Unit 7 Cell Growth & Division Amoeba

Something to Think About !!!! 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: Living things grow by producing more cells. 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 Overload 1.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 Materials 1.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? Replacement Cells get damaged and need to be replaced. Not all cells can be reproduced. Growth The addition of more cells to make the organism larger

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 M Phase S Phase G 2 Phase

Cell Cycle It is a series of events that cells go through as they grow and divide. 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 90% of time is spent in interphase I N T E R P H A S

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)

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 envelope Spindle

Chromosomes move to the equator of spindle Metaphase Chromosomes move to the equator of spindle Each chromatid is attached to spindle with centromere Spindle centromere

Metaphase

Sister chromatids are pulled apart to opposite poles of the cell Anaphase Centromeres split Sister chromatids are pulled apart to opposite poles of the cell Each chromatid is now a separate chromosome Sister Chromatids

Anaphase

Telophase Nuclear envelopes (2) reform Chromosomes begin to uncoil and return to a tangled looking mess.

Telophase

Cytokinesis Cytoplasm divides Two new daughter cells are now separate Cytokinesis usually occurs at the same time as telophase. Pinching in of cell membrane

Okay, Now it’s your turn!

1 2 3 4 5 6 7 Interphase? Prophase? Metaphase? Anaphase? Telophase? 1 2 3 4 Prophase Anaphase Interphase 5 6 7

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.

Malignant Pancreatic Cancer Tumors

Benign Facial Tumors (neurofibromatosis)

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. Offspring are genetically identical to their parents.

1. Binary Fission Asexual Reproduction in single- celled organisms 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

Binary Fission in Paramcecium

Binary Fission in Bacteria

Regents Practice Question # 1 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.

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.

Yeast Budding Desert Cactus Hydra Budding

Regents Practice Question # 2 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

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

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

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

3. 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.

P L A N R I R E G N A T I O

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

Examples: strawberries, blackberries, spider plants, mint , ivy 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 Strawberry Plant Ivy Plant

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

Pieces of roots, stems, or leaves develop into new plants. Cuttings Pieces of roots, stems, or leaves develop into new plants. Cutting Rooting Planting

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

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

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

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

Regents Practice Question # 6 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

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