Concept explainers
For each of the terms in the left column, choose the beast matching phrase in the right column
a. telomere | 1. protein complex that keeps sister chromatids together until anaphase |
b. G-bands | 2. origin of replication in yeast |
c. kinetochore | 3. repetitive DNA found near centromere in higher eukaryotes |
d. nucleosome | 4. specialized structure at the end of a linear chromosome |
e. ARS | 5. complexes of DNA, protein and RNA in the eukaryotic nucleus |
f. satellite DNA | 6. small basic proteins that bind to DNA and form the core of the nucleosome |
g. chromatin | 7. complex of DNA and proteins where spindle fibers attach to a chromosome. |
h. cohesion | 8. beadlike structure consisting of DNA wound around histone proteins |
i. histones | 9. protein complex that protects telomeres from degradation and end-to-end fusions |
j. shelterin | 10. regions of a chromosome that are distinguished by staining differences. |
a.
To determine:
The phrase that describes “telomere”.
Answer to Problem 1P
Correct answer:
Telomere: specialized structure at the end of a linear chromosome.
Explanation of Solution
Telomeres are the structures that are present at the end of the chromosomes and have a repetitive sequence of nucleotides and are responsible for the growth or mitosis that takes place in the cell. The telomere shortens with age that implies the loss of power of division for the cell.
b.
To determine:
The phrase that describes “G-bands.”
Answer to Problem 1P
Correct answer:
G-bands: regions of chromosome that are distinguished by staining difference
Explanation of Solution
G-bands are present in the chromosome as alternating structures and are stained by specific dyes to distinguish them from the other regions of the chromosome. The G in the G-bands stands for Giemsa based on the type of strain that is used to visualize them.
c.
To determine:
The phrase that describes “kinetochore.”
Answer to Problem 1P
Correct answer:
Kinetochore: complex of DNA and protein where spindle fibers attach to a chromosome.
Explanation of Solution
Kinetochores are the spherical structures that are present near the centromere and attach the spindle fibers along with the centromere during the cell division cycle. These are made up of complex of proteins that are associated with the centromeres.
d.
To determine:
The phrase that describes “nucleosome.”
Answer to Problem 1P
Correct answer:
Nucleosome: beadlike structures consisting of DNA wound around histone proteins.
Explanation of Solution
Nucleosomes are the rounded bead-like structures that are made up tightly coiled DNA and the histone proteins that wound the DNA and connect them through linker DNA or H1 histone protein. These nucleosomes then further condense to form chromosomes.
e.
To determine:
The phrase that describes “ARS.”
Answer to Problem 1P
Correct answer:
ARS: origin of replication in yeast.
Explanation of Solution
Origin of replication in yeast is different than other eukaryotes. It consists of autonomously replicating sequences (ARS) that are present at the origin once the yeast has entered into START phase. This phase is permanent, and the proteins are formed for the replication of DNA.
f.
To determine:
The phrase that describes “satellite DNA.”
Answer to Problem 1P
Correct answer:
Satellite DNA: repetitive DNA found near the centromere in higher eukaryotes.
Explanation of Solution
Satellite DNA is only present in the higher eukaryotes like vertebrates. These are usually present near the end of the chromosome and have repetitive sequences of nucleotides. The satellite DNA is very crucial for identification purpose during DNA fingerprinting analysis.
g.
To determine:
The phrase that describes “chromatin.”
Answer to Problem 1P
Correct answer:
Chromatin: complexes of DNA, protein, and RNA in the eukaryotic nucleus.
Explanation of Solution
Chromatin is the structure that resembles small threads and are widely distributed inside the nucleus of the cell. The chromatin condenses during cell division to form chromosomes that divide into separate cells at the time of formation of daughter cells.
h.
To determine:
The phrase that describes “cohesin.”
Answer to Problem 1P
Correct answer:
Cohesin: the protein complex that keeps sister chromatids together until anaphase.
Explanation of Solution
Cohesins are the proteins that are very crucial during cell division as it prevents the chromosomes from separating before the anaphase. The chromosomes stick together till the metaphase where they can attach to the spindle fibers and then get correctly distributed to the respective daughter cells. Cohesin prevents the separation of chromosomes before this phase.
i.
To determine:
The phrase that describes “histones.”
Answer to Problem 1P
Correct answer:
Histones: small basic proteins that bind to DNA and form the core of the nucleosome.
Explanation of Solution
Histones are the basic proteins that are rich in arginine and lysine and participate in forming nucleosomes that further condense to form chromosomes. The histones are of five types that are H1, H2a, H2b, H3, and H5.
j.
To determine:
The phrase that describes “shelterin.”
Answer to Problem 1P
Correct answer:
Shelterin: the protein complex that protects telomeres from degradation and end-to-end fusions.
Explanation of Solution
Shelterin belong to the class of protein that perform protective functions during cell divisions. These proteins prevent the degradation of the protein complexes from the action of different types of proteases that are present inside the nucleus. These also function to inhibit the end-to-end fusion of two adjacent chromosomes.
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Chapter 12 Solutions
GENETICS:FROM GENES TO GENOMES-ACCESS
- Which is the largest among the followings? a. Nucleotide b. Nitrogenous base c. Phosphate d. Carbon Based on the locations of centromeres, what type describes a centromere locates slightly away from the mid-point so that the two arms are unequal? a. Telocentric b. Acrocentric c. Submetacentric d. Metacentricarrow_forwardIn a germline progenitor cell before DNA replication (2N), a translocation occurred between a telocentric and submetacentric chromosome resulting in a translocation heterozygote. The location of the translocation is illustrated below. Draw the Prophase I pairing conformation that would result from this translocation. The four types of chromosomes you have now can be labeled as follows: T-WT (telocentric wild type), T-TL (telocentric translocation), SM-WT (submetacentric wild type), and SM-TL (submetacentric translocation). Using these labels, list (please do not draw) the possible outcomes of Anaphase I and the possible phenotypes for each outcome. Please explain your reasoning for each phenotype in a few words. asaparrow_forwardA typical eukaryotic chromosome found in humans has about 100 million bp of DNA. As noted in Chapter 11, 1 DNA base pair has a linear length of 0.34 nm.A. What is the linear length of the DNA in a typical human chromosomein micrometers?B. What is the linear length of a 30-nm fiber of a typical humanchromosome?C. Based on your calculation in part B, would a typical human chromosome fit inside the nucleus (with a diameter of 5 μm) if the 30-nm fiber were stretched out in a linear manner? If not, explain how a typical human chromosome fits inside the nucleus during interphase.arrow_forward
- After DNA replication, a eukaryotic chromosome _________ . a. consists of two sister chromatids b. has a characteristic X shape c. is constricted at the centromere d. all of the abovearrow_forwardIn the eukaryotic nucleus during interphase, a strand of chromatin consisting of eight conserved histone proteins, and a short region of double-stranded DNA wrapped around them, is: A. properly referred to as the radial miniband B. properly referred to as the supersolenoid C. properly referred to as the chromosome D. properly referred to as the nucleosome E. properly referred to as the solenoidarrow_forwardA chromosome that has spindle fibers attached to a specific chromosomal region… a. has a localized centromere b. is very rare c. has a holocentric centromere d. has reduced histone content e. has a dispersed centromerearrow_forward
- Define the following terms:a. histonesb. heterochromatinc. euchromatind. intergenic sequencese. tandem repeatsarrow_forwardLampbrush and polytene chromosomes are characteristic because of the fact that A. nucleosomes are 3-dimensionally distinct from "normal" chromosomes B. microscopy shows they have regions with loosely bound DNA near tightly bound regions C. multiple centromeres were discovered on their linear sequence by in situ hybridization D. DNAse is unable to cleave the linkage between strandarrow_forwardA diploid plant cell contains 2 billion base pairs of DNA. a. How many nucleosomes are present in the cell? b. Give the number of molecules of each type of histone protein associated with the genomic DNA.arrow_forward
- Consider the following DNA molecule (shown in the picture) and assume this is the DNA sequence of the entire chromosomes. list the amino acid sequences of the possible protein or proteins that could be produced from this DNA sequence what would be the DNA sequence of a sister chromatid generated from this chromosome sequence? (specify the 5' nd 3' ends)arrow_forwardDraw a chromosome and a pair of homologs (or homolog pairs, or homologous chromosomes). Label on the chromosome and homologous pair; the centromere and sister chromatids. In each of these drawings explain how many and where are the Watson and Crick double strand DNA molecules. 2.Diagram of the cell cycle (not cell division) for an organism with two chromosomes (n=2, 2n=4). Include; interphase (including the G1, S, G2 phases), mitosis and cell cycle checkpoints. 3.For an organism with 4 chromosomes draw: a. Metaphase of Mitosis, b. Metaphase of meiosis I, Metaphase of meiosis II.arrow_forwardSuppose that E. coli synthesizes DNA at a rate of 100,000 nucleotides per minute and takes 40 minutes to replicate its chromosome. (a) How many base pairs are present in the entire E. coli chromosome? (b) What is the physical length of the chromosome in its helical configuration—that is, what is the circumference of the chromosome if it were opened into a circle?arrow_forward