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Genetics Chromosome Number Fruit fly example: 8 chromosomes total

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Presentation on theme: "Genetics Chromosome Number Fruit fly example: 8 chromosomes total"— Presentation transcript:

1 Genetics Chromosome Number Fruit fly example: 8 chromosomes total
__ came from male parent __ came from female parent

2 Genetics Homologous chromosomes- paired chromosomes having genes for the same ____ located at the same _____ on the chromosome ______- having two of each kind of chromosome (__); normal body cells Diploid cells have two complete sets of chromosomes/two complete set of genes

3 Genetics Gametes (sex cells) of sexually reproducing organisms have only a _____ set of chromosomes _______- having one of each kind of chromosome (__) Fruit fly gametes would be n = 4

4 Genetics The Work of Gregor Mendel
________- scientific study of heredity _______ ______- Austrian monk who experimented using pea plants Determined rules of inheritance ____________- joining of male & female gametes to form single cell

5 Genetics Genes & Dominance Studied 7 different pea plant ____
_____- a characteristic that can be passed on to offspring For each trait, studied a contrasting character: Ex. _____ _____- green or yellow


7 Genetics Original pair of plants = __ generation
Offspring = __ generation _______- offspring of parents that have different forms of a trait Results? Every offspring had a character of ____ ____of the parents


9 Chapter 11- Genetics Two conclusions:
Inheritance determined by ______ passed from one generation to the next ____- the functional units of inheritance Each trait controlled by ___ gene with ___ contrasting forms _______- alternate forms of a gene


11 Genetics Second conclusion called the principle of __________:
Some alleles are _______ and others are ________ ________- an allele of a gene that is always expressed (__) _________- an allele of a gene that is expressed only when the dominant allele is not present (__)

12 Genetics Segregation What had happened to _________ alleles (traits) in plants? Mendel allowed __ plants to self-pollinate Produced __ generation which showed recessive trait in 1 out of 4 plants (__ ratio)


14 Genetics Dominant allele ________ recessive trait in F1 generation
Reappearance in F2 generation showed that at some point alleles became ________ Mendel suggested that they _________ from one another during ______ formation


16 Genetics Law of Segregation- states that every individual has ____ alleles of every gene; when gametes are produced, each gamete receives ____ of these alleles

17 Genetics Probability & Punnett Squares
Every time Mendel repeated a particular cross, he obtained _________ results ¾ plants showed ________ trait; ¼ showed ________ trait Mendel realized that __________ could be used to explain results

18 Genetics Genetics & Probability
__________- the likelihood that a particular event will occur Two possible outcomes for a coin flip: heads or tails Probability of each occurring is _____ Chance of heads is 1 in 2, or ____

19 Genetics Chance of heads coming up three in a row?
Each flip is an ______________ event: Probability of three heads in a row- ½ x ½ x ½ = ____ Way alleles segregate is _______, like a coin flip Principles of probability can be used to ________ outcomes of genetic crosses

20 Genetics Punnett Squares
Gene combinations from a given cross can be determined using a ________ ______ Letters in Punnett square represent ______ ________ from each parent are shown along one side and the top of the square Used to _______ and _______ genetic variations resulting from a cross


22 Genetics __________- if an organisms two alleles for a trait are the same Can be homozygous dominant (__) or homozygous recessive (__) _____________- when the two alleles for the same trait are different (__) Homozygous = ________ for trait Heterozygous = ________ for trait

23 Genetics __________- the physical expression of the genes; how the trait looks Ex.- Tall; short; yellow seeds; green seeds _________- allele combination that an organism contains TT; Tt; tt

24 Genetics Probability & Segregation
Probability predicts that if the alleles _________, then a ___ phenotypic ratio should be seen Each cross showed a 3:1 ratio Mendel’s law of segregation proven correct

25 Genetics Since probabilities predict __________:
the larger the number of __________, the closer the _____ comes to the probability

26 Genetics Exploring Mendelian Genetics Mendel further investigated:
Alleles segregate- but do alleles _________ together? or are they __________ of one another?

27 Genetics Independent Assortment
Mendel followed two _________ genes through two generations Crossed purebred plants for seed _____ and seed ______ Round, yellow seeds (____) with Wrinkled, green seeds (____)

28 Genetics Only provided hybrid plants needed for next cross
All F1 plants had genotype ____ F2 generation showed ___ plants that had phenotypes not found in the ________ So… Alleles for different traits segregate ___________ of one another


30 Genetics Summary of Mendel’s Principles
Inheritance is determined by individual units called ______. Genes passed from _______ to ________. When two or more forms (_______) of a gene exist, some forms may be ________, others _________.

31 Genetics In most sexually reproducing organisms, each adult has ___ copies of each gene – one from each parent. These copies are _________ from one another during ______ (gamete formation) Alleles for _________ genes usually segregate ___________ of one another

32 Genetics Complex patterns of Inheritance
Important exceptions to Mendel’s principles Some alleles are _______ dominant nor recessive Many traits controlled by ________ alleles, or multiple genes

33 Genetics Incomplete dominance Appearance of a ______ phenotype
Due to one allele being not completely _________ over another 3rd phenotype somewhere __ ________ the two homozygous phenotypes


35 Genetics Codominance Expression of _____ alleles
(ex. White bull crossed with a red cow yields a roan calf) Both alleles contribute to the __________

36 Genetics Multiple phenotypes from multiple alleles
More common for multiple alleles to control a trait in a __________ Only two alleles of a gene can exist within the _______ Multiple ______ for a single _____ can be found within a population Examples: _____ _____- A, B, o ______ _____ ____- C, cch, ch, c


38 Genetics Polygenic Inheritance
Traits that are determined through expression of ___ ___ _____ genes Polygenic traits show wide _____ of phenotypes Ex- _________, __________, _______



41 Genetics Genetics & the Environment
Characteristics of any organism not solely determined by ______ Determined by interaction between genes and _________ Genes provide ____, how plan goes also depends on ___________

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