Dominant and recessive traits are represented byusing letters. 9. Dominant traits are represented by capital letters. 10.Recessive traits are represented by lower case letters.
Example: B = brown hair b = red hair
BB = brown hair / purebredBb = brown hair / hybridbb = red hair / purebred
11.Purebred (True-bred)—An organism that always produces offspring with the same form of a trait as the parent. Also known as homozygous.
Example: Purebred blonde haired parents will always have blonde haired children.
12. In Mendel’s experiments, P stood for the parent generation, F1 stood for the first generation, and F2 stood for the second generation.
13.Hybrid—An organism that has two different alleles for a trait. ALSO known as heterozygous.
14.Homozygous—an organism that has 2 identical alleles for a trait
Example– BB – homozygous for brown hair bb – homozygous for red hair
15.Heterozygous—an organism that has two different alleles for a trait
Example – Bb – heterozygous for brown hair
***there cannot be a hetero red***
16.Phenotype—physical make-up of an organism ***you can actually see phenotype*** Ex. -- Tall and short.
17.Genotype—genetic make-up of an organism ***you cannot see genotype*** Ex. -- BB, Bb, bb
Punnett Square—A chart used in genetics to show all the possiblecombinations of alleles.
Teach how to work punnett squares !
worksheets
Chromosomes are: • located inside the nucleus of cells. • made of DNA which carries genetic
information from parent to offspring.
Chromosome Theory
The chromosome theory states that genes are carried from parents to their offspring on chromosomes.
Chromosome theory was developed by an American geneticist, Walter Sutton, who studied grasshopper cells.
Both parents contribute chromosomes to the offspring, but in order for the offspring to have the correct number of chromosomes in the end, each parent may only contribute one-half the total needed.
The number of chromosomes determine the type of organism!!
Humans have 46 total chromosomes. • 23 in each sex cell.Grasshoppers have 24 chromosomes. • 12 in each sex cell.Dogs have 78 chromosomes. • 39 in each sex cell.House flies have 12 chromosomes. • 6 in each sex cell.
DNA is the genetic material that carries information about an organism and is passed from parent to offspring.
Meiosis: the process by which the number of chromosomes is reduced by half to form sex cells.
– sperm from the male
– egg from the female.
During meiosis:
1. the chromosome pairs separate, and
are distributed to four different cells.
The resulting sex cells have only half as many chromosomes as the
other cells in the organism.
Each gene pair has an allele from mom and an allele from Dad.
You have 23 pairs of chromosomes per cell. Each parent contributes one half of the pair. Each chromosome contains thousands of genes.
Gene: a segment of DNA on a chromosomethat codes for a specific trait.
Mutation—any change in a gene or chromosome.
• A mutation is any permanent change in the sequence of DNA in a gene or a chromosome of a cell.
• If mutations occur in reproductive cells, they can be passed from parent to offspring.
• Cancer, diabetes, and birth defects all result from mutations in genes.
Mutations
• A pedigree shows genetic traits that were inherited by members of a family.
• This illustration shows the pedigree for a family in which cancer was common in each generation.
Inheritance of Disease
Lesson 2 - VS• Scientists use Punnett squares and
pedigrees to predict and analyze genetic outcomes.
Selective BreedingSelective breeding is the process of selecting a few organismswith desired traits to serve as parents of the next generation.
People use selective breeding to increase the value of plants or animals, such as fruits or vegetables or dairy cows.
Examples of selective breeding:
Inbreeding – crossing two parents that have identical or similar sets of alleles.
Ex: Purebred horses with exceptional speed are crossed to produce offspring to run very fast. Purebred dogs are crossed to maintain hunting skills.
2. Hybridization – the crossing of two genetically different parents for getting the best traits from both parents.
Ex: Farmers cross the corn that have the sweetest kernels with a parent that is disease resistant.
3. Cloning - A clone is an organism that is genetically identical to the organism from which it is produced. Example : A cutting from a plant that grows a new plant is genetically identical to the mother plant.
Purebred advantages include:
1.Working animals perform better
2.Food animals produce better tasting foods
3.Plants may have higher yields
4.Plants may have better tasting foods
Advantages and Disadvantages of
Purebreds & Hybrids
Purebred disadvantages may include:
1. Inbreeding increased the probability of genetic disorders
2. Purebred species are more expensive
3. Plants may produce unattractive foods
4. Plants may not have disease resistance
Hybrid advantages include:
1. Food animals able to produce more food
2. Plants may have higher disease resistances
3. Plants may have more “curb appeal” (attractive appearance, better shipping, etc.)
4. Animals may have larger litters and better survival rates for the young
Hybrid disadvantages include:
1.May not always get the desired trait
2.May be more expensive to produce & seeds may not always have high viability
3.May not taste as good as purebred
• Scientists today are using what they have learned about genetics to help people.
• In genetic engineering, the genetic material of an organism is modified by inserting DNA from another organism.
Genetic Engineering Genetic Engineering is the transfer of genes from one organism into the DNA of another organism. This is also called “gene splicing.” because the DNA molecule is cut open and a gene is “spliced “ into it. Usually involves bacteria.
Examples of benefits of genetic engineering.
It can produce medicines such as insulin for diabetics.It can improve food crops by making them more tolerant to certain conditions – drought, frost, It may be used one day to replace genes for curing genetic diseases.
Bacteria have been genetically engineered to produce human insulin.
Human Growth Hormone(Sisters )
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