Amoeba

Something to Think About !!!!

1.When a living thing grows, what happens to its cells?

2. Does an animal get larger because each cell increases in size or because it makes more of them?

Answers to Think About It:

1.Living things grow by producing more cells.

2.The cells of an adult animal are no larger than those of a young animal –there are just more of them.

One More Thing To Think About ……

Why do cells make so many new cells rather than continuing to grow indefinitely?

Answer : One More Thing To Think About:

The larger a cell becomes, the more demands the cell places on its DNA and the more trouble the cell has moving enough nutrients and wastes across the cell membrane.

DNA Overload1.The information that controls a cell’s function is stored in DNA

2.DNA is located in the cell’s nucleus

3.DNA is able to meet the cell’s need when cells are small

4.If a cell were to grow too large, there is not enough information in the DNA molecule to control the larger cell

Exchanging Materials1.If cells were to grow larger than normal, the cell’s volume and its surface area would prevent the cell from maintaining homeostasis.

It becomes more difficult for the cell to move needed materials in and waste products out

When do new cells need to be produced?

1.Replacement

• Cells get damaged and need to be replaced.

• Not all cells can be reproduced.

2.Growth

• The addition of more cells to make the organism larger

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Life Span of Various Human Cells

Cell Type

Lining of esophagus

Lining of small intestine

Lining of large intestine

Red blood cells

White blood cells

Smooth muscle

Cardiac muscle

Skeletal muscle

Nerve cells

Life Span Cell Division

2-3 days Can divide

1-2 days Can divide

6 days Can divide

Less than 120 days Cannot divide

10 hours to decades Cannot divide

Long-lived Can divide

Long - lived Cannot divide

Long-lived Cannot divide

Long-lived Most do not divide

The Cell Cycle

G1 Phase

S Phase

G 2 Phase

M Phase

Cell Cycle

1. It is a series of events that cells go through as they grow and divide.

2.The cell cycle consists of four phases:

• G1 - Cells increase in size

synthesize new proteins

synthesize new cell organelles

• S - Chromosomes are copied which gives the cell a duplicate set of DNA

• G2 - Preparation for Mitosis

INTERPHASE

90% of time is spent in interphase

Mitosis (M Phase)

1. It is the part of the cell cycle where the division of the nucleus and cytokinesis, (division of the cytoplasm), take place.

2. Mitosis is divided into 4 steps(phases)

• Prophase

•Metaphse

•Anaphase

•Telophase(cytokinesis)

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Prophase • 1st and longest phase of mitosis• Nuclear envelope disappears

• Chromosomes condense – • Now, you can see sister chromatids and centromere

• Spindle forms(microtubule structure that helps separate the chromosomes.)

Sister Chromatids

Centromere

Nuclear envelopeSpindle

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Metaphase• Chromosomes move to the equator of

spindle

• Each chromatid is attached to spindle with centromere

Spindle

centromere

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Metaphase

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Anaphase• Centromeres split

• Sister chromatids are pulled apart to opposite poles of the cell

• Each chromatid is now a separate chromosome

Sister Chromatids

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Anaphase

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Telophase• Nuclear envelopes (2) reform• Chromosomes begin to uncoil and return

to a tangled looking mess.

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Telophase

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Cytokinesis• Cytoplasm divides• Two new daughter cells are now separate• Cytokinesis usually occurs at the same time as

telophase.

Pinching in of cell membrane

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Okay, Now it’s your turn!

Interphase? Prophase? Metaphase? Anaphase? Telophase?

1 2 3 4

5 6 7

AnaphaseTelophase MetaphaseTelophase

Prophase Anaphase Interphase

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What is Cancer ?

•Cancer is uncontrolled cell division (mitosis) that can’t be stopped.

•A mass of cells called a tumor is a result of this uncontrolled cell division.

•There are 2 types of tumors:

•Benign = non-cancerous

•Malignant = cancerous and they invade and destroy other tissues.

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Malignant Pancreatic Cancer Tumors

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Benign Facial Tumors(neurofibromatosis)

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Cancerous Cells Affects Homeostasis

•Interferes with nervous system tissue and blocks important nerve connections.

•Cancer cells absorb nutrients needed by the healthy cells.

•Prevent organs from functioning properly.

Lung Cancer

Asexual Reproduction

It Only Takes One !

Characteristics of Asexual Reproduction

•Only one parent is involved.Only one parent is involved.

•Offspring are genetically identical to their Offspring are genetically identical to their parents. parents.

Asexual Reproduction in single- celled organisms

1. Binary Fission

•The simplest type of asexual reproduction.

•A unicellular organism divides by mitosis to form two daughter cells of equal size.

•Both the nucleus and cytoplasm divide equally.

•Amoebas, paramecia, and bacteria reproduce this way.

•All cells that come from a single cell are genetically identical to each other

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Binary Fission in Paramcecium

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Binary Fission in Bacteria

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Regents Practice Question # 1A pattern of reproduction and growth in a one celled organism is shown below.

Which statement best describes this pattern of reproduction?

(1) All genetic material comes from one parent.(2) Only some of the genetic material comes from one parent.(3) The size of the parent determines the amount of genetic material.(4) The size of the parent determines the source of the genetic material.

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Regents Practice Question # 1 ( Answer)

A pattern of reproduction and growth in a one celled organism is shown below.

Which statement best describes this pattern of reproduction?

(1) All genetic material comes from one parent.(2) Only some of the genetic material comes from one parent.(3) The size of the parent determines the amount of genetic material.(4) The size of the parent determines the source of the genetic material.

Asexual Reproduction in multi-cellular organisms

•It can be a result of wound repair or growth.

•There are many different methods for asexual reproduction in multi-cellular organisms.

•Budding

•Sporulation

•Regeneration

•Vegetative Propagation

2. Budding

•A new organism develops as part of a parent.

•The new organism is called the bud

•The bud is a duplicate of the parent. It may separate or remain attached to form a colony.

•In budding there is an equal division of the nucleus, but unequal division of cytoplasm. So, one of the daughter cells is larger than the other.

Hydra Budding

Yeast Budding

Desert Cactus

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Regents Practice Question # 2The diagram below illustrates asexual reproduction in yeast.

Yeast produce offspring that usually have(1) genes that are different from those of the

parent(2) genes that are identical to those of the

parent(3) half of the genetic information of the parent(4) organelles that are not found in the parent

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Regents Practice Question # 2 (Answer)The diagram below illustrates asexual reproduction in yeast.

Yeast produce offspring that usually have(1) genes that are different from those of the

parent(2) genes that are identical to those of the

parent(3) half of the genetic information of the parent(4) organelles that are not found in the parent

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Regents Practice Question # 3Which diagram represents the reproductive process of budding?

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Regents Practice Question # 3 (Answer)Which diagram represents the reproductive process of budding?

Correct Answer

3. Sporulation3. Sporulation

•Spores are specialized asexual reproductive cells that

contain a nucleus and small amount of cytoplasm.

•Spores are produced in large numbers by mitosis.

•They are surrounded by a tough protective coat that enables them to survive extreme conditions such as heat or cold.

•When conditions are favorable, the spores develop into a new organism.

•Bread mold, mushrooms, mosses, and ferns reproduce this way

Sporulation in Ferns

Diagram of Mold Spores

Moss Sporulation

4.Regeneration

•The development of a new organism from a part of a parent organism

•Occurs in starfish, planaria and sponges

•Regeneration can also replace lost body parts. For example lobsters can replace a lost claw.

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PLANARIAN REGENERATION

Starfish Regeneration

Vegetative Propagation

•Occurs only in plants.

•New plants develop from the roots, stems, or leaves of the parent plant

•There are many different ways for this type of reproduction to occur:

runners

bulbs and tubers

cuttings

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Runners

•Stems that grow over the surface of the soil and at certain points the runner puts down roots and new plants grow from there.

•Examples: strawberries, blackberries, spider plants, mint , ivy

Ivy Plant

Strawberry Plant

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Bulbs and Tubers

•Any plant that stores its complete life cycle in a specialized underground storage structure.

•Each bulb can develop into a new plant.

•Examples: onions, tulips, chives , lilies, potatoes, carrots, radishes

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Cuttings

•Pieces of roots, stems, or leaves develop into new plants.

Cutting Rooting Planting

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Regents Practice Question # 4

Thousands of genetically identical trees have been discovered growing in a remote, undisturbed mountain area in Colorado. These trees are most likely the result of

(1) genetic engineering(2) asexual reproduction(3) meiotic cell division(4) biotechnology

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Regents Practice Question # 4 (Answer)

Thousands of genetically identical trees have been discovered growing in a remote, undisturbed mountain area in Colorado. These trees are most likely the result of

(1) genetic engineering(2) asexual reproduction(3) meiotic cell division(4) biotechnology

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Regents Practice Question # 5Which process usually results in offspring that exhibit new genetic variations?

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Regents Practice Question # 5 (Answer)Which process usually results in offspring that exhibit new genetic variations?

Correct Answer

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Regents Practice Question # 6A technique used to reproduce plants is shown in the diagram below.

This technique is a form of(1) sexual reproduction (2) gamete production (3) asexual reproduction (4) gene manipulation

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Regents Practice Question # 6 (Answer)A technique used to reproduce plants is shown in the diagram below.

This technique is a form of(1) sexual reproduction (2) gamete production (3) asexual reproduction (4) gene manipulation