BIOLOGY 1A03 Lecture Notes - Trisomy, Triple X Syndrome, Xyy Syndrome

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31 Jan 2013

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BIOLOGY 1A03 Full Course Notes

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A population comprised of genetically diverse individuals, will be more likely to survive and successfully reproduce than a population, which is composed of genetically identical individuals. Process called non-disjunction: gametes: some have extra chromosomes while others are missing chromosomes, aka aneuploidy, can happen during meiosis i or ii. Meiosis i: homologous pairs don"t" separate properly. Meiosis ii: sister chromatids don"t separate properly. No crossing over in figure in textbook. Other mistakes involve chromosome structure alterations: look at banding patterns genetic disorders, deletions, duplications (of sex chromosomes eg klinefelter"s, also, crossing over errors may occur. Individuals have too many or too few of specific chromosomes. Examples of trisomy of autosomal chromosomes in humans. Down syndrome: trisomy of chromosome 21, short in stature, special needs. Patau syndrome: trisomy of chromosome 13 ( 47 chromosomes, severally mentally challenged, cleft palate, deaf, malformed organs.

Related Questions

1. How does meiosis generate genetic diversity?

a) crossing over

b) random alignment at metaphase I

c) synapsis

d) both crossing over and random alignment at metaphase I

2. What would happen if crossing over occurred between sister chromatids?

a) Genetic diversity would decrease due to the loss of gene combinations.

b) Genetic diversity would increase due to the addition of gene combinations.

c) Gene rearrangement would lead to changes in gene expression.

d) Nothing would happen becasue sister chromatids are genetically identical or nearly identical.

3. Animals that sexually reproduce are _____ and produce _____ gametes. (haploid, diploid; haploid, haploid; diploid, diploid; diploid, haploid)

4. The F1 generation of a cross between two individuals, one that is homozygous dominant for a trait and the other that is homozygous recessive for the trait, will yield progeny with the same phenotype. (true or false)

5. Homologous chromosomes separate from each other in:

a) mitosis

b) meiosis I

c) meiosis II

d) They never separate from each other during any form of cell division

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What is a genome? What is a genome made of? Describe the bacterial genome. How do bacteria reproduce? What is binary fission? Distinguish between a chromosome and chromatin. Where are chromosomes located in eukaryotic cells? What is the chromosome made of? What is a centromere? What is the centromere's role? What are sister chromatids and how do they arise? Distinguish between somatic cells and germ (gametes) cells. Describe the cell cycle. What are the different phases? What occurs during S phase? What is interphase? How is the cell cycle controlled?

Describe mitosis. What are the phases of mitosis? What occurs in each of the phases of mitosis? What is cytokinesis? How does this differ between plant and animal cells? What is a kinetochore? Where does it form? What is its role? What is the role of microtubules in mitosis? What is a centriole and what is it composed of? What is a centrosome and what is its role in mitosis? What is the metaphase plate and why is this important? What is the mitotic spindle, its role and its makeup? What defines a diploid cell? How many copies of each chromosome is in a diploid cell? What about a haploid cell? Why do the daughter cells of mitosis always have the same complement of chromosomes?

Describe meiosis. What are the phases of meiosis? What occurs in each of the phases of meiosis? Distinguish between meiosis I and meiosis II and describe how each of these processes compare to mitosis. Why do animal cells undergo meiosis? What is a gamete? What is a zygote? What are recombination, crossing-over, and chiasma? When and why does this occur? What is meant by 'homologous pair of chromosomes'? Why don't the daughter cells of meiosis have the same genetic makeup? What controls the segregation of chromosomes into the gametes?

What are genetic characters? What are genetic traits? What is an allele? What is a locus? How many alleles at each locus would a human cell have and why? Distinguish between genotype and phenotype. What is meant by a dominant gene? What is meant by a recessive gene? How do these differ? What is the genotype of a homozygous dominant organism? What is its phenotype? What is the genotype of a homozygous recessive organism? What is its phenotype? What is the genotype of a heterozygous organism? What is its phenotype? What is a genetic cross? Distinguish between the P, F1, and F2 generations. What is a true-breeding line? What is the genotype and phenotype of a cross between homozygous dominant and homozygous recessive parents? If the F1 progeny are crossed, what would be the genotype and phenotype of the F2 generation? What would be the phenotypic ratio? What would be the genotypic ratio? Be ready to generate Punnet square tests or probability analyses of crosses involving more than one genetic locus. Describe a dihybrid cross where two alleles are homozygous dominant in one parent and homozygous recessive in the other. What would be the phenotypic ratio of the F2 generation from this dihybrid cross? What is meant by independent assortment? Be prepared to calculate probabilities resulting from different crosses.

Distinguish between complete and incomplete dominance. How would incomplete dominance alter the results of a hybrid cross? What would the resulting F2 generation phenotype and genotype ratios be? What is codominance? How does this affect the results of crosses? Be prepared to determine likely blood types of parents based on the blood types of their offspring. What is a polygenic trait? What is a carrier state for a genetic disease? What is meant by linked genes? How does this affect expected outcomes of genetic crosses? How is gene linkage used for chromosomal mapping? Distinguish between autosomes and sex chromosomes. What sex chromosomes are found in women? What sex chromosomes are found in men? What are sex-linked traits? Be prepared to give the results of crosses that involve sex-linked recessive traits. What is the process of nondisjunction? What are the likely results? Why is this important? What is a Barr body? Recognize the genetic abnormality of Downs Syndrome, Turner's Syndrome, and Klinefelter's Syndrome.

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BIOLOGY 1A03 Lecture Notes - Trisomy, Triple X Syndrome, Xyy Syndrome

BIOLOGY 1A03 Full Course Notes

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