Cell Physiology

Physiology = the study of the vital processes of an organism

1) Homeostasis

= a steady state that a tissue, organ, system or organism

maintains by self-regulating adjustments

= ability to adapt to a change and stay in a balanced state

- ie)

kidney will double in size if the other is removed

goose bumps & shivering conserve body heat

going into shock in an emergency

- cells maintain homeostasis with their environment by means

of the plasma membrane

- the cell membrane is a differentially permeable or semi permeable membrane

between the cell and its environment (or neighboring cell)

= allows certain substances to cross into and leave the cell while other

substances are prohibited

- Factors Affecting the Selective Permeability of the Plasma Membrane:

1. Particle size

2. Particle solubility

3. Concentration inside or outside of the cell

4. Electrical charge of the Particle

(ions move across the membrane slowly if same charge as cell membrane)

5. Plasma membrane structure

2) Structure of the Plasma Membrane (a.k.a. Fluid Mosaic Model)*

= lipid bilayer embedded with proteins

- the 2 layers are composed of mobile phospholipid molecules

: phospholipids have a polar water soluble end (hydrophilic) and a non polar fat

soluble end (hydrophobic)

: the hydrophilic ends face the outer environment & the inner cell components

-special protein molecules (glycoproteins) embedded in the lipid bilayers

serve different functions:

a. Markers = so cells can identify each other

- explains transplant and transfusion rejection

b. Receptors for chemical messages (hormones)

c. Regulators of what enters or attaches to cells

d. Transporters carrying specific materials into & out of the cell

FLUID MOSAIC MODEL OF THE PLASMA MEMBRANE

3) Transport of Substances

- substances are moved through the cell membrane in a variety of ways:

A) Passive Transport

= movement of materials across a cell membrane without the cell using its own energy

(with the concentration gradient)

- modes of passive transport:

1. Simple Diffusion

= the random movement of substance from an area of high concentration to an

area of low concentration

- establish equilibrium (although motion is not stopped on the microscopic level)

- used for small, non-polar molecules, ions and gases

- factors affecting diffusion = concentration, temperature, & pressure

2. Osmosis

- is the diffusion of water

- as water molecules enter a cell, pressure occurs

inside against the cell membrane

- in plant cells this pressure is referred to as turgor

pressure

: gives plants their rigidity

: when turgor pressure = osmotic pressure,

equalibrium is reached

- the type of solution the cell is in will affect osmosis:

a) Isotonic Solution

: iso = same, tonic = strength

: solute concentration (molecules dissolved in water) inside the cell equals the

solute concentration outside the cell

: is perfect for cells

b) Hypotonic Solution

: hypo = lower

: solute concentration outside the cell is less than that found inside the cell

: water flows inward causing increased pressure within the cell

: the cell walls of plant cells allow them to withstand this pressure

:animal cells lack cell walls so would swell and eventually burst (cytolysis) therefore

they have water removing mechanisms

- single celled organisms have contractile vacuoles (ie. Paramecium)

- multicellular organisms have specialized organs (ie. Kidneys, lungs sweat glands)

c) Hypertonic Solution

: hyper = higher

: solute concentration outside the cell is greater than that found inside the cell

: the organism loses water = cells shrink

: causes plasmolysis (a.k.a. Reverse osmosis)

- plants cell wilt

(caused by lack of water, excess fertilizer)

- animals cells dehydrate

(caused by drinking salt water, swimming in high

content salt water, treating a cut with salt solution)

3. Facilitated Diffusion

- special channel protein molecules in the cell membrane speed up the movement

of molecules already moving across the cell membrane

= a ‘fast pass’

- very selective

ie. Glucose diffuses into red blood cells 100’s of times faster than other sugars)

What type of solution is each of the following cells in?

A B C

B) Active Transport

= movement of substances across the cell membrane

requiring the cell to use its own energy

- energy is needed to move molecules from an area of

low concentration to an area of high concentration

(against the concentration gradient)

- modes of active transport:

1. Facilitated Transport

= a ‘protein pump’

- special protein carrier molecules in the cell membrane receive an energy boost

from the cell which helps them transport molecules against the concentration

gradient*

- some actively pump materials out of the cell as well

- Energy used is in the form of ATP (Adinosine Triphosphate)

1Protein Pump (specific to Na+ based on shape)

2NRG causes the pump to change its shape forcing the substance through (Na+)

3New shape of pump allows substance 2 (K+)

to enter

4Release of the phosphate causes the pump to revert to original shape forcing Substance 2 (K+) through

2. Endocytosis

- endo = into; cytosis = movement of substances within the cell by means of the

cytoplasm

- transport of large molecules (ie. lipids, proteins, amino acids) into the cell by

engulfing (surrounding) the molecule with pseudopods until it has been

enclosed within a vacuole

- molecules are then digested by enzymes from the lysosomes

- two forms of endocytosis:

a) Phagocytosis

: process through which cells engulf solid particles

: ie. amoeba, white blood cells

b) Pinocytosis

: process through which cells engulf liquid droplets

: ie. fat droplets are engulfed by cells in the small

intestine

3. Exocytosis

- exo = out of

- large molecules (ie. wastes, excess water) are stored in vacuoles which move

to and join with the cell membrane expelling their contents

= opposite of endocytosis

4. Metabolism

= all the chemical reactions that build up and tear down molecules within the cell

- involves energy production and use within the cell

- all organisms require energy in order to complete life processes

ie. active transport, reproduction, movement, growth and repair, etc.

- this energy is obtained on a cellular level

A) Energy

= the capacity for doing work or causing change

- cannot be created or destroyed, only changed from 1 form to another

= First Law of Thermodynamics

: ie. heart attack victims receive electrical energy which is converted to

mechanical energy

- there are many forms of energy (light, heat, chemical, electrical, mechanical, etc.)

however, ultimate energy source for all living organisms is the sun

1. Energy Storage and Transformation

- energy storage and conversion processes are critical for sustaining life

- ATP (adenosine triphosphate) is a compound that stores chemical energy in cells

: energy is kept in these small packets so that it can be used quite readily

= ie. keeping one hundred loonies for buying things instead of a single $20 bill

: whenever energy is needed, the terminal (end) phosphate breaks off of ATP

= a bit of energy is released and ADP (adenosine diphosphate) is left

Adenosine

Phosphate Phosphate

Phosphate

Adenosine

Phosphate Phosphate

NRG

: ADP can be used as an energy source (strip end phosphate AMP) but is not an

efficient energy source (like using quarters to purchase goods).

= is an energy carrier

(picks up NRG released during oxidation-reduction reactions and uses it to

attach a phosphate and form ATP again)

ADP

+ P

- P = CYCLIC

ATP

2. Oxidation-Reduction Reactions

= transfer of electrons from 1 atom/molecule to another to go from high energy

(unstable) reactants to low energy (stable products)

- energy is released in large amounts

3. Electron Transport Systems

- rapid release of energy is not suited for cells

: causes damage (cells = proteins; energy = heat)

= NRG is released in a series of steps as particles are passed from 1 acceptor

molecule to another

- ie. like a hot potato

Types of Metabolic Reactions = photosynthesis, respiration, and fermentation

B) Photosynthesis (pp. 97 fwd)

General Formula: 6CO2 + 6H2O + Solar NRG chlorophyll> C6H12O6 + 6O2

process through which solar energy is converted into chemical energy stored in

the bonds of glucose molecules

occurs in the chloroplast

Involves 2 stages:

o Light-Dependent Reactions

o Light-Independent Reactions

(Calvin Cycle)

i) Light- Dependent Reactions Site: in the disk shaped thylakoids of the grana Purpose: Produce ATP & harvest H+ ions to use in the

Light Independent Reactions Involves:

o Photolysis - process by which H2O is split into H+ ions & O atoms by the sun

o Phosphorylation - process of adding a phosphate to ADP creating ATP (requires energy)

a) Photosystem II

Inputs are light and water

Photons of sunlight strike photosystem II (chlorophyll a) causing the release of 2

high energy electrons to the “Primary Electron Acceptor”

These electrons pass down an Electron Transport Chain releasing energy to form

ATP from ADP by phosphorylation

b) Photosystem I

Electrons at the base of the ETC in Photosystem II are reenergized by the sun

and passed to the ‘Secondary Electron Acceptor’

These electrons pass down a 2nd, shorter ETC releasing NRG to form more ATP

At the same time, photolysis splits water into H+ ions, an O atom & 2 electrons

electrons = will replace the 2 e_’s lost by chlorophyll a

H+ ions = picked up by the carrier molecule NADP, forming NADPH,

which will be used in the Light Independent Reactions

Oxygen = given off as a byproduct in the form of O2 gas

**All molecules of NADPH & ATP created in the Light Phase are used in the Calvin

Cycle

ii) Light Independent Reactions (Calvin-Benson Cycle) Occurs in the gel between the grana called stroma Purpose: Build carbohydrate molecules using products of the light-dependent

reactions Does not require solar energy as it uses the energy stored in the ATP molecules

= occurs day and night

3 CO2 molecules from the atmosphere enters the chloroplasts via stomates

Energy from ATP is used to join each CO2 to carrier molecule, Rubisco (RuBP)

The Rubisco carriers force the 3 CO2 to bond forming a 3 Carbon compound

called Phosphoglyceric Acid (PGA).

o The 3 RuBP are freed to pick up more CO2

Energy from ATP is used to join the PGA molecules with H+ ions donated by

NADPH to form PGAL (Phosphoglyceraldehyde)

Both ADP and NADP are recycled to the Light-Dependent Phase

PGAL can be used as it is or molecules of PGAL can be combined to form more

complex carbohydrates (ie. Glucose, sucrose, starch)

What gas is released in the Light Dependent Reactions?

1. Carbon dioxide

2. Oxygen

3. Water vapour

4. All of the above

What is made in Photosystem I & II?

1. C6H12O6

2. ATP

3. CO2

4. All of the above

What new gas enters the Calvin Cycle?

1. Carbon dioxide

2. Oxygen

3. Water vapour

4. All of the above

What is produced by the Calvin Cycle?

1. Sugars

2. ATP and NADPH

3. O2

4. All of the above

D. Cellular Respiration (pp. 107 fwd)

The process by which mitochondria in the cells of all living organisms break down

glucose to make ATP

= convert the NRG stored in glucose to a form the cell can use

Chemical equation for cellular respiration:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP

complementary to photosynthesis

= products of photosynthesis used in cellular respiration

Two types:

Aerobic respiration: requires O2; results in complete breakdown of glucose

Anaerobic respiration: requires no O2, incomplete decomposition of glucose

i) Aerobic Respiration

Involves 3 stages: Glycolysis, the Kreb’s Cycle, & the Electron Transport System

a) Glycolysis Site: occurs in the cytoplasm of the cell Purpose: Split sugar into 3 C molecules to be processed in the mitochondria does not require the presence of oxygen

1. A molecule of glucose is split into two 3 carbon molecules of PGAL

using two molecules of ATP.

2. Each PGAL molecule is converted into Pyruvate by removing a H+ ion & e-‘s.

Energy is released in this process (creates 2 ATP per pyruvate).

3. The H+ ions & e-‘s are picked up by the carrier molecule NAD which

becomes NADH.

4. The pyruvate and NADH molecules are carried over to the next stages.

Net Results:

1 C6H12O6 produces:

2 pyruvate

2 NADH

4 ATP (-2 invested) = 2 ATP

b) Krebs Cycle (a.k.a. Citric Acid Cycle) Site: occurs in matrix (inner compartment )

of the mitochondrion in cell Purpose: break down pyruvate to harvest H+ ions

& e-‘s to put through the ETC requires oxygen

1. To prepare pyruvate for entering the Krebs cycle, a carrier molecule, Coenzyme

A, picks up each pyruvate and converts it into Acetyl CoA by removing a Carbon,

Hydrogen and electrons.

Carbon atoms are joined to Oxygen to form CO2 while the H and e-`s are picked

up by NAD creating NADH.

For each acetyl CoA : 1 CO2 is created (exhaled)

1 NADH

**The 2 acetyl CoA molecules can now enter the Kreb Cycle.

2. The Krebs Cycle is like a big circular assembly line. Each acetyl CoA is picked up

by a Citric Acid, a 4 Carbon carrier molecule which carries it through the cycle.

3. Each acetyl CoA is broken down by stripping off H+ ions & e-‘s which are picked up

by the carrier molecules NAD & FAD producing NADH & FADH2.

Carbon atoms are joined to Oxygen to form CO2.

= nothing is left of the original glucose molecule (taking apart Leggo)

4. The energy released from this process produces ATP.

Net Results:(for each acetyl CoA)

: 1 ATP

: 3 NADH and 1 FADH2

: 2 CO2

Matrix

Christae

(fold)

c) Electron Transport System (a.k.a. Electron Transport Chain) Site: occurs in the cristae (inner folded membranes) of the mitochondrion Purpose: produce ATP via phosphorylation requires oxygen

1. 2 ATP are used to put the NADH and FADH2 from Glycolysis and the Krebs

Cycle into the Electron Transport System.

2. The NADH and FADH2 are each stripped of H+ ions & e-‘s.

4. These ions and electrons are sent to a series of carrier molecules (enzymes)

which pass them from 1 enzyme to the next, releasing NRG to create ATP.

= like a hot potato

5. The hydrogen ions and e-‘s join with oxygen to form H2O(g) which is exhaled.

Each NADH produces 3 ATP, and each FADH2 produces 2 ATP.

Net Results:

6 H2O (exhaled)

10 NADH produce 30 ATP

2 FADH2 produce 4 ATP

34 ATP (but 2 invested) = 32 ATP

**Most of the ATP for aerobic respiration is produced in this stage

**ATP Totals for aerobic respiration:

Glycolysis – 2 ATP Citric Acid Cycle – 2 ATP

Electron Transport Chain – 32 ATP

1 Glucose = ~36 ATP in all for aerobic respiration

GLYCOLYSIS PREP FOR KREBS

CYCLE

KREBS

CYCLE

E- TRANSPORT

CHAIN

INPUT

OUTPUT

ii) Anaerobic Respiration (a.k.a. Fermentation)

Also called incomplete cellular respiration

Does not require oxygen to make ATP

Is Glycolysis but in the absence of O2 pyruvate is converted into more stable

products

2 types:

a) Alcohol Fermentation

o used by yeast

o as there is no O2 the pyruvate is rearranged forming ethanol & releasing CO2

Net Results:

2 ATP

CO2 (make bread rise)

Ethanol (produce beer, wine)

b) Lactate Fermentation

o used by anaerobic bacteria and muscles

o lack of O2 causes pyruvate to be converted to lactic acid & CO2 is released.

o bacteria (ie. milk turns sour)

o muscle cells: a lack of sufficient oxygen during strenuous exercise causes

lactic acid build up in muscles resulting in muscle cramps and fatigue

Net Results:

2 ATP

CO2

Lactic Acid

Comparing Aerobic and Anaerobic Respiration

ATP production : Aerobic = 36 vs Anaerobic = 2

**Aerobic Respiration is more efficient due to the Electron Transport Chain

= is where most ATP is formed

- like complete combustion of fuel in a car

4. Metabolism

= all the __________________ that build up and tear down molecules within the cell

- involves ___________________________and_________ within the cell

- all organisms require energy in order to complete life processes

ie. active transport, reproduction, movement, growth and repair, etc.

- this energy is obtained on a __________________

A) Energy

= the capacity for doing work or causing change

- cannot be ___________________________only changed from 1 form to another

= First Law of Thermodynamics

: ie. heart attack victims receive_______________ which is converted to

__________________

- there are many forms of energy (light, heat, chemical, electrical, mechanical, etc.)

however, ultimate energy source for all living organisms is __________________

1. Energy Storage and Transformation

- energy ___________________________ processes are critical for sustaining life

- ATP (adenosine triphosphate) is a compound that _________chemical energy in cells

: energy is kept in these small packets so that it can be used quite readily

= ie. ______________________________________________________

: whenever energy is needed, the terminal (end) phosphate breaks off of ATP

= a bit of energy is released and ADP (adenosine diphosphate) is left

Adenosine

Phosphate Phosphate

Phosphate

Adenosine

Phosphate Phosphate

NRG

: ADP can be used as an energy source (strip end phosphate AMP) but is not an

efficient energy source ____________________________________

= __________________

(picks up NRG released during __________________reactions and uses it to

attach a phosphate and form ATP again)

ADP

+ P

- P = CYCLIC

ATP

2. Oxidation-Reduction Reactions

= _________of electrons from 1 atom/molecule to another to go from _________

(unstable) reactants to __________________ (stable products)

- energy is released in __________________

3. Electron Transport Systems

- rapid release of energy is not suited for cells

: causes damage (cells = proteins; energy = heat)

= NRG is released in a __________________as particles are passed from 1 acceptor

molecule to another

- ie. ____________________

Types of Metabolic Reactions = photosynthesis, respiration, and fermentation

B) Photosynthesis (pp. 97 fwd)

General Formula: 6CO2 + 6H2O + Solar NRG chlorophyll> C6H12O6 + 6O2

process through which _________________is converted into __________

stored in the bonds of glucose molecules

occurs in the chloroplast

Involves 2 stages:

o Light-Dependent Reactions

o Light-Independent Reactions

(Calvin Cycle)

i) Light- Dependent Reactions Site: in the disk shaped thylakoids of the ________ Purpose: Produce ________& harvest _____to use in

the ______________________________ Involves:

o Photolysis - process by which __________is split into _________________by the _____

o Phosphorylation - process of adding a ____________to ______creating _______ (requires energy)

c) Photosystem II

Inputs are __________and __________

Photons of sunlight strike photosystem II (chlorophyll a) causing the release of 2

high energy electrons to the “Primary Electron Acceptor”

These electrons pass down an ____________________releasing energy to form

ATP from ADP by phosphorylation

d) Photosystem I

Electrons at the base of the ETC in Photosystem II are _______by the _____

and passed to the ‘Secondary Electron Acceptor’

These electrons pass down a 2nd, shorter _____releasing NRG to form more ATP

At the same time, photolysis splits _______into H+ ions, an O atom & 2 electrons

electrons = will replace the __________ by chlorophyll a

H+ ions = picked up by the carrier molecule_______, forming _______

which will be used in the Light Independent Reactions

Oxygen = given off as a byproduct in the form of __________

**All molecules of NADPH & ATP created in the Light Phase are used in the Calvin

Cycle

ii) Light Independent Reactions (Calvin-Benson Cycle) Occurs in the gel between the grana called stroma Purpose: Build ________________molecules using products of the light-dependent

reactions Does not require solar energy as it uses the energy stored in the ______ molecules

= occurs ____________________

3 CO2 molecules from the atmosphere enters the chloroplasts via ________

Energy from ATP is used to join each CO2 to carrier molecule, __________

The Rubisco carriers force the 3 CO2 to bond forming a 3 Carbon compound

called Phosphoglyceric Acid __________

o The 3 RuBP are freed to pick up more CO2

Energy from ATP is used to join the ______ molecules with _______ donated

by NADPH to form __________ (Phosphoglyceraldehyde)

Both ADP and NADP are __________ to the Light-Dependent Phase

PGAL can be used as it is or molecules of PGAL can be combined to form more

complex carbohydrates ____________________

D. Cellular Respiration (pp. 107 fwd)

The process by which mitochondria in the cells of all living organisms break down

glucose to make ATP

= ______________________________________________________

Chemical equation for cellular respiration:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP

complementary to photosynthesis

= _______________________________________________________

Two types:

Aerobic respiration: requires _____results in complete breakdown of glucose

Anaerobic respiration: requires _________________incomplete

decomposition of glucose

i) Aerobic Respiration

Involves 3 stages: Glycolysis, the Kreb’s Cycle, & the Electron Transport System

a) Glycolysis Site: occurs in the __________ of the cell Purpose: Split sugar into 3 C molecules to be processed in the mitochondria does not require the presence of oxygen

1. A molecule of glucose is split into two 3 carbon molecules of __________

using two molecules of ATP.

2. Each PGAL molecule is converted into __________ by removing a H+ ion & e-‘s.

Energy is released in this process ____________________

3. The H+ ions & e-‘s are picked up by the carrier molecule__________ which

becomes __________

4. The pyruvate and NADH molecules are carried over to the next stages.

Net Results:

1 C6H12O6 produces:

__________ pyruvate

__________ NADH

__________ ATP (-2 invested) = 2 ATP

b) Krebs Cycle (a.k.a. Citric Acid Cycle) Site: occurs in ____________________

of the mitochondrion in cell Purpose: break down pyruvate to harvest H+ ions

& e-‘s to put through the ETC requires oxygen

1. To prepare pyruvate for entering the Krebs cycle, a carrier molecule,

________ picks up each pyruvate and converts it into ________________by

removing a Carbon, Hydrogen and electrons.

Carbon atoms are joined to Oxygen to form ________ while the H and e-`s are

picked up by NAD creating ____________________

For each acetyl CoA : __________ CO2 is created (exhaled)

__________ NADH

**The 2 acetyl CoA molecules can now enter the Kreb Cycle.

2. The Krebs Cycle is like a big circular assembly line. Each acetyl CoA is picked

up by a _______a 4 C carrier molecule which carries it through the cycle.

3. Each acetyl CoA is broken down by stripping off __________which are picked

up by the carrier molecules NAD & FAD producing __________&________.

Carbon atoms are joined to Oxygen to form CO2.

= nothing is left of the original glucose molecule ____________________

4. The energy released from this process produces __________

Net Results:(for each acetyl CoA)

: ______ ATP

: ______ NADH and ____ FADH2

: ______ CO2

Matrix

Christae

(fold)

c) Electron Transport System (a.k.a. Electron Transport Chain) Site: occurs in the __________ (inner folded membranes) of the mitochondrion Purpose: produce ATP via ____________ requires _________

1. ________ are used to put the NADH and FADH2 from Glycolysis and the Krebs

Cycle into the Electron Transport System.

2. The NADH and FADH2 are each stripped of H+ ions & e-‘s.

6. These ions and electrons are sent to a series of carrier molecules __________

which pass them from 1 enzyme to the next, releasing ____ to create ____

= like a hot potato

7. The hydrogen ions and e-‘s join with oxygen to form _________which is exhaled.

Each NADH produces __________ and each FADH2 produces __________

Net Results:

6 H2O (exhaled)

10 NADH produce _______ ATP

2 FADH2 produce _______ ATP

_______ ATP (but 2 invested) = ___________

**Most of the ATP for aerobic respiration is produced in this stage

**ATP Totals for aerobic respiration:

Glycolysis – 2 ATP Citric Acid Cycle – 2 ATP

Electron Transport Chain – 32 ATP

1 Glucose = __________ in all for aerobic respiration

GLYCOLYSIS PREP FOR KREBS

CYCLE

KREBS

CYCLE

E- TRANSPORT

CHAIN

INPUT

OUTPUT

ii) Anaerobic Respiration (a.k.a. Fermentation)

Also called ______________________________

Does not require __________________ to make ATP

Is Glycolysis but in the absence of O2 pyruvate is converted into more stable

products

2 types:

a) Alcohol Fermentation

o used by ___________

o as there is no O2 the pyruvate is rearranged forming ____ & releasing ___

Net Results:

2 ATP

CO2 (make bread rise)

Ethanol (produce beer, wine)

b) Lactate Fermentation

o used by ______________________________

o lack of O2 causes pyruvate to be converted to ________& ____ is released.

o bacteria (ie. milk turns sour)

o muscle cells: a lack of sufficient oxygen during strenuous exercise causes

lactic acid build up in muscles resulting in muscle cramps and fatigue

Net Results:

2 ATP

CO2

Lactic Acid

Comparing Aerobic and Anaerobic Respiration

ATP production : Aerobic = _______ vs Anaerobic = ______

**Aerobic Respiration is more efficient due to the ________________

= is where most ATP is formed

- like complete ____________________