Chapter 11 Learning Curve
What would happen to the daughter cells if the G2 phase of the parent cell is shortened?
The cells would be smaller than normal.
A couple has a baby that only has one X chromosome and no Y chromosome. This could have occurred because:
-there was nondisjunction of sister chromatids in meiosis II of the father. Meiosis in the mother was normal. -there was nondisjunction of the sister chromatids in meiosis II in the mother. Meiosis in the father was normal. -there was nondisjunction of homologous chromosomes in meiosis I in the mother. Meiosis in the father was normal. -there was nondisjunction of the paired X and Y chromosomes in meiosis I in the father. Meiosis in the mother was normal.
In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell?
46
Why don't plant cells use a contractile ring to divide their daughter cells?
A contractile ring can't "pinch" a cell wall.
Nondisjunction can only occur in the sex chromosomes and not the autosomes.
false
Mitotic cell division is considered asexual because:
the daughter cells receive DNA from one parent cell, and the daughter cells are genetically identical.
Which are the functions of cyclins?
Cyclins activate kinases that regulate passage of cell cycle checkpoints.
Muscle cells in the mammalian heart are multinucleate, meaning that multiple nuclei are present in the cytoplasm of individual large cells. Predict what is different about the cell cycle in a muscle cell
Cytokinesis does not occur.
Replication of DNA in a eukaryote occurs during which phase of the cell cycle?
S phase
Suppose you analyze a time-lapse video of a cell under a microscope, and you observe what appears to be four chromatids tightly aligned along their lengths. Which of the answer choices is an interpretation of this observation?
The chromatids represent a bivalent and the cell is probably in Prophase I of meiosis.
A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells?
These cells likely contain damaged DNA.
Which of the answer choices is true about gametes?
They fuse to form a new organism during fertilization.
In which phase of mitosis do sister chromatids separate?
anaphase
When do sister chromatids separate in meiosis?
anaphase ii
Asexual reproduction occurs in:
animal cells. plant cells. bacterial cells. unicellular eukaryotes.
The microtubules that form the mitotic spindle extend out from the centrosome. Where would you expect to find the plus (fast-assembling) end of a spindle microtubule?
away from the centrosome and toward the kinetochore
How does meiosis generate genetic diversity?
both crossing over at prophase I and random alignment of homologs at metaphase I
What characteristics do you expect to observe with a microscope if you investigate the division of mitochondria and chloroplasts in eukaryotic cells?
circular DNA attached to the plasma membrane and binary fission
The division of genetic material in a eukaryotic cell is called:
mitosis
Genes that promote cancer are called:
oncogenes.
Reproduction by mitotic cell division:
results in two daughter cells that are genetically identical.
Which cellular conditions promote progression of the cell cycle?
the expression and synthesis of cyclin proteins the accumulation of cyclins the activation of CDKs binding of cyclins to CDKs
The centrosome is:
the microtubule organizing center for the mitotic spindle.
Synapsis is best described as:
the pairing of homologous chromosomes in prophase I
The protein p53 is an example of:
a tumor suppressor.
Which statement is true regarding binary fission?
DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions.
A zygote is:
diploid
A cell that is not actively dividing is in what phase of the cell cycle?
G0
Meiosis _____ is similar to mitosis in that _____ separate.
II; sister chromatids
Suppose you are observing some cells with a microscope, and you see a cell that appears to be dividing. You can see that as the cell starts to pinch in half, the DNA seems to be attached to the plasma membrane via a membrane protein. On further analysis, you find that this organism's DNA is circular - that is, it consists of a closed loop. What can you conclude about this organism and its mode of cell division?
It is a prokaryote that is dividing by binary fission.
At which stage of the cell cycle could you see sister chromatids with a microscope?
M
Which of the answer choices is a characteristic of meiotic cell division?
Meiotic cell division results in halving the number of chromosomes.
How must spindle microtubules attach to chromosomes during prometaphase of meiosis I?
Spindle microtubules from one pole must attach to both kinetochores in a pair of sister chromatids.
The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does this mean?
The amino acid sequence for FtsZ is similar to tubulin. The overall protein structure of FtsZ is similar to tubulin. The two proteins evolved from a common ancestral protein. The gene sequence for FtsZ is similar to tubulin.
What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?
The sister chromatids would not separate. The chromosome would not line up properly at metaphase. One of the daughter cells would have an extra copy of that chromosome.
What is the function of histone proteins?
to package DNA in eukaryotic chromosomes
A proto-oncogene is a "normal" gene that, if mutated, can become an oncogene and lead to a cell becoming cancerous.
true
Nondisjunction can occur in both mitosis and meiosis.
true
