Download CELLULAR STRUCTURE AND FUNCTION

Unit Four
PLASMA MEMBRANE
Functions of the
Plasma Membrane
 ________________:
Maintaining balance
in an organism’s
internal environment.
 Regulates the
materials that
______________
and ____________ a
cell
PLASMA MEMBRANE




Thin, flexible
__________________
between the cell and
its environment
Allows ____________
into the cell
Allows
__________________
and other products to
leave the cell
Separates cells from
the watery
environments in
which they exist
PLASMA MEMBRANE


The key property is its
ability to be selectively
permeable
__________________
permeable: allows
some substances to
pass through while
keeping other
substances out
What types of materials would
cells want to keep out?
PLASMA MEMBRANE




Phospholipid Bilayer is
the arrangement of
lipids tail to tail
Each phospholipid is
structured as a head
with two tails
Phosphate heads are
__________________
(attract water)
Fatty acid tails are
__________________
(repel water)
PLASMA MEMBRANE



Polar heads face
________________
Nonpolar tails face
________________
toward each other
This creates a
barrier that is polar
on the surface and
non polar in the
middle
PLASMA MEMBRANE



Water ____________
substances will not
move easily through
this membrane
They are
_________________
by the nonpolar
middle
Separates the
environment inside
the cell from the
environment outside
the cell
PLASMA MEMBRANE
Components of the
plasma membrane
1. ______________
o
- structure, support
2. ______________
- structure, support,
receptors, transport
of materials
3. ______________
- chemical signals
o
Also known as the
fluid mosaic model
PLASMA MEMBRANE
Proteins
 _________________:
transmit signals to the
inside of the cell
 Anchor the membrane
and maintain its shape
 __________________
proteins: span the
membrane; create
tunnels through which
substances enter and
leave
 Creates selective
permeability
PLASMA MEMBRANE
Cholesterol
 Prevents nonpolar
tails from
________________
to one another
Carbohydrates
 ________________
to proteins and help
identify chemical
signals
What type of macromolecule is
cholesterol?
ORGANELLES
Cell Structures
______________________:
specialized
cell structure which
performs certain functions
1. _________________
- a semi-fluid material found
inside the cell
2. _________________
- a combination of both the
cytosol and the cell’s
organelles
ORGANELLES
3. ________________
- supporting network of
long, thin protein fibers
that provide an anchor
for the organelles within
the cell
Made up of two structures:
4. ________________
- long hollow proteins that
form the rigid skeleton of
the cell
5. ________________
- thin protein threads that
help give the cell its shape
and enable it to move
ORGANELLES
5. The _____________
- control center of cells
- directs protein production
- controls cell division
- Surrounded by a double
membrane called the
nuclear
_____________________
- ___________________:
complex DNA found
throughout the nucleus
ORGANELLES
6. ________________
- inside the nucleus;
produces ribosomes
7. ________________
- sites where proteins are
manufactured within cells
- found throughout the
cytosol and on some
endoplasmic reticulum
What functions do proteins
serve inside of cells?
ORGANELLES
Endoplasmic Reticulum
- folded sacs and
interconnected channels
- sites for protein and lipid
synthesis
- Two types of ER:
8. ______________ER
- has ribosomes on it
9. ______________ER
- lack ribosomes; makes
complex carbs and lipids
ORGANELLES
10. ____________
Apparatus
- flattened stack of
membranes
- modifies, sorts, and
packages proteins into
vesicles (sacs)
- the proteins can be
used intracellular or
intercellular
11. _____________
- storage structures for
materials and waste
products
ORGANELLES
12. _____________
- contain digestive
enzymes for digesting
worn out cell parts
- also digest bacteria
and viruses within cells
13. _____________
- microtubules used
during cell division
ORGANELLES
14. ______________
- converts glucose into
usable cellular energy
- yields ATP molecules
- powerhouse of the cell
15. ______________
- captures light energy
and converts it into
chemical energy
- used for photosynthesis
- not found in animal or
fungi cells
Would a plant cell have mitochondria,
chloroplasts or both types of organelles?
ORGANELLES
16. Cell ___________
- rigid structure made up of
cellulose (carbohydrate)
______________________
the cell membrane of the
plant
- also found in fungi and
bacteria cells
Why do plants need rigid cell
walls while animal cells do not?
ORGANELLES
__________________
are used
by some cells for
locomotion (movement)
17. ______________
- short hair-like structures
that flutter back and forth
18. ______________
- longer structures that
move with a whip-like
motion
CELL FUNCTIONS
Two Main Types of Cells
1.
_________________Cell
s
- lack a nucleus and
other membrane bound
organelles
- includes: bacteria
2.
________________Cells
- cells that have nuclei
- includes: protists,
plants, fungi and animals
CELL FUNCTIONS
Cellular Transport
- moving substances
into and out of a cell
Components:
1. ___________
Energy: energy in
motion
2. ____________
Motion: constant
random movement
CELL FUNCTIONS

Passive Transport
 __________________:
movement of
substances from
regions of higher
concentration to
regions of lower
concentration
 __________________:
the amount of a
substance in a
particular area


Passive movement or
(transport) because
no cell energy is used
Energy comes from
kinetic energy and
Brownian movement
CELL FUNCTIONS

Dynamic
_________________
 continuous movement
but no overall change
 O2, CO2, and H2O
diffuse across
membranes without
help

_________________
Diffusion
 the movement of
diffusion with help from
proteins
CELL FUNCTIONS
Facilitated Diffusion Proteins
1.) ___________________
proteins:
- change shape to move
substances across cell
membranes
2.)
_____________________pr
oteins:
- tunnel through the
membrane
- allow substances to pass
through
Both proteins are
______________________
in what they allow to enter
or leave
CELL FUNCTIONS

_________________
 diffusion of water from
areas of higher
concentration to areas of
lower concentration

Passive Transport
 Includes processes of:
diffusion, osmosis and
facilitated diffusion
 These do _______require
cellular energy
How do home reverse osmosis
systems work?
CELL FUNCTIONS

Types of Solutions:
1.) ________________
- cells remain unchanged
(at equilibrium)
2.) ________________
- cells shrink due to low
H2O concentration
(water moves out)
3.) ________________:
- cells swell & burst due
to high H2O concentration
(water moves in)
Why might grocery stores continually
water their produce?
CELL FUNCTIONS

Active Transport
 Movement of substances
against the concentration
gradient
 Substances move from
areas of lower
concentration to areas of
higher concentration


Requires cell
______________and
the use of
_________________
proteins called pumps
Example: Na-K pumps
CELL FUNCTIONS
Large Particle Transport
 Substances too large to
move through the cell
membrane by diffusion
____________________:
- movement of large
substances into cells
____________________:
- movement of large
substances outside cells
CELL FUNCTIONS
Cellular Growth
 Cells grow until they reach




their size limit
They then either stop
growing or they divide
Ratio of
____________________
area to
____________________
limits cell size
Diffusion over large areas
is slow and inefficient
Small cells maintain more
efficient transport systems
CELL CYCLE

The Cell Cycle
 Reproduction by a




process of
_________________
and dividing
One cell gives rise to
two identical cells
Repeated
continuously
Result is a steady
supply of
______________cells
Only performed by
eukaryotic cells
CELL CYCLE
____________________:
stage during which cells
grow, carry out cellular
functions and replicate
o divided into three stages or
steps
o
1.) _________phase: starts
right after the last cell
division
- cells grow, carry out normal
cell functions, prepare to
replicate DNA
- muscle and nerve cells do
not go beyond this point
CELL CYCLE
2.) _____ phase:
- period where the
cell replicates its DNA
for cell division
3.) _____phase:
- cells prepare for
division of their nuclei
What do you call a cell that no
longer spends time in interphase?
CELL CYCLE
__________________
 stage of the cell cycle
during which the cell’s
nucleus and nuclear
material divide
 divided into four steps
or phases:
1.) _____________
2.) _____________
3.) _____________
4.) _____________
CELL CYCLE
___________________
 The cell’s chromatin
tighten (condense)
into chromosomes
 Similar chromosomes
pair up making an Xshaped structure
 These structures are
called
______________
chromatids
CELL CYCLE
PROPHASE
 _________________
structure which holds the
sister chromosomes
together

_________________
organelles that move to
opposite poles of cells

______________fibers
attach to the centromeres
of sister chromatids
CELL CYCLE
___________________




Spindle fibers move the
chromatids to the center
(equator) of cells
The shortest phase of
mitosis
Ensures that the new
cells have
___________________
copies of the
chromosomes
“Meet in the Middle
During Metaphase”
CELL CYCLE
__________________
 Sister chromatids
are pulled apart
 Spindle fibers
shorten
 Pulls the
chromosomes
towards opposite
poles
CELL CYCLE
__________________
 Chromosome arrive
at opposite poles of
the cell
 The chromosomes
relax and
uncondense
 __________identical
___________of
chromosomal DNA
CELL CYCLE
__________________
 the division of the
cell’s cytoplasm to
create two new cells
 the cell divides into
two daughter cells
with identical nuclei
 also known as
“cellular cleavage”
What happens if the two daughter
cells fail to completely cleave?
CELL CYCLE
Regulating the Cell Cycle
 _______________ and
enzymes controls the
cell cycle.
 Proteins called
____________ bind to
enzymes called cyclindependent kinases
(CDKs)
 The CDKs are in the
stages of interphase
and mitosis
 CDKs start various
activities in cell cycles