Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Introduction to cell biology uottawa > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

what are lipids

A

Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix
poorly, if at all, with water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

fatty acids are made of what components?

A

carboxylic acid,

long carbon chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

if a fatty acid link a glycerol it forms what molecule

A

triglyceride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

2 types of fat and what distingues them?

A

saturated
unsaturated

unsaturated has double bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

the main component of phospholipids is

A

fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

the double bond has an impact on

A

fluidity of the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

higher levels of unsaturation leads to

A

lower melting point

less viscous(oil)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

est-ce que toutes les espèces ont le meme niveau d’insaturation?

A

non, their variations are due to the adaptations to specific environment conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

is it possible to change the lipid composition of the plasma membrane depending on the temperature for some species?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the fundamental role of the membrane?

A

to act as a selective permeable barrier, regulating the cell’s chemical composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the main component of the plasma membrane?

A

phospholipids

it is a bilayer of phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the roles of the plasma membrane?

A

compartmentalization

site for biochemical activities

providing a selectively permeable barrier

transporting solutes

responding to external stimuli

intercellular interaction

energy transduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

phospholipid is made of what

A

lipid made up of glycerol joined to 2 fatty acids and a phosphate groupe and choline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

which part of phospholipid is hydrophobic and hydrophilic?

A

head-hydrophilic

tail = hydrophobilc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

if it has parts that are hydrophobic and hydrophilic then it is named as

A

amphipathic

(with both a hydrophilic
region and a hydrophobic region).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

because of their amphipathic nature, the phospholipids do what when they assemble?

A

this causes phospholipids to assemble
into bilayers, exposing their hydrophilic
(polar) head to the polar water molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

can polar molecules cross the

bilayers membrane?

A

non

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what means that amolecule is hydrophobic?

A

it means that it can not interact with water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

phospholipids can differ based on what?

A

Phospholipids can differ based on the fatty acid chains (length, number and position of double bond),

the fatty acid linkage (ester versus ether)

the head group (Phosphatidyl choline, Phosphatidyl
ethanolamine, Phosphatidyl serine, Phosphatidyl inositol…)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

if the fluidity is increased for the plasma memebrane

explain the impact on the permeability and protein functions?

A

it increases the membrane permeability and proteins functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

name the 3 possible movements of phospholipids?

A

lateral shift

transverse diffusion

flex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

permeability of the membrane is higher for

A 
•
smaller molecules
•
less polar (charged) molecules
•
more hydrophobic molecules
•
highly lipid soluble substances
•
gas (ex: O 2 , CO 2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what means when a barrier is efficent?

A

it maintains the concentration of all the molecules inside the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are transport proteins?

A

are transmembrane proteins that can modify temporarily the permeability
of the membrane by allowing only specific molecules to cross (enter or leave the cell).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

explain the fick’s law of diffusion

A

The flux of molecules goes from regions of high concentration to
regions of low concentration
. The magnitude of this diffusion is proportional to the concentration gradient
between the two compartment (ex: across the plasma membrane).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

the flux of molecules going from high to low concentration is du to

A

stochastic(random) movement of each molecule in all direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

net movement of a population of molecules towards…………(

A

lower concentrations (chemical gradient)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

if the molecule is polar or charged, its net movement also depends on both

A

the chemical gradient

and

the electric gradient across the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is an electric gradient?

A

it is a difference in the charges across the membrane(intern and extern) of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

passive (simple) diffusion across the phospholipids double layer, requiers energy(hydrolysis of ATP)?

A

NON
it does not require the energy(hydrolysis of ATP

it is a passive diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

c’est que les regles à suivre pour savoir quels molecules vont passer par simple diffusion(passive diffusion)

A


Substances follow their own concentration gradient (from high concentration to low concentration)

Gas follow their own partial pressure gradient (from high partial pressure to low partial pressure) CO2 and O2

At equilibrium there is an equal number of molecules passing in each direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Note that diffusion can be facilitated by membrane transport proteins (channels) that are ………….

and give examples

A

highly selective and
let specific molecules go through

(ex: aquaporins in the kidney ducts)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what are aquaporins?

A

they are proteins that let molecules of water to pass through by simple diffusion(passive)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

why there are transport proteins that can do passive diffusion?

A

because there are molecules who have difficulty to pass through the plasma membrane like sucrose, ions(Ca2+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

transport proteins are embedded where?

A

in the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

The cell is able to modify (regulate) the entry/exit of molecules through…

A

the expression of genes that code for transport proteins (which are then inserted in the membrane)

•
the temporary opening and closing of some of these transport proteins (depending on a stimulus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

by regulating the entry/exit of molecules, the cell can maintain

A

•
a specific cellular concentration of each solute (ions, molecules)
•
a specific electric potential across the membrane (by keeping some ions outside and others inside)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what is the charge inside the cell normally and is due to what?

A

negative normally

due to the presence of phosphate groups and proteins that are both -ve charged and to the movements of ions in/out of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what is a membrane potential?

also called

A

The charge difference (voltage) across the plasma membrane—. The attraction of opposite charges across the plasma membrane is a
source of potential energy.

electrical potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

the resting membrane potential has a value of

A

70 mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

If a molecule is not charged (or large), its diffusion across the membrane
only
depends on

A

depends on the chemical gradient concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

If a molecule is charged (and small), its diffusion across the membrane
depends on

A

If a molecule is charged (and small), its diffusion across the membrane
depends on
both

43
Q

if we have to take in account the chemical gradient and electrical gradient then this combination is called

A

electrochemical gradient

44
Q

Ions are charged and their facilitated diffusion therefore depends on the

A

electrochemical gradient

45
Q

true or false

Its diffusion does not depend on the concentration gradients of other

A

true

46
Q

Each ion has its own

equilibrium potential which is

A

: the difference in charges across the membrane due to the

difference in its concentration (so it results from both the chemical and the electrical gradient).

47
Q

what is a non-penetrating molecule?

A

is a substance that can not cross the membrane because of the selective permeability

48
Q

what is osmosis

A

it is a net movement of water towards the compartment with higher concentration of non-penetrating solutes across a selectively permeable membrane

49
Q

what is osmolarity

A

: concentration of all solutes in a solution both penetrating and non penetrating osmole/L)

50
Q

if it has a higher concentration of solutes than the cell (penetrating and non penetrating).
the solution has what type of osmolarity?

A

hyperosmotic

51
Q

if it has a lower concentration of solutes than the cell (penetrating and non penetrating).
the solution has what type of osmolarity?

A

hypoosmotic

52
Q

if it has the same concentration of solutes as the cell (penetrating and non penetrating).

the solution has what type of osmolarity?

A

isoosmotic

53
Q

give the 3 types of osmolarity

A

hyperosmotic

hypoosmotic

isoosmotic

54
Q

what is tonicity?

A

: ability of a solution to create a net movement of water inside or outside of a cell. It is calculated as
the concentration of non penetrating solutes only , those that can exert an effective

Tonicity is therefore the effective osmolarity
with
regards to the osmotic pressure and is expressed
as “
effective os mole/L

55
Q

give the 3 types of tonicity

A

hypertonic

hypotonic

isotonic

56
Q

if a solution has if it has a higher concentration of non penetrating solutes than the cell.
it has what type of tonicity?

A

hypertonic

57
Q

if a solution has if it has a lower concentration of non penetrating solutes than the cell.
then it has what type of tonicity?

A

hypotonic

58
Q

if a solution has if it has the same concentration of non penetrating solutes as the cell. it has what kind of tonicity?

A

isotonic

59
Q

what is osmotic pressure?

A

is the minimum pressure required so there is no movement of water across a
semi permeable membrane.

The
osmotic pressure is a
function of the difference in
the concentration of non
penetrating molecules!Page  33
60
Q

the osmolarity depends on what pour avoir lieu?

A

Osmosis depends on the concentration of non penetrating molecules inside and outside the cell

61
Q

if an ionic compound like NaCl, KCl, HCl dissociate in water , what happens to the osmolarity and tonicity?

A

Th e osmolarity (and tonicity) of these molecules is therefore
doubled when in solution or inside the cell.

62
Q

Movements of water inside and outside the cell through osmosis
can create an

A

osmotic pressure and

change the volume of a cell

63
Q

Higher tonicity inside the
cell…………..(decreases/increases)the osmotic
pressure inside the cell

A

increases

64
Q

what structure helps in plant cells to resist the increased osmotic pressure?

A

the cell wall

65
Q

what is osmoregulation?

A

Osmoregulation, the control of solute concentrations and water balance, is a necessary adaptation for life in various environments.

66
Q

what are transport proteins?

A

are membrane proteins that can modify the permeability of the membrane by allowing
only specific molecules to cross (enter or exit the cell).

67
Q

the regulation of permeability by transport proteins through

A

… expression of genes that code for or these transport proteins
(which are then inserted in the membrane

… temporary activation/deactivation (opening/closing) of these transport proteins following a stimulus

68
Q

passive transport requiers energy, ATP?

A

NON

69
Q

types of transport proteins that can do passive diffusion

A

uniporter

ion channel

carrier

70
Q

explain the uniporter

et comment on peut l’activer?

A

(transports a single

Activation: ligand (molecule that binds specifically to another), stress (physical deformation), change in voltage
membrane potential ) or always “

71
Q

explain the ion channel?

A

(simply letting ions pass in either direction

72
Q

what is a carrier and in which transport it is present?

A

passive transport

(change in shape to let the molecule pass in a either

it is a proteine that has a specific shape to a very specific molecule and it can change its shape to let this molecule to go
through the plasma membrane. it facilitates the diffusion of the molecule through the membrane

73
Q

an example of a carrier in all tissues?

A

GLUT1

glucose transporter

74
Q

explain the active transport and what it requires energy from what(2)

A

Membrane protein can transport
molecules against their concentration gradient (from low to high)

             This requires energy from either the : • The hydrolysis of ATP ( ATPase )  primary active transport • The potential energy stored in ionic gradients maintained by the cell  secondary active transport
75
Q

These active transport proteins are all
……….
and it does what?

A

carriers, also called pump

helps maintain specific
intracellular concentration gradients (ex: Na
++, Cl –, K ++, H ++…) by carrying molecules in only one direction
(against their concentration

76
Q

Transport proteins that move a single molecule with active transport are

A

uniporter

77
Q

how we name the transport protein that can carry 2 or more molecules at a time with active transport?

A

cotransporter

78
Q

explain how it works for a cotransporter

A

. One ion provides the energy (down its concentration gradient),
while the other molecule is carried against its concentration gradient.

79
Q

give examples of cotransporter

A

symporter and antiporter

80
Q

proteins are made of

A

polumer of amino acids

81
Q

amino acid are bound by what bond

A

peptide bond between the carboxyl group and an amino group of two amino acids

82
Q

the properties of amino acids are given based on their

A

their side chain (R)

83
Q

explain the primary structure

A

: linear sequence of amino acids of a protein.
The order of amino acids is determined by the DNA sequence of the gene
that codes for this protein.

84
Q

The sequence of amino acids is specific to

…………

A

the function of the protein, its localization,

and its interaction with other molecules.

85
Q

explain the secondary structure

and name the types

A 
structure of the protein made of
segments that are
coiled or folded

determines the protein’s shape

alpha helices
beta pleated sheets

86
Q

the secondary structure results from

A 
The secondary structure results from
hydrogen bonds between
the hydrogens and oxygen atoms of the amide groups found along
the backbone (not the amino acid side chains R groups).
87
Q

the tertiary structure is a

A

Three
dimensional shape stabilized by interactions
between side chains (R groups of the amino acids).

88
Q

The tertiary structure is determined (stabilized)by…

A 
•
Hydrophobic interaction: hydrophobic (nonpolar) amino acids
cluster together at the core of the protein (away from ambient
water molecules).
•
Covalent bonds (disulfide bridge)
•
van der Waals interactions
•
Hydrogen bonds
•
Ionic bonds
52
89
Q

explain the quaternary structure:

A

Association of two or more polypeptides (in some proteins only)
It is the overall protein structure that results from the aggregation of polypeptide subunits.
Each subunit is coded by a single gene!

90
Q

c’est quoi le classement of membrane protein

A

integral proteins

peripheral proteins

lipid-anchored proteins

91
Q

explain the integral proteins

A

: penetrate the hydrophobic core, and are embedded in the membrane. Typically contain
one or more transmembrane helices (e.g. ion channels, transporters, receptors).`

92
Q

explain the peripheral proteins

A

: sit on the membrane surface. Noncovalently bonded to the polar head groups of the lipid
bilayer and/or to an integral membrane protein (e.g. proteins involved in the membrane sugar, lipid and protein
metabolism: oxidase, oxygenase, lipase…).

93
Q

explain the lipid-anchored proteins

A 
covalently
bonded
to a lipid group that resides within
the membrane. The lipid can be
phosphatidylinositol, a fatty acid, or a
glycosylphosphatidylinositol (GPI)
(e.g. hydrolytic enzymes, adhesion
molecule, receptors).
94
Q

true or false

Integral can pass multiple times through
the
hydrophobic part of the plasma
membrane

A

true

95
Q

what is exocytosis

A

: secretion of molecules outside the cell by the fusion of vesicles with the plasma

96
Q

what is endocytosis?

A

: cellular uptake of molecules via the formation of vesicles from the plasma

97
Q

There are three types of endocytosis:

A 
•
Phagocytosis (“cellular eating”)
•
Pinocytosis (“cellular drinking”)
•
Receptor mediated endocytosis
98
Q

Both endocytosis and exocytosis can………….

by doing:

A

rejuvenate or remodel the plasma membrane continuously:

•
formation of new vesicles (from the Golgi apparatus) that fuse with the membrane (added by exocytosis)
•
recycling of parts of the membrane (removed by endocytosis)

99
Q

what is phagocytosis

A

: when a cell engulfs a large particle or a small organism e.g. a prey) by
extending pseudopodia around it and packaging it within a membranous sac called a food vacuole.

The particle is then digested after the food vacuole
fuses with a lysosome containing hydrolytic enzymes.

100
Q

what is pinocytosis

A

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

Cell continually “gulps” droplets of extracellular fluid into small vesicles, formed by infoldings of the plasma
membrane. Coat proteins help form those “pits” (coated pits).

101
Q

pinocytosis is specific or non-specific

and why?

A

phase endocytosis”) is nonspecific:

many substances can be transported inside the cell at the same time

102
Q

what is receptor-mediated endocytosis

A

specialized type of pinocytosis that enables the cell to acquire bulk
quantities of specific substances.

103
Q

what are the steps of receptor-mediated endocytosis

A

This is done through membrane proteins that act as receptor exposed to the extracellular fluid:
1.
Specific solute binds to the receptor proteins
2.
These receptors cluster in coated pits which invaginate
3.
The plasma membrane pinches off to form vesicles containing the bound molecules
4.
The substance is liberated from the vesicle inside the cell
5.
The emptied receptors are recycled to the plasma membrane by the same vesicle

Introduction to cell biology uottawa (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions