Mitosis and Meiosis Chapters 5.1, 5.2, and 7.1

Proto-oncogenes (accelerator)

cyclin allows cells to pass through G2 and divide

How might a cell be affected by the development a degradation-resistant cyclin mutant?

if the cyclin could not be degraded, the MPF would always be active. therefore, the cell would be continuously pressured to move through the G2 checkpoint, even if the conditions were not right.

Can the change in cyclin concentration during mitosis be explained by the fact that the cell divides in two and thus divides the material in the cell into two smaller volumes? If no, propose an explanation for the change in concentration that is seen.

no, when the cell divides there would be fewer cyclin molecules in each daughter cell than in the parent cell, but the daughter cells have a smaller volume, so the concentration should be the same.

In some cells, mitosis occurs without cytokinesis. What would the resulting cell look like?

one cell with two nuclei

How does this drug inhibit the growth of cancer? the cell will never divide because it never finished mitosis. Paclitaxel affects not only cancer cells, but normal cells as well. Would the effect of Paclitaxel be seen first in organs that have quickly dividing cells (like the intestines and hair follicles) or in organs that have slow or nondividing cells (like muscles and the nervous system).

organs with cells that frequently divide will be the most affected.

Gametes (germ cells):

reproductive cells - egg and sperm - that contain only half the genetic material of all the other cells in the body because they only have a single copy of each chromosome and are therefore haploid cells. Unlike somatic cells, DNA is passed down from the gamete to the offspring of a parental organism. Germ cells use meiosis to form gametes.

The M Checkpoint checks...

-All chromosomes are attached to the spindles. -m phase checkpoint checks on the metaphase to make sure the chromosomes are lined up in the middle of the cell and if they are attached to the spindle correctly, if not, they won't be separated correctly.

G2 Checkpoint Checks...

-Check if there is ample supply of energy and raw materials available. -The G2 checkpoint checks if DNA was replicated correctly in the S phase -if the cell is growing well enough, if the cell has the resources it needs -checks if the DNA is damaged and in good conditions

G1 checkpoint

-Check if there is ample supply of energy, nutrients and raw materials available. - There is adequate room in the environment for more cells - cell cize -the G1 checkpoint is the point in the cycle where the cell goes into or out of G0 and appears to regulate whether the cell is in G0 or not -G1 checkpoint regulates if the cell is growing well enough -if its dNA is damaged -is the cell receiving signals form growth factors

How many cells are present at the beginning of mitosis? How many cells are present at the end of mitosis?

1 cell in the beginning. 2 cells at the end.

Remember the equations for surface area and volume.

1. Surface area = length × width × number of sides = 1 × 1 × 6 = 6. 2. Volume = length × width × height = 1 × 1 × 1 = 1. 3. Surface area-to-volume ratio = 6:1.

To determine the number of possible chromosome combinations that can result from independent assortment, you can use this formula: Combinations = 2^n where n = number of different chromosomes. 1. What is the number of possible chromosome combinations for a human cell with 23 different chromosomes?

2^23 is equal to 8,388,608

Terms: DNA molecule, chromosome, chromatin, chromatid, and centromere.

A DNA molecule is a molecules that contains genetic information that codes a cells inheritable characteristics. DNA molecules provide the information needed for a cell to grow and develop through instruction. A chromosome is a string of DNA that contains genetic information. Chromatins are the name for a structure formed by the wrapping of DNA around a protein called a histone, the DNA is wrapped loosely around like a bowl of unraveling yarn. Chromatid is the name for one half of a chromosome structure. A chromatid is a copy of the DNA, there are normally two because they are identical copies of the same DNA so that when they divide, there is. one copy of DNA for each cell. Only after the synthesis phase are there are two chromatids. Centromere is the pinched region that holds the x-shaped chromosome together.

Zygote:

A diploid cell resulting from the fusion of two haploid gametes (fertilization); a fertilized ovum. A Zygotes contain a mixture of DNA from each parent. The process of meiosis is in charge of how genetic material is mixed in the zygote of sexually reproducing organisms.

Mitotic Reproduction:

A form of reproduction performed asexually by eukaryotes. The offspring is genetically identical to the parent organism. Some examples of mitotic reproduction are budding, when after stem cutting a plant and a new plant grows, and fragmentation, when a new sea star grows off of the arm of another.

Meiosis:

A process (happens only in reproductive cells) used by germ cells solely to produce gametes. The specific process involves nuclear division where one diploid cell with 23 pairs of chromosomes is divided into four haploid cells. There are two stages of cellular division known as meiosis I and meiosis II. DNA is divided during the process of meiosis and reduces the amount of chromosomes in the cells that are divided by a half. Results in gamete cells that fertilize to create new organism that is created through mitosis.

Centromere:

An area of which a chromosome that looks pinched. A set of protein cylinders next to the nucleus that duplicates theirselves and regulate items moved around the nucleus. It is vital to count chromosomes by the number of centromeres present, when the 46 chromosomes duplicate there are 92 chromatids but still only 46 chromosomes.

What is an example of a body cell (somatic cell) in your body?

An example of a body cell is a liver cell, a cell specialized to convert toxic substances into less toxic substances so that they can be excreted as waste through the kidneys. -red blood cells -neuron cells -skin cells

Multicellular organism

An organism made up of many cells.

Apoptosis:

Apoptosis is the name for programed cellular death. Some cells have a predetermined time for when they are supposed to end their lifespan. Apoptosis can take place when internal and external signals tell genes to produce self-destructive enzymes or in cells that are dangerous and have DNA that has been harmed and makes sure that the cell damaged beyond repair does not go on to divide. Apoptosis cells can be recycled by the cells in the immune system to build other molecules.

Human embryos have webbed digits (fingers and toes) early in their development. The cells between the digits undergo apoptosis during later stages of development. With a partner, draw a model to show how apoptosis leads to changes in the structure of digits during later stages of development.

Apoptosis or programmed cell death happens in the early stages of an organisms development, particularly in their hands. In its early stages, organisms start out with webbed hands, over time, the webbing is programmed to die between the fingers and the toes and eventually once the cells die, the fingers and toes are separated. Important in morphology.

Autosomes:

Autosomes are a type of chromosome that include genes that do not have direct correlation to the organisms sex. Chromosome pairs 1 through 22 are in charge of making up the autosomes.

What percentage of your genetic material is from your mother and what percentage is from your father?

Because each of my cells have one chromosome from my mother and another one from the father, there is a 50/50 mixture.

2. Every cell in your body originated from one cell. What does this mean about the DNA in each of your body cells?

Because every cell in my body is originated from the same cell, they all share identical DNA and genetic information.

What is the difference between the genetic material on two sister chromatids and the genetic material on homologous chromosomes?

Because sister chromatids are identical duplications of a chromosome, they contain identical genes. On the other hand, homologous chromosomes are two chromosomes that are similar in length and do share the same genes, but the genes nor the chromosomes in general are not exact copies of each other and therefore the genetic material is not as exactly identical as it is in sister chromatids. Further, homologous chromosomes do not have identical genetic information because they are derived from two different organisms, a father organism and a mother organism while a sister chromosome contains the genetic information from only one organism.

Where is mitosis in the cell cycle?

Before G2 and after G1

Binary fission is a cell division in prokaryotic organism (bacteria), which have no nucleus. In addition, prokaryotic cells typically have only one circular chromosome. Predict how binary fission in prokaryotic cells might be different than mitosis in eukaryotic organisms.

Binary fission is simpler because there are no multiple chromosomes to separate. Only one of the DNA needs to be copied then they move to both sides of the cell and cytokinesis occurs.

Binary Fission:

Binary fission, asexual reproduction that is used by prokaryotes is a separation of the body into two new bodies. In the process of binary fission, an organism duplicates its genetic material, or deoxyribonucleic acid (DNA), and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA

How are mitosis and binary fission similar or different?

Both processes involve a replication of cells and require the giving of one copy of all the DNA to the two new cells. However, binary fission occurs in cells with a more centralized DNA in a single circular chromosome as opposed to a line of chromosomes in animal cells. Further, Binary fission does not have the nuclear envelope. Chromosome is replicated during s-phase for mitosis, but in binary fission is replicated at all times.

What are the final products of mitosis and meiosis? How does the arrangement of chromosomes during metaphase affect the genetic makeup of the final products?

Both start off with 46 chromosomes however, the products of mitosis are two daughter cells with full sets of 46 chromosomes (diploid cells). While the product of meiosis is four daughter cells, they only have half as many chromosomes as the original cell (haploid cells). That is because in metaphase I of meiosis, homologous chromosomes have two pairs of chromosomes and the chromosomes of each pair are facing opposite poles and during the anaphase, the pairs of chromosomes are separated. On the other hand, during metaphase of mitosis, the chromatids face opposite poles and the chromosome is being split instead of a pair of two chromosomes. Then in metaphase II of meiosis the cell is split along with the two chromosomes, since there are half as many chromosomes as the original cells, the four remaining cells only half as many chromatids and are haploid cells.

Describe the differences in the normal cells and the cancerous cells shown in Figure 7.

Cancer cells are harmful because they do not follow traditional cell processes, for instance, they might not create the healthy lung tissue necessary for respiration processes. Normal cells respond to external factors and end division when coming in contact with other animal cells. On the other hand, cancer cells do not control cycles, reproduce when they shouldn't and they do not perform their normal function. In addition, cancer cells cannot communicate with healthy cells and are not regulated before division.Some cancer cells can secrete a growth hormone, that makes blood vessels divert to those cancer cells and supplies them with nutrients, taking nutrients away from healthy cells.

Cancer:

Cancer occurs when cells are uncontrollably dividing and cells no longer respond to the growth regulations. The cells that are dividing in multiplicity result in clumps known as tumors. Tumors can either stay localized or perform metastasis which means that some cells separate and spread to other places of the body creating new tumors. Disruption of regulation in a cell can occur when the body is exposed to chemicals or radiation that cause mutations in DNA, which therefore affect the regulatory factors in a cell cycle. That is not always the case, in other instances cancer can be influenced by carcinogens, substances that cause cancer growth i.e. pollutants or smoking. Other causes of cancer can be inherited and passed down generations.

Cell Differentiation:

Cell differentiation is the process by which a cells transforms from one cell into another type or specializes. The process of cell differentiation can result in organs or animals as a byproduct. Cells are specialized during cell differentiation to perform a specific function and have .developed. Other examples are skin cells, stomach cells, neuron cells, brain cells, liver cells, muscle cells and more that need their functions regulated. When cell becomes specialized, the less they are able to divide, so they go into the G0 and do not divide anymore.

Explain the importance of mitosis of cells in a skinned knee and during the growth of a plant.

Cells will start to undergo mitosis to replace the damaged cells. A growing plant needs multiplying cells so the plant can get bigger.

Centrioles

Centrioles are a type of organelle that are in the shape of a cylinder that are made up of short microtubules. Centrioles are located in the centrosome.

Chromatin:

Chromatin is formed when DNA wraps around proteins called histones. Occurs when chromosome is unraveling. Like a bowl of yarn that is undone.

How do chromosomes fit inside the nucleus of a microscopic cell?

Chromosomes are able to fit inside the nucleus of a cell because they are coiled extremely tight.

Chromosome

Chromosomes are strings of DNA that are made up of genes. Each body cell has 46 chromosomes. Chromosomes are about 10 feet or three meters long when stretched out.

How does crossing over contribute to genetic diversity?

Crossing over creates genetic recombinations by exchanging chromosomes segments, the gene recombinations were not found in either of the parent cells and are genetically diverse.

Crossing over:

Crossing over is a regulated process that occurs during prophase I during meiosis I that involves the exchanges of portions of the chromosome in between homologous pairs. Crossing over produces a recombination of genes. It starts of with the two homologous chromosomes paired up during prophase, during the step, chromatids are in close proximity to each other and can have segments that overlap. Occasionally, the segments break off and reattach to the other chromosomes. Segments of chromosome from the mom are switching from chromosomes from the dad giving genetic variation. Combining the two chromosomes and making a brand new chromosome to deliver to child.

Cyclins:

Cyclins are a collection of proteins that work to activate kinases enzymes. Cyclins can be both created and destructed at quick speeds during the cell cycle. Both cyclins and kinases are internal factors that occur in the cell cycle more significantly during checkpoints, in charge of when a cell divides and making sure it divides at a proper time.

Cytokinesis:

Cytokinesis is the step that follows mitosis, during cytokinesis, a cells cytoplasm and organisms are divided and results in two genetically identical daughter cells. After the cytokinesis, the cells begin the cycle again, starting with interphase. Cytokinesis is practically the splitting of cytoplasm. After cytokinesis, the cell goes to the G1 stage.

What does this model tell you about the structure and location of DNA in prokaryotic and eukaryotic cells?

DNA can be found in both prokaryotic and eukaryotic cells. DNA shares the same structure in both cells and in both cells is located in the center. However, the prokaryotic cell does not have organelles or a nucleus, so the DNA is not in the nucleus like it is in an eukaryotic. Also, prokaryotic cells have single circular DNA while eukaryotic cells have DNA that is contained in nuclear envelopes in the chromosome. In both, DNA is used as a blueprint for genetic material.

DNA:

DNA is a genetic material that codes the information for the characteristics and traits of an organism. The information located inside of DNA instructs cells to grow and for organisms to grow in general. DNA is found in all living organisms.

1. DNA must be coiled into special structures before a cell divides. Why do you think it is necessary for the DNA to be structured this way before cell division occurs?

DNA needs to coil tightly around protein before division occurs because the tighter it is, the easier for mitosis to occur. Tightness makes it easier to separate since they are super coiled and organized.

Daughter cells:

Daughter cells are genetically identical cell with genetically identical nuclei. Daughter cells are created during cytokinesis, at the end of mitosis.

Genetic Variation:

Differences among individuals and populations in the composition of their genes or other DNA segments. Ex: Cats offsprings have varying traits. Different forms of the same gene are called alleles For every trait, there are two copies of the same genes that are located in the homologous chromosomes

Diploid (2n):

Diploid cells are body cells which contain two copies of each chromosome. They can be shown as 2n. The copies are not identical as one comes from the mother organism while the other chromosome comes from the father organism. The diploid chromosome of the human body is number 46. It as two copies of all of its DNA or chromosomes. The cells used in mitosis are diploids.

Meiosis divides one cell into four cells, but each resulting cell has half the amount of DNA as compared to the original cell. How do you think this is possible?

Diploid cells contain two copy of each chromosome. During meiosis, diploid cells are split into four haploid cells. Haploid cells only contain one copy of each chromosome which is half as many as diploid cells. Since chromosomes contain DNA and because haploid or the remaining four cells only consist of half as many chromosomes as the original diploid cell, that means that the resulting cells only half as much DNA as the original cell.

How does independent assortment increases variation in an organism's offspring?

During meiosis, chromosomes are randomly split into daughter cells and do not depend on the other chromosome in a homologous pair. Therefore, the chromosomes have unique combinations and further then unique combination of genetic material.

Describe to a partner what happens to the chromosome as the cell progresses into mitosis.

During mitosis, the DNA coils tightly around proteins, chromosomes are tightly packed together and have been duplicated in the synthesis stage to form the shape of an x.

Describe a specific situation in which an organism's cells would need to divide.

During reproduction, a single cell of a zygote divides into an embryo, and then becomes a fetus which then becomes a baby. Cells also need to divide to make when we have to repair or replace a cell that has been destroyed, for instance, when someone skins their knee. For unicellular organisms reproduction is done through mitosis. You start life as an individual cell and becomes a complex organism with each of them with exact copies of DNA.

How do you think the cell divides its DNA evenly to give each daughter cell an identical copy of the genetic material?

During s-phase, each chromatid makes a copy and they stay attached at centromere, becoming a chromosome. The two chromatids have an identical copy of each other that are attached by the centromere until anaphase, in metaphase, one chromosome faces one pole and the other faces the other, the copies eventually go diverging ways. Each cell needs one blue, one red, one green and one white of each chromosome when they divide. Later, when the spindle forms, it attaches to both copies of chromosome and plays a game of tug of war and then in the end splits the chromosome apart. The game of tug of war that the spindle plays participates in ensuring identical division of the DNA during mitosis. By the telophase, each of two new cells has one chromatid of each chromosome. A chromatid or half of a chromatid is equal to a chromosome which contains the DNA and therefore both cells have identical genetic material.

Fertilization:

Fertilization is the process that consists of the fusion of two different gametes, one from the mother and one from the father and ultimately producing a zygote with a complete set of DNA. The Zygote has unique combinations of genes because of genetic variation. Fertilization produces a genetic mixture from both parental organisms. During fertilization, the nuclei of both the sperm cell and the egg cell join together to create a single nucleus.

Why do gametes have half a set of DNA? What would happen if they had a full set of DNA? Explain your answer.

Gametes only have half a set of DNA because they are haploid cells and only contain one copy of each chromosome. Gametes are sex cells, one type of gamete is an egg cell that comes from females and the other type is a sperm cell which comes from males. An offspring is a combination of a genetic mixture from both parents. If a gamete had a full set of DNA then there would not be an equal mixture of both sex cells. For example, the offspring should develop 23 chromosomes from each gamete. 23 from the egg cell and 23 from the sperm cell to have an equal mixture of genetic material from each parent cell. That way, each parent can contribute an equal amount of chromosomes.

Gap 1 (G1):

Gap 1 is the first stage of the interphase of the cell cycle. During Gap 1, cells grow, maintain normal functions and make copies of their organelles. Cell also get larger.

Gap 2 (G2)

Gap 2 takes place after synthesis. Cellular growth takes place during Gap 2. The cell prepares for cell division with the appearance of centrosomes (include microtubules and centrioles)

Genes:

Genes are segments of DNA that contain genetic information. Almost every cell in the body has a full set of genes, however, cells only use the genes that are required to perform the cells function.

Gene Expression:

Genes can be expressed which means that they are instructed to make proteins and perform specific functions or not expressed which means that they are instructed to not make proteins. Cells only need to be expressed to generate the proteins it needs to take on a specific function and structure, otherwise, not all cells need to be expressed.

Haploid (n):

Haploids cells can be expressed as n. It means to have only one copy of each pair of homologous chromosomes. The gametes or sex cells are called haploid cells. Haploid cells only have 23 chromosomes which is equivalent to one of each pair.

How many chromosomes do human body cells have?

Human body cells have 46 chromosomes each.

If a cell has damaged DNA, what do you think happens during the G2 checkpoint?

If a cell has damaged DNA, the G2 checkpoint would prevent it from becoming replicated, further the cell possibly could be either excreted from the cycle or recycled. It can go through apoptosis or remain frozen and not divide.

Although bacteria and other single-celled organisms can produce genetically identical offspring, they sometimes still exchange DNA by passing it from bacterium to bacterium. What might be the advantage of exchanging DNA in this way?

If one cell needs genetic information but does not have it, the bacterium can provide it with the genetic information needed. The bacterium works as a donor. It is good to have genetic variation.

Colchicine is a poison that acts to inhibit the development of spindle fibers. Describe the effects on mitosis in a cell that has been treated with colchicine.

If the spindle fibers are not formed correctly, they will not function correctly. This could cause the chromosomes to be unevenly divided or other complications.

Mitosis, which occurs in body cells, produces two genetically identical cells. Like meiosis, mitosis includes metaphase. However, the alignment of chromosomes differs, which affects the genetic makeup of the final cells. Explain Answer these questions about metaphase in meiosis and mitosis. 1. How do the arrangements of chromosomes in metaphase I and metaphase II of meiosis compare to each other and to the metaphase stage of mitosis?

In metaphase I of meiosis the chromosomes are arranged on either side of the equator of the cell. The chromosomes are facing different poles while during the metaphase I of mitosis, the chromatids are facing different poles of the cell. Additionally, for mitosis, the chromosomes are arranged in a single file line while only during metaphase II of meiosis are the chromosomes in a single file line.

Anaphase:

In the anaphase, Spindle fibers pull chromosomes to force the sister chromatids to detach from each other to go to opposite sides of the cell. One side of the cell will take one chromatin and the other side will take the other chromatin. Each of the new cells will include one copy of each chromosome because each cell needs the exact same genetic material.

Interphase:

Interphase Is the name for the resting stage of the cell cycle. During interphase, cell growth occurs and cells prepare for cellular division. Results in organelles and DNA being replicated and duplicated. Also, the cell grows to ensure that it is large enough to divide. The phase is important for preparing the cell to divide. Chromosomes are duplicated during the interphase, which means that DNA is duplicated. It is crucial to duplicate the genetic material before splitting. Most of the cell cycle is during this phase. Just as the cell has been formed, chromosomes and centrioles on the outside. During outside, the centrosomes are duplicated and the DNA is loose and not tightened up. Through interphase, the chromosomes become visible and during the s-phase, the DNA is copied to form the shape of an X.

Why is it important that DNA is copied before the cell divides?

It is important that DNA is copied before the cell divides because DNA is the blueprint for the cell. The DNA provides information for how the cell should function. The DNA must be copied so that each of the two new cells have a full blueprint.. If it does not do before, there would be an unequal distribution of DNA. The cell makes a copy so that during mitosis, each cell gets a full blue print.

What patterns do you observe for Karyotypes

Karyotypes come in pairs of two, the first few chromosomes are biggest and gradually the sizes get smaller as the rows progress.

Kinases

Kinases are an internal factor that can affect the cell cycle. Kinases are enzymes and when they experience activation, a phosphate group is moved from the ATP to another molecule. The process of a phosphate group being transferred from Adenosine Triphosphate to a target molecules increases the energy in a molecule. Cyclins help activate kinases enzymes. Kinases can be found almost always in a cell.

Use what you have learned about meiosis and sexual reproduction to construct an explanation for why offspring are not exact replicas of their parents. In your answer, include a discussion of sexual reproduction, independent assortment, and crossing over.

Meiosis allows for a mixing and matching of chromosomes, because homologous chromosomes pairs are aligned along the equator randomly and create a genetic variation in the daughter cells, and also because of crossing over, where segments of a chromosome can be exchanged. The mixing and matching of genetic material in the chromosome or sometimes specifically in the chromatid allows for genetic variation in sexually reproducing organisms.

Mitosis vs. Meiosis:

Mitosis occurs in body cells and is used for the growth and development of an organism. On the other hand, meiosis occurs in germ cells to produce gametes or sex cells. In addition, Mitosis produces two daughter cells that are haploid because they contain half the amount of chromosomes as the parent cell. While meiosis produces four haploid cells.

Why aren't all organisms made of just one cell? Why do cells divide, instead of simply growing larger?

Not all organisms are made up of just one cell because cells perform different functions depending on where they are located in the body. Cells divide instead of simply growing larger so that they can reproduce offspring or multicellular organism. Cells cannot become too big because of the ratio of surface area to volume. If the volume grows bigger than the surface area, the surface area does not allow diffusion to happen and the cell cannot divide.

According to this model, do all the gametes produced by an organism have the same genetic material? Use evidence to support your claim.

Not all the gametes produced by an organism have the same genetic material because within the four daughter cells, DNA is exchanged between chromosomes and gametes do not have identical genetics because they experience genetic variation through independent assortment and crossing over

Chromatid

One half of a duplicated chromosome.

Prophase:

One of the main stages of mitosis. During the prophase stage, chromatin is condensed into chromosomes, the chromosomes become visible, the nuclear envelope is destructed, formation of spindle fibers.

Predict How do you think organisms like the planarian regenerate parts of their body? How could humans benefit from this knowledge?

Organisms like the planarian are able to regenerate parts of their body because of cell division. During cell division, a plants DNA is replicated into each divided cell. The DNA provides the information that tells the amputated planarian or organism how to maintain life on its own.

Growth Factors:

Regulatory proteins that ensure that the events of cell division occur in the proper sequence and at the correct rate. The factors are usually external and stimulate the cell cycle and division. Cells also grow to maintain homeostasis. Oxygen, nutrients and waste need to be absorbed and excreted by the cell through diffusion across the membrane in adequate amounts and at an adequate speed. A cell must grow or divide in order to maintain a cell size that can suit the diffusion of nutrients and waste products across a cells membrane.

Sex Chromosome:

Sex chromosomes are found in organisms that reproduce sexually. The sex chromosomes are in charge of the sexual characteristics for a species. More specifically, there are two biological sex chromosomes referred to as x and y chromosomes. The XY system is used to determine an organisms sex. An organism that has both one x and one y chromosome is of the male sex while an organism that has two x chromosomes is considered of the female sex.

As you explore the lesson, gather evidence to explain how meiosis and sexual reproduction increase genetic diversity.

Sexual reproduction provides genetic diversity because the sperm and egg that are produced contain different combinations of genes than the parent organisms.Each resulting cell, or gamete, resulting from meiosis has only half the amount of DNA as the parent cell.

Predict Advances in which fields most likely influenced changes in microscope technology?

Since microscopes are comparable to magnifying lenses. It is more than likely that advances in the eyeglass or optical field led to advances in microscope technology. The optical field made better glasses for people to see, advances in workmanship allowed development in microscopes.

Scientists are currently studying ways telomerase could be used to slow down aging and fight diseases like cancer. How might these studies influence society?

Since regenerating telomeres prevents age loss because telomerase in society would cause people to remain younger their entire lives or slow down the aging process by preventing cells from telomere loss. In addition, telomerase makes telomeres, so it is bad for cancer cells because having telomerase allows it to elongate telomeres so that the cancer cells continue to divided. In normal cells the shorter a telomere is, then the cell does not divide. Cancer cells lose control of telomeres and elongate them instead of shortening them so the cell cannot keep track of how many cells have been divided and telomerase promotes the production of cancer cells. We need to create a drug that blocks telomerase in cancer cells so that they cannot elongate telomeres anymore and will not overproduce.

Sister chromatid:

Sister chromatids are what occurs when both halves of the chromosome are put together. Each halve of the chromosome is a chromatid with identical double helixes. The two chromosomes are held together like an x by the centromere. When split up, they are still individual chromosomes.

Why does a skin cell need to divide more frequently than a liver cell?

Skin cells need to divide more frequently than liver cells because they are prone to damage. For example, in the digestive tract, toxins often time enter the body and are destructive and the body needs to divide frequently to replace the damaged tissues of the internal lining of the digestive track every few days for that reason whereas liver cells or cells in organisms only need to divide in the case of death or injury of a cell and therefore do not have to divide as frequently. Skin cells constantly lose cells that are damaged but are able to constantly replenish them as well to replace damaged cells. However, liver cells are able to replace cells if lost, they are in fact one of the only organs that if damaged, can replace lost cells

Metaphase II: (meiosis)

Spindle fibers put the 23 chromosomes along the equator of the cell. Two sister chromatids are still prevalent during this stage. The cell is a haploid. There is no more crossing over but the chromosomes meet in the middle and the spindle fibers attach to the centromeres.

Prophase II: (Meiosis)

Starts with the product of Meiosis I, 2 daughter cells. Phase where the nuclear membrane dissociates, the centrosomes and centrioles diverge to opposing sides of the cell and the spindle fibers are conjoined.

Centrosomes:

Structures that are used in mitosis in animal cells. Centrosomes are located in a small area of the cytoplasm. Organizes the spindle that is dividing the nucleus and the cell. In animals, the centrosome is made out of centrioles in the middle and microtubules on the outside. Plant cells lack the centrioles.

Telomerase:

Telomerase is an enzyme that helps organisms regenerate telomeres to prevent age loss. Lobsters are an example of organisms that use telomerase to gain telomeres. They are not good in cancer cells because they promote telomere growth.

Telomeres:

Telomeres are formed by the ends of chromosomes and are made up of nucleotides. They serve a purpose of stopping chromosome ends from joining together with each other and prevent the loss of genes because instead of a nucleotide being lost from a gene, it is lost from the nucleotide. The loss of telomeres has a connection to the aging of organisms.

The S phase stands for synthesis, which means to make or build something more complex out of simpler parts. Scientists know that during the S phase DNA is being made in the nucleus of the cell. Why do you think the cells needs to make more DNA at this time in the cell cycle?

The DNA needs to be copied so each cell has a complete set of DNA.

G0 Stage:

The G0 stage is needed for cells that perform cellular functions but do not divide frequently. Because they rarely divide, these cells do not have to be prepared for cellular division. Some cells only enter this stage when division is required. Some examples of cells that go through the G0 stages are lymphocytes, which are white blood cells that are only divided when the body needs to fight off an infection. On the other hand, cells can reman in the G0 stage at all times. Another example are neurons cells. Some cells never get to divide which is why major injuries to the brain creates challenges for healing because the cells cannot replicate.

M Stage:

The M stage is the umbrella name for mitosis, cellular division, and cytokinesis, the division process that occurs directly after mitosis.

Synthesis (S stage)

The S stage is short for synthesis. The stage between Gap 1 and Gap 2. During the S-stage, the cell stops growing while the DNA/chromosomes are replicated before the cell divides. This is the second stage of interphase.

Prophase I (Meiosis)

The beginning stage of meiosis. During this phase, the nuclear membranes are destroyed, the centrosomes and centrioles relocate to opposing sides of the cell and the spindle fibers. form The homologous chromosomes join into pairs while the duplicated chromosomes condense. The sex chromosomes undergo synapsis. Chromosome one from dad and one from mom are wrapping around each other really tightly and swapping parts of their chromosomes, changing gene. The process is known as crossing over.

Cell Cycle Checkpoints:

The cell cycle checkpoints are used to safety and more specifically regulate the conditions of a cell, particularly if a cell is damaged or not, measures a cell size and determine if a cell is in stable condition for replication. Cell checkpoints are critical and appear towards the later part of each phase.If a cell does not meet checkpoint requirement, the cell can either fix it if possible or if not the cell does apoptosis.

Cell cycle:

The cell cycle is a process that occurs in eukaryotic cells or cells with a nuclei. The cell cycle consists of the growth of a cell, the division of the cell, and replication of a cells DNA. There are two stages of the cell cycle, one stage is known as the resting phase and the other stage is known as the division stage.

Do you think this model of the cell cycle is accurate for all cells? Explain your answer.

The cell cycle is the same for all cells. The only difference is the length of all of the phases of interphase. Also, not all cells go through the cell cycle, some go through the G0 stage instead. Additionally, skin cells stays in interphase for much less time than a liver cell because liver cells do not continuously divide and often spend a long period of time in G1. G1 and G0 are parts of the interphase where a cells stays before DNA replication. When they get signal to divide they go to the s-stage. Plant cells and animals cells go through same cell cycle events. Only difference is plant cells have a cell plate that forms a new cell wall to form two cells.

Make a claim for how the cell cycle relates to the growth and maintenance of organisms. Discuss the stages of the cell cycle, mechanisms that regulate it, and how this cycle is related to the growth and maintenance of organisms.

The cell cycle promotes cell growth and cell division to help cells maintain homeostasis. For example, during G1 and G2, cells divide and grow. The checkpoints are the mechanisms that regulate the cell by making sure it is undamaged and in stable conditions so that it can perform healthy replication. Cells are also maintained by internal and external factors that control when a cell divides. They need to replace more cells but only when needed, check point allows control of the division.

Cell Theory:

The cell theory is the foundation for biological research. The cell theory has been amended over time but the most up to date definition of the cell theory states that all organisms are made of cells, that all existing cells are produced byproduct of other living cells, and defines cells as the most basic unit of life. Scientists have been able to develop the theory because of better access to microscopes.

What would new cells in Telophase contain if replication of chromosomes did not occur before cytokinesis and would the cells be viable?

The cells would have only half the amount of DNA needed. The cells would not have enough DNA to be viable.

What do you think the chances are that there is someone in the world exactly like you?

The chances are very low, even if people look alike, they cannot have the same exact genetic material.

Describe the arrangement of chromosomes in metaphase I. Why do you think chromosomes are arranged in this way?

The chromosomes in metaphase 1 align both sides of the equator of the cell but facing opposite poles. This particular alignment allows for spindle fibers to play a fair game of tug of war and pull the chromosomes to either side of the cell.

Explain why it is necessary that the nuclear membrane disintegrates during mitosis.

The chromosomes must be able to get out of the nucleus.

Cellular division has two parts - mitosis is the division of the nucleus and cytokinesis is the division of the cell into two new cells. Explain why mitosis has to come before cytokinesis in the cell cycle.

The chromosomes must be on opposite sides of the cell before the cells divide.

Telophase:

The chromosomes uncoil from around the proteins becoming chromatin and the spindle fibers disintegrate. In the telophase. the nuclear envelope reforms. The Nuclei move apart from each other to form two new cells with a full set of 46 chromosomes.

What differences do you see among the different pairs of chromosomes and the chromosomes within a pair?

The different pairs of chromosome share similar colors to the chromosomes in the pair but vary in shapes and size. The chromosomes in the pair look the most alike and even though they have some differences but are very similar in characteristics for the most part.

Telophase II: (meiosis)

The final stage of Meiosis II where nuclear membranes surrounds each chromosome on opposing sides of the cell. The spindle fibers are separated and cytokinesis occurs. There should be a product of four haploid cells. The four cells are totally different and only have half as much DNA as the original cell. Cytokinesis takes place afterwards.

Asexual reproduction:

The form of reproduction performed by prokaryotic cells and eukaryotic cells that can occur quickly. In asexual reproduction, the offsprings genes are identical to the original or parental organisms.

Homologous Chromosomes:

The homologous chromosomes are the chromosomes that an organism inherits from a parental organism. There are two homologous chromosomes that are inherited one each from the mother and one from the father organism. These chromosomes have similar length and physical appearance but might differ. Each chromosome has copies of the same genes but the copies might be different.. There are two of each chromosome at the beginning. Chromosome one from dad and chromosome one from mom, each chromosome has hundreds of genes so there are hundreds of copies of genes. There are the chromosomes number two as well. One from each parent, the number two chromosomes are shorter. Chromosomes are duplicated to make two sister chromatids in the x-shape with exact copies of DNA.

Independent assortment

The idea that the way one pair of homologous chromosomes separates into gametes does not affect the way another pair separates

Gametes:

The name for the sex cells such as sperm cells and egg cells.

Telophase I (Meiosis)

The nuclei is divided into two and then afterwards the cell undergoes cytokinesis.

Do the chromosomes in Figure 2 on the previous page belong to a female or a male? Explain how you know.

The organism in figure 2 is a male because it has both an x and a y chromosome.

Metaphase I (Meiosis)

The pairs of homologous chromosomes align with the equator of the cell known as the metaphase plate. The chromosomes attach to the spindle fibers by the centromeres. There are two raised to the number of pairs of how chromosomes can have independent orientation. Some of the chromosomes are from the mother and/or the father. This process is in charge of chromosomal combinations and promotes diversification in genetics.

Anaphase I (Meiosis)

The pairs of homologous chromosomes dissociate from each other and travel to opposing sides of the cell. However, the sister chromatids remain joined together.

Record observations describing what happens to the part of the planarian that was amputated. How does this piece change over time?

The part of the planarian that is amputated separates from the main body surface and causes the overall planarian to become shorter. The piece gradually gets bigger over a 15 days period eventually becoming its own new organism because it is able to develop a head, eyespots and internal organs that allow it sustain life as a separate being. Not only mitosis to make more cells, but also differentiation because the organism makes a head where there was none before, possible because of cells, an example of asexual reproduction or cloning which is usually very rare in animals; only in starfish, worms, very simple animals, or maybe in lizards.

Sexual reproduction:

The production of new living organisms by combining genetic information from two individuals of different types (sexes) Sexual reproduction occurs when zygotes, the product of the fusion of egg and sperm cells, assembles. Sexual reproduction produces offspring with a genetic mixtures of genes from both parents. Sexual reproduction takes a relatively long amount of time.

What are the products of meiosis I? Explain in terms of number of cells and the genetic material contained in those cells.

The products of meiosis 1 are two haploid daughter cells. Half the number of chromosomes that were in the original diploid cell. Half as many chromosome one and half as many chromosome two.

Metaphase:

The second stage of Mitosis, spindle fibers join with each chromosome by the centromere. Spindle fibers line the chromosomes along the equator of the cell. The after phase and longest stage of mitosis. The spindle fibers work as tug of war ropes.

A sensory neuron serving the toe of a giraffe has an average length of nearly 4.6 meters. Use what you have learned about cell surface area and volume to explain how this cell can function properly.

The sensory neuron cell of the giraffe has a relatively long length which is good for transporting oxygen, nutrients and wastes across the cell membrane. The giraffes neuron has a long surface area, the larger the surface area. That means there is a compatible surface area to volume ratio, particularly since the volume is so small. Because the cell has a suitable cell size, and can absorb materials and expel wastes effectively. New response.

Anaphase II: (meiosis)

The sister chromatids are pulled apart from each other and move to opposite sides of the cell. Sister cells diverge to opposing sides of the cell that are facing.

Somatic cells (body cells):

The somatic cells are body cells. Body cells are any cells in the body that are not sex or gamete cells. They contain two copies of every chromosome. Somatic cells are diploid cells because they have two copies of each chromosome, however, the two copies are not alike because one comes from the father and the other comes from the mother. Body cells reproduce through mitosis which produces genetically identical daughter cells from a parent cell.

Mitosis:

The stage of cellular division. During mitosis, a cells nucleus is divided into two genetically identically nuclei, they each come with their own set of DNA. Mitosis does not occur in sex cells. It allows foor one cell with 46 chromosomes to split into two cells with identical 46 chromosomes. Root of body growth and nail growth. Produces identical body cells. Ensures DNA in first cells are in all copied cells. Ex: -Lizards regenerate new cells through mitosis -forming a scab is caused by mitosis. Ensures DNA in first cells are in all copied cells.

Meiosis 2:

The step where sister chromatids are split into new gametes. DNA is not copied between meiosis I and meiosis II.

Meiosis 1:

The step where the homologous chromosomes are split.

Describe the pattern you observe in the surface area-to-volume ratios as the cell gets larger.

The volume gets larger but the surface area doesn't get as large. We want a surface area to volume ratio that is high. The larger the surface area, the better, because the surface area of the cell is necessary for a cells to have successful diffusion of nutrients and waste along the cellular membrane.

Factors of Cell division:

There are internal and external factors of cell division. If a cell gets too big, there is a chance it volume will become bigger than its surface area which is bad. Further, cells divide so that they can better transport, nutrient, water and waste materials along a cells membrane.

Human cells have 46 chromosomes. How many chromosomes should be present during the G2 phase of the cell cycle? How many should be in each daughter cell after cytokinesis? Explain your answers.

There should be 46 chromosome during the G2 cycle, in each daughter cells, the chromatids are split, each daughter cell gets 46 chromosomes. Half a chromatid is equal to one chromosome

Cancer, which can be considered as unregulated cell division, often results from mutations in proto-oncogenes and tumor suppressor genes. Usually mutation in more than one gene from each group is involved. Suggest two or more combinations of mutations that would tend to allow the cell cycle to become unregulated.

a mutation is any proto-oncogene along with a mutation that would allow a defective cell to continue dividing a mutation is a gene that repairs DNA would allow additional mutations in either or both groups to go unrepaired and allow the cell cycle to continue.

Propose an explanation for the changes in the maturation promoting factor (MPF) concentration throughout the cell cycle based on your knowledge of the concentration of CDK and cyclin.

as the concentration of cyclin increases, there is more cyclin to bind to the CDK, so the concentration of MPF increases.

If cyclin was always available in the cell at higher concentrations, what effect would this have on the cell cycle?

cells would progress through mitosis even if they were not ready.

Predict the result of a mutation that allows a cell to move past checkpoint G2 even though the DNA replication has not been completed.

the DNA in the daughter cells would not be complete and the cells would not survive.

Recall that the purpose of the kinases is to phosphorylate other molecules, thus bringing them to a higher energy state. With this in mind, identify the three parts of the maturation promoting factor (MPF).

the MPF is made from a kinase, a cyclin, and a phosphate group.

How does paclitaxel inhibit the growth of cancer?

the cell will never divide because it never finished mitosis.

Predict the result of a mutation that allows a cell to move past checkpoint M even though the chromosomes were not prepared for division.

the chromosomes might end up in the wrong daughter cell. for example, one cell might get both copies of a chromosomes while the other gets none.

describe the changes in the concentration of cyclin (CDK) dependent kinase as the cell moves through different phases of the cell cycle.

the concentration of CDK does not vary throughout the cell cycle.

describe the changes in the concentration of cyclin as the cell moves through different phases of the cell cycle.

the concentration of cyclin is minimal at the start of G1 but increases until almost through mitosis, and quickly drops to a minimal level once again.

Predict the result of a mutation that allows a cell to move past checkpoint G1 even though the cell has not grown sufficiently.

the daughter cell would be small and possibly not able to store enough nutrients within the cell to survive.

Karyotype:

the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

Tumor suppressor genes (brake)

would tend to slow down division when cells are crowded