Living Things
Characteristics of Living Things:
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Defining life is complicated. No one
characteristic definitively identifies an
organism as living.
Characteristics of Living Things:
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Some characteristics that living
things share:
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1)
2)
3)
4)
5)
6)
7)
8)
9)
Made up of cells
Reproduction
Based on Genetic Code
Metabolism
Motility
Responsiveness
Development / Growth
Living things Evolve
Living things are Adapted
Characteristics of Living Things:
1) Made up of cells: collection of living matter
enclosed in a barrier that separates the cell
from its surroundings
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Smallest unit of an organism that can be
considered alive. They grow, respond to
surroundings, and reproduce.
Living organisms can consist of one cell
(unicellular)
Larger and more complex organisms such as
animals are composed of many cells
(multicellular)
Cells can exist in many sizes, shapes, and
have different functions. Ex) the human body
is made up of over 85 different types of cells.
Characteristics of Living Things:
2) Reproduction: 2
basic types
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Asexual: the new
organism has a
single parent. EX:
single-celled
organisms dividing
in half to form two
Sexual: two cells
from different
parents unite to
produce the first
cell of the new
organism.
Characteristics of Living Things:
3) Based on Genetic Code
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Explaining how organisms
inherit traits is one of the
greatest achievements of
biology. We have used this
information to diagnose
diseases, to identify
suspects, and in determining
paternity.
The directions for inheritance
are carried on a molecule
called DNA.
Characteristics of Living Things:
4) Metabolism
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Sum of all chemical
reactions within a
cell or organism.
These chemical
reactions will require
energy.
Organisms must get
energy from the
environment either
by eating food and
then breaking it
down or using
sunlight to create
food and then
breaking it down.
Characteristics of Living Things:
5) Motility
 Self –propelled motion.
 This helps organisms collect food and escape
predators
 ** remember not all living things posses all 9
characteristics.
Characteristics of Living Things:
6) Responsiveness
 Responding to
stimuli is one of
the most basic
properties of life.
 Stimuli can be
anything from
chemicals to
temperature to
touch as long as it
the presence of
the stimuli created
a response.
Characteristics of Living Things:
7) Development / Growth
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Ordered sequence of
progressive changes
that result in increased
complexity
Increase in size
Development of new
physical structures
Refinement of
reasoning and
behavior
Characteristics of Living Things:
8. Living things Evolve
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Living things adjust to environmental changes
through biological changes over time
Evolution provides new ways for organisms to use
energy, maintain order, and perpetuate
themselves.
Occur slowly over the course of many generations
Characteristics of Living Things:
9. Living things are Adapted
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Specific structures and
behaviors that allow
organisms to survive in its
own environment
Increase the individual’s
ability to combat
disorganization and
improve the chance of
perpetuating into the
future
Life Processes
 Nutrition
– use of nutrients by an organism
 Digestion – process that breaks down large
food molecules into forms that can be used
by the cell
 Absorption – ability of a cell to take in
nutrients, water, gases, and other substances
into and out of the cell
 Transport – movement of nutrients, water,
gases, and other substances into and out the
cell
Life Processes
 Biosynthesis
– cellular process of building
new chemical compounds for the purpose
of growth, repair, and reproduction
 Homeostasis – ability of an organism to
maintain a steady internal state
regardless of external influence
Life Processes
 Secretion
– release of substances from a cell
 Photosynthesis – cellular process in which a
plant makes food from water and carbon
dioxide using energy from the sun
 Respiration – release of energy from chemical
breakdown of compounds within a cell
 Excretion – ability of a cell to rid itself of
waste products
Discovery of the Cell
The People
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In 1665 Englishman
Robert Hooke used a
compound microscope
to look at thin slices of
cork. He saw
thousands of small
empty chambers he
called "cells" after the
small rooms of a
monastery.
The People
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In Holland around
the same time Anton
van Leeuwenhoek
used a single-lens
microscope to look at
pond water. He saw
hundreds of tiny
living organisms.
The People
In 1838 German
botanist Matthias
Schleiden concluded all
plants are made of
cells.
 In 1839 German
Biologist Theodor
Schwann said cells also
compose all animals.
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The People
In 1855 German
physician Rudolf
Virchow stated all
new cells were
produced from the
division of existing
cells.
 These conclusions
(confirmed by other
biologists) make up
the cell theory.
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The Cell Theory:
1) All living things are composed of cells
 2) Cells are the basic units of structure
and function in living things.
 3) New cells are produced from existing
cells.
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Exploring the Cell
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Compound light microscope:
uses two magnifying lenses
and a series of mirrors to
magnify an object. The total
magnification of looking
through two lenses at once
is found by multiplying the
magnification of each lens
together.
Problem with light
microscopes: limitation of
detail or resolution because
light radiation is diffracted
(scattered) as it passes
through matter.
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Electron microscopes can produce
images 1,000 times smaller than light
microscopes because the wavelength of
electrons is shorter than that of light.
Transmission electron microscopes
(TEM): using a beam of electrons
allows us to see cell structures and
large proteins. However the beam can
only pass trough thin samples so the
object must be cut into ultra thin slices.
Scanning electron microscopes (SEM):
electrons are scanned over the object
producing 3D image. Organisms don't
have to be cut into thin stripes
Problems with electron microscopes:
Electrons are easily scattered by
molecules in the air so they have to be
used in a vacuum. As a result all
objects have to be preserved or
nonliving.
Cell Types
General
Characteristics
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Cells can vary greatly in size
from bacteria at 0.2
micrometers to amebas that
can be seen with the unaided
eye at 1000 micrometers.
Typically cells fall between 5
and 50 micrometers
Despite the variety of sizes,
shapes, and functions all
cells have two things in
common.
 All cells are surrounded by
a barrier called a plasma
membrane
 All cells contain DNA
Prokaryotic vs Eukaryotic
Cells are divided into two broad groups
based on whether or not they have a
nucleus. A nucleus is a large membrane
bound structure that contains genetic
material (DNA).
 Prokaryoctic: cells that do not have a
nucleus or any internal membranes.
 Eukaryotic: cells that contain a nucleus as
well as other internal membranes that
each perform a different function
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Prokaryotic
Since these cells
do not have
internal structures
that divide up tasks
they must stay
smaller and
simpler.
 Contains genetic
material not bound
by a nucleus. This
genetic material is
normally in the
form of rings called
plasmids.
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Both
All are
surrounded by a
cell membrane
 All contain DNA
and RNA
 Some cells are
capable of moving
using cilia or
flagella.
 All contain
ribosomes to make
proteins.
 All contain
cytoplasm and a
cytoskeleton.
 Some cells have
a cell wall.
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Eukaryotic
Generally larger
and more complex
 Many of these cells
are highly specialized
to perform single
tasks for the larger
organism (cell
specialization)
 Most contain
dozens of structures
bound by membranes
called organelles
 All contain a
nucleus which
separates the genetic
material from the rest
of the cell. There is
normally more DNA.
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Pieces of the Cell
Organelles Found in Both Prokaryotic and Eukaryotic Cells
• Plasma/cell membrane: regulates
what enters and leaves the cell,
provides protection, and support.
• Cell Wall: present in most plants,
some algae, fungi, and prokaryotic
cells (NOT ANIMAL CELLS). Located
outside the membrane. The cell wall
provides support and protection.
• Cytoplasm: Fluid that suspends the
structures of the cell and aids in
transport of materials
• Ribosomes: Synthesis proteins.
• Cilia: small hair like projections that
help the cell move or move material
across the membrane
• Flagella: long tail like projects. Same
function as cilia. Both are not
normally found in plant cells.
Organelles found in all Eukaryotic cells
• Nucleus: contains almost all the cell’s
DNA which controls cell functions (the
mitochondria and chloroplast have their
own DNA). The nucleus is surrounded by
the nuclear envelope which is composed
of two membranes full of nuclear pores
that allow materials to move in and out
of the nucleus. Most nuclei contain a
dense region known as the nucleolus.
This is where making ribosomes begins.
• Rough Endoplasmic Reticulum: series of
membranes that are covered in
ribosomes. It receives instructions from
DNA inside the nucleus, allows the
ribosomes to make the proteins, and
then transports them to the next
destination.
• Smooth Endoplasmic Reticulum: make
lipids
Organelles found in all Eukaryotic cells
• Golgi apparatus/complex: stacks of
membranes that modify, sort, and
package proteins made in the rough
ER for reactions or structures inside
the cell, or to be secreted out of the
cell
• Lysosome: structure made by the
golgi. They are filled with enzymes
that break down lipids,
carbohydrates, and proteins for the
cell to use. They also break down
old organelles and other waste to
be excreted.
• Vacuole: saclike structures used for
storage of water, salt, and nutrients.
In many plant cells there is one
large central vacuole that is filled
with liquid to provide structural
support for heavy leaves and
flowers
Organelles found in all Eukaryotic cells
• Mitochondria: converts
chemical energy stored in
food into a usable form of
energy for the cell by using
enzymes (made in the ER)
and chemical reactions to
break the food down. It is
enclosed in two
membranes and the inner
membrane is folded to
allow more surface area for
the reactions. They also
contain their own DNA
Organelles Found in Animal Eukaryotic Cells
• Centrioles: organelles that help the cell divide
• Remember that animal cells can have cilia and flagella
like a prokaryotic cell
Organelles Found in Plant Eukaryotic Cells
• Chloroplast: convert energy from the
sun into chemical energy stored in
the form of sugar through
photosynthesis. Chloroplasts are
surrounded by two membranes and
contain DNA. After the food is
created it will be moved to the
mitochondria for breaking down.
• Plant cells are also the only
eukaryotic cells to have a cell wall.
• Remember that the vacuole of plant
(one large vacuole) looks different
from the vacuole in an animal cell
(many small bubbles) and has the
added function of structural support.
Cell Transport of Materials
The Plasma Membrane Structures
 The plasma/cell membrane will control what enters and leaves the cell. In
order to achieve this function it is made up of several structures.
 Lipids: the plasma membrane is primarily made of two layers of lipids
(lipid bilayer) that maintain the boundary of the cell.
 Transport Proteins: imbedded in the membrane to create gaps in the
membrane for larger molecules to pass through.
 Receptor Proteins: attached to receive messages from other cells in the
form of hormones that communicate what the cell needs to be doing.
 Carbs: attached to the surface of the cell as a form of identification.
The Plasma Membrane Functions
 The membrane is selectively permeable
which means only certain things will be
able to go through the membrane.
 Cells exist in a liquid environment (inside
and out) so the materials that are going to
be moved are dissolved or suspended in
water
 There are two basic ways to move
materials across the cell membrane:
 Passive transport moves materials from
an area of high concentration to an area
of low concentration and requires no
energy.
 Active transport either moves extremely
large materials that are not capable of
going through the membrane or it move
materials from low concentration to
high concentration. This requires energy
from the cell.
Types of Passive Transport
 Diffusion: the movement of materials
that can fit though the membrane from
high to low concentration. This occurs
because molecules are in constant
motion. When they run into each other
they will ricochet off and move in
opposite directions causing them to
spread out into an area of low
concentration
 Osmosis: the diffusion of water
 Facilitated diffusion: a protein creates a
gap in the membrane in order to allow
larger particles to diffuse. These proteins
are very specific to only one type of
substance.
 Remember that all types of passive
transport require no energy.
Types of Solutions that Cause Osmosis
 Since water is small and can fit directly
through the membrane while most
molecules dissolved in water cannot,
water can be moved in an effort to create
equal concentrations on both sides of
the membrane.
 When cells are placed in solutions that
have different concentrations from the
internal environment of the cell it
creates osmotic pressure and the water
will move through osmosis to restore
equilibrium.
 Once an equal concentration is reached
particles that can move through the
membrane will continue to move
because particles never stop moving.
However there will be no change in the
concentration as particles will move
back and forth equally. This is dynamic
equilibrium.
Types of Solutions that Cause Osmosis
 If a cell is placed into a
solution with the same
concentration of dissolved
particles as what is inside
the cell, water will move
in and out of the cell at a
constant rate and the cell
will not change. This type
of solution is called an
isotonic solution.
Types of Solutions that Cause Osmosis
 If the cell is placed into a
solution that has a higher
concentration of dissolved
particles than what is
inside the cell, the water
inside of the cell will move
out of the cell and into the
solution in an effort to
dilute it so that the
concentrations are equal.
This will cause the cell to
shrink. This type of
solution is called a
hypertonic solution.
Types of Solutions that Cause Osmosis
 If the cell is placed into a
solution that has a lower
concentration of dissolved
particles than what is inside
the cell, the water in the
solution will move into the
cell in an effort to dilute it so
that the concentrations are
equal. This will cause the cell
to swell and possibly burst.
This type of solution is
called a hypotonic solution.
Types of Active Transport
 Active transport using proteins: transport
proteins can act as pumps by changing
shapes in order to force materials from an
area of low concentration to an area of high
concentration (against the concentration
gradient)
 Endocytoses: the cell can engulf or wrap
around particles that are too large to go
through a protein. Two types:
 Phagocytosis: engulfs solid particles
such as food
 Pinocytosis: engulfs liquids
 Exocytosis: releases materials from the cell
by having a vacuole fuse with the
membrane and release the contents to the
outside.