Starter1. Describe the structure and

main function of the following organelles:

a) Nucleusb) Flagellac) Contractile Vacuole

Startera) Nucleus, a spherical structure

surrounded by a porous membrane that contains genetic information for the control of the functioning of the cell.

b) Flagella, made up of fibers that contract making the flagellum move from side to side and important in the movement of the cell.

Starterc) Contractile vacuole, is a

membrane bound organelle found in aquatic protists that pumps water from within the cell to the outside to maintain osmotic equilibrium(water balances within the cell).

2 / 3 correct for Achieved

Starter2. Describe where most of the

chloroplasts would be found inside this cell and explain why they are found there.

3. Cells like Euglena are rarely visible, unless you use a microscope. Explain why single cells like this never grow larger.

Starter2. Description of where most

chloroplast are found in this cell, eg. near the outer edge of the cell.

Explanation why most chloroplasts are found in this position, eg. light intensity is highest here for efficient photosynthesis.

Starter3. Description of why single cells never

grow larger, eg the surface area to volume ratio decreases so that they cannot absorb materials efficiently.

Explanation of why single cells never grow larger, eg so that the cell must divide to increase the surface area to volume ratio again so that it will function more efficiently. This keeps the cell size small.

RespirationRespiration involves the

breakdown of glucose to produce water, carbon dioxide and energy.

C6H12O6 + 6O2 enzymes 6H2O + 6CO2 + Energy

The majority of respiration occurs in the mitochondria.

RespirationThe energy is stored as chemical

energy in molecules of adenosine triphosphate (ATP).

The ATP is formed when a molecule of adenosine diphosphate (ADP) and a phosphate group combine.

+ →Adenosine P P P

Adenosine P P P

RespirationEnergy is released when ATP

is broken down into ADP.

Adenosine P P PEnergy

ATP

ADP + P

Energy from

breakdown of glucose

Energy released

from breakdown

of ATP

Respiration

RespirationRespiration

occurs in four stages:

1. Glycolysis2. Transition Reactions3. Krebs Cycle4. Electron Transport Chain

1. GlycolysisGlycolysis is the sequence of

reactions, occurring in the cytoplasm, that converts glucose (C6) into pyruvate (C3) and a small amount of ATP.

Glucose Pyruvate ATP

C6H12O6 → 2CH3COCOOH + 2ATP

1. GlycolysisIf conditions inside the cell are

anaerobic then pyruvate remains in the cytoplasm to be broken down.

In animals the pyruvate forms lactic acid (causes muscle cramps).

In plants pyruvate forms ethanol and CO2 (fermentation).

1. GlycolysisTwo NAD+ molecules (coenzymes)

collect hydrogen and become NADH.

They carry this hydrogen to the mitochondria and then pass it to the electron transport chain.

Coenzyme – organic, non-protein molecules that carry chemical groups between enzymes.

1. GlycolysisGlucose

2 x Pyruvat

e

2 ADP

Num

erou

s ch

emic

al

reac

tions

2 ATP

NAD+

NADH

C6

C3

1. GlycolysisSome organisms (e.g. anaerobic

bacteria) use glycolysis as their only energy source.

A much greater amount of ATP is produced if the pyruvate is then broken down inside the mitochondria.

2. Transition ReactionsThe pyruvate enters

the mitochondria where it is broken down into acetyl (C2), CO2 and Hydrogen.

Coenzyme A (CoA) binds to the acetyl group (COCH3) and is changed to acetyl coenzyme A (Acetyl CoA).

CO2

CoA

2 x Pyruvat

e

NADH

C3

Acetyl CoAC2

Acetyl Group enters Krebs Cycle

2. Transition ReactionsThis is an important link where the acetyl

group is carried to the matrix of the mitochondria.

Other food molecules (fats and proteins) can enter the respiration process, as they can be broken down to acetyl groups.

The CoA does not enter the mitochondria and returns to pick up another acetyl group.

3. Krebs CycleTakes place in the

inner matrix of the mitochondria.

During the process carbon dioxide is released as a waste product and a small amount of ATP is synthesized.

Many NAD+’s get filled with hydrogen (NADH) and are carried to the electron transport chain.

CO2Kreb

s CycleAcetyl

Group

C2

C6

ADP ATP NAD+

NADH

ADPATP

NAD+

NADH

C4

C5

CO2

4. Electron Transport ChainThe electron transport chain (respiratory chain) is located in the cristae of the mitochondria.

On the membranes are many cytochromes, which pass the hydrogen down the chain.

The oxidation and reduction actions release enough energy to charge about 3 ATP per Hydrogen bouncing down the chain.

4. Electron Transport ChainAt the end of the process the low-

energy hydrogen reacts with the oxygen breathed in and forms water.

O2 + 4H+ + 4e- → 2H2O

If no oxygen is available respiration stops at glycolysis.

Mitochondria

Crista

Cytochromes

2H + ½ O → H2O

ATP

GlycolysisKrebsCycle

2 ATP

2 ATP

34 ATP

CoA

Acetyl CoA

NADHNADH NAD+

NAD+

Electron Transport

Chain

CO2

CO2

2H + ½ O2 → H2O

Factors Affecting RespirationRate of Respiration refers to the

speed at which glucose is broken down to produce energy.

This can be affected by:1.Amount of oxygen present.2.Amount of glucose/fat present.3.The energy demand.4.Temperature.

Homework

Complete Biozone Pg. 297 – 298