2.1 Plant and Animal Cells
pg. 29
Biology – The study of living organisms and life processes.
How do you know if something is alive?
To answer this question, you must examine the characteristics of
living things. Before it can be classified as living it must express
these seven characteristics:
a) Living things are composed of CELLS
b) Living things require ENERGY
c) Living things produce WASTES
d) Living things RESPOND TO THE ENVIROMENT
e) Living things GROW and REPRODUCE
f) Living things produce OFFSPRINGS
g) Living things have a LIFE SPAN
The Cell Theory states:
1. All living things are made up of cells.
2. All cells come from pre-existing cells.
3. The cell is the smallest entity to express the characteristics of
life.
Prokaryote: is a cell that does not contain a nucleus or other
membrane – bound organelles.
Eukaryote: is a cell that contains a nucleus and other organelles,
each surrounded by a thin membrane.
Cell Structure
Eukaryotic cells are made up of specialized parts called organelles,
which carry out specific functions necessary for life.
Organelle: is a cell structure that performs a specific function for
the cell.
Structures Common to Plants and Animal Cells
All cells must perform the same basic activities to stay alive:
Use energy, store materials, take materials from the
environment, get rid of wastes, move substances to where
they are needed, and reproduce.
Each organelle has a specialized function in the cell, the various
organelles work together to meet the needs of the cell, and the
whole organism.
Figure 2: Plant and animal cells have many of the same organelles, but there are some
differences.
Cytoplasm: jelly like liquid that is mostly water, which suspends
organelles, stores many substances need by the cell, and where
many chemical reactions occur.
Cell Membrane: made up of a bi-layer of phospholipids molecules,
which is very flexible and will not break. The function is to control
what enters and leaves the cell, it allows some items to pass, such
as; water and stops other, such as; proteins. Therefore the
membrane is said to be semi - permeable.
Nucleus: The nucleus contains the genetic information which
instructs the cell on it cellular activities. Chromosomes are made
up of DNA (deoxyribonucleic acid), is the coded information that
controls cellular activities. Each cell must have a complete set of
chromosomes, 23 pairs (46) for human cells.
Mitochondria: is the „power plant‟ of the cell. This organelle is
responsible for cellular respiration, producing ATP, which used by
the cell as an energy source. Cellular respiration uses glucose and
oxygen as reactants and produce carbon dioxide and water as waste
products and ATP.
Glucose + Oxygen → Carbon dioxide + Water + ATP
Golgi Bodies: (Golgi apparatus) are responsible for collecting and
processing materials (proteins). Golgi bodies are also responsible
for producing and secreting mucus.
Vacuoles: is a fluid filled sac, and have various functions within
the cell. The containing some substances, removing unwanted
substances from the cell, and maintain internal fluid pressure. .
Organelles in Plants Cells Only
Plant cells have the same structures as animal cells, but also have
some additional organelles.
Cell Wall: surrounds the outside of the plant cell. It is made up of
cellulose and maintains the rigid shape of the cell and is porous to
substances. The cell wall supports the cell and protects it from and
physical injury.
Central Vacuoles: one or two large vacuoles, which take up most
of the internal space of the cell. They maintain turgor pressure and
the keeps the cell plump. If water level drops the plant becomes
flaccid because of a loss of turgor pressure, and begins to wilt.
Chloroplasts: are specialized organelles found in plants
responsible for photosynthesis. These organelles contain a green
pigment called chlorophyll, which captures light energy.
Light energy + Water + Carbon dioxide → Oxygen + Glucose
Check Your Learning, questions 1 – 8, pg. 32
2.3: The Importance of Cell Division
pg. 36
How does a single cell created through fertilization, become a fullgrown multicellular plant or animal?
Cell Division for Reproduction
The ability to reproduce is an important characteristic of all living
things.
All cells, singled celled and multicellular organisms, use cell
division to reproduce. The parent cell produces two daughter cells,
carrying the exact same genetic information to that of the parent
cell. This type of reproduction is called asexual reproduction.
Asexual Reproduction: is the process of producing offspring from
only one parent; the production of offspring that are genetically
identical to the parent.
Multicellular organisms also reproduce to pass their genetic
information along to their offspring. Some reproduce through
asexual reproduction, while other reproduces through sexual
reproduction.
Sexual Reproduction: is the process of producing offspring by the
fusion of two gametes; the production of offspring that have
genetic information from each parent.
The cell from one parent must fuse to one cell from another parent.
The cells used to produce a new individual must contain only half
of the DNA compared to a normal cell.
These cells are produced by each parent are called sex gametes,
female an ovum and male a sperm. These sex cells are created
through a produce called Meiosis.
Cell Division for Growth
Organisms grow, and the number of cells which they are made up
of increases. Cells don‟t just increase in size, but increase in
number.
All cells require energy, nutrients, water, and oxygen to survive.
Chemicals that enter or leave a cell must be dissolved in water,
creating a solution. These chemicals are used in chemical reactions
that occur within the cell cytoplasm.
The chemicals used during cell activity and growth enter the cell
by passing through a cell membrane. This movement occurs
through a process of diffusion. The chemicals move from an area
of high concentration to an area of low concentration with
expending energy by the cell.
Waste products move in the opposite direction when leaving the
cell, by the same process.
Diffusion: is a transport mechanism for moving chemicals into and
out of the cell, from an area of higher concentration to an area of
lower concentration.
Concentration: is the amount of a substance (solute) present in a
given volume of solution.
Osmosis: is the movement of fluid, usually water, across a
membrane toward an area of high solute concentration.
Cell Division for Repair
Everyday your body sheds millions of dead cells, which are
replaced by new ones. Red blood cells are replaced every 120 days.
All organisms need to repair themselves to stay alive.
Check Your Learning, questions 1 – 6, pg. 37
2.5: The Cell Cycle
pg. 40
Interphase: is the phase of the cell cycle during which the cell
performs its normal functions and its genetic material is copied in
preparation for cell division.
It is the longest stage of the cell cycle, and performs all the life
functions; growth, cellular reproduction and specialized functions.
The Cell cycle is broken into three parts; G1 – growth and
development, S – DNA Replication (synthesis), and G2 –
continued growth, cell functions and the preparation for cell
division.
Cell Divisions
Cell division occurs in two parts; Mitosis and Cytokinesis.
Mitosis: is the stage of the cell cycle in which the DNA in the
nucleus, is divided; the first part of cell division.
Mitosis consists of four phases, Prophase, Metaphase, Anaphase
and Telophase (PMAT).
Prophase: is the first stage of mitosis, in which the chromosomes
become visible and the nuclear membrane dissolves.
The chromosomes, long strands, short and thicken into a compact
form. They have already replicated, and are known as chromatid
sister pairs, which are held together at their centromeres. The
nuclear membrane disappears and allows the chromatids to freely
float in the cytoplasm.
Chromosomes: are structures in the cell nucleus made up of a
portion of the cell‟s DNA, condensed into a structure that is visible
under a light microscope.
Chromatid: is one of two identical strands of DNA that make up a
chromosome.
Centromere: is the structure that holds chromatids together as
chromosome.
Metaphase: is the second stage of mitosis, in which the
chromosomes line up in the middle of the cell.
The chromatids align along the equator, and it appears to have
spindle fibres attached to their centromeres which also run to the
opposite poles, attaching to the centrosomes (centrioles).
Anaphase: is the third phase of mitosis, in which the chromosomes
split at their centromeres and sister chromatids separate into
daughter chromosomes, and appear to be pulled by the spindle
fibres, each moving toward opposite ends of the cell (poles).
Telophase: is the final phase of mitosis, in which the chromatids
unwind and a nuclear membrane reforms around the chromosomes
at each end of the cell.
Cytokinesis: is the stage in the cell cycle when the cytoplasm
divides to form two identical cells; the final part of cell division.
Daughter cell: is one of two genetically identical, new cells that
result from the division of one parent cell.
Cell Division – The Big Picture
Figure 6: The stages of cell division
Checkpoints in the Cell Cycle
At each checkpoint, specialized proteins monitor cell activities and
the cell‟s surroundings. Messages are sent to the nucleus which
then determines when the cell will divide.
The cell will remain in interphase and not divide if;
* Signals from the surrounding cells tell the cell not to divide.
* There are not enough nutrients to provide for cell growth.
* The DNA within the nucleus has not been replicated.
* The DNA is damaged.
Damaged cells are usually destroyed, if they can not be repaired.
Check Your Learning, questions 1 – 7, pg. 44
2.7: Cell Division Going Wrong: Cancer
pg. 48
Cancer is a group of diseases I which cells grow and divide out of
control. Cancer is caused when the DNA has changed and the cell
not longer stays in interphase for the normal time period. Finally
one or more checkpoints have failed.
All organisms can develop cancer if their DNA is modified.
Environmental factors, chemical pollutants, UV rays, and radiation
are some factors that can cause cancer. Some cancers are
genetically inherited, but cancer can not be caught from some one
who has it.
Cell Growth Rates and Cancer
Cancer occurs when the cell uncontrollably divides and
checkpoints fail to stop the dividing. This uncontrolled division
causes rapid cell mass growth, known as a tumour.
Tumour: is a mass of cells that continue to grow and divide
without any obvious function in the body.
Benign tumour: is a tumour that does not affect surrounding
tissues other than by physically crowding them.
Malignant tumour: is a tumour that interferes with the functioning
of surrounding cells; a cancerous tumour.
The original (primary) tumour is located in one spot and when
some tumour cells break away and move to a different location in
the body. At the new location the tumour begins to grow and
causes cancer at this new location.
Metastasis: is the process of cancer cells breaking away from the
original (primary) tumour and establishing another (secondary)
tumour elsewhere in the body.
Figure 1: A tumour is a mass of cells with no function. A tumour can remain benign, or
it can become malignant. Tumour cells can metastasize, spreading to other areas of the
body. Malignant and metastatic tumours are considered cancerous.
Causes of Cancer
When cells divide, the DNA is replicated (exact copy of the parent
DNA), and the process is error free. When errors occur in the DNA
it is known as a mutation. The cells may die, but if they live and
replicate, they copy the error DNA and pass it on to the daughter
cells.
Mutation: is the random change in the DNA.
Cancer cells will continue to grow out of control, until all nutrients
are used and the surrounding healthy cells die.
Carcinogen: is any environmental factor that causes cancer.
Environmental factors, such as; Tobacco smoke, radiation (X-Rays
and UV Rays), some viruses (papillomavirus HPV and Hepatitis
B), certain chemicals in plastics, and many organic solvents.
Smoking and Cancer
Lung cancer is the most common type of cancer in Canada for
individuals over 40 years of age. Smoking is the cause 9 out of 10
cases of lung cancer. Smoking is also a contributing factor in a
dozen other types of cancer. Lung cancer can be prevent by not or
giving up smoking in the first place, second hand smoke is also
dangerous.
Figure 3: The carcinogens in tobacco smoke can affect all of these parts of the body.
Cancer Screening
Cancer screening means checking for cancer even if there are no
symptoms. Screening can be done at home, medical checkups, or
special appointments. Screening is even more important for people
with a family history of cancer.
Females – Pap test – used regularly to detect for early signs of
cervical cancer.
Males – PSA test – used to detect prostate cancer.
Skin checkups by the doctor or dermatologist are important, to
look for changes in moles, new growths, and sores, to prevent
cancer.
The “ABCD of Moles”: A – Asymmetry, B – Border, C – Colour,
D – Diameter.
[See Table 1: The ABCD of Moles, Benign vs. Malignant, page 50.]
Reducing Your Cancer Risk
Cancer prevention and early detection are very important. The
risks include personal, family medical history, carcinogens in your
environment, and life style choices. You can make life style
changes, which can have a big impact o you likelihood of getting
cancer.
Lifestyle Choices
You can reduce you risk of catching cancer getting eating a healthy
diet, including more fruits, vegetables, and decreasing fatty meat
intake. Super foods contain substances that help protect your body
from cancers. These foods only lower the chance of getting cancer,
it does not prevent cancer.
Figure 4: These cancer-fighting “super foods” are rich in many substances that help keep
you healthy.
Diagnosing Cancer
Imaging Technologies
Treatments for Cancer
Cancer treatment tries to slow down the growth of tumours, or
destroy as many cancer cells as possible. There are three main
methods for treating tumours.
Surgery: physically removing the cancerous tissue, and is
sometimes preferred.
Chemotherapy: The method uses drugs to combat the tumour, by
slowing or stopping the cancer cells from dividing and spreading to
other parts of the body. The drugs can be injected or taken orally.
There are side effects are; hair loss, nausea, and fatigue. The
benefits are greater then the side effects.
Chemotherapy is the first stages of cancer treatment. It will shrink
the tumour prior to surgery.
Radiation: Ionizing radiation kills cells, by preventing its ability to
divide. The radiation must be directed at the tumour using a
focused beam.
Check Your Learning, questions 1 – 10, pg. 55
2.9: Specialized Cells
pg. 58
Specialized Cell – is a cell that can perform a specific function.
The Cell Theory states:
1. All living things are made up of cells.
2. All cells come from pre-existing cells.
3. The cell is the smallest entity to express the characteristics of
life.
A single cell follows the cell cycle. During mitosis the nuclear
material is divided up equally. Cytokinesis occurs and the
cytoplasm and its organelles are divided up amongst two new
daughter cells.
This process ensures that the two daughter cells are exact copies of
the parent cell.
In a single cell, there are organelles found within the cytoplasm
that perform specific functions, which support the health of the cell.
In organisms, there are specialized cells that perform specific
functions to support the health of the organism. Cells do not do
every job at once. Certain cells are designated to perform one
singular function. These cells perform their one job very well, and
other specialized cells perform their jobs also. The combination of
each job (types of cells) maintains the health of the organism.
These specialized cells are instructed by their genetic material to
perform one task. These cells can not do anything else. The cells
changes physically and chemically to perform their role and they
look different from other cells.
Animal cells show a wide variety of specialization.
Muscle Cells – Muscle fibres have a high concentration of
Mitochondria. These cells perform a lot of work. (contractions)
Red Blood Cells – are responsible for carrying oxygen to the cells.
They have a special protein called hemoglobin which allows them
to increase their oxygen carrying capacity by 70 X.
Bone Cells – have a high concentration of calcium. This mineral is
needed to repair bones and build bones.
White Blood cells – These cells are responsible for your immune
system. They engulf foreign invaders.
Nerve Cells – long and thin cells responsible for transporting nerve
singles to coordinate body activity.
Red Blood Cells
Muscle Cells
Fat Cells
Nerve Cells
Plant Cells also have specialization.
Guard Cells – are responsible for opening a closing the stomata.
Mesophyll Cells – contain an organelle called a chloroplast. The
chloroplast contains chlorophyll pigment. This is the primary sight
of photosynthesis.
Epidermal Cells – the outer layer of plants. This is a protective
layer. It prevents disease from entering the plant.
Epidermal Cells
Xylem Cells
Check Your Learning:
Photosynthetic Cells Phloem Cells
Questions 1 - 6
pg. 60