BI236 Lecture Notes - Lecture 4: Mitosis, Deoxyribose, Deoxyribonucleotide
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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.
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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. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.
| a. | analogous |
| b. | vestigial |
| c. | homologous |
| d. | convergent |
14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:
| a. | to repair DNA by excising (removing) nucleotides damaged by UV light. |
| b. | in lysosomes, to break down lipids that otherwise accumulate in the nervous system. |
| c. | to produce the UV blocking pigment melanin in the skin cells |
| d. | in red blood cells to carry oxygen to the skin. |
15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:
| a. | inheritance of acquired characters. |
| b. | the founder effect. |
| c. | disruptive selection. |
| d. | natural selection. |
16. In the structure of DNA that Watson and Crick proposed, the sides of the "ladder" of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the "ladder", a:
| a. | purine always pairs with a pyrimidine. |
| b. | purine always pairs with a purine. |
| c. | pyrimidine always pairs with a pyrmidine. |
| d. | The structure of the double helix is not determined by how the bases pair. |
17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:
| a. | rRNA. |
| b. | tRNA. |
| c. | mRNA. |
| d. | RNA polymerase. |
18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is "corrected" by:
| a. | repeating S phase to see if the error rate is lower the second time around. |
| b. | enzymes that proofread the DNA and repair errors. |
| c. | messenger RNA during the process of transcription. |
| d. | Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed. |
19. Mendel's principle of segregation says that:
| a. | when gametes are formed, each gamete receives only one allele for a particular gene. |
| b. | some genes are dominant to others. |
| c. | a testcross must be used to determine the genotype of an organism with a dominant phenotype. |
| d. | all of the above |
20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:
| a. | it is a dominant allele. |
| b. | new mutations causing this disease are common in that population. |
| c. | it is not expressed in the phenotype of heterozygous individuals. |
| d. | the disease is contagious and can be transmitted by nonheritable means. |
21. Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.
| a. | natural selection. |
| b. | adaptation to similar environments |
| c. | convergent evolution |
| d. | All of the above phrases can be used to correctly fill this blank. |
22. In humans, which of the following sex chromosome compliments could be found in males?
| a. | XY |
| b. | XX |
| c. | Y |
23. The proteins that are associated with eukaryotic chromosomes:
| a. | help to package the DNA within the nucleus. |
| b. | are involved in gene expression, through binding with the DNA. |
| c. | may be replicating or transcribing the DNA. |
| d. | All of these are true of proteins that are associated with eukaryotic chromosomes. |
24. A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):
| a. | codon. |
| b. | gene. |
| c. | polypeptide. |
| d. | anticodon. |
