Download ch7biopptupdate2013

Chapter 7Cell Structure &
Function
I. Life is Cellular
A-The Discovery of the Cell
•
•
It was not until the _________ that
scientists began to use microscopes to
observe organisms.
In 1665 ____________used an early
compound microscope to see tiny chambers
in cork.He called these chambers cells
after the tiny rooms in monasteries….we
know these not to be empty now.
Mid-1500’s
Robert Hooke
• About the same time in
Holland________________used a singlelens microscope to look @ pond water,
Anton van
Leeuwenhoek
• In 1838 Matthew Schleiden concluded
plants were made of cells
• 1839 Theodore Schwann said all animals
were made of cells
• 1855-Virchow said cells could only come
from existing ones.
These 3 things
compile_________________
– All living things composed of ___________
– Cells are the basic units of
___________________of living things
– New cells are produced from
______________________.
Existing cells
cells
Structure and
function
B-Exploring the Cell
• Most microscopes use lens to magnify the image
of a specimen with light or electrons
• _________________,which scans cells w/a
laser beam can make 3-d images of cells
• Video technology make it possible to watch
cell growth , division and development
Confocal light
microscopy
• Light makes it difficult to visualize tiny
structures because it
scatters/______________________allow
things like proteins to be visualized (things
as much as 1000 x smaller can be
visualized….TEMS allow you to see
specimens cut into ultra thin slices
Electron
microscopes
• With light microscopes stains need to often be
used since most living cells are transparentsome stains are structure specific
• Some dyes show fluorescence dyes give off
light of a ceratin color when viewed under
specific wavelenghths
• May be able to track specific molecules
• W/ a ______________specimens do not have
to be cut to see 3-D images….both must be
placed into a vacuum so air molecules do not
scatter electrons/TEM-shows details
• 1990’s____________________________have
revolutionalized visualization of surfaces and
atoms have been observed…can be used in
ordinary air and can show DNA structure
SEM
Scanning probe
microscopes
pollen
C .Prokaryotes and Eukaryotes
• Cells typically range from
_________micrometers,but some bacteria are .2
and some amoeba are 1000 micrometers
• All cells have 2 things in common:
» cell membrane-a barrier
» @ some point they contain_______
5-50
micrometers
DNA
2 broad categories:
– _____________________________genetic material is NOT contained in a
nucleus/generally less complicated than
other cells/carry out all cell
activities…present day members are
________________.
– Only organelles are ribosomes and they are
NOT MEMBRANE BOUND
Prokaryotes
bacteria
•
•
•
_____________________________contain a nucleus w/ genetic
material,generally larger,much diversity
HAVE all organelles/most membrane
bound
Include all organisms EXCEPT bacteria
Eukaryotes
Division of Labor
Section 7-2
•A cell is made up of many parts with different
functions that work together. Similarly, the parts of a
computer work together to carry out different
functions.
•Working with a partner, answer the following
questions.
•1. What are some of the different parts of a computer?
What are the
functions of these computer
parts?
•2. How do the functions of these computer parts
correspond to
the functions of certain
cell parts?
Go to
Section:
Venn Diagrams
Section 7-2
Prokaryotes
Cell membrane
Ribosomes
Cell wall
Animal Cells
Lysosomes
Go to
Section:
Plant Cells
Cell membrane
Ribosomes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Vacuoles
Mitochondria
Cytoskeleton
Cell Wall
Chloroplasts
Eukaryotes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton
II. EUKARYOTIC CELL
STRUCTURE
• Organelles
• 2 major parts of eukaryotic cells
nucleus
cytoplasm
Specialized
structure that
performs important
functions within an
eukaryotic cell.
/”little organs”/
Cytoplasm is material
inside membrane and
outside nucleus
The Nucleus
• Contains nearly all the cell’s DNA
• Codes for instructions to make proteins and
other molecules
• Surrounded by nuclear envelope---has many
pores to allow material in and out
• Contains chromatin—has DNA bound to
protein,usually spread throughout nucleus,but
condenses during cell division to make
CHROMOSOMES,containing genetic info
• Usually contain Nucleolus—assembly of
ribosomes begin here.
Organelles That Store , Cleanup and Support
• Vacuoles
• Sac like structures that store water
,salts ,proteins, and carbs
• Plants may have a single large water
filled vacuole
• Contractile vacuoles control water in
paramecium
• VESICLES-store and move between
organelles and cell surface
• Lysosomes
• Small organelles filled w/enzymes
• May digest or break down lipids,carbs,and
proteins into small molecules that can be
used by the rest of the cell
• Lysosomes remove “junk”,or used up
organelles…-very important that this aspect /
function occurs
• May be in some/ very few plants
Figure 7-7 Cytoskeleton
Section 7-2
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Go to
Section:
Michondrion
Cytoskeleton
• Network of protein filaments that help cell maintain
shape
• Also involved in movement
• MICROFILAMENTS are threadlike structures made of
a protein-actin….make a major network and a tough
framework///allows amoebas and such to move
• MICROTUBULES-hallow structures made of proteins
called tubulins—important in holding a cell’s shape---form a mitotic spindle in cell division/which helps
separate chromosomes
• CENTRIOLES are microtubules near nucleus in
animals and help organize cell division
• Microtubules also help make projections like cilia or
flagella
• Arranged in “9+2” pattern of microtubules
ORGANELLES THAT BUILD PROTEINS
•
•
•
•
•
Ribosomes :
Proteins are assembled here
Made out of small particles of RNA and protein
Found throughout cytoplasm
Coded instructions from nucleus tell how to
make proteins
• Cells active in protein synthesis have a lot of
ribosomes
ER
• Endoplasmic Reticulum
• ER-Site where lipid components of cell
membrane are assembled ,along w/
proteins and other materials exported from
cell(those proteins are made there)
• Rough ER is involved in protein synthesis,because
ribosomes are on it-finishes twisting and folding
• Smooth ER involved in lipid metabolism and
detoxifying poisons
• Newly made proteins leave ribosomes and insert on
rough ER ,where they may be modified
• If cell makes a lot of protein ,there is much ER
• Smooth ER may contain many specialized enzymes
GOLGI BODY:
• proteins from rough ER go here in this
stack of membranes/get “address tags”
to package and export to correct placebundled in vesicles
• Golgi modifies ,sorts , packages
proteins and other materials from ER
for storage or release from cell
ORGANELLES THAT CAPTURE AND RELEASE
ENERGY
• ==Mitochondria and Chloroplasts
• Most all eukaryotic cells contain
mitochondria that convert chemical
energy stored in food into compounds
convenient for cell to use
• Mitochondria have an outer and inner
membranes
• In humans,nearly all mitochondria
comes from ovum(egg cell)
• Chloroplasts
• Capture energy from sunlight and convert
into chemical energy in photosynthesis
• Contain 2 membranes and chlorophyll
Organelle DNA
•
•
•
•
•
•
Organelle DNA
In chloroplasts and mitochondria
Small DNA molecules
Maybe descendants of early prokaryotes
----Endosymbiotic theory says these
prokaryotic ancestors developed a symbiotic
relationship w/ early eukaryotes and resided
within---evolving into mitochondria
• All cells have a
_____________________________and
some have a cell wall
Cell membrane
A. Cell Membrane
• Regulates what enters and leaves the cell and also provides
_____________________________.
• Almost all cell membranes are made of a double layered sheet
called a ___________________________-flexible,yet strong
barrier
• Cell membranes usually have a protein molecule imbedded in
the bilayer w/ carbohydrate molecules attached
• Called a _________________model
• Some of the proteins form channels or pumps to move material
across the membranes
• Some of the carbs act as ____________________tags
Protection
and support
Phospholipid
bilayer
Fluid mosaic
Chemical id tags
B. Cell Walls
• In plants,algae,fungi, and many prokaryotes
• Lie _______________the cell membrane
• Usually porous enough to let water,O2,CO2 and
certain other substances to pass through easily
• Main function is support and protection
• Usually made of fibers of ____________________produced in cell and secreted to surface
• Mostly _____________________-tough carb fibers/to
withstand gravity
Carbohydrate
and protein
outside
cellulose
C.Diffusion Through Cell
Boundaries
• Every cell is in a liquid environment
• Cell membrane regulates the movement of
cell materials from one side to the other
1.Measuring concentration
–
•
Cytoplasm is a solution of various substances
in water
_____________of a solution is the mass of solute
in given volume of solution---ie. Mass/volume…..If
you have 15 g salt in 3 mL water,what is the
concentration?------_______….If you have 24 g salt
in 2mL water you would have 12 g/mL salt….Which
solution is more concentrated?______________
12 g/mL
5g/mL
concentration
DIFFUSION
Diffusion-Passive
Transport-needs no energy
moves WITH concentration gradient
–
•
In a solution the particles move
constantly,spreading out randomly….tending to
move where more concentrated to an area less
concentrated…This is called
__________________.
– ____________________= concentration of a
solute is the same throughout a system
– does not require energy because random
movement
if equilibrium is reached,particles keep moving
across the membrane,still balancing concentration
isotonic
Figure 7-17
Osmosis
Section 7-3
Higher Concentration
of Water
Water molecules
Cell
membrane
Lower Concentration
of Water
Sugar molecules
Go to
Section:
D. Osmosis
– Some molecules are too large or too strongly
charged to make it across the lipid bilayer----thus
impermeable to it
– Most membranes are selectively permeable
– _____________________is the diffusion of water
across a selectively permeable membrane
– water moves easily and will move to balance the
concentration of a solute,water moving from area
of higher to lesser conc. For the WATER
– ____________________-same strength of a solute
on both sides of a cell membrane
osmosis
isotonic
– more concentrated side of solute is
____________________
– less concentrated side is____________________
– Osmosis exerts a pressure known as
____________________________on the
hypertonic side of a membrane….This could
results in a cell bursting
– Bursting not so much a problem in larger
organisms….tend to be in isotonic environments
• Osmotic pressure may not allow a plant or bacterial
cell to burst , but could weaken the cell wall
hypertonic
hypotonic
Osmotic pressure
• Many cells have water channel proteinsaquaporins-allowing water to pass as they are
lipid soluble
E.Facilitated Diffusion
»
»
»
Some molecules,like glucose ,diffuse quickly
across due to ________________________
These allow only certain molecules to pass
Since it is diffusion it does not require energy and
still goes from area of higher to lower
concentration
» Use channel proteins
» Channel proteins provide a tunnel for the
substrate to pass across the membrane.
Carrier proteins actually bind the
substrate then change shape and deposit
the substrate on the other side of the
membrane
VESICULAR
TRANSPORT_Endocytosis and
Exocytosis
•
•
•
Transports larger molecules and even clumps of
matter
________________________is the process of
taking material inward by enfolding,or pockets
In endocytosis ,the pocket breaks loose from the
cell membrane and forms a vacuole…large
molecules,food and even whole cells can be taken
in this way
endocytosis
2 examples of endocytosis are
– ___________________-extensions of cytoplasm
surround a particle and package it in a food
vacuole,then the cell engulfs it ---This is how
amoebas eat-----is a form of active transport
• _______________-Cells use this to take up liquids in
the environment—tiny pockets filled w/ liquid form
along the cell membrane and pinch off to form
vacuoles
phagocytosis
pinocytosis
– ___________________________--releases
large amounts from the cell by pinching off
or a contractile vacuole as in paramecium--also active transport
exocytosis
Figure7-20 Active Transport
Section 7-3
Molecule to
be carried
Low
Concentration
Cell
Membrane
High
Concentration
Molecule
being carried
Low
Concentration
Cell
Membrane
High
Concentration
Energy
Go to
Section:
Energy
IV. The Diversity of Cellular Life
A. Unicellular Organisms
--Single-celled Organisms that do
all a living thing would
----They dominate life on earth in
terms of numbers
B. Multicellular organisms
•
Multicellular organisms
–
Made up of many cells
–
Depend on communication and cooperation between
specialized cells
---_______________-cells throughout organism can develop in
different ways to perform different tasks
Cell specialization
– 3 Types of cell junctions
– 1) gap junctions-hallow tubes carry out
chemical communication-eg.heart tissue
– 2)desmosomes-protein filaments create
elasticity between skin cells
– 3)Tight junctions- adhere closely and are
more impermeable
•
•
•
•
1. Specialized animal cells
– eg. Red blood cells equipped to carry oxygen
;cells specialized to produce proteins produced
in pancreas(have many ribosomes and rough
ER);muscle cells have actin and myosin
cytoskeleton elements for contraction
2. Specialized Plant cells
______________________-are tiny openings on
underside of leaves and exchange gases
_____________________-regulate gaseous
exchanges in stomata,changing shape due to
plant’s internal conditions
•
stomata
Guard cells
C. Levels of Organization
– 1. individual cells
– 2. _____________________-group of similar cells w/
particular function
– 3. ______________-group of tissues working
together
– 4. ______________-group of organs working
together for particular function
•
tissue
organ
Organ system
Levels of Organization
Section 7- 4
Muscle cell
Go to
Section:
Smooth muscle tissue
Stomach
Digestive system