BIO141: MasteringBio - Chapter 5
Mitosis Phases
1) Prophase 2) Metaphase 3) Anaphase 4)Telophase
Question 31
A) X^H Y^0 B) It could be X^BX^B or X^BX^b C) 100% D) X^BX^b E) X^BX^B or X^BX^b
The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?
Anaphase (Sister chromatids separate and start their migration toward opposite poles during anaphase)
How is the aging process linked to telomeres?
Cells with short telomeres can no longer divide, so damaged tissues cannot be repaired.
At the end of the mitotic (M) phase, the cytoplasm divides in a process called ____________________.
Cytokinesis (Cytokinesis is the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.)
Chromosomes contain most of the cell's ________ which acts as the molecule of heredity
DNA
If it were to be stretched out, the DNA in one of your cells would be taller than you. How does such a large quantity of DNA fit within the nucleus of one of your cells?
DNA is associated with proteins that compact the DNA to form a package called chromatin (Before cells divide, their DNA compacts even further to form sister chromatids)
A breeder wants to set up a program to produce zebrafish with long fins. Having long fins is a dominant trait compared to the short fin wild type. Before she can market her zebrafish, she needs to perform a test cross on the long-finned fish she plans to use as a breeder. How can she tell whether her fish are homozygous or heterozygous for the long-finned trait?
Do several test crosses between the long-finned fish and the short-finned fish; if the offspring are always long finned, the long-finned parent is probably homozygous.
Imagine that, in cats, eye color is controlled by a single gene and that black eyes are dominant to orange eyes. All the offspring of a cross between a black-eyed cat and an orange-eyed cat have black eyes. This means that the allele for black eyes is __________ the allele for orange eyes.
Dominant traits are expressed even if an organism inherits only one copy of the allele whereas recessive traits are expressed only if an organism inherits two copies of the recessive allele.
Which of the following has the greatest potential as a cancer treatment?
Find a way to turn off the gene for making telomerase in cancer cells, since the cells would stop dividing when the telomeres were gone.
Meiosis starts with a single diploid cell and produces ____________.
Four haploid cells
Imagine that a deaf male has a child with a hearing female. You know that the male must have the genotype dd, but the female could be either Dd or DD. If the couple's first child has hearing, can you determine the mother's genotype? (Hint: Draw Punnett squares for the two possible crosses.)
Her genotype cannot be determined.
Why are linked genes inherited as a set rather than independently?
Linked genes are located near each other on the same chromosomes, so they tend to move together.
Complete Crossing over happens during __________.
Meiosis
The chromosomes line up in the center of the cell during which phase of mitosis?
Metaphase (Metaphase occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.)
Which of the following problems during DNA replication is being illustrated with the kids in the video?
Nucleotides at the ends of the DNA strands are lost when DNA replicates.
How have Mendel's laws fared as we have learned more about cell biology and processes such as meiosis?
Our new knowledge has helped to explain some of the exceptions to Mendel's laws of inheritance.
The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?
Prophase (Prophase is the first phase of mitosis, when the centrosomes begin moving toward opposite poles an the nuclear envelope breaks up.)
During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?
Prophase I (segments of nonsister chromatids trade places during prophase I, resulting in recombination.)
Except during ______________, cell division in humans result in daughter cells that have the same number of chromosomes and are genetically identical to each other and to the parent cell.
Sexual reproduction (Egg and sperm cells have half the number of chromosomes as their parent cells)
___________________ are linked together at the centromere.
Sister chromatids
The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?
Telophase (Telophase is the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form.)
Which cells are most likely to have the gene for making telomerase switched on?
The cells in a developing embryo.
Use the Punnett square from the introduction and the ones you drew for Part A to select the three statements that are true about the inheritance of this form of deafness.
The child of a deaf man and a DD hearing woman will definitely have hearing. If a deaf child is born to hearing parents, both parents must be Dd. If a deaf man and a hearing woman have a deaf child, the mother's genotype must be Dd.
What must happen before a cell can begin mitosis?
The chromosomes must be duplicated. (Before mitosis can begin, the chromosomes, or genetic material, must be copied, which occurs during interphase.)
The inheritance pattern for red-green color blindness is different for males compared to females. Similar to the inheritance pattern for hemophilia in the royal families of Europe, red-green color blindness is rare in females although they can be carriers for this trait. Why is the inheritance pattern different for males and females?
The gene for this trait is located on the X chromosome.
Imagine that five hypothetical genes are arranged on a chromosome in the following order: G--H--I--J--K. Which two genes are most likely to have a crossover occur between them?
The probability of crossing over increases the farther the genes are from one another on the same chromosome.
Which of the following is NOT true about naked mole rats?
Their cells do not produce telomerase.
What do we call a genetic cross that follows two separate characters, such as pea seed color and pea seed shape?
a dihybrid cross
This karyotype corresponds to which of the following individuals?
a female with Down Syndrome
If you are a male, the Law of Independent Assortment indicates that your gametes contain _____.
a random mix of the chromosomes you inherited from each parent
Many enzymes are named for the substrate on which they work, either to build or disassemble molecules. Also, enzyme names often end in "-ase." For example, lactase is the enzyme that breaks down lactose. With a name like "telomerase," we can deduce that telomerase is probably:
an enzyme that regulates the assembly of DNA at the ends of chromosomes
Duplication of the chromosomes by a cell occurs ______________.
before a cell divides (Chromosomes replicate before cell division. This ensures that genetic material is appropriately distributed to the daughter cells.)
A duplicated chromosome remains tightly paired with its partner at a region called _________________.
centromere
DNA and protein together form a complex called _____________
chromatin
The DNA of every eukaryotic cell is stored in one or more ______________ located in the ____________
chromosomes, nucleus
Mendel's Law of Independent Assortment states that __________.
each pair of alleles segregates independently of the other pairs of alleles
Mendel observed that pairs of alleles were separated or segregated in gametes and that they were rejoined in fertilization. We know that pairs of _____ are segregated in _____ and then are rejoined through fertilization.
homologous chromosomes ... meiosis
During prophase I of meiosis,
homologous chromosomes stick together in pairs.
Random orientation of homologous pairs of chromosomes during meiosis I results in alternative arrangements that contribute to genetic variation in offspring. This is called __________.
independent assortment
A cell preparing to undergo meiosis duplicates its chromosomes during ____________.
interphase
Mendel formulated his principles of inheritance based on _____
observations on the outcomes of breeding experiments. The underlying processes were unknown at the time.
In animals, meiosis __________
produces four gamete cells.
The correct order of events during meiosis is:
prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.
What are telomeres?
regions of DNA at the end of chromosomes which do not code for making proteins
Before a cell divides, it copies all of its chromosomes. While the two copies of a chromosome are attached they are called _____________.
sister chromatids
As we now understand it, the Law of Independent Assortment applies _____.
to pairs of genes that are on different chromosomes, but NOT to pairs of genes that are close together on the same chromosome
