Water and the
Cell Membrane
Q: What molecule takes a shape that looks like a twisted
ladder? What is the real name of this shape?
A: DNA. The DOUBLE HELIX looks like a twisted ladder.
Remember: Before RNA can be transcribed, the two
separate
strands of DNA must first _____________________
nitrogen
between the ________________
bases.
Q: What are the 3 types of RNA?
messenger RNA
(mRNA)
transfer RNA
(tRNA)
ribosomal RNA
(rRNA)
1. Where are proteins translated
that will be modified or packaged?
Endoplasmic Reticulum
_____________________________
2. Which organelle is responsible for
actually modifying and packaging
the protein?
Golgi apparatus
_____________________________
Nucleus
Endoplasmic
Reticulum
Golgi
Apparatus
The entire complicated process of cellular respiration can
be summed up by one chemical equation. What is the
name of each molecule involved?
glucose
?
oxygen
?
water
?
carbon
?
dioxide
1. Which organelle is the
location for most energy
conversion in animal cells?
The Mitochondria
_____________________________
2. What energy carrying
molecule is created using the
energy released from glucose
during cellular respiration?
ATP
_____________________________
Name the organelles we have learned about so far:
nucleus
1. Compartment containing the DNA of the cell: ___________________
endoplasmic reticulum
2. Compartment where special proteins are translated: ___________________
Golgi apparatus
3. Compartment where proteins are modified or packaged: ________________
mitochondria
4. Compartment where energy is placed into ATP: ___________________
Each of these organelles has its own membrane to keep the
correct molecules inside the organelle and the incorrect
molecules outside of the organelle. Because of this, they are
membrane-bound
referred to as ____________________
organelles.
Endoplasmic
Reticulum
Nucleus
Golgi
Apparatus
vesicle
aqueous
Every cell is full of an __________________
solution which
contains of all of the biomolecules needed for the chemistry
of life.
CYTOPLASM
Q: According to your vocabulary reference sheet, what does aqueous mean?
Aqueous means that it is full of water.
A: ____________________________________________________________
= water
In order to understand solutions, you have to
understand 2 words:
The substance being dissolved
Solute: _______________________________________
The substance doing the dissolving
Solvent: ______________________________________
solvent
water
solute
salt
saltwater
solution
Water can dissolve many things, including almost all of the
biomolecules. Being in a solution allows them to float
through the water and easily reach each other to carry out
the chemical reactions that are a part of the cell’s
metabolism
_______________________.
enzyme
WATER CAN DISSOLVE SO MANY THINGS
POLAR
BECAUSE ITS MOLECULES ARE ___________.
Molecules are formed when atoms share
electrons
_________________.
If they do not
share them equally, then there will be a
positive
__________________
side of the
negative
molecule and a __________________
side of the molecule. Since water is
polar it can dissolve everything that is
polar or has a full charge.
δ-
δ+
polar
Because water is a _____________
solvent , it can
dissolve 3 of the 4 classes of biomolecules:
carbohydrates
proteins
______________________,
______________________,
nucleic acids
and ______________________.
lipids
Water cannot dissolve ____________
because they are
_______________.
(Lipids are also known as _________.)
nonpolar
fats
Lipids are the main biomolecule in all of the cell’s
membranes
__________________.
But the membrane must be able to
interact with water since water is the solvent of the solution
cytoplasm
in the cell called ____________________.
To make this
happen, the cell attaches a _____________________
group
phosphate
phospholipid
to the lipid to create a __________________________.
phospholipid
Name of Molecule: _______________________
The phosphate group will dissolve in the water very well,
while the rest of the lipid will not. Because of this, the
attracted
phosphate group is _________________
to the water
repelled
while the lipid is pushed away or __________________.
water
Since cells are full of ____________
and almost always
surrounded by ____________,
water
this causes the
phospholipids to arrange themselves in pairs.
This arrangement of phospholipids is known as a
bilayer
phospholipid __________________.
Q: What does the prefix bi- mean?
Bi- means two.
A: __________________________
Bicycles have 2 wheels.
If you are bilingual, you speak 2 languages.
Biannual events happen every 2 years.
1
2
Bilayers have 2 layers.
inside
Remember: Membranes keep the correct molecules ______________
of
outside
the cell or organelle, and they keep other molecules _______________
of
the cell or organelle. However, some small molecules that necessary for
life can squeeze through the lipid bilayer uncontrolled. These include the
carbon dioxide
oxygen
gases __________________
and ____________________________
and
water
one of the most important molecules for the cell: __________________.
If a membrane allows molecules across, it is called a
permeable
___________________
membrane.
Cell membranes only allow some molecules through, so they
semi-permeable
are called ____________________
membranes
The process of water moving across a semiosmosis
permeable membrane is called _____________.
Water moves across a cell membrane in a very predictable pattern. It
purest
moves from where it is __________________
to where it is
least pure
________________________.
This means it moves from where there
are fewer solutes dissolved across to the side of the membrane
where there are more solutes. You can think of the water as moving
to the side where water molecules need the most help dissolving a
solutes
large number of _____________________.
Water moves
into the cell.
Water moves
out of the cell.
It may sound like a good thing that water can travel across the
semi-permeable cell membrane without any help, but this can
also be a big problem.
1. If too much water enters a cell because of osmosis, the cell
swell
can _____________
to a size that is too large and eventually
burst
it will ______________.
2. If too much water leaves a cell because of osmosis, the cell
shrink
can _____________
to a size that is too small.
die
Both of these situations will cause the cell to __________,
so
the movement of water is an important concern for all living
things.
The picture shows a cell model and the solutions
associated with it. For each of the following models,
decide which will occur:
1. Water will leave the cell causing it to shrink
2. Water will enter the cell causing it to swell
3. The water level is balanced and neither will occur
swell
shrink
neither
shrink
shrink
swell
swell
shrink
swell
swell
neither
shrink
shrink
swell
swell