Transcript Chapter 5: The Cell

Chapter 7: Cell
Structure and Function
Robert Hooke
(1635-1703)
• English Scientist
• First to use the
microscope to
observe cells
• Coined the term
“cell”
• Looked at cork
cells
Anton van Leeuwenhoek
1632-1723
• Dutch scientist
• Invented the
first compound
microscope
• First to observe
LIVING cells
• Blood cells and
protists
Robert Brown
1773-1858
• Scottish
botanist
• In 1831 he was
the first person
to observe the
nucleus of a cell
Schleiden & Schwann
1804-1881 1810-1882
Developing Cell Theory
1838
• Schleiden
• Said “all
plants are
made up of
cells”
• Schwann
• Said “all
animals are
made up of
cells”
Johannes
Purkinje
Rudolph
Virchow
• Coined the term • Said “all cells
“protoplasm” to
arise only from
refer to the
preexisting
jellylike material
cells”
that fills the cell.
Cell Theory Overview
1. All organisms are made of one
or more cells.
2. All cells carry on life activities.
3. New cells arise only from other
living cells.
Prokaryotic vs Eukaryotic
• PROKARYOTIC
• Simplest form
• Lack membrane
bound
structures
• Example:
bacteria and
some protists
• EUKARYOTIC
• Most common
• Possess
membrane
bound
structures and a
nucleus
• Found in most
living things
Sizes of Cells
• Eukaryotic are
usually larger
than prokaryotic
• Both nutrients
and wastes are
constantly
entering and
exiting cells
• Vary in size and
shape
Cell Structures and
Organelles
Organelles = specialized
internal structures of
eukaryotic cells
CELL WALL
• Found in most bacteria and all
plant cells
• Gives cell its shape and
provides protection
• Allows passage of materials
• In plant cells, it is made of
cellulose
• http://www.cellsalive.com/
THE NUCLEUS
• Control center or
“ city hall ” of
cell.
• Largest
organelle
• Controls
metabolism and
cell
reproduction
Structure of nucleus
• Nuclear envelope = membrane
that surrounds the nucleus that
acts in manner similar to the
cell membrane
• Nucleolus = dense are in center
of nucleus where DNA,RNA, and
proteins are found.
*site where ribosomes are produced
Picture of nucleus:
MICROFILAMENTS
• Long, solid,
threadlike
structures
• Made of actin
• Involved in
muscle
contraction and
cyclosis
– Movement of
cytoplasm
MICROTUBULES
• Hollow,
cylindrical
structures
• Helps to give
cell its shape
• Made of tubulin
• Involved in
mitosis
• More
information
Cytoplasm
• Watery material lying within the
cell between the cell membrane
and the nucleus
• Formally called the protoplasm
by Purkinje
• Contains all the other organelles
RIBOSOMES
• Very small
• “mini factories”
of the cell
• Responsible for
protein
synthesis with
the help of RNA
• Examples: John
Morrell,
Gateway
ENDOPLASMIC
RETICULUM (ER)
• Fluid filled
canals
• Continuous
paths for
transport of
materials
• Divides the cell
into
compartments
ER continued
• Acts as a “street
system” in a city
or conveyer at a
factory
• Rough ER =
surface lined
with ribosomes
• Smooth ER = no
ribosomes
GOLGI BODIES
• Packaging, storage
and processing of
proteins
• “ Post Office ” of
the cell
• Protein arrives
from the ER to be
packaged in
vesicles.
ER, Ribosome, & Golgi
LYSOSOMES
• Many strong digestive enzymes
• Produced by Golgi Bodies
• Involved in digestion of food in
the cell
• Helps break down worn out
organelles and wastes
• “ Garbage Truck ”
• Recycles cell materials
VACUOLES
• Found mainly in plants but a few
are found in animal cells
• Many different types
• Examples: Food and contractile
• Act as a storage unit
Contractile vacuoles
• Location in plant
cells where
excess water
collects
Chloroplasts
• A special type of chromoplast
that contains chlorophyll
• Most important
• Contains grana and stroma
• Contain their own DNA
• Site of photosynthesis
Chloroplast Structure
MITOCHONDRIA
• Release energy used by the cell
• “power plant”
• Double membrane for extra
surface area
• Responsible for cellular
respiration
– Process by which energy is
released using oxygen
Mitochondria structure
Mitochondria
(powerhouse)
• Act similar to
electric power
plant
• Upto 300 to 800 per
cell
• What advantage is
their to having its
own DNA?
• Can replicate itself
Organelle DNA
• The only two organelles that
contain their own DNA are
mitochondria and chloroplasts
• In animals, all of an organisms
organelle DNA is maternal in
origin.
• Why?
CELL MEMBRANE
• Controls what materials move in
and out
• Helps to maintain homeostasis
• Similar to the “city limits”
• Made up of three substances :
– Lipids, proteins, and carbohydrates
Fluid-Mosaic Model
Protein functions
1) Transport proteins = control
movement of materials.
2) Receptors = act to signal cell
when to begin or stop
metabolizing.
3) Enzymes = start chemical rxns.
4) Binding site for internal
structures.
Selectively permeable
Some substances
pass through
while others
may not.
Regulates
chemical
composition
Maintains
homeostasis
Diffusion
• Movement of
molecules from
a region of high
concentration to
a region of low
concentration
Osmosis
• Diffusion of WATER across a
selectively permeable
membrane from a region of high
water concentration to a region
of low water concentration.
• Osmotic pressure =
– Increased pressure resulting from
osmosis
Isotonic solution
• Same concentration of dissolved
substances in solution as there
is in the cell
• Same water concentrations
• Net result
– No net gain or loss of water
Hypotonic solution
• Lower concentration of
dissolved substances in solution
than in the cell
• More water outside the cell than
inside the cell
• Net result :
Hypertonic pressure
• A high concentration of
dissolved substances outside
the cell
• More water in the cell than
outside the cell
• Net result :
Facilitated diffusion vs
Active transport
• Facilitated
diffusion
• No energy needed
• Concentration
gradient
determines
movement
• Uses protein
channels
• ACTIVE
• Usually works
against the
conc. Gradient
• Often a
transport protein
helps the
movement (ATP)
Sodium-potassium pump
Endocytosis
• Transport of material into the
cell by means of a vesicle
1. Pinocytosis = small amounts of
liquid engulfed
2. Phagocytosis = small amounts
of solid ingested
Exocytosis
• Transport of material out of the
cell by means of a vesicle
• Exocytosis movie
Cellular organization
• Simplest form of life: unicellular
Ex. bacteria, protists, algae
• Multicellular:
– The simplest form is that of a
colony
– Little if any cellular specialization
– Example: Volvox (algae)
Organization
CELLS
TISSUES
ORGAN SYSTEM
ORGANISM
ORGANS
Tissues:
• A group of cells which
are structurally similar
and perform the same
function.
1. Epithelial Tissue
• Tissue that covers
surfaces inside and
outside the body
• Example: skin
• Sheets of closely packed
cells
2. Connective Tissue
• Supports and
binds tissues
and organs
together
• Widely
separated cells
• EX. bone, blood
3. Nervous Tissue
• Specialized for
electrical
impulse
transport
• Ex. brain, spinal
cords, nerves
4. Muscle Tissue
• Specialized for
contraction
• Lots of mitochondria
Organs
• Group of tissues that work
together to perform a specific
function
• Ex. heart, stomach, flower
Organ system
• Group of organs that perform a
specific task
• Ex. digestive, skeletal,
circulatory
Assignment
• Pages 197-198
– 1-10,11,12,15,17,18,22,26,27
Page 199 1-11