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Core Biology
Overview
Cells
Features of Life and
the Cell
Living Things and Their
Parts
 The word living is not easy to
define. Biologists recognize that
all living things share certain
features.
Features of Living Things
Reproduce
Grow
Develop
Need Food
Use Energy
Made of Cells
Respond
Adapt to
Environment
Reproduce
Reproduce
means to form
offspring
similar to the
parents.
Grow
Living things
grow by using
materials and
energy from
their
environment to
increase their
size.
Development
Development
is all the
changes that
occur as a
living thing
grows.
Need Food
All things that are
living need food.
Living thing can
either make their
own for or not.
Producers make their
own food.
Consumers eat
producers and
consumers.
Producers
Producers are
living things that
make or
produce their
own food.
Consumers
Consumers are
living things that
eat, or
consume, other
living things.
The Order of things
Living Things use Energy
Energy is the
ability of do
work.
Moving and
changing is the
work that living
things use
energy for.
Animals get
their energy
from the food
that they eat.
Plants get their
energy from
photosynthesis.
What is a cell?
 The CELL is the smallest unit of
matter that CAN Carry on ALL the
PROCESSES OF LIFE.
Who first used the
microscope?
 One of the First
Microscopes was made
by the Dutch drapery
store owner Anton von
Leewenhoek. With his
hand-held microscope,
Leewenhoek became
the FIRST person to
OBSERVE and
DESCRIBE
MICROSCOPIC
ORGANISMS and
LIVING CELLS.
Dead plant cells first?
 . In 1665, the English
Scientist Robert Hooke
used a microscope to
examine a thin slice of
cork and described it as
consisting of "a great
many little boxes". It
was after his observation
that Hook called what he
saw "Cells".
Three parts of Cell Theory
Cell Theory Contributers
 In 1838, German Botanist Matthias Schleiden studied a
variety of PLANTS and concluded that all PLANTS
"ARE COMPOSED OF CELLS".
 The next year, German Zoologist Theodor Schwann
reported that ANIMALS are also made of CELLS and
proposed a cellular basis for all life.
 . In 1855, German Physician Rudolf Virchow induced
that "THE ANIMAL ARISES ONLY FROM AN ANIMAL
AND THE PLANT ONLY FROM A PLANT" OR " THAT
CELLS ONLY COME FROM OTHER CELLS".
Are Cells alike?
CELL DIVERSITY
 Not all cells are alike. Even cells within
the same organism show Enormous
Diversity in Size, Shape, and Internal
Organization. Your Body contains at
least 200 Different Cell Types.
Example of large cell
CELL SIZE
 A few types of cells are large enough to
be seen by the unaided eye. The Female
Egg is the largest cell in the body, and
can be seen without the aid of a
microscope.
Can cells be any size?
MOST CELLS ARE SMALL FOR TWO REASONS:

#1 Cells are limited in size by the RATIO between
their Outer Surface Area and Their Volume. A SMALL
CELL HAS MORE SURFACE AREA THAN A LARGE
CELL FOR A GIVEN VOLUME OF CYTOPLASM. This
is important because the nutrients, oxygen, and other
materials a cell requires must enter through it
surface. As a cell grows larger at some point its
surface area becomes too Small to allow these
materials to enter the cell quickly enough to meet the
cell's need.
Cell Size Cont.
Cell Size cont.
 #2 THE CELL'S NUCLEUS (THE BRAIN)
CAN ONLY CONTROL A CERTAIN
AMOUNT OF LIVING, ACTIVE
CYTOPLASM.
Cell Shape
CELL SHAPE
 1. Cells come in a
variety of Shapes.
 2. Notice the neurons on
the wall, the basic cell of
our Nervous
System. This diversity of
form reflects a diversity
of function.
 3. Most Cells have a
Specific Shape.
Why a special shape?
 THE SHAPE OF A CELL DEPENDS ON
IT'S FUNCTION.
 Examples: Cells of the Nervous System
that carry information from your toes to
your brain are long and threadlike.
 Blood Cells are shaped like round disk
that can squeeze through tiny blood
vessels.
What is on the inside?
INTERNAL ORGANIZATION
 1. Cells contain a variety of
Internal Structures called
ORGANELLES.
 2. An organelle is a Cell
Component that PERFORMS
SPECIFIC FUNCTIONS FOR
THE CELL.
 3. Just as the organs of a
multicellular organism carry
out the organism's life
functions, the Organelles of a
cell Maintain the Life of the
Cell.
On the inside cont.
 4. There are many
different cells;
however, there are
certain features
common to all, or
most Cells.
What is on the outside?
 The entire cell is Surrounded by A THIN
MEMBRANE, called the CELL
MEMBRANE
What does the Nucleus
do?
 A Large Organelle
near the Center of
the Cell is the
NUCLEUS. IT
CONTAINS THE
CELL'S GENETIC
INFORMATION AND
CONTROLS THE
ACTIVITIES OF THE
CELL.
Layout of the Nucleus
Why else is the nucleus
important?
 The PRESENCE OR ABSENCE of a
NUCLEUS is important for Classifying Cells.
 ORGANISMS WHOSE CELL CONTAIN A
NUCLEUS AND OTHER MEMBRANE-BOUND
ORGANELLES ARE CALLED EUKARYOTES.
 ORGANISMS WHOSE CELLS NEVER
CONTAIN (OR LACK) A NUCLEUS AND
OTHER MEMBRANE-BOUND ORGANELLES
ARE CALLED PROKARYOTES.
What type of cell is
bacterium?
 UNICELLULAR ORGANISMS such as
bacteria and their relatives are
Prokaryotes.
 More on bacterium later…
Where are these cells
classified?
 The difference between Prokaryotes and
Eukaryotes is such an important
distinction that Prokaryotes are placed in
Two Kingdoms, Separate from
Eukaryotes.
Need to know more?...
More on the big difference.
THE CELL MEMBRANE
 A Cell cannot survive if it is totally
isolated from its environment. The Cell
Membrane is a complex barrier
separating the cell from it's external
environment.
Cell Membrane function
 The Cell Membrane Functions like a
GATE, Controlling what ENTERS and
LEAVES the Cell.
 This "Selectively Permeable" Membrane
regulates what passes into and out of the
cell.
 All cells, from all organisms, are
surrounded by a CELL MEMBRANE.
More Cell Membrane
 The Cell Membrane
is a thin layer of Lipid
and Protein that
separates the cell's
content from the
world around it.
SELECTIVELY
PERMEABLE
 The Cell Membrane CONTROLS the
ease with which substances pass into
and out of the cell-some substances
easily cross the membrane, while others
cannot cross at all. For this reason, the
Cell Membrane is said to be
SELECTIVELY PERMEABLE.
Cell Membrane makeup
 Cell Membranes are
made mostly of
PHOSPHOLIPID
MOLECULES.
Phosphate + Lipid.
Every thing you wanted to
know about PHOSPHOLIPID
MOLECULES
 Phospholipids are a kind of Lipid that
consists of TWO FATTY ACIDS (TAILS),
and PHOSPHATE GROUP (HEADS).
 A Phospholipid Molecule has a POLAR
"Head" and Two NONPOLAR "Tails".
 POLAR - The two ends of the
Phospholipid Molecule have different
properties in Water.
Properties in water
 The Phosphate Head is HYDROPHILIC
meaning "WATER LOVING". Because of its
hydrophilic nature, the head of a Phospholipid
will orient itself so that it is as close as possible
to water molecules.
 The Lipid Tails are HYDROPHOBIC meaning
"WATER-FEARING", the Hydrophobic tails will
tend to orient themselves away from water.
 When dropped in WATER, PHOSPHOLIPIDS
line up on the surface with their Phosphate
Heads Sticking into the Water and Lipid Tails
pointing up from the surface.
Take a look…
Passive transport
Passive Transport
Explained
 In passive transport
substances literally transport
themselves across the cell
membrane without the cell
expending energy.
Active Transport
Active Transport
Explained
 Active Transport is the opposite
of passive because it requires
energy from the cell.
 Movement of a substance
against a concentration
difference.
Diffusion
 Diffusion is a
process by which
substances
spread through a
liquid or gas.
 In diffusion things
move from high to
low concentration.
Osmosis Explained
Why bilayer?
 Cells are bathed in aqueous, or watery,
environment. Since the inside of a cell is
also an aqueous environment, both sides
of the Cell Membrane are surrounded by
Water Molecules. These Water
Molecules cause the Phospholipids of the
Cell Membrane to form TWO LAYERS.
Lipid bilayer
 Cell Membranes CONSIST of TWO
Phospholipid LAYERS Called a LIPID
BILAYER.
 Heads face the watery fluids inside and
outside the cell.
 Lipid Tails are sandwich inside the Bilayer.
Peripheral proteins
 A Variety of PROTEIN MOLECULES are
EMBEDDED in the Lipid Bilayer.
 Some Proteins are Attached to the
surface of the cell membrane, these are
called PERIPHERAL PROTEINS,
Integral proteins
 The Proteins that are Embedded in the
Lipid Bilayer are called INTEGRAL
PROTEINS.
 Some Integral Proteins extend across
the entire Cell Membrane and are
exposed to both the inside of the cell and
the exterior environment. Others extend
only to the inside or only to the exterior
surface.
Lets take a look…
Protein wrap up
 There are many kinds of Proteins in membranes;
they HELP to MOVE Material INTO and OUT of
the Cell.
 Some Integral Proteins form Channels or Pores
through which certain substances can pass.
 Other Proteins bind to a substance on one side of
the Membrane and carry it to the other side of the
Membrane.
 Integral Proteins exposed to the Cell's External
environment often have Carbohydrates attached to
them serve as identification badges that allow cells
to recognize each other and may act as Site where
viruses or chemical messengers such as
hormones can attach.
FLUID MOSAIC MODEL OF
CELL MEMBRANES
 Membranes are FLUID and have the consistency
of vegetable oil.
 The Lipids and Proteins of the Cell Membrane are
always in motion.
 Phospholipids are able to drift across the
membrane, changing places with their neighbor.
 Proteins in and on the membrane Form
PATTERNS, or MOSAICS.
 Because the Membrane is FLUID with a MOSAIC
of Proteins, scientists call the modern view of
Membrane Structure THE FLUID MOSAIC
MODEL
ORGANELLES
Where are organelles
found?
 1. EVERYTHING BETWEEN THE CELL
MEMBRANE AND THE NUCLEUS IS THE
CELL'S CYTOPLASM.
 2. CYTOPLASM consists of TWO MAIN
COMPONENTS: CYTOSOL and
ORGANELLES.
 3. CYTOSOL is a jellylike mixture that consists
MOSTLY OF WATER, along with PROTEINS,
CARBOHYDRATES, SALTS, MINERALS and
ORGANIC MOLECULES.
 4. Suspended in the Cytosol are tiny
ORGANELLES (ORGANS).
3 Organelles found in
plant cells but not animals
 Cell wall
 Large plastids
 Vacule
What is an organelle?
 Suspended in the Cytosol are tiny
ORGANELLES (ORGANS).
 ORGANELLES ARE STRUCTURES
THAT WORK LIKE MINIATURE
ORGANS,
THEY CARRY OUT SPECIFIC
FUNCTIONS IN THE CELL.
MITOCHONDRIA (MET-oh-KAHNdree-uh)
 THE "POWERHOUSE"
OF THE CELL.
 Mitochondria are the
sites of Chemical
Reactions that transfer
Energy from Organic
Compounds to
ATP. Energy contain in
food is released.
Converted to ATP. ATP
is the molecule that most
Cells use as their main
Energy Currency.
MITOCHONDRIA
 Mitochondria are Usually more numerous in
Cells that have a High Energy Requirement Your muscle cells contain a large number of
mitochondria.
 Mitochondria is surrounded by TWO
Membranes.

A. The smooth outer membrane serves as a
boundary between the mitochondria and the
cytosol.
MITOCHONDRIA part 2

B. The inner membrane has many
long folds, known as CRISTAE (KRIStee).
 The Cristae greatly increases the surface
area of the inner membrane, providing
more space for the Chemical Reactions
to occur.
RIBOSOMES (RIE-buhSOHMZ)
 Unlike most other organelles, Ribosomes
Are Not Surrounded by a membrane.
 Ribosomes are the site of PROTEIN
SYNTHESIS (Production or
Construction) in a cell.
ENDOPLASMIC RETICULUM
(ER) (EN-doh-PLAZ-mik riTIK-yuh-luhm)
 . The ER is a system of membranous tubules and sacs.
 The ER functions Primarily as an Intracellular
Highway, a path along which molecules move from one
part of the cell to another.
 The amount of ER inside a cell fluctuates, depending
on the Cell's Activity.
 Poisons, waste, and other toxic chemicals are made
harmless.
 ER is an extensive network of membranes that
connect the Nuclear Envelope to the Cell Membrane.
 Transports materials through the cell.
ENDOPLASMIC RETICULUM
(ER)
 Can be ROUGH OR
SMOOTH.

A. ROUGH ER is studded
with RIBOSOMES and
processes PROTEINS to be
exported from the cell.

B. SMOOTH ER IS NOT
Covered with RIBOSOMES
and processes LIPIDS and
CARBOHYDRATES. The
Smooth ER is involved in the
synthesis of steroids in gland
cells, the regulation of calcium
levels in muscle cells, and the
breakdown of toxic
substances by liver cells.
GOLGI APPARATUS (GOHLjee)
 1. The Golgi Apparatus is
the Processing, Packaging
and Secreting Organelle of
the Cell.
 2. The Golgi Apparatus is a
system of membranes.
Made of Flattened SAC
like Structures called
CISTERNAE.
 3. It works Closely with the
ER, the Golgi Apparatus
modifies proteins for export
by the cell.
LYSOSOMES (LIE-suhsohmez)
 1. Lysosomes are small spherical organelles
that enclose hydrolytic enzymes within a single
membrane.
 2. Lysosomes are the Site of Food Digestion in
the Cell.
 3. Lysosomes are formed from pieces of the
GOLGI APPARATUS that break off.
 4. Lysosomes are common in the Cells of
Animals, Fungi, and Protists, But Rare in Plant
Cells.
Cytoskeleton
 Cytoskeleton is
the supporting
framework of the
cell.
 Made of proteins
called
microtubules and
microfilaments.
MICROFILAMENTS
 MICROFILAMENTS
 1. MICROFILAMENTS are NOT HALLOW and
have a structure that resembles ROPE made of
TWO TWISTED CHAINS OF PROTEIN called
ACTIN.
 2. MICROFILAMENTS can CONTRACT, causing
movement.
 3. Muscle Cells have many microfilaments.
MICROTUBULES
 MICROTUBULES
 1. Microtubules are HALLOW TUBES like plumbing pipes.
They are the Largest Strands of the Cytoskeleton.
 2. Microtubules are made of a PROTEIN called TUBULIN.
 3. Microtubules have THREE FUNCTIONS:

A. To maintain the shape of the cell.

B. To serve as tracks for organelles to move along within
the cell.

C. When the Cell is about to divide, bundles of
Microtubules known as SPINDLE FIBERS come together
and extend across the cell to assist in the movement of
Chromosomes during Cell Division.
Vacuoles
 Storage, every
good factory
needs plenty of
storage for
materials.
 Vacuoles in plant
cells can store
water and other
items.
Overview of Animal Cell
Overview of Plant Cell
Summary of Animal cell
and function