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THE NATURE OF
LIVING THINGS
Chapter 20
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
BIOLOGY
What
alive?
 1.
makes something
metabolic processes
 2. generative processes
 3. responsive processes
 4. control processes
 5. unique structure
1. METABOLIC PROCESSES




Chemical reactions, energy
changes
1. Nutrient uptake
 Autotrophs
 Heterotrophs
2. nutrient processing
3. waste elimination
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2. GENERATIVE PROCESSES


Individual Growth
 Add to
 Structure
 Repair
 Store nutrients
Reproduction
 Asexual
 Sexual
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3. RESPONSIVE




PROCESSES
Respond to changes in their
bodies and their
surroundings
1. Irritability
 Response to stimulus
2. Individual adaptation
3. Population adaptation
 Evolution
4. CONTROL PROCESS



Makes sure everything in carried
out in the right way
1. Coordination
 Chemical pathways are
coordinated and linked
 Enzymes – proteins that run
these pathways
2. regulation
 The pathways run at a proper
rate
 Homeostasis – maintain a
constant internal environment
STRUCTURAL SIMILARITIES





Cells – basic units of life
 Unicellular
 multicellular
Tissues – similar cells working
together
Organs – groups of tissues
Organ systems
Individual
EARLY CELL THEORY
 Anton
van
Leeuwenhoek
(1632-1723)
 First to see
individual
cells
 Called them
“animalcules”
LEEUWENHOEK’S
MICROSCOPE
THE CELL
 Robert
Hooke
(1635-1703)
 Studied thin
slices of cork
 Termed the
structures
“cells”
CELL THEORY
Schleiden
and Schwann
All
living things consist of
cells or products of cells
Living
cells only come from
living cells
FIVE COMMON TRAITS OF
CELLS:
1.
2.
3.
4.
5.
Cell membranes
Cytoplasm
Genetic material
Energy transfer molecules
Enzymes and coenzymes
TWO
MAJOR
CELL
TYPES
FOUND IN
ALL LIVING
THINGS
PROKARYOTIC (BACTERIA)

Cell wall
Capsule
 Fimbriae (Pili)
 Flagellum

Cell (Plasma)
membrane
 Cytoplasm
 Plasmids
 Nuclear region with
DNA (Nucleoid)
 Ribosomes

EUKARYOTIC (ALGAE, PROTOZOA,
FUNGI, PLANTS, ANIMALS)

Cell Wall (maybe)
Flagellum
 Cilia

Cell Membrane
 Cytoplasm
 Nucleus
 Ribosomes
 Organelles

1. CELL WALLS
 Rigid
, solid (sort of) layers of
material – certain molecules are
able to get through
 Strength and protection, but no
flexibility
 Cell wall materials:
 Cellulose (plants)
 Chitin (fungi)
 Peptidoglycan (bacteria)
2. CELL MEMBRANES
Cell membrane is composed of a bi-layer of
phospholipids studded with proteins
 Phospholipid - molecule made of glycercol and fatty
acids
Fatty acid end - hydrophobic (insoluble
in water)
Glycerol end - hydrophilic (soluble in
water)
Proteins - (various functions)
Cholesterol – helps keep the shape of
membrane
Carbohydrates – interactions with other
cells

CELL MEMBRANE
CELL MEMBRANE
FUNCTIONS
Shape
 Taking up and releasing of
molecules
 Sensing stimuli
 Attaching to other cells and
objects
 Identifying self/non-self

DIFFUSION

Movement of molecules from a place of high
concentration to a place of lower concentration



Passive process (no energy needed)
Must be no barrier to stop motion
Rate of diffusion related to kinetic
energy, size of molecules,
concentration
Dynamic Equilibrium - when molecules are
equally distributed and movement is equal in all
directions
 In the case of the cell:


Membrane does not influence direction
DIFFUSION IN CELL
OSMOSIS

Movement (diffusion) of water
molecules through a selectively
permeable membrane separating
two solutions
 Passive movement from an area
of higher concentration to an
area of lower concentration
 Selectively Permeable
Membrane -- only certain
molecules can pass through)
Amount of water in a cell is
critical!
Too much can dilute cell contents and interfere
with the chemical reactions
 Too little can cause buildup of waste products
 Different types of Solutions:

Isotonic solution: water and dissolved
mineral concentrations in cell equal to
surroundings
 Hypertonic solution: more solutes, less
water
 Hypotonic solution: more water, less
solutes

SOLUTIONS
3. NUCLEUS
 “Brain”
of the cell
 Nuclear Membrane
 Separates nucleoplasm from cytoplasm
 Nuclear pores allow molecules to pass
in and out of nucleus
 Nucleolus
 Used in manufacture of ribosomes
 DNA – Deoxyribonucleic Acid
 Chromatin – uncondensed, stringy DNA
 Chromosomes – condensed DNA
NUCLEUS (ELECTRON MICROSCOPE)
4. ENDOPLASMIC RETICULUM (ER)
One
of the larger structures
seen in a cell
Set of folded membranes
providing a large surface area
for chemical reactions to occur
Rough ER has ribosomes
associated with it’s surface
“Manufacturing Plant” of cell
5. GOLGI APPARATUS
Flattened smooth membranous sacs (resembling
stack of pancakes)
 Site of synthesis, packaging and release of
certain molecules
 Enzymes converted from inactive to active form
and packaged
 Vesicles pinched off to form lysosomes
 “UPS” of the cell

6. MITOCHONDRION
Small bean shaped
Folded inner surfaces called cristae
Up to 10,000 or more per cell
Involved in aerobic cellular respiration
Aerobic cellular respiration – reactions
(in oxygen) involved in release of
energy from food molecules
Produces ATP (Adenosine
Triphosphate)
“Powerhouse” of the cell
7. CHLOROPLASTS

Found only in plants and algae





Light energy converted to chemical
bond energy through photosynthesis
Photosynthesis – process of using
sunlight to produce sugar
Thylakoids – small green discs
containing chlorophyll
Grana – stacks of thylakoids
Stroma – space around grana
NON MEMBRANOUS ORGANELLE
• Ribosome
– Very small structure
– Two main parts - subunits
– Composed of Ribonucleic Acid (RNA) and
proteins
– Made in the nucleolus
– Function in protein manufacture
– Can be found free in the cell and also can be
found associated with ER (rough)
– Do we need a lot of protein?
• YES!!!! So we need lots of ribosomes
RIBOSOME
AEROBIC CELLULAR RESPIRATION
Cells need lots of energy
 Series of chemical reactions (in O2) in which
glucose is broken down into carbon dioxide,
water and energy (ATP)

Process controlled by enzymes
 Glucose bonds contain chemical
potential energy
 Chemical bond energy from glucose
released to the cell in the form of ATP
(adenosine triphosphate)
 ATP powers metabolic activity of cell

CELLULAR RESPIRATION
C6H12O6 + 6O2
 (glucose)
(oxygen)

Gives 
6CO2
(carbon)
dioxide
+ 6H2O + (ATP + heat)
(water)
(energy)
PHOTOSYNTHESIS
Process
in which plants, algae and some
bacteria transform light energy to
chemical bond energy
In algae and green plants, takes place in
chloroplasts
 chlorophyll - green pigment that absorbs
light, initiating the light-capturing
stage
PHOTOSYNTHESIS


6CO2
+ 6H2O + Sunlight + chlorophyll
(carbon)
(water)
dioxide
Gives 
C6H12O6 + 6O2 +
(glucose) + (oxygen) +
6H2O
(water)
DIFFERENCES BETWEEN PLANT
AND ANIMAL CELLS

Plants





Vacuoles
Chloroplasts
Make their own
food
Cell walls
No centrioles

Animals





No vacuoles
No chloroplasts
Have to consume
food
no cell walls
centrioles
CELL DIVISION

Why do cells divide?
To increase number of cells in the
body
Allows the organism to grow
 To maintain the body
Replace worn out cells
To repair damaged tissues

CELL DIVISION
 What
happens during cell division?
 Mitosis
Replicated genetic information
equally distributed to 2 daughter cells
 Cytokinesis (cell splitting)
Cytoplasm divides into two new cells
Each new cell gets one daughter
nucleus
Both cells have complete set of
genetic information
CELL CYCLE

Interphase
G1
 Synthesis
 G2


Mitosis

Prophase
 Metaphase
 Anaphase
 Telophase
Cytokinesis

INTERPHASE
ONION CELL
PROPHASE
ONION CELL
METAPHASE
ONION CELL
ANAPHASE
ONION CELL
TELOPHASE
ONION CELL
CYTOKINESIS
Cytokinesis in plant and animal
CELL DIVISION
Cancer: Cell division running amok!!!
Cancer is the condition in which cell growth is
uncontrolled and the cells produced are
abnormal.
These cells cannot function as “normal” cells.
Left unchecked, they will continue to divide, will
use up the energy available, and not contribute
to the organism as a whole.
Malignant tumor: cells can move throughout the
body (metastasize)
Ultimately, if not treated, cancer will result in
death of the organism.
Cancer’s Seven Warning Signs:







A persistent unexplainable change in bowel or
bladder habits
A sore that does not heal
Unusual bleeding or discharge
A lump or thickening in the breast or
testes…or elsewhere
Persistent indigestion or difficulty in
swallowing
An obvious change in a wart or a mole
A nagging cough or hoarseness