Chapter 9.1 The Cell Cycle

Chapter 9.1 The Cell Cycle

by Nikki Chenevert

Chapter 9 The Cell Cycle​

by: Nikki Chenevert​

​You will need to be ready at all times to do the following:

​So pull out your highlighter,

​something to write with and

separate your Chapter 9 packet

​

and let's roll!

​Chapter 9: The Cell Cycle

 

Vocabulary:

Cell cycle-the life of a cell from the time it is first formed until its own division into two daughter cells. (cell growth followed by nuclear division and cytokinesis)

​

Chromosome-one DNA molecule and associated protein molecules

​

Chromatin-DNA and proteins that make up eukaryotic chromosomes, when cell is not dividing, in a dispersed form, a mass of long thin fibers.

​

Sister chromatid-two identical copies of a chromosome produced through DNA replication

​

​Chapter 9: The Cell Cycle

 

Vocabulary:

Chromatin-DNA and proteins that make up eukaryotic chromosomes, when cell is not dividing, in a dispersed form, a mass of long thin fibers.

​

Sister chromatid-two identical copies of a chromosome produced through DNA replication

​

Centromere-region of sister chromatids where they are joined together.

​

Mitosis-the division of the genetic information in the nucleus

​

Cytokinesis-the division of the cytoplasm

​Chapter 9: The Cell Cycle

 

Vocabulary:

​Mitosis-the division of the genetic information in the nucleus

​

Cytokinesis -the division of the cytoplasm

​

9.2-

​

Karyotype-the complete set of metaphase chromosomes of a species, arranged according to size and centromere position.

​

Oncogenes-a gene capable of inducing one or more characteristics of cancer cells.

​

Binary fission-splitting or dividing into two parts

​Figure 9.1 How do dividing cells distribute chromosomes to daughter cells?

The Key Roles of Cell Division

​

The ability of organisms to produce more of their own kind is the one characteristic that best distinguishes living things from nonliving matter.

Cell division (mitosis):

the reproduction of cells

Multiple Choice

Cell division is also known as

• interphase

• meiosis

• mitosis

• replication

This unique capacity to procreate, like all biological functions, has a cellular basis. In 1855, Rudolf Virchow, a German physician, put it this way: “Where a cell exists, there must have been a preexisting cell, just as the animal arises only from an animal and the plant only from a plant.”

​

He summarized this concept with the Latin saying “Omnis cellula e cellula,” meaning

​

“Every cell from a cell.”

The continuity of life is based on the reproduction of cells, or cell division.

The series of confocal fluorescence micrographs starting at the lower left and moving clockwise, follows the events of cell division as the cells of a two-celled marine worm embryo become four.

​Chromosomes (blue) are attached by specific proteins (green) to cell machinery (red) and are moved during division of a rat kangaroo cell.

​Cell division plays several very important roles in life.

​

​

​

The division of one prokaryotic cell actually reproduces an entire organism. (asexual reproduction). The same is true of a unicellular eukaryote.

​

​

​

​

​

The division of one prokaryotic cell actually reproduces an entire organism. (asexual reproduction). The same is true of a unicellular eukaryote.

​

Cell division enables multicellular eukaryotes to develop from a single cell, like the fertilized egg that gave rise to the two-celled embryo in Figure 9.2b .

And after such an organism is fully grown, cell division continues to function in

*renewal and

*repair,

*replacing cells that die from accidents or normal wear and tear.

​

For example, dividing cells in your bone marrow continuously make new blood cells (Figure 9.2c )

​

​

​

And after such an organism is fully grown, cell division continues to function in

*renewal and

*repair,

*replacing cells that die from accidents or normal wear and tear.

​

For example, dividing cells in your bone marrow continuously make new blood cells (Figure 9.2c )

​

​

​

​9.1 Most cell division results in genetically identical daughter cells

​Cell cycle-the life of a cell from the time it is first formed until its own division into two daughter cells. (cell growth followed by nuclear division and cytokinesis)

Passing identical genetic material to cellular offspring is a crucial function of cell division.

​

In this chapter, you’ll learn how this process occurs in the context of the cell cycle. After studying the mechanics of cell division in eukaryotes and bacteria, you’ll learn about the molecular control system that regulates progress through the eukaryotic cell cycle and what happens when the control system malfunctions.

​

Because a breakdown in cell cycle control plays a major role in the development of cancer, this aspect of cell biology is an active area of research.

​(Biologists use the words daughter or sister in relation to cells, but this is not meant to imply gender.)

​

The cell division process is an integral part of the cell cycle , the life of a cell from the time it is first formed during division of a parent cell until its own division into two daughter cells.

​

Multiple Choice

How would living things differ if cell division took place only for reproduction?

• All living things would be single-celled.

• Multicellular organisms would be much smaller.

• Living things would be more genetically diverse.

• Multicellular organisms would be unable to repair damaged cells.

Multiple Choice

What is a series of events a cell goes through as they grow and divide?

• Cell Division
• Cell Cycle
• Cytokinesis
• Mitosis

​Write down the question and only the letter of what you think is the correct answer:

​

Q-What is the best description of the structure of a chromosome in the nucleus of a non-dividing cell?

​

a. One long DNA molecule, associated with many proteins.

b. Two long DNA molecules wound around each other, with no proteins.

c. One long DNA molecule, with no proteins.

d. Two long DNA molecules wound around each other, associated with many proteins.

​

​

Q-What is the best description of the structure of a chromosome in the nucleus of a non-dividing cell?

​

a. One long DNA molecule, associated with many proteins.

b. Two long DNA molecules wound around each other, with no proteins.

c. One long DNA molecule, with no proteins.

d. Two long DNA molecules wound around each other, associated with many proteins.

​

​

​Feedback:

Correct! If you had trouble with this question, review the following material: Within the nucleus of a non-dividing cell, the DNA is organized into discrete units called chromosomes, structures that carry the genetic information. Each chromosome contains one long DNA molecule associated with many proteins.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-Which of the following statements best describes microtubules?

​

a. Microtubules are permanent cellular structures that help the cell to move from place to place.

​b. Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell.

​c. Microtubules are made up of subunits of actin, and function in muscle contraction and changes in cell shape.

​d. Microtubules are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-Which of the following statements best describes microtubules?

​

a. Microtubules are permanent cellular structures that help the cell to move from place to place.

​b. Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell.

​c. Microtubules are made up of subunits of actin, and function in muscle contraction and changes in cell shape.

​d. Microtubules are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus.

​Feedback:

​

Correct! If you had trouble with this question, review the following material: Microtubules—hollow rods constructed from globular proteins called tubulins—shape and support the cell and serve as tracks along which organelles equipped with motor proteins can move. Microfilaments are made up of subunits of actin, and function in muscle contraction and changes in cell shape. Intermediate filaments are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-How can a protein outside the cell cause events to happen inside the cell?

​

a. A protein outside the cell can phosphorylate a protein inside the cell, which transduces a signal and causes a response.

​b. A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell.

​c. A protein can pass through the membrane and into the cell, causing signaling inside the cell.

​d. A protein outside the cell can cause the H⁺ ion concentration outside the cell to be higher, which allows substances to pass into the cell and transduce a signal.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-How can a protein outside the cell cause events to happen inside the cell?

​

a. A protein outside the cell can phosphorylate a protein inside the cell, which transduces a signal and causes a response.

​b. A protein outside the cell can bind to a receptor protein on the cell surface, causing it to change shape and sending a signal inside the cell.

​c. A protein can pass through the membrane and into the cell, causing signaling inside the cell.

​d. A protein outside the cell can cause the H⁺ ion concentration outside the cell to be higher, which allows substances to pass into the cell and transduce a signal.

​Correct! If you had trouble with this question, review the following material: The hydrophobic interior of the membrane impedes direct passage of proteins into the cell. Reception, the target cell’s detection of a signaling molecule coming from outside the cell, occurs when a protein binds to a receptor protein located at the cell’s surface, changing the shape of the receptor protein and initiating transduction. Transduction occurs within the cell and typically involves several steps, converting the external signal into a form that brings about a specific cellular response inside the cell.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-What effect does phosphorylating a protein have on that protein?

​

a. Phosphorylation adds one or more phosphorus atoms to the protein, allowing it to perform a particular function.

​b. Phosphorylation may have no effect at all on the protein.

​c. Phosphorylation adds energy to the protein, allowing it to form ATP from ADP and P_i.

​d. Phosphorylation changes the shape of the protein, most often activating it.

​Write down the question and only the letter of what you think is the correct answer:

​

Q-What effect does phosphorylating a protein have on that protein?

​

a. Phosphorylation adds one or more phosphorus atoms to the protein, allowing it to perform a particular function.

​b. Phosphorylation may have no effect at all on the protein.

​c. Phosphorylation adds energy to the protein, allowing it to form ATP from ADP and P_i.

​d. Phosphorylation changes the shape of the protein, most often activating it.

​Correct! If you had trouble with this question, review the following material: Protein phosphorylation causes a shape change in the phosphorylated protein. The shape change results from the interaction of the newly added phosphate groups with charged or polar amino acids on the protein being phosphorylated. The shape change alters the function of the protein, most often activating it, but in some cases phosphorylation instead decreases the activity of the protein.

​Concept 9.1: Most cell division results in genetically identical daughter cells

​

The reproduction of a cell, with all its complexity, cannot occur by a mere pinching in half; a cell is not like a soap bubble that simply enlarges and splits in two. In both prokaryotes and eukaryotes, most cell division involves the distribution of identical genetic material—DNA—to two daughter cells. (The exception is meiosis, the special type of eukaryotic cell division that can produce sperm and eggs.) What is most remarkable about cell division is the accuracy with which the DNA is passed from one generation of cells to the next. A dividing cell replicates its DNA, distributes the two copies to opposite ends of the cell, and only then splits into daughter cells

​Cellular Organization of the Genetic Material

​9.1 Most cell division results in genetically identical daughter cells

1. Cellular Organization of the Genetic Material

   1. Genome: all of the genetic information in a cell.

                                                              i.      Prokaryotic: 1, circular chromosome

                                                            ii.      Eukaryotic: multiple, linear chromosomes

1. Chromosome: one DNA molecule and associated protein molecules

2. Chromatin: DNA and proteins that make up eukaryotic chromosomes, when cell is not dividing, in a dispersed form, a mass of long thin fibers.

3. Somatic cells: all body cells, except reproductive cells. 

                                                              i.      Human cells have 23 pairs of chromosomes, 46 total (2n=46)

1.      One copy from each parent

1. Gametes: reproductive cells

                                                              i.      Human cells have 23 chromosomes, (n=23)

​​9.1 Most cell division results in genetically identical daughter cells

1. Cellular Organization of the Genetic Material

​Genome: all of the genetic information in a cell.

A cell’s endowment of DNA, its genetic information, is called its genome .

​

  i.      Prokaryotic: 1, circular chromosome

  ii.      Eukaryotic: multiple, linear chromosomes

​

​​9.1 Most cell division results in genetically identical daughter cells

1. Cellular Organization of the Genetic Material

​Genome: all of the genetic information in a cell.

A cell’s endowment of DNA, its genetic information, is called its genome .

​

  i.      Prokaryotic: 1, circular chromosome

  ii.      Eukaryotic: multiple, linear chromosomes

Although a prokaryotic genome is often a single DNA molecule, eukaryotic genomes usually consist of a number of DNA molecules. The overall length of DNA in a eukaryotic cell is enormous. A typical human cell, for example, has about 2 m of DNA—a length about 250,000 times greater than the cell’s diameter. Before the cell can divide to form genetically identical daughter cells, all of this DNA must be copied, or replicated, and then the two copies must be separated so that each daughter cell ends up with a complete genome.

​The replication and distribution of so much DNA are manageable because the DNA molecules are packaged into structures called chromosomes (krōʹ-muh-sōm) (from the Greek chroma, color, and soma, body), so named because they take up certain dyes used in microscopy (Figure 9.3 ).

​

​Chromosome: one DNA molecule and associated protein molecules

​The replication and distribution of so much DNA are manageable because the DNA molecules are packaged into structures called chromosomes (krōʹ-muh-sōm) (from the Greek chroma, color, and soma, body), so named because they take up certain dyes used in microscopy (Figure 9.3 ).

​

​Chromosome: one DNA molecule and associated protein molecules

​​Each eukaryotic chromosome consists of one very long, linear DNA molecule associated with many proteins (see Figure 4.8 ).

​

1. Chromatin: DNA and proteins that make up eukaryotic chromosomes, when cell is not dividing, in a dispersed form, a mass of long thin fibers.

2. Somatic cells: all body cells, except reproductive cells. 

                                                              i.      Human cells have 23 pairs of chromosomes, 46 total (2n=46)

1.      One copy from each parent

1. Gametes: reproductive cells

                                                              i.      Human cells have 23 chromosomes, (n=23)

The DNA molecule carries several hundred to a few thousand genes, the units of information that specify an organism’s inherited traits. The associated proteins maintain the structure of the chromosome and help control the activity of the genes. Together, the entire complex of DNA and proteins that is the building material of chromosomes is referred to as chromatin . As you will soon see, the chromatin of a chromosome varies in its degree of condensation during the process of cell division.

​When a cell is not dividing, each chromosome is a long thin chromatin fiber.

​

​In preparation for cell division, the DNA is replicated and the chromosomes condense.

​Distribution of Chromosomes During Eukaryotic Cell Division

1. DNA is in a dispersed form, a mass of long thin chromatin fibers.

2. DNA replication in dispersed form

3. Chromatin fibers coil and fold to making condensed chromosomes for divison.

4. Sister chromatids-two identical copies of a chromosome produced through DNA replication

5. Cohesin-proteins hold sister chromatids together tightly at the centromere

​End of today's lecture

​Ans 32: (a) mitosis occurs during asexual reproduction.

Mitosis occurs only in the somatic cells of the body and occurs in both sexually as well as asexually rrproducing organism.whereas meiosis only occurs in sexually reproducing organisms occurs only in germ cell.The two chromatids of chromosomes are genetically similar in mitosis and genetically different in meiosis due to crossing over.

Ans 33:(c): The chromatids seperate.

Ans 34: (a) mutation only occurs in germ line(reproductive cells)

Because mutation also occurs in somatic cells which is not transmitted to offspring but the germ line mutation is heritable found in offsprings.

35: (d) adenine and guanine are purines

The nucleotide of DNA consists of pentose sugar , phosphate group and one of the four nitrogenous bases (thymine, adenine,cytosine and guanine).

RNA has the same nucleotide as DNA except that Uracil replaces thymine.

36: (c) more than one triplet can code for the same amino acid.

Means genetic code is degenerate.

Multiple Choice

Among the following, the term that includes the others is ___.

• interphase
• nuclear division
• mitosis
• cell cycle

Question: Mitosis and cytoplasmic division results in the formation of two genetically identical cells?

​True or False

​

​Ans: True Explanation:

- Mitosis is a form of eukaryotic cell division that produces two daughter cells with same genetic component as the parent cell. It contains four phases known as prophase( Chromatin condenses into chromosome, nuclear envelope breaks down and centrioles begin to separate and moves to opposite sides of cell) , metaphase( the chromosomes align in the equator of the cell forming metaphse plate), anaphase( chromosomes break at centromeres and sister chromatids move to opposite sides of cell) and telophase( chromosomes at poles becoming more diffuse and nuclear envelope reforms). After mitosis, cytoplasm division occurs which separates these two genetically identical cells.