Bio Chapter 5

Front 1

Membranes are composed of...

Back 1

Membranes are composed of
phospholipids and proteins

Front 2

Membranes are commonly
described as a ...

Back 2

fluid mosaic
– This means that the surface
appears mosaic because of
diverse proteins embedded in
the phospholipids and fluid
because the proteins can drift
about in the phospholipids

Front 3

Because of the hydrophobic
properties of the tail of
phospholipids, lipid bilayers are...

Back 3

naturally self-healing.

Front 4

Double bonds in the unsaturated fatty acid tails of many
phospholipids produce kinks that prevent phospholipids from
packing tightly together, keeping the membrane ...

Back 4

fluid

Front 5

Steroid cholesterol

Back 5

helps stabilize the membrane at warm
temperatures but also keep the membrane fluid at lower
temperatures.

Front 6

Membranes contain proteins..

Back 6

= integrins, which give the
membrane a stronger
framework

Front 7

Integrins attach to the...

Back 7

extracellular matrix on
the outside of the cell as
well as span the
membrane to attach to
the cytoskeleton

Front 8

Glycoproteins

Back 8

involved in cell-cell
recognition, a second function of the
plasma membrane proteins

Front 9

The outside surface of the membrane has...

Back 9

The outside surface of the membrane has
carbohydrate bonded to proteins or lipids
in the membrane

Front 10

This cell cell recognition allows
cells in an embryo to...

Back 10

sort themselves
into tissue and organs

Front 11

Glycoproteins enable the immune system
to

Back 11

recognize and reject bacteria,
virus etc.

Front 12

the four human blood types
designated A, B, AB, O reflect

Back 12

variation in the carbohydrates on
surface of the red blood cells.

Front 13

Many membrane proteins
function as

Back 13

enzymes, which
work as a team to carry out
sequential steps in a
pathway

Front 14

Other proteins function as
receptors...

Back 14

for chemical
messenger from other cells.

Front 15

A receptor protein has a
______ that fits a specific
messenger, e.g. a hormone

Back 15

shape
-Binding of the messenger to
the receptor triggers a chain
reaction involving other
proteins

Front 16

Membrane proteins are important in..

Back 16

transport (transport proteins)

Front 17

membranes exhibit selectively
permeability

Back 17

Because membranes allow
some substances to cross or be
transported more easily than
others

Front 18

Their hydrophobic interior is
one reason for this selective
permeability

Back 18

– Nonpolar molecules
(carbon dioxide and
oxygen) cross easily
– Polar molecules (glucose
and other sugars) do not
cross easily

Front 19

fluid

Back 19

a substance whose molecules move freely
past one another; fluids have no defined shape;
liquids and gases are fluids

Front 20

solute

Back 20

is a substance that can be dissolved

Front 21

solvent

Back 21

fluid capable of dissolving a solute

Front 22

Diffusion

Back 22

process in which particles spread out evenly in an available
space;
– Particles move from an area of more concentrated particles to an area
where they are less concentrated
– This means that particles diffuse down their concentration gradient

Front 23

passive transport

Back 23

Diffusion across a cell membrane does not require energy
(osmosis and facilated diffusion are types of passive diffusion)

Front 24

The concentration gradient itself represents...

Back 24

potential energy for diffusion

Front 25

osmosis

Back 25

Water moves across membranes in response to solute
concentration inside and outside of the cell by a process
-Passive

Front 26

– Osmosis will move water across a membrane ___ its
concentration gradient until the concentration of solute
is equal

Back 26

down

Front 27

Tonicity

Back 27

term that describes the ability of a
solution to cause a cell to gain or lose water

Front 28

Isotonic

Back 28

indicates that the concentration of a solute is the
same on both sides

Front 29

Hypertonic

Back 29

indicates that the concentration of solute is
higher outside the cell

Front 30

Hypotonic

Back 30

indicates a higher concentration of solute inside
the cell

Front 31

osmoregulation

Back 31

organisms are able to maintain water
balance within their cells

Front 32

Many substances that are necessary for viability of
the cell do not freely diffuse across the membrane
– They require the help of specific transport proteins
called...

Back 32

aquaporins

Front 33

aquaporins assist in...

Back 33

facilitated diffusion

Front 34

facilitated diffusion

Back 34

a type
of passive transport that does not require energy

Front 35

Cells have a mechanism for moving a solute
against its concentration gradient

Back 35

– It requires the expenditure of energy in the form of ATP
– The mechanism alters the shape of the membrane
protein through phosphorylation using ATP

Front 36

A cell uses two mechanisms for
moving large molecules across
membranes

Back 36

Exocytosis
Endocytosis
In both cases, material to be
transported is packaged within a
vesicle that fuses with the membrane

Front 37

Exocytosis

Back 37

is used to export
bulky molecules, such as
proteins or polysaccharides (e.g.
the excretion of insulin by cells
of the pancreas)

Front 38

Endocytosis

Back 38

is used to import
substances useful to the
livelihood of the cell
– Phagocytosis; pinocytosis

Front 39

Passive transport

Back 39

Diffusion
Facilitated diffusion
Osmosis

Front 40

Active transport

Back 40

Use energy and moves against concentration gradient

Front 41

Cells are small units, a chemical
factory, housing thousands of
chemical reactions

Back 41

The result of reactions is
maintenance of the cell,
manufacture of cellular parts,
and replication

Front 42

Energy

Back 42

capacity to do work
and cause change

Front 43

work is accomplished ...

Back 43

when an
object is moved against an
opposing force,

Front 44

Kinetic energy

Back 44

energy of motion

Front 45

Potential energy

Back 45

energy that an object
possesses as a result of its
location

Front 46

Kinetic energy performs work by..

Back 46

transferring motion to
other matter
– For example, water moving through a turbine generates
electricity
– Heat, or thermal energy, is kinetic energy associated
with the random movement of atoms

Front 47

An example of potential energy is

Back 47

water behind a dam

Front 48

Chemical energy

Back 48

potential energy because of its
energy available for release in a chemical reaction
– The physical energy (walking) rely upon the chemical energy
from our diet;

Front 49

field of thermodynamics

Back 49

Study of Energy transformations within matter
– Biologists study thermodynamics because an organism exchanges
both energy and matter with its surroundings

Front 50

The first law of thermodynamics

Back 50

energy in the universe is
constant (not created nor destroyed) e.g photosynthesis

Front 51

The second law of thermodynamics

Back 51

energy conversions
increase the disorder of the universe

Front 52

Entropy

Back 52

measure of disorder, or randomness

Front 53

exergonic reaction

Back 53

chemical reaction that releases
energy
– This reaction releases the energy
in covalent bonds of the
reactants

Front 54

Cellular respiration

Back 54

also
releases energy and heat and
produces products but is able to
use the released energy to
perform work

Front 55

endergonic reaction

Back 55

requires
an input of energy and yields
products rich in potential energy
– The reactants contain little
energy in the beginning, but
energy is absorbed from the
surroundings and stored in
covalent bonds of the
products; more energy in the
products

Front 56

Example of exergonic reaction

Back 56

Burning wood which had a lot of
cellulose (chemical energy)
when burned releases the
energy in cellulose thus,
producing heat, light, carbon
dioxide, and water (which has
less energy)

Front 57

Example of endergonic reaction

Back 57

– E.g. Photosynthesis makes
energy-rich sugar molecules
using energy in sunlight
– E.g cell making proteins from
amino acids

Front 58

metabolism

Back 58

combination of the thousands of endergonic and exergonic chemical reactions in a living organism

Front 59

Metabolism requires energy, which is taken from...

Back 59

sugar
or other molecules containing energy

Front 60

metabolic pathway

Back 60

series of chemical reactions
that either break down a complex molecule or build up
a complex molecule

Front 61

A cell does three main types of
cellular work

Back 61

– Chemical work—driving
endergonic reactions
– Transport work—pumping
substances across membranes
– Mechanical work—beating of
cilia

Front 62

To accomplish work, a cell must
manage its energy resources, and
it does so by...

Back 62

energy coupling—
the use of exergonic processes to
drive an endergonic one

Front 63

ATP

Back 63

adenosine
triphosphate, is the
energy currency of
cells
-ATP is the immediate
source of energy that
powers most forms of
cellular work.

Front 64

ATP is composed of ...

Back 64

It is composed of
adenine (a nitrogenous
base), ribose (a fivecarbon
sugar), and three
phosphate groups.

Front 65

Hydrolysis of ATP releases
...

Back 65

energy by transferring its
third phosphate from ATP to
some other molecule

Front 66

phosphorylation

Back 66

Hydrolysis of ATP releases
energy by transferring its
third phosphate from ATP to
some other molecule
– In the process, ATP
energizes molecules

Front 67

ATP is a renewable source of energy for the cell

Back 67

– When energy is released in an exergonic reaction, such
as breakdown of glucose, the energy is used in an
endergonic reaction to generate ATP

Front 68

energy of activation (EA)

Back 68

the energy that must be overcome in order for a chemical reaction to occur. Activation energy may also be defined as the minimum energy required to start a chemical reaction.

Front 69

The cell uses____ to drive
(speed up) biological reactions

Back 69

catalysis

Front 70

enzymes

Back 70

proteins
that function as biological
catalysts

Front 71

Enzymes speed up the rate of
the reaction by...

Back 71

lowering the
EA , and they are not used up
in the process

Front 72

Each enzyme has a particular
target molecule called the

Back 72

substrate

Front 73

Enzymes have unique threedimensional
shapes

Back 73

The shape is critical to
their role as biological
catalysts

Front 74

As a result of its shape,
the enzyme has an

Back 74

active site where the
enzyme interacts with the
enzyme’s substrate

Front 75

For optimum activity, enzymes require certain
environmental conditions

Back 75

Temperature is very important, and optimally, human
enzymes function best at 37ºC, or body temperature
– High temperature will denature human enzymes

Front 76

Enzymes also require...

Back 76

a pH around neutrality for best
results

Front 77

Some enzymes require ...

Back 77

nonprotein helpers

Cofactors
Coenzymes

Front 78

Cofactors

Back 78

are inorganic, such as zinc, iron, or copper

Front 79

Coenzymes

Back 79

organic molecules and are often
vitamins
– We need vitamins in our food or as supplements because of
their role in metabolism driven by enzymes

Front 80

Inhibitors

Back 80

chemicals that
inhibit an enzyme’s activity
– One group inhibits
because they compete
for the enzyme’s active
site and thus block
substrates from entering
the active site

Front 81

competitive inhibitors

Back 81

One group inhibits
because they compete
for the enzyme’s active
site and thus block
substrates from entering
the active site

Front 82

noncompetitive inhibitors

Back 82

inhibitors do not act directly with the active
site
– These bind somewhere else and change the shape of
the enzyme so that the substrate will no longer fit the
active site
– Penicillin, an antibiotic, is an example of a
noncompetitive inhibitor because it blocks the active
site of an enzyme that some bacteria use to make their
cell wall.

Front 83

Enzyme inhibitors are important in regulating ...

Back 83

cell
metabolism

Front 84

feedback inhibition

Back 84

Often the product of a metabolic pathway can serve as
an inhibitor of one enzyme in the pathway