Transcript Reproduction - SSHS Science 9

Unit 1: Reproduction
Chapter 5: Cell Growth and
Reproduction Overview
 In this chapter you will learn:
1.) the importance of cell theory in developing a better
understanding of cell biology.
2.) the importance and processes of cell division.
3.) how different organisms use various types of
asexual reproduction for propagation.
* Propagation means to produce offspring.
For example, trees propagate themselves by
scattering seeds.
4.) how to use a microscope and all of its functions.
Ebola Virus
“Tree Man”
http://interestingstrangefacts.com/dede-koswaratree-man/
 https://www.youtube.com/watch?v=xmVseKdB6So
“China’s Elephant Man”
http://alveryscottkent.wordpress.com/2013/07/1
8/the-curiosity-of-chinas-elephant-man/
 https://www.youtube.com/watch?v=PQpPeMGQv90
Importance of Cells
 Cells make up every part of the human body: skin, hair,
nails, blood and blood organs.
 Cells are the building blocks of life. Every living
organism is made up of cells. During the 1800’s scientists
constructed what they have come to know as cell theory.
 Cell Theory is based upon three important principles.
1.) All living things are composed of one or more cells.
2.) The cell is the functional unit of life.
3.) All cells come from pre-existing cells.
Two Main Types of Cells
 Eukaryotic Cells – need food in order to live.
- animal and plant cells are
eukaryotic cells
 Prokaryotic Cells – no membrane around their
nuclear material.
- single celled organisms that can
live on their own.
- virus (cold, or flu)
When we talk about cells, just how big
are we talking about?
 http://www.cellsalive.com/howbig.htm
 http://www.brainpop.com/health/geneticsgrowthanddevel
opment/cellspecialization/
 http://www.brainpop.com/health/bodysystems/cells/
 http://www.youtube.com/watch?v=zufaN_aetZI&feature=
related
Taking a look at Cells
There are over 100
trillion cells that
make up the human
body that all started
from a single
fertilized egg.
Though we have
many cells, they all
don’t look alike.
How do Cells Move?
 Outside the cell membrane, some cells have
a flagellum, a whip-like tail that helps the
cell move.
 Some cells have tiny hairs called, cilia, that
either move the cell or the environment
surrounding the cell.
Animal Cell
Plant Cell
Cells: The Basic Unit of Life
Animal Cell
Plant Cell
Take a look at both cells. Make a list of the
common features of the cells.
Common Features of Animal and Plant
Cells
 Cell Membrane
 Mitochondrion
 Nucleus
 Cell membrane
 Cytoplasm
 Ribosome
 Endoplasmic Reticulum
 Nucleolus
 Chromosome
Plant cells have three more structures
than animal cells
 Cell wall - made up of cellulose it
protects and supports the cell
 Chloroplast - contains chlorophyll
(green pigment) used in photosynthesis
 Vacuole - stores water, food and waste
products until they are needed.
* A plant cells vacuole is much larger than
an animal cells vacuole
Tour of a Plant Cell
http://www.youtube.com/watch?v=PXbv95P3uhI
http://www.youtube.com/watch?v=X6N82No4Nz8
Cells are the basic unit of structure
and function in all living things. If
you look inside cells, there are even
smaller structures called
organelles.
The Job of Each Organelle
* Organelle – specific structure of a cell.
 Cell Membrane: covers the entire cell and acts
as a gate keeper. Outer layer of cell. Decides what
gets into and out of the cell.
 Nucleus: acts as a command or control center;
directs all of the cell’s activities. It acts like a boss
that hands out directions to the other cell parts.
Cell Structures Continued …
 Cytoplasm: nutrients are absorbed, transported
and processed. Floats around the cells and carries
organelles.
 Mitochondrion: oval shaped organelle that
provides cells with energy. It breaks down food
and releases energy.
 Nucleolus: found inside the nucleus of some
cells; involved in the making of proteins.
Continued ….
 Endoplasmic reticulum: acts like a
conveyor belt. It moves food, waste and
water around the cell.
 Golgi apparatus: packs up and stores
proteins until needed for use inside or
outside the cell.
 Lysosome: breaks down food, cell waste
and worn out cell parts.
Continued ….
 Chromosomes: thread like structures
containing genetic information (DNA)
 Genes: genetic information that
determines the specific characteristics of
an individual
 Ribosome: builds proteins.
 Centriole: small protein structure
important to cell division (found only in
animal cells)
How a cell is like a factory
 http://www.brainpop.com/science/cellularlifeandgenetics/
cellstructures
Cell Biology Video
 http://www.youtube.com/watch?v=zufaN_aetZI&feature=
related
How cells relate to a Factory
 http://www.sciencenetlinks.com/pdfs/cellsystem_actsheet.
pdf
20 Little Known Facts About the
Human Body
 http://www.teach-
nology.com/worksheets/science/trivia/human/index.html
Hidden Life of a Cell
 http://www.youtube.com/watch?v=4GZXRMG5i_w
Cell Division
What is Cell Division?
 Cell division is the process in which a cell, called a parent
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cell, divides into two or more cells called daughter cells.
The division of a cell to make more cells.
All cells come from preexisting cells through cell division.
The 100 trillion cells in your body started off as a single,
fertilized egg cell.
This cell divided into two cells, then each of those two cells
is divided into two cells, and so on.
Importance of Cell Division
 Healing and Tissue Repair
- Healing and Tissue Repair are important
functions of cell division.
- The replacement of dead cells is also an
important function of cell division.
*You don’t go through life with the same cells
that you had at birth. Every second millions of
your body cells are injured or die.
Healing of Skin
Skin Graft – Healing of the Skin
 http://www.youtube.com/watch?v=SiqvFF7qpAc
 http://www.youtube.com/watch?v=5OaqwYD4oQQ&feat
ure=related
Growth
 Cell division helps us to grow as the number of cells in our
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body increases.
As the number of cells in an organism increases, so does the
size of the organism.
Growth of all living things depends on cell division.
Human growth begins with the division of a fertilized egg
cell.
The relationship is very important between the surface area
of the cell membrane and the volume of cytoplasm. As a cell
grows, the volume of cytoplasm increases faster than the
surface area of the cell.
Reproduction of Organisms
 Cell division is important because it keeps the life of
organisms going.
 Unicellular organisms like bacteria can reproduce on their
own.
 Multicellular organisms require cell division to reproduce.
The Cell Cycle
 Cells alternate between stages of dividing and not
dividing.
 The sequence of events from one division to
another is called the cell cycle.
 The stage between cell division is called
Interphase.
 Cell division involves the division of nuclear
materials and the sharing of cytoplasm, which
includes the organelles.
 http://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter2/anim
ation__how_the_cell_cycle_works.html
Interphase
 During this stage, cells take
in nutrients, such as sugars,
and produces building
materials such as proteins.
 These materials are used by
the cell for energy, growth
and repair of damaged
parts.
 After a period of rapid
growth, the cell prepares
for division by duplicating
its chromosomes within
the nucleus.
Different Phases of Cell Division
 http://www.johnkyrk.com/mitosis.html
 http://www.brainpop.com/science/cellularlifeandgenetics/
mitosis/
 http://www.youtube.com/watch?v=VlN7K1-9QB0
 http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy
cle/MitosisFlash.html
Cytokinesis
 The separation of the cytoplasm and its contents into equal
parts. This process is called cytokinesis.
 Half of the cytoplasm, containing about half of the
organelles, goes into each daughter cell.
 Cytokinesis differs in animal and plant cells.
Differences in Cytokinesis
Animal Cell
 The cell membrane pinches
together in the middle,
separating the cytoplasm
into equal parts and
creating two new cells.
Plant Cell
 A new cell wall forms
along the middle, creating
two new cells.
Interphase
 Interphase – during this phase, the
cell grows then prepares for cell
division by duplicating its genetic
material.
 Cell grows, DNA replicates, continues
to prepare for cell division ( mitosis)
Mitosis
Mitosis
 The process of dividing nuclear material.
 During this process, duplicated chromosomes, copied
during interphase, divide and move to opposite ends of
the cell.
 The nuclear division producing two daughter nuclei
identical to the original nucleus.
 Though mitosis is described in stages, the process of
cell division is continuous.
Mitosis
 The process of dividing nuclear material.
 During this process, duplicated
chromosomes, copied during interphase,
divide and move to opposite ends of the cell.
The Phases of Mitosis
1. Interphase – during this phase, the cell grows then
prepares for cell division by duplicating its genetic
material.
2. Prophase – during this phase, the individual
chromosome, now made up of two identical strands of
genetic information, shorten and thicken. They become
visible with the use of a light microscope. Spindle
fibres also form.
3. Metaphase
- during this stage, the double
stranded chromosomes line up in the middle of
the cell. Spindle is fully formed.
4. Anaphase – during this stage, each chromosome splits.
The two halves move to opposite poles of the cell. If this is
done correctly, each daughter cell will have a complete set of
genetic information.
4. Telophase –
in this stage the chromosomes
reach the opposite poles of the cell and a nuclear
membrane begins to form around each set.
Cytokinesis begins. The cells cytoplasm divides
into roughly two equal parts, and the two
daughter cells are formed.
5. Interphase – The daughters begin growth and
duplication of genetic material.
Cytokinesis
 Cell Division continues with the separation
of the cytoplasm and its contents into 2
equal parts. This also means that the
organelles are split up into 2 equal parts.
5.8 Reproduction and Cell Division
 Organisms of all species
reproduce.
 They may reproduce sexually or
asexually.
Asexual Reproduction
 In asexual reproduction a single organism
gives rise to offspring with identical
genetic information.
 The cells of the human body, other than
those found in male and female
reproductive organs, reproduce asexually
by mitosis.
Sexual Reproduction
 In sexual reproduction genetic
information from two cells is
combined to produce a new
organism.
 Sexual reproduction occurs when
two specialized sex cells unite to
form a fertilized egg called a
zygote.
 * Note: Some organisms use both
methods of reproduction.
 Example: Bacteria – able to
exchange genetic information in a
form a sexual reproduction.
 Most plants reproduce sexually, in
the process that results in seeds.
Binary Fission
 In binary fission, the organism splits directly
into two equal sized offspring, each with a
copy of the parent’s genetic material.
Budding
 In budding, the offspring begins as a small
outgrowth from the parent.
 Eventually, the bud breaks off from the
parent, becoming an organism on its own.
 Budding occurs in some single-cell
organisms such as yeast.
Hydra
Fragmentation
 In fragmentation, a new organism is formed
from a part that breaks off from the parent.
 Many types of algae and some animal and
plants can reproduce this way.
 If a starfish is cut through its central disk,
each section will develop into a new starfish
that contains identical genetic information.
Spore Formation
 In spore formation, the organism undergoes
frequent cell division to produce many similar,
identical cells called spores.
 The spores are usually housed within the parent
cell.
 Many spores have a tough, resistant coating that
allows them to survive after the parent cell dies.
 Example: Penicillium mould reproduces by
forming spores.
 Each spore can develop into a mature organism.
Vegetative Reproduction
 Many plants make use of vegetative reproduction by
producing runners that can develop into another plant.
 Example: Spider Plant and strawberries
A child frozen in time
http://www.youtube.com/watch?v=apoyqV1QRIk
Fragmentation
http://www.youtube.com/watch?v=d5dOSyaKWTQ
Binary Fission
http://www.youtube.com/watch?v=Th4v_Q1iHfY
Spore Formation
http://www.youtube.com/watch?v=t47BPcQ9krA
Asexual Reproduction
 http://www.youtube.com/watch?v=jk2RJm5RBEk
Budding
http://www.youtube.com/watch?v=ztPAGISkO7E
Chapter 6: DNA The Genetic Material
 DNA is the genetic material found in the
chromosomes of a cell.
 It contains all of the information that
determines how cells function and respond
to their environment.
 DNA is one of the very few molecules
capable of duplicating itself.
What makes Humans different
from other organisms?
 A look at a human cell as it divided would
show that humans have 46 chromosomes.
 A dog has 78 chromosomes and a mouse has
40.
 Something that is the same with all living
beings, whether it is an eagle, mouse, toad,
or fish is that all chromosomes are
composed of the same chemical,
deoxyribonucleic acid, DNA.
 DNA provides the directions that guide the repair of worn
cell parts and the construction of new ones.
 DNA describes how cells will respond to changes in their
environment and to messages from other cells.
What does DNA look like?
What DNA is made up of
 DNA is made up of a series of chemicals called
nitrogen bases.
 These nitrogen bases are used like letters or
characters in a code.
 DNA uses a four character code made up of the
nitrogen bases adenine (A), thymine (T),
cytosine and guanine (G).
 The order that the bases appear in is the code.
 The genetic code is arranged in what might be
described as “words” – three character sequences
of the nitrogen bases and those words combine to
form “stories” a complete description of a
molecule that can be read by the cell and used as
a blueprint to make that molecule.
What is a Gene?
 A gene is a long section of DNA that determines a
characteristic.
 Your hair color, skin color, and nose length are just some
of the things that genes do to make us all unique
individuals.
 This genetic code of life is stored in the 6 billion
nitrogen bases of DNA, arranged in about 100,000 genes
on the 46 chromosomes.
 If a single DNA from a single cell were stretched into a
line, its length would be greater than your height.
DNA Replication
Remember that before a cell
divides, each strand of genetic
information makes a duplicate.
The DNA molecule can make
perfect copies of itself in a process
called DNA replication.
DNA in Humans
 Humans have 46 chromosomes arranged in 23 pairs.
 One chromosome in each pair comes from your mother and
the other comes from your father.
 The chromosome from each parent carries the same genes,
so you have copies of each gene, but within each copy there
may be small differences in the code.
Example: All humans carry a set of genes that allows follicle
cells in our scalp to build hair. One gene determines the
structure of the hair. Curly, straight, etc.
DNA Video
 http://www.youtube.com/watch?v=zwibgNGe4aY
What are genes?
http://www.youtube.com/watch?v=5MQdXjRPHmQ
DNA Video
 http://www.allaboutscience.org/dna-double-helix-
video.htm
 http://video.google.ca/videosearch?hl=en&q=DNA%20Vi
deo&um=1&ie=UTF-8&sa=N&tab=wv#
6.2 DNA, Mutations and Cancer
 DNA floats in solutions that contain many
chemicals that come from outside the cell and
may be harmful.
 DNA may be exposed to radiation from the Sun
or to viruses which can cause changes to the
sequence of nitrogen bases.
 Changes in the genetic code are called
MUTATIONS.
 Mutations of cells and DNA is what leads to
cancer.
Cancer
 Cancer occurs when cell division goes out of control.
 Cancer cells can divide more quickly than they should.
 All cancers are caused by mutations in genes that regulate cell
division.
 Any substance or energy that causes a mutation of the gene is
called a carcinogen.
Example: Ultraviolet radiation from the sun
Cigarettes (cigarette smoke)
Cancer Cells
 Normal cells in multicellular organisms cannot
divide when isolated from one another.
 Cell to cell communication is essential for normal
cell division.
 With cancer cells, they can divide in isolation.
 Human body has many different types of cells that
each has a unique shape that carries out s
specialized function.
 http://hcd2.bupa.co.uk/fact_sheets/html/testicular_cancer
.html
 As the organism grows from a fertilized egg,
different clumps of cells specialize, forming nerve
cells, liver cells, or bones cells just to name a few.
 Unlike normal cells, cancer cells do not change
shape and do not specialize as they mature.
 Because cancer cells do not carry out the regular
functions of a normal cell they are inefficient.
They use up the energy and resources of the
other cells of the body to reproduce but do not
do the same work as normal cells.
Cancer Cells
 Cancer cells do not specialize. ( ex. Liver
cell)
 They do not do any of the work that a
normal cell would do.
 They serve no purpose in our bodies.
 They use up the energy and resources of the
other cells of the body to reproduce but do
not do the same work as normal cells.
Tumours
 Rapid cell growth can result in a mass of
cells called a Tumour.
 Harmless tumours are called BENIGN.
These tumors remain in a confined area
causing little damage to the organism.
 Dangerous tumours spawn cells that can
break away and move to other areas of the
body. These tumours are MALIGNANT.
Cancer Cells
 http://www.youtube.com/watch?v=8LhQllh46yI
 Cloning the Tasmanian Tiger
http://www.youtube.com/watch?v=sJL-_HutrsA
http://www.youtube.com/watch?v=y0yzqcIrCV0
http://www.youtube.com/watch?v=UMr862sv8OQ
Video
 http://streamingdigitalmedia.com/brain_tumour/stream/g
ene_chiarello.asx
Cloning
 Cloning is a natural process, repeated
daily in nature.
 The majority of organisms on earth
produce exact duplicates of themselves
by asexual reproduction.
 Cloning is the process of forming
identical offspring from a single cell or
tissue.
How are frogs cloned?
 Extract the nucleus from an unfertilized egg cell by inserting
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a fine glass tube into the cytoplasm.
The cell without the nucleus is called an “enucleated” cell.
Next, a nucleus from a frog embryo is in early stages of
development and extracted and then inserted into a
enucleated cell.
The egg cell with the transplanted nucleus begins to divide.
As the cell divides the frogs grows and eventually becomes a
full grown frog.
 What are the pros and cons of cloning?
 What ethical issues relating to cloning can
you think of?
 Imagine that farmers were able to easily
clone any animal in their herd or flock.
What might be the benefits for food
production?
Cloning Videos
 http://www.youtube.com/watch?v=7tbxN5uwaqA
 http://www.youtube.com/watch?v=AdPXF448mjs
 http://www.youtube.com/watch?v=OCro5zfc3uc
 http://www.guardian.co.uk/gall/0,,627251,00.html
 Celebrity Sheep Died at Age 6
Dolly, the first mammal to be
cloned from adult DNA died Feb.
14, 2003. Prior to her death, Dolly
had been suffering from lung cancer
and crippling arthritis. Although
most Finn Dorset sheep live to be
11 to 12 years of age, post
examination of Dolly seemed to
indicate that, other than her cancer
and arthritis, she appeared to be
quite normal. The unnamed sheep
from which Dolly was cloned had
died several years prior to her
creation.
 http://www.howstuffworks.com/cloning.htm
Sexual Reproduction
 Sexual Reproduction is common among
multicellular organisms.
 In sexual reproduction genetic information
from two cells is combined to form the
genetic code for a new organism.
 In complex animals it involves two
specialized sex cells, a sperm and an egg
that combine to form a zygote.
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8.
9.
Copy down the concept map of reproduction on page 202.
What is sexual reproduction?
What is Conjugation? Give an example of where it is used?
What is a Hermaphrodite? What type of species reproduce
this way?
What is meant by “Separate Sexes” as a way of
reproduction?
What is the Diploid chromosome number.
What is the Haploid chromosome number.
What are Aphids? What way do they reproduce?
What are Somatic cells. Found on page 206.
 Sexual reproduction produces new combinations of genes
that may allow organisms to adapt better to a given
environment.
 Offspring in sexual reproduction are not identical to each
parent or usually not identical to each other.
Questions to think about.
 How do the offspring produced by sexual reproduction
resemble the original organisms?
 Why might the offspring of an organism that reproduces
sexually might be able to adapt better to a new environment
than offspring of an organism that reproduces asexually?
Conjugation
 In Conjugation, two cells come in contact with each
other and exchange small pieces, but rarely all, of their
genetic information.
 Bacteria who normally reproduce asexually through
binary fission may also reproduce sexually through
conjugation.
 If the genetic material that is exchanged includes genes
that allow the bacteria to survive in a new environment,
both of the cells will now be able to survive in the
environment.
 Conjugation increases the diversity of bacteria species.
Hermaphrodites
 An organism that can create both male and
female sex cells is called a Hermaphrodite.
 Examples: tomato plants, sponges, and
earthworms.
 They contain male sex cells that produce
sperm and female sex organs that produce
eggs.
 Hermaphrodites can reproduce with any
other member of their species.
Separate Sexes
 Males are determined by their
chromosomes, X and Y.
 X comes from the mother,Y comes
from the father.
 Females have a pair of X chromosomes
in each cell.
 External Fertilization is when sex cells
unite outside the female’s body. For
example, female fish release their egg cells,
and the male releases the sperm.
 Internal fertilization - sperm meets the
egg inside the body.
Aphids
Organisms that survive by sucking
juices from plants.
If you look at the underside of new
leaves or buds of a plant in the
summer, more than likely you will
see a mass of tiny green or brown
organisms.
Meiosis
 Meiosis is the process that forms sex cells.
 During meiosis the chromosome number is reduced in
half.
 Example: A human cell containing 46 chromosomes
undergoes meiosis to produce sex cells that have 23
chromosomes.
 46 chromosome number is referred to as the diploid
chromosome number. Written as 2n
 23 chromosome number is referred as the haploid
chromosome number and is written as “n”
 Organisms that reproduce sexually show a greater range in
their characteristics than organisms that reproduce asexually.
 Because the male and female sex cells come from different
individuals in most species, sexual reproduction ensures a
recombination of genes.
 Chromosomes that are similar in shape, length and gene
arrangement are called homologous chromosomes.
 Your appearance is determined by the way the genes from
your homologous chromosomes interact.
Stages of Meiosis
 Cells that reproduce by normal cell division
and mitosis are called Somatic cells.
 Example: skin cells and muscle cells.
 Reproduction cells produce sex cells that
contain only half the number of chromosomes
through the process of Meiosis.
Meiosis involves two cell
divisions that produce four
haploid cells.
 Do questions p. 197 # 1, 3
How do you clone animals. Describe the process.
Do questions p. 205 # 1 – 4
Do questions p. 207 # 1-5
Zygote Development
Strategies for the Survival of Offpring
Spores - A spore is a reproductive body
covered with a protective shell. If
environmental conditions are not good for
life, the organism may produce spores that
enter a state of suspended animation. Once
conditions are good, the spores germinate
and enter into a growth phase.
Seeds – A seed contains the plant embryo wrapped
in a protective package that contains food. Seeds
bring nutrients to their environment that help them
get a head start on growth.
The Simple Microscope
 The simple microscope has only one
lens between the object and the eye.
Transmission Electron Microscope
Microscope
Compound Light Microscope
 An important advance in the development of the microscope
came when scientists added a second lens to the simple
microscope.
 An image magnified 10x by the first lens and 10x by the
second lens could be viewed as if it were 100x larger.
The Microscope
 A microscope is a tool used by scientists to make things
appear larger than they really are.
 You can use a microscope to look very closely at things
or to magnify things that are very small.You can see
things many times larger than actual size.
 The power of a microscope is described with a number
followed by the letter "x". For example, if through a
microscope you can see something 25 times larger than
actual size, its magnification power is 25x.
 With most microscopes you can change lenses to
increase or decrease magnification power.
Transmission Electron Microscope
 Used in order to see very tiny viruses or the
detail within a human cell.
 Today, transmission electron microscopes
are capable of 2 000 000x magnification.
 Instead of light, the electron microscope
uses beams of electrons.