BIOL 260 Chapter Notes - Chapter 4.4: Homologous Chromosome, Zygosity, Y Chromosome

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22 Feb 2017

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Heredity is the transmission of genetic characteristics from parent to offspring. All human cells, with the exception of eggs, sperms, and a few other, have 46 chromosomes. Male has one x and one y. Male pretty much determines the sex of the child. X chromosome is bigger than y: all other are autosomes. Sperm and eggs, and cells on their way to becoming sperm and eggs are called germ cells. All other cells of the body are called somatic cells. Genes and alleles: the location of a particular gene on a chromosome is called its locus. Homologous chromosomes have the same gene at the same locus, although they may carry different forms of that gene, called alleles. One allele is dominant and the other is recessive. The dominant allele will mask the recessive one: homozygous: identical alleles, heterozygous: different alleles, the paired alleles that an individual possesses for a particular trait constitute the genotype.

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According to this:

Read the following New York Times article and then answer the questions below and then answer the questions New Clues to Sex Anomalies in How Y Chromosomes Are Copied

http://www.nytimes.com/2009/09/15/science/15chrom.html?scp=1&sq=sex%20anomalies&st=cse

This activity contains 5 questions.

When discarding bad genes, what does the Y chromosome recombine with?

	the other Y chromosome
	the compliment X chromosome
	itself
	nothing

What holds a pair of copied chromosomes together?

	chromatid
	centrosome
	centromere
	chromatin

A person with Turner's syndrome has which of the following?

	a single X chromosome
	two X chromosomes
	a single Y chromosome
	two Y chromosomes

Where is the male-determining gene on the Y chromosome?

	close to the end of the right arm
	close to the end of the left arm
	near the middle of the right arm
	near the middle of the left arm

Briefly explain how an individual can have some cells with no Y chromosome and other cells with a double-Y chromosome . (in your response, go beyond the article, search the web, use experiences from your life, broaden your horizons)

You must make 2 reflective, thoughtful, deep, constructive critiques of your class mates posts. as part of a threaded discussion following their initial post. The critiques must not about you, but about science!

Here's the first peson. Needs to reply for some of her answers as it says above.

1. When discarding bad genes, the Y chromosomes recombines with itself.

2. The centromere functions to hold a pair of copied chromosomes together.

3. A person with Turnerâs syndrome is born with a single X chromosome.

4. The male-determining gene on the Y chromosome is located close to the end of the left arm.

5. An individual can have some cells with no Y chromosomes and other cells with double Y chromosomes, due to the differing variants present in regards to the genotypes of the cells in a single individual. When the Y chromosome is compared to other chromosomes such as the X chromosome, mutations and deviation in the distance of the centromere are much more prevalent due to the Y chromosome lacking a backup system to promote repairs.¹ (Links to an external site.) Even if a mutation caused a condition such as the XYY syndrome where two Y chromosomes are present, that mutation and genotype would not be present in every single cell of the individual.² (Links to an external site.) The presence of different genotypes offers an tentative explanation to as why a single individual can have some cells with no Y chromosomes while also housing other cells with double Y chromosomes.

Source 1 http://www.nytimes.com/2009/09/15/science/15chrom.html

Source 2 https://www.healthline.com/health/xyy-syndrome

Here's the second person. Needs to do the same as it says above.

1. Itself

2. Centromere

3. A single X chromosome

4. Close to the end of the left arm

5. Briefly explain how an individual can have some cells with no Y chromosome and other cells with a double-Y chromosome.

In some cases, the Y chromosome reaches over to a neighboring counterpart and the two chromosomes fuse. This results in the loss of part of the chromosome. Jacobâs Syndrome is sometimes also called XYY syndrome because the person has two Y chromosomes. Although a person can survive with this genetic mutation, some physical traits may be observed such as taller than average height, weak muscle development or late speech development.

Source 1 https://www.healthline.com/health/xyy-syndrome

Source 2 http://www.isna.org/faq/y_chromosome

13. Meiosis differs from mitosis in that:
a. meiosis results in the production of two new cells, whilemitosis results in the production for four new
cells., b. meiosis is used for growth and repair, while mitosis isused for production of eggs and sperm., c.
cytokinesis can be unequal following meiosis, but is approximatelyequal following mitosis., d. meiosis
involves one cell division, while mitosis involves two celldivisions., e. meiosis results in the production of
diploid cells, while mitosis results in the production of haploidcells.
14. Bits of maternal and paternal chromosomes are exchanged betweenhomologous chromosomes during
synapsis of meiosis I. This process is called:
a. crossing over., b. random mating., c. random fertilization., d.random shuffling of parental
chromosomes.,
e. mutation.
15. The advantage of sexual reproduction over asexual reproductionis that:
a. all young are genetically identical to the parent., b. malesmust evolve a copulatory organ., c. genetic
variability in the population is increased., d. females must evolvea vagina., e. mates are not needed.
16. Many different types of information are used to constructphylogenetic trees. Which of the following types
of information is the most direct measure of evolutionaryrelatedness?
a. physiology, b. gene sequence data, c. the fossil record, d.information about the structure of ribosomes.,
e. information about the structure of enzymes
17. A species is:
a. a group of individuals that can interbreed under naturalconditions and produce fertile offspring., b.
denoted by both a genus and a species name., c. the onlybiologically defined taxon., d. a group of
organisms with a large number of traits in common., e. all of theabove.
18. The process of spermatogenesis results in:
A. 4 diploid sperm; B. 1 diploid sperm and 3 haploid polar bodies;C. 1 haploid sperm and 3 haploid
polar bodies; D. 4 haploid sperm
19. Which cell division process results in an unequal division ofthe cytoplasm?
A. Spermatogenesis; B. Testiculargenesis; C. Oogenesis; D. None ofthe above
20. Meiosis is the process by which:
A. 1 diploid cell becomes 4 haploid cells; B. 1 diploid cellbecomes 1 haploid cell and 3 haploid polar
bodies; C. 1 haploid cell becomes 4 diploid cells; D. Both A andB
21. The phase of mitosis where chromosomes line up at the equator(middle) of the cell is called:
A. Anaphase; B. Telophase; C. Interphase; D. Metaphase
22. Chromosome #6 from Mom and Chromosome #6 from Dad form achromosome pair called:
A. Sister Chromatids; B. Centromeres; C. Homologous Chromosomes; D.Spindle Apparatus

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Please explain, and no hand-written work please, please type answer

Sex-Linked Traits (traits located on the sex chromosomesâusually the X chromosome)

Follow the directions for the lab. Enter data you obtain for the following crosses and answer questions on this answer sheet. (NOTE: The traits used in this Module 3 Lab are sex-linked. Therefore, you CANNOT click the âignore sexâ button for these crosses. You need to see separate results for males and females to analyze data for sex-linked traits.)

Question: In this lab exercise, should you click the "ignore sex" button for the crosses?

1. a. Perform a monohybrid cross between a female fly with a tan body and a wild-type male fly. Show results for the F₁ offspring. (NOTE: You will use these F₁ flies in the next cross.)
ENTER DATA HERE:

Question: Are the phenotypes of the F₁ offspring what you would have predicted for this cross: why or why not?

Question: Each F₁ female received a tan allele from her mother and a wild allele from her father. Why do all of the F₁ females show the wild-type phenotype?

Question: Compare the number and type (X or Y) of sex chromosomes found in female and male flies.

Question: Compare the number of alleles present on the X and Y chromosomes.

Question: How can you tell that tan body is a sex-linked trait?

Question: How can you tell whether tan body is located on the X chromosome or the Y chromosome?

Question: If tan body was located on the Y-chromosome, what would be the phenotype of all the male F₁ offspring? Is this what you obtained for the cross above?

Question: If tan body was located on the Y-chromosome, could females even show the trait? (HINT: When analyzing the cross results, remember that Y-linked traits are passed down only from affected males to their sons. Females cannot display Y-linked traits since they do not have Y chromosomes. On the other hand, both males and females can inherit X-linked traits since they both have X chromosomes.)

PUNNETT SQUARE:

List the genotypes of the parent flies in this cross (HINT: You must use X and Y symbols):

List the gametes produced by each parent fly in this cross:

Show the Punnett Square for the above cross.

BIOL 260 Chapter Notes - Chapter 4.4: Homologous Chromosome, Zygosity, Y Chromosome

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