question

What are some of the difficulties a cell faces as it increases in size?

answer

The larger a cell becomes, the more demands the cell places on its DNA. In addition, a larger cell is less efficient in moving nutrients and waste materials across the cell membrane.

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DNA

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where living cells store critical information

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What happens to the information in the DNA as the cells grows

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that information is used to build the molecules needed for cell growth.

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4. What materials are essential to being exchanged to keep the cell in good working order?

answer

Food, oxygen, and water need to enter while waste needs to leave

question

What happens during an information crisis

answer

as the cell grows, the information does too. However the DNA, which stores the information doesn't grow, so there is too much information in the cell

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other than too much information, why is cell size limited

answer

Because the rate at which food and oxygen are used up and wasste is produced depends on the cell's volume.

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surface area formula

answer

(length X width)

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volume formula

answer

(length X width X height)

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What happens as a cell continues to grow

answer

as a cell continues to grow, it becomes more difficult to get sufficient amounts of oxygen and nutrients in and waste products out.

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cell division

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the process by which a cell divides into two new daughter cells

question

what happens before cell division occurs

answer

before cell division occurs, the cell replicates, and copies all of its DNA. This replication of DNA solves the problem of information overload because each daughter cell gets one set of genetic information. It also solves the problem of increasing size by reducing cell volume.

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reproduction

answer

the formation of new individual

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How do asexual and sexual reproduction compare?

answer

The production of genetically identical offspring from a single parent is known as asexual reproduction. Offspring produced by sexual reproduction inherit some of their genetic information from each parent.

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asexual reproduction

answer

when two cells are produced by cell division and are genetically identical to the cell that produced them; occurs in many multicellular organisms

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sexual reproduction

answer

involves the fusion of two separate parent cells; during this an offspring is produced by the fusion of special reproductive cells formed by each of two parents

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most ____________ and plants reproduce sexually and most _____________________ reproduce asexually

answer

animal; single celled organisms

question

What are some pros and cons of asexual reproduction

answer

pro: for some organisms, it is a survival strategy because it betters their chance of survival over other organisms pro: having genetically identical offspring is an advantage as long as conditions remain favorable pro: very quick con: if conditions change in ways that no longer fit the organism that is bad

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Why is sexual reproduction important

answer

con: takes more time pro: the time it takes is good for species that live in environments where seasonal changes effect weather and food availability pro: provides genetic diversity

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What is an organism that reproduce asexually and sexually

answer

yeast (mostly asexually though)

question

What is the role of chromosomes in cell division?

answer

Chromosome make it possible to separate DNA precisely during cell division.

question

Why can't you split a cell in half without preparation. What do cells do instead?

answer

This can't happen because the DNA might end up unevenly in the cells. Before splitting, the cells make a complete copy of their genetic information before the division begins.

question

chromosomes

answer

packages of DNA that genetic information is bundled into

question

Where is DNA found in Prokaryotes?

answer

Prokaryotes lack nuclei and many of the organelles found in eukaryotes, so their DNA molecules are found in the cytoplasm along with most of the other contents of the cells. These cells usually contain a single, circular DNA chromosome that has all or the cell's genetic information.

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chromatin

answer

the complex of chromosome and protein in eukaryotic cells

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nucleosomes

answer

these are produced when DNA tightly coils around the histones; beadlike structures that then pack together to form thick fibers, which condense even further during cell division.

question

What is the chromosome shape we usually see?

answer

This is a duplicated chromosome with supercoiled chromatin

question

Why do cells go to such lengths to package their DNA in chromosomes?

answer

This is because it ensures equal division of DNA when a cell divides

question

What are the events of the prokaryote cell cycle

answer

During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells. Each daughter cell then moves into a new cell cycle of activity, growth, and division.

question

cell cycle

answer

a series of events that cells go through as they divide

question

prokaryotic cell cycle

answer

a regular pattern of growth, DNA replication, and cell division that take place very rapidly

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The eukaryotic cell consists of four phases

answer

1. G1 2. S 3. G2 4. M

question

interphase

answer

the period of growth in cell division; this is the first three steps of the cell phases

question

G1 Phase

answer

this is the cell growth phase. Here cells increase in size and synthesize new proteins and organelles. The "G" stands for gap but this and the other "G" phase are periods of intense growth and activity

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S Phase

answer

this is the cell's DNA replication phase. Here the cells synthesize the DNA and the chromosomes are replicated. At the end of this, there should be twice as much DNA; the "s" stands for synthesis.

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G2 Phases

answer

this phase is the cells preparation for cell division. Here many of the organelles and molecules required for cell division are produced. It is the shortest phase, and the end of interphase

question

M phase

answer

this phase it the cell division. The "m" stands for mitosis. The first stage of this is mitosis, which is the division of the cell nucleus. The second stage is called cytokinesis, which is the division of the cytoplasm. Often cytokinesis begins while mitosis is taking place. This is a short phase.

question

mitosis

answer

part of eukaryotic cell division during which the cell nucleus divides

question

What events occur during each of the four phases of mitosis?

answer

During prophase, the genetic material inside the nucleus condenses and the duplicated chromosomes become visible. Outside the nucleus, a spindle begins to form. During metaphase, the centromeres of the duplicated chromosomes line us across the center of the cell. Spindle fibers connect the centromere of each chromosome to the two poles of the spindle. During anaphase, the chromosomes separate and move along spindle fibers to opposite ends of the cell. During telophase, the chromosomes, which were distinct and condensed, begin to spread out into a tangle of chromatin.

question

-mitosis, the second phase of the m phase, can last anywhere from a few minutes to several days. What are its phases called?

answer

1. Prophase 2. Metaphase 3. Anaphase 4. Telephase

question

prophase

answer

the longest phase; during this the genetic material condenses, chromosomes begin to show, and a spindle starts to form.

question

centromere

answer

the area where duplicated strands of the DNA molecules that are seen are attached to

question

chromatid

answer

also called sister chromatid; each DNA strand in the duplicated chromosome; after mitosis, these are separated and divided between the new daughter cells

question

spindle

answer

a fanlike system of microtubules that help to separate the duplicated chromosomes.

question

spindle fibers

answer

these extend from a region called the centrosome

question

centrioles

answer

tiny paired structures located on the centrosome; not in plant cells

question

centrosome

answer

region where spindle fibers and centrioles are located.

question

What happens as prophase ends?

answer

The chromosomes coil more tightly, the nucleolus disappears, and the nuclear envelope breaks down

question

metaphase

answer

the shortest phase of mitosis, where the centromeres line up across the center of the cells and the spindle fibers connect each of these to each of the two poles of the spindle

question

anaphase

answer

this phase begins when sister chromatids separate and move apart. These are considered an individual chromosome. When this movement stops and the chromosomes are completely separated, this phase is over

question

telophase

answer

this is the final phase, where a nuclear envelope re-forms around each cluster of chromosomes. The spindle then breaks apart and a nucleolus becomes visible in each nucleus. Now mitosis is complete

question

How do daughter cells split apart after mitosis?

answer

Cytokinesis completes the process of cell division-it splits one cell into two

question

cytokinesis in animal cells

answer

the cell membrane is drawn inward until the cytoplasm is pinched into equal parts, that each contain a nucleus and cytoplasmic organelles

question

How does cytokinesis occur in plant cells?

answer

Because the cell membrane isn't flexible enough to draw inward because of the rigid cell wall that surrounds it, the cell plate must form halfway between the divided nuclei. The cell plate develops into cell membranes that separate the two daughter cells. A cell wall tehn forms in between the two new membranes

question

How is the cell cycle regulated?

answer

The cell cycle is controlled by regulatory proteins both inside and outside the cell.

question

What happens when cells come into contact with each other?

answer

They stop dividing and growing. This was tested when scientists were growing cells in the laboratory. When the cells came into contact, they stopped growing and dividing. The neighboring cells were then scraped off, and the cells began dividing and growing again. This shows that controls on cell growth and division can be turned on and off.

question

What happens when you get and injury?

answer

When an injury occurs, cells at the edge of the injury are stimulated to divide rapidly. New cells for, and when the healing process nears completion, the rate of cell division slows, controls on growth are restored, and everything remains normal

question

cyclin

answer

a protein that regulates the cell cycle. When it is injected into a non-dividing cell, a mitotic spindle forms.

question

internal regulatory proteins

answer

proteins that respond to event occurring inside a cell. These make sure the cell cycle happens in order, like keeping the cell from mitosis till the DNA is duplicated

question

external regulatory proteins

answer

proteins that respond to events outside the cell; these direct cells to speed up or slow down the cell cycle.

question

growth factors

answer

these proteins are a group of external regulatory proteins. They stimulate the growth and division of cells. They are important especially during the embryonic development and would healing.

question

Other than the grow factors group, what do the external regulatory proteins do?

answer

They cause cells to slow down or stop their cells. This prevents excessive cell growth and keeps body tissues from disrupting one another.

question

Why do cyclins do within cells?

answer

Cyclins are continually produced and destroyed within cells. Cyclin production signals cells to enter mitosis, while cyclin destruction signals cells to stop dividing and enter interphase

question

What two ways do cells end their life cycle

answer

a cell may die by accident due to damage or injury, or a cell may go through apoptosis (be programmed to die)

question

Apoptosis

answer

a process of programmed cell death; once triggered, the cell undergoes a series of controlled steps leading to its self-destruction

question

What are the parts of apoptosis?

answer

First the cell and its chromatin shrink, then parts of the cell's membranes break off. Neighboring cells then quickly clean up the cell's remains

question

Why is apoptosis important?

answer

it shapes the structure of tissues and organs in plants and animals. Like the gap between toes is like that because apoptosis occurs. When this doesn't occur properly, a number of diseases, like Parkinson's disease, can result

question

How do cancer cells differ from other cells?

answer

Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, the cells divide uncontrollably.

question

Why is cell growth regulated so carefully?

answer

This is because the consequences of uncontrolled cell growth in a multicellular organism are very severe. Cancer is an example of this

question

cancer

answer

a disorder in which body cells lose the ability to control growth

question

tumor

answer

a mass of cells where cancer cells form. Not all tumors are cancerous. There are two types, cancerous and benign (noncancerous)

question

benign tumor

answer

this is a tumor that is noncancerous. It does not spread to surrounding healthy tissues or to other parts of the body.

question

cancerous tumor

answer

these have malignant tissues, which invade and destroy surrounding healthy tissue.

question

malignant tissues

answer

invades and destroys surrounding healthy tissue

question

What happens as cancer cells spread?

answer

They absorb the nutrients needed by other cells, they block nerve connections, and they prevent the organs they invade from functioning properly. Soon, the delicate balances that exist in the body are disrupted, and life-threatening illness results.

question

What causes cancer?

answer

Cancers are caused by defects in the genes that regulate cell growth and division. There are several sources of such defects: smoking or chewing tobacco, radiation exposure, other defective genes, and even viral infection.

question

What are the parts of the growth of cancer cells?

answer

1. A cell begins to divide abnormally (because of defects in the genes) 2. The cancer cells produce a tumor, which begins to displace normal cells and tissues 3. Cancer cells are dangerous because they have a tendency to spread once they enter the bloodstream or lymph vessels. The cancer then moves into other parts of the body and forms secondary tumors

question

metastasis

answer

the process during which cancer cells move into other parts of the body and for secondary tumors

question

How do cancer cells affect the cell cycle?

answer

The control over the cell cycle has broken down when cancer is present. Some cancer cells will no longer respond to external growth regulators, while others fail to produce the internal regulators that ensure orderly growth.

question

p53

answer

this gene halts the cell cycle until all chromosomes have been properly replicated. If these are damaged or defective, they cause cells to lose the information needed to respond to signals that normally control their growth.

question

What are some treatments for cancer

answer

surgery radiation chemotherapy

question

surgery on cancer

answer

when a cancerous tumor is localized, it can be removed by surgery (skin cancer)

question

radiation on cancer

answer

this needs to be a carefully targeted beam. It works because cancer cells copy their DNA more quickly than normal cells do, and are especially vulnerable to damage from radiation.

question

chemotherapy on cancer

answer

this is the use of compounds against cancer. This is a highly researched process and it is even able to cure some forms of cancer. The only downside is that because most chemotherapy compounds target rapidly dividing cells, they also interfere with cell division in normal, healthy cells, so there are many side effects.

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