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 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?
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
Life Span of Various Human Cells
Cell Type
Life Span
Cell Division
Lining of esophagus
2-3 days
Can divide
Lining of small intestine
1-2 days
Can divide
Lining of large intestine
6 days
Can divide
Red blood cells
Less than 120 days
Cannot divide
White blood cells
10 hours to decades
Cannot divide
Smooth muscle
Long-lived
Can divide
Cardiac muscle
Long - lived Cannot divide
Skeletal muscle
Long-lived
Cannot divide
Nerve cells
Long-lived
Most do not divide9
The Cell Cycle
G1 Phase
M Phase
S Phase
G 2 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:
I • G1 - Cells increase in size
90% of time is
N
spent in interphase
synthesize new proteins
T
E
synthesize new cell organelles
R
P • S - Chromosomes are copied which gives the
H
cell a duplicate set of DNA
A
S • G2 - Preparation for Mitosis
E
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
Spindle
Nuclear envelope
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15
Metaphase
• Chromosomes move to the equator of
spindle
• Each chromatid is attached to spindle
with centromere
Spindle
centromere
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Metaphase
17
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!
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Interphase? Prophase? Metaphase? Anaphase? Telophase?
Telophase
Telophase
Metaphase
Anaphase
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.
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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
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Asexual
Reproduction
It Only Takes One !
Characteristics of Asexual Reproduction
•Only one parent is involved.
•Offspring are genetically identical to their
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
Binary Fission in Paramcecium
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Binary Fission in Bacteria
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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.
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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.
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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
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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 # 3
Which 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
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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
R
L
E
A
G
E
N
N
A
E
R
R
I
A
A
T
I
O
N
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
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 # 5
Which 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 # 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
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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
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