Name:_______Key______________________ Date:___________ Period:_______
CHAPTER 8 STUDY GUIDE
1. How do the structure and location of a prokaryotic chromosome differ from that
of a eukaryotic chromosome?
Prokaryote cells lack a nucleus and membrane-bound organelles. The
chromosomes are located in the cytoplasm throughout the cell. Prokaryote
cells asexually reproduce by binary fission.
Eukaryote cells have a nucleus and membrane-bound organelles. The
chromosomes are located in the nucleus. Eukaryote cells asexually
reproduce by mitosis.
2. Does chromosome number indicate whether an organism is a plant or an animal?
Explain.
Yes, chromosome numbers indicate whether an organism is a plant or an
animal. Animals and plants have different numbers of chromosomes and
that is how you can determine what an organism (by looking at the
chromosomal numbers).
3. Draw a chromosome and label the parts.
A = centromere
B = chromatid
4. Name the proteins that DNA wraps around to form a chromosome in eukaryotic
cells.
Histone
5. The less tightly coiled DNA-protein complex is called?
chromatin
6. Contrast sex chromosomes to autosomes.
Sex chromosomes are the chromosomes that determine the gender of an
organism. Autosomes are all of the chromosomes that do not determine
and organisms gender.
7. How many chromosomes do most human cells have? What about human
reproductive cells?
Human cells have 46 chromosomes. Human reproductive cells have 23
chromosomes.
8. If you were shown a karyotype, how would you know if the person whose
chromosomes you were “looking” at were from a male or a female?
You would look at the two last chromosomes at the bottom. If the
chromosomes looked the same (XX) then it would be a female. But if the
chromosomes looked different (XY) then it would be a male.
9. Compare and contrast diploid and haploid cells.
Diploid cells contain 2 sets of chromosomes, 46 chromosomes for
humans. Haploid cells contain only 1 set of chromosomes, 23
chromosomes for humans.
10. Prokaryotic cells divide by which process?
Prokaryote cells divide by binary fission since they lack a nucleus.
11. Draw and describe binary fission. What kind of cells go through binary fission?
During binary fission the prokaryote cell copies its DNA. Then the 2
copies of the DNA spread out to opposite sides. The cell then splits into
two equal and identical cells. Only prokaryote cells go through this kind of
division.
12. What is the name of the process by which the cell’s cytoplasm divides?
cytokinesis
13. Explain the main difference between cytokinesis in animal cells and cytokinesis
in plant cells.
Cytokinesis in animal cells is a little easier than in plant cells. For animals
cells the cell membrane pinches off. In plant cells, the Golgi apparatus will
release vesicles that will line up in the middle of the cell forming what is
called a cell plate.
14. Draw a diagram of the cell cycle and describe what the key thing is that happens
in each of the stages
The cell cycle starts by going through interphase, which is made up of G1,
S, and G2 phases. G1 is the first phase where the cell starts growing. Then it enters into
the S phase where the DNA is replicated. After the replication, G2 is started and the cell
grows more and starts preparing for cell division. After interphase, cell division starts.
Mitosis, division of the nucleus, occurs. Then it leads into cytokinesis, division of
cytoplasm. After cytokinesis, both daughter cells enter into interphase and continue
through the cell cycle.
15. What are the three stages of interphase?
G1, S, and G2
16. Draw, label and describe the steps of mitosis.
During prophase the nuclear envelope disappears, the chromosomes
condense and appear, and the centrioles start appearing and move towards the
poles. During metaphase the spindle fibers attach to the chromosomes at the
centromere and move them along the equator (middle). The centrioles move to
opposite sides creating two poles. The cell then enters anaphase. The spindle
fibers pull the chromatids apart and drag them towards the poles. Telophase is the
last phase. This is where the nuclear envelope starts appearing around the
chromatids, the chromatids start loosening to chromatin, and the centrioles start to
disappear.
17. In the cell cycle, where are the three checkpoints and what makes each of them
important?
There is a checkpoint at the end of G1, G2, and mitosis. All of them are
important to check to make sure that the cell is the correct size (G1), the
DNA replicated correctly and that the cell is prepared to divide (S), and
then to make sure that everything divided correctly (G2)
18. How does cancer occur? What exactly is cancer?
Cancer occurs when the cell cycle breaks down. Something is missing that
causes the cell to not respond to normal signals to not divide. Cancer cells
are not made correctly and continue to reproduce at a fast rate. These cells
divide quickly and start forming tumors. Cancer cells do not stay in one
place like normal cells either that is why cancer will spread.
19. What is the debate with stem cell research?
Embryonic stem cells can only be acquired by destroying the fetus. Some
people believe that a fetus is a living human and to destroy it is murder.
20. Draw and describe the steps of meiosis.
Meiosis goes through two cell divisions, meiosis I and meiosis II. During
prophase I crossing-over occurs, the nuclear envelope disappears, the
chromosomes condense and appear, and the centrioles start appearing and
move towards the poles. During metaphase I the spindle fibers attach to
the homologous chromosomes at the centromeres and move them along
the equator (middle). The centrioles move to opposite sides creating two
poles. The cell then enters anaphase I. The spindle fibers pull the
chromosomes apart and drag them towards the poles. Telophase I and
cytokinesis I make up the last phase. This is where the nuclear envelope
starts appearing around the chromosomes, the chromosomes start
loosening to chromatin, the centrioles start to disappear, and the cytoplasm
splits creating two cells. Both daughter cells then go through meiosis II
simultaneously. During prophase II the nuclear envelope disappears, the
chromosomes condense and appear, and the centrioles start appearing and
move towards the poles. During metaphase II the spindle fibers attach to
the chromosomes at the centromeres and move them along the equator
(middle). The centrioles move to opposite sides creating two poles. The
cell then enters anaphase II. The spindle fibers pull the chromatids apart
and drag them towards the poles. Telophase II and cytokinesis II make up
the last phase. This is where the nuclear envelope starts appearing around
the chromatids, the chromosomes start loosening to chromatin, the
centrioles start to disappear, and the cytoplasm splits creating two cells.
21. Name the female gamete. The male gamete?
Female gamete – ovum or egg
Male gamete - sperm
22. Differentiate between spermatogenesis and oogenesis (list a minimum of two
differences). If it helps, draw a picture.
Spermatogenesis is when sperm is created. It goes through meiosis and
produces four sperm cells.
Oogenesis it when an ovum or egg is created. It goes through meiosis and
produces one egg and three polar bodies. The reason the polar bodies form
is due to the fact that during cytokinesis I and cytokinesis II the cytoplasm
is not divided evenly between the cells.
23. Why is meiosis essential to sexual reproduction?
Meiosis is essential to sexual reproduction because it reduces the amount
of chromosomes in a cell. This way when two individuals come together to reproduce
their gametes combine to form a zygote which has 46 chromosomes. If meiosis was
not used then the new individual would have two the amount of chromosomes that its
supposed to have.
24.What is beneficial in sexual reproduction? (“evolutionary advantage”)
The benefit to sexual reproduction is the genetic diversity it allows for. If
there was not any genetic diversity then the organism would not be able to adjust and
survive in the new environment.
25. How do the end products of meiosis differ from the end products of mitosis?
Meiosis produces 4 haploid cells that are genetic differently from the
parent. Mitosis produces 2 diploid cells that are identical to the parent.
26. How does anaphase I in meiosis differ from anaphase in mitosis?
Anaphase I separates homologous chromosomes where anaphase in
mitosis separates chromatids.
27. Explain the role of crossing-over in ensuring genetic variation.
Crossing-over is when a portion of one chromatid switches material with
the portion of a different chromatid. This helps to create genetic
recombination (makes new combinations of genetic material).
28. During which stage of meiosis is the diploid number of chromosomes reduced to
the haploid number of chromosomes?
Telophase I