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Looking at chromosomes
Karyotyping – 22 autosomal pairs, 1 sex pair
Recognizing abnormalities in karyotypes

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To gene tics!!!!
What is a gene?
A gene is a unit of heredity that is passed down from parent to child. Genes are located on chromosomes that are in all of our cells, including the sperm and egg that make a baby.
Genes are made of molecules or chemicals called DNA. The pattern of DNA will determine if the gene is working properly. The
DNA has to be in a certain pattern or order, like the numbers in a phone number.

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I can describe the evidence Mendel obtained for dominance, segregation, and the independent assortment of genes on different chromosomes.
I can summarize Mendel’s laws of segregation and independent assortment
I can calculate & compare ratios and probabilities of genotypes and phenotypes for genetic crosses with the following inheritance patterns:
- Dominant / Recessive
-Testcrosses
- Multiple Dominance / Multiple Alleles
- Incomplete Dominance
Codominance
- Sex-Linked

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I can use / interpret pedigrees which graphically illustrate the inheritance patterns above.
I can explain the effect that gene linkage and crossing over have on the variability of organisms.
I understand that traits can be controlled by one pair of genes or they may be polygenic meaning they are controlled by many genes (ex. skin colour, height)

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1.
2.
3.
4.
What is genetics?
Who is Gregor Mendel (and what did he discover about passing on of traits)?
What are the basic genetic terminology that I need to know?
Phenotype
Genotype
Dominant
Recessive

Genetics – the study of heredity which is the transmission of characteristics from parents to offspring

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 the transmission or passing of traits from parent to offspring.
“Heredity: the thing a child gets from the other side of the family” –
Marcelene Cox

Small sections of DNA are responsible for a
“trait”. These small sections are called
“Genes”.
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Gene - A segment of DNA that codes for a specific trait
Trait - A characteristic an organism can pass on to it’s offspring through DNA

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 born on July 22, 1822 to peasant parents in a small agrarian town in
Czechoslovakia
In 1843 he entered an
Augustinian monastery in Czechoslovakia
He was later sent to the
University of Vienna to study

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The pea flower
Pistil
Stamen
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The male part of the flower ( stamen ) was easily removed to prevent self-pollination.
Pea flowers are easy to cross-pollinate (he could control the pollination)
They were easy to grow.

Dominant Recessive
Round wrinkled
Yellow seed
Purple flower
Green seed
White flower

Inflated pod
Constricted pod
Green pod Yellow pod

Tall is dominant over short.
Flower postion:
Axial is dominant over terminal

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Mendel tested all 34 varieties of peas available to him through seed dealers. The garden peas were planted and studied for eight years .
Mendel's experiments used some 28,000 pea plants.
So just imagine what life would have been like living in the same monastery as Brother Gregor??

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Phenotype - Characteristics that can be observed. Tall and short are phenotypes
Genotype – Actual coding of the gene.
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Examples of genotypes are: TT, Tt, tt
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TT is tall, Tt is hybrid tall, tt is short
Allele – An allele is one of two or more versions of a gene. Tall and short are the alleles for height in pea plants.
Dominant – Tall is stronger over short so the tall allele will be expressed
Recessive – Short is the weaker allele and won ’ t show unless both alleles for short are present

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Homozygous – pure a genotype in which both alleles of a pair are the same
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Heterozygous – hybrid a genotype in which the alleles of a pair are different

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 two or more alternate forms of a gene.
The alleles are located at the same position on one of the pairs of homologous chromosomes

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Filial generation one
A term Mendel used for the first generation in his experiements.

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The second generation.
A term Mendel used for the offspring of the
F1 generation.

 the alleles an organism contains

 the observable traits of an organism that arise because of the interaction between genes

 a chart used by geneticists to show the possible combinations of alleles in offspring AND
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Used to calculate the probability of inheriting a particular trait
 Probability – The chance that a given event will occur

Parent
Parent
Offspring

Y-Yellow y-white
Genotype:
1:2:1
(YY:Yy:yy)
Phenotype:
3 Yellow
1 White

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Give the genotype and phenotype for the following cross: TT x tt (T = Tall and t = Short)

Step One: Set Up Punnett Square (put one parent on the top and the other along the side)
T T t t

Step Two: Complete the Punnett Square t t
T T
Tt Tt
Tt Tt

Step Three: Write the genotype and phenotype t Tt
T T
Tt
Genotype:
4 – Tt
4:0:0 t
Tt Tt
Remember: Each box is 25%
Phenotype:
4:0 tall
100% Tall

 a cross that involves one allele pair of contrasting traits

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When studying genetics you are examining the inheritance of biological traits which are passes from parents to offspring.

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Mendel proved over and over that a blend is not always the result of the crossing of traits. He found that when he crossed two traits that one trait always dominated the other trait no matter what method of cross-fertilization he used.
For example, when he crossed a plant that produced round seeds with a plant that produced wrinkled seeds he always saw offspring with round seeds.
This was also proved true with other characteristics of the pea plant. He reasoned that factors (now known as genes) control the traits of plants and that there were alternate forms of these factors.

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A dominant trait is the trait that is expressed most often. A dominant trait will overrule or mask a recessive trait.
For example, in garden peas purple flowers are dominant over white flowers. If a pea plant receives one allele for purple and one allele for white, the flower will be purple.

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Mendel created a system of symbols he used to record the results of his experiments. Upper case letters are used for the dominant traits while lower case letters are used for the recessive traits.
For example, yellow seeds are dominant over green seeds so the allele for yellow seeds is represented by (Y) and the allele for green seeds is represented by (y).

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A hybrid parent contains one dominant allele and one recessive allele. For example, a round hybrid parent would be (Rr). R is the allele for round while r is the allele for wrinkled.
Mendel discovered that when he crossed two hybrid parents 75% of the offspring expressed the dominant trait (round) while 25% expressed the recessive trait (wrinkled).

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Purple 75 %
White 25 %
Genotype Ratio
D:H:R
1:2:1
Phenotype Ratio
D:R
3:1 Purple