Download Name - Humble ISD

Name ____________________________________________________________________
Test Date______________
UNIT 5 - THE WORKING CELL
I. CELL TRANSPORT
A cell is defined as the smallest ____________________ unit of life. In order to maintain ______________________,
_____________________ must be moved into the cell and ______________________ must be transported out of the
cell. In addition, some cells produce _______________ and other materials designated for export. All materials moving in
and out of the cell must pass through the ____________________________________, a ________________________
____________________________ boundary found in _________ cells.
There are two basic mechanisms for transport of materials into and out of the cell:
A. Passive Transport (pgs. 183 – 187)
Does not require ________________. Movement of substances from a __________________ concentration to
____________. There are three types of passive transport:
1. Diffusion – Due to the random movement of molecules in a ____________________ or ________. Many
substances move across the ___________________________ by diffusion, for example, ___________________.
2. Facilitated Diffusion – Diffusion of ____________________________________________ through a
_______________________________. Protein channels provide larger openings for larger molecules like
_________________. In addition, due to the ________________ fatty acid tails that make up most of the
phospholipid bilayer, __________________ molecules and _________________ utilize protein channels. This
includes _________________, which utilizes specialized protein channels known as ________________________.
3. Osmosis – Diffusion of water from a _____________ water concentration to a __________ water concentration
through a ______________________________ membrane. There are comparative terms used to describe the
water versus solute concentration on either side of a membrane:
 Hypertonic = _________________ solute; ___________________ water
 Hypotonic = __________________ solute; ___________________ water
o Water always moves from ___________________ → _________________________
 Isotonic = Relative concentrations of __________________ and _________________ are ___________
o There will be ________ net movement of water if two solutions are isotonic
Cells must have a mechanism for counteracting the pressure osmosis can create, otherwise a cell could swell &
burst or explode when it is placed in a _________________________ environment.
 Cell Wall - Rigid boundary found in ________________, ______________, and _______________ cells
 Contractile Vacuole - Actively ___________ water out of cell in single-celled organisms without
_________________________________
 Blood/Extracellular Fluid – Designed to be _______________ with cells
B. Active Transport – Requires energy in the form of ___________ (pgs. 188 – 189)
1. Protein Pumps – Energy-requiring process during which membrane proteins pump molecules across a membrane
against a concentration gradient from a _________ concentration to a ___________ concentration. An example
is the sodium-potassium pump. Its purpose is to establish an ____________________________ gradient in cells by
pumping _______ sodium ions (______) into the cell for every ______ potassium ions (_____) pumped out of the
cell. This slight ____ charge inside the cell relative to the outside is very important for ______________________
____________________________ and _______________________________.
2. Endocytosis – “________________________”. Larger substances are moved into the cell from the exterior by
extending ______________________, forming a ________________ around the substance. Examples include
macrophages, amoeba, etc.
3. Exocytosis – “______________________”. Export of molecules from the inside of the cell to the exterior of the cell
by a ________________ fusing with the cell membrane. Mechanism used to release _______________________
from cells
II. METABOLISM
There are countless numbers of chemical reactions occurring in every cell all the time. Virtually all of these reactions
require the action of _____________________, catalytic ______________________. A catalyst ______________ a
chemical reaction without being _____________________________________. An enzyme works by lowering the
activation energy, that is the energy required to ___________________________________________________.
Enzymes share four common features:
A. Enzymes work best within a narrow _______ and _________________ range. This is because of the importance of the
________________ or ________________________ of the enzyme. When the pH or temperature is altered, the
_________________________ and interactions are also changed, changing the shape of the enzyme.
B. Enzymes do not make a reaction happen that couldn’t happen on its own; they simply make the reaction occur much
________________________.
C. Enzymes are not _____________________________________. The same enzyme may be used over and over again.
D. Enzymes are _____________________________. The substrate is the ________________________. The substrate
fits into a portion of the enzyme called the _______________________. As the substrate fills the active site, this leads
to a phenomenon known as _____________________________, almost like a ___________. It is this induced fit
that is responsible for lowering the __________________________________________ of the reaction.
III. CHEMICAL ENERGY AND LIFE (pp. 201, 202)
A. Energy and Life
Energy is the _____________________________. Cells require energy for _________________ reactions,
_____________________ transport, cell ____________________, and maintaining __________________. We obtain
energy from _______________, but most energy originally comes from the ________. Plants are able to capture the
sun’s energy and use it to produce glucose, ____________. This process, known as _________________, occurs in
the ___________________ of plant cells. The reaction for photosynthesis is:
______________________________________________________________________________________________
Plants and other organisms that can make their own food are known as ________________________. Humans and
other organisms that have to obtain food are known as _____________________________. Although glucose
is the preferred energy molecule for the cell, other _________________________, ___________, and __________ can
also be broken down for energy.
B. Chemical Energy
The chemical energy in food (and all molecules) is stored in the ____________________________. This is
___________________________ energy. When the bonds are broken and the ___________________ are released,
some energy is lost as ___________, but a percentage of the potential energy can be converted to useable energy in
the form of ____________. Food molecules cannot be used as a direct energy source for the cell because food
contains too much energy ... if it were released all at once, it would be _______________ and ___________________.
C. ATP
__________________________________ is a ________________________ that is composed of:
 ___________________ - nitrogen base
 ___________________ - _______ carbon sugar
 ______________________
Energy is stored in ______________________________________. These “rechargeable batteries” are mostly present
in the cell in two forms:
 ATP - ____________________________________. Has ___ phosphate groups.
 ADP - ____________________________________. Has ____ phosphate groups.
 ________ has the most phosphate bonds, and therefore contains the most _______________ or stored energy.
 Cells are able to use and recycle ATP by breaking off or adding a ________________ group.
1. Energy can be used when a ___________ bond is _______________________.
__________________________________________________________________
2. Energy is stored; that is, ATP is “recharged” by ____________ a phosphate group to ___________.
__________________________________________________________________
*Under normal conditions, both of these processes are occurring at the _____________ and ______________ in a cell*
IV. CELLULAR RESPIRATION - ____________________________ ENERGY PRODUCTION (pp. 221-223, 226-229)
Cellular respiration is the breakdown of _______________________ in the presence of _________________ to “make”
___________. The oxygen required for cellular respiration is ___________ into the _________, __________ into the
____________, and is delivered to the __________________ of the body cells by ________________. The glucose
needed is obtained through ____________________. The glucose is transported in the blood and enters the body cells
via ___________________________________.
There are two major parts to cellular respiration:
A. Glycolysis – Means __________________________. Occurs in the ____________________ of the cell. Glycolysis
does not require ___________________. The splitting of glucose, or glycolysis, occurs very quickly with the aid of
_____________________, producing two _______-C molecules known as _________________________. In
addition, when the bonds of glucose are broken, the high energy electrons that are released are caught by
____________, a molecule that acts as an electron carrier. This electron energy will be converted to ATP later in the
process. Glycolysis requires __________ ATP to occur, but results in the formation of _________ ATP, for
a net ________________ of ________ ATP.
 Reaction: ______________________________________________________________________
 Net Energy Gain = _____________________
B. Oxidative Respiration – Glycolysis releases less than ¼ of the chemical energy stored in glucose. Most of its potential
energy remains bound in the _________________ formed from glycolysis. In aerobic conditions, meaning ____ is
available, the pyruvic acid formed from the breakdown of ___________________ during ______________________
enters the _______________________________________ of the cell where the __________________ of oxidative
respiration complete the breakdown of glucose to produce ________________, _________, and _______________.
 Reaction: _________________________________________________________________
Oxidative respiration is a 2-part process:
1. Krebs Cycle – Series of reactions that occur in the _______________________, in which the energy stored in
______________________ is released in the form of high-energy ________________ when bonds are broken
and pyruvic acid is completely broken down to ____________. There are only ______ additional ATP produced in
the Krebs Cycle; most of the energy released is captured in the form of electron energy, producing additional
__________. In addition, a second type of electron carrier is utilized, producing 2 “filled” ____________.
 Net Energy Gain = _________________________________________________________________
2. Electron Transport Chain – In this step, the electron carriers, ___________ and ______________ “dump” their
electrons. These electrons are passed along a series of molecules embedded in the inner membrane of the
___________________ of ___________________ cells. This same process occurs in the ____________________
of __________________ cells. As the electrons “fall” down the ETC, the energy they release is used to power an
enzyme known as ___________________________, which attaches phosphate groups to _________ to produce
_________. This process is known as _____________________________________________ because
_______________ must be present. It is the __________________________ of oxygen that “pulls” the electrons
down the ETC. As the electrons are collected by oxygen, ___________ is produced.
 Net Energy Gain = ____________________
*Combined Reactions of Glycolysis + Oxidative Respiration (Krebs &ETC) = Cellular Respiration*
_____________________________________________________________________________
*Total ATP Yield Per Molecule of Glucose:*
Glycolysis =
Krebs Cycle =
ETC =
_________ ATP
_________ ATP
_________ ATP
V. FERMENTATION - _______________________ ENERGY PRODUCTION
(pp. 223, 224)
Glycolysis is constantly occurring in the _____________ of every cell under _________________ conditions, meaning
___________________ is not required. The reaction for glycolysis is:
_______________________________________________________________________________________________
Glycolysis is the first step for all cellular energy production.
 If oxygen is available, _________________________________ follows glycolysis. Pyruvic acid is broken
down to __________________________________ and _______ ATP are produced.
 If oxygen is not available, some types of cells have a back-up mechanism for glucose metabolism called
______________________. If a cell cannot switch to fermentation, it cannot survive without oxygen.
o Cells that can carry out cellular respiration and fermentation are known as _______________________
______________________.
o Cells that cannot switch to fermentation are known as ______________________________________.
A. General Description
In fermentation, the pyruvic acid formed during glycolysis does not enter the _______________________, instead,
the entire pathway takes place in the ________________. Fermentation does not produce any additional
_____________, but the removal of ______________________ from the cytosol allows the process of
glycolysis and the net gain of _______ ATP to continue.
B. Types of Fermentation - The 2 most common fermentation pathways used by cells are:
1. Lactic Acid Fermentation – Pyruvic acid is converted to __________________.
May be utilized by:
 Human Muscle Cells – Occurs when demand on muscles exceeds supply of oxygen. As lactic acid builds
up in the muscle cells, it is felt as ______________________. This is referred to as ________________.
As activity slows, and oxygen is re-supplied, the muscle cells switch back to _______________________
and the lactic acid is sent to the _______________________ to be broken down.
 Bacteria & Fungi – There are some types of bacteria & fungi that carry out lactic acid fermentation in
_______________________ conditions. This is utilized by the dairy industry to produce ___________ and
________________________.
 ______________________________________________________________________________
2. Alcoholic Fermentation – Pyruvic acid is converted to ___________________ and _________. When oxygen
supplies are depleted, ____________ and many bacteria switch to alcoholic fermentation. This process is used
commercially for ____________________________________
 ______________________________________________________________________________
**TOTAL ATP GAIN IN FERMENTATION = ________ ATP **