2.5 Cell Metabolism

What is metabolism?

All of the biochemical reactions that take place in a cell, critical to survival.

Most biochemical reactions occur in…

metabolic pathways

What are metabolic pathways?

Step by step processes where a substrate is converted into a product by an enzyme (aerobic respiration).

Biochemical processes are influenced by…

the nature and arrangement of internal membranes.

What are the two final stages of aerobic respiration?

Krebs cycle and electron transport chain.

Where do these final stages occur and what do they require?

In the mitochondria and require oxygen.

Structure of the mitochondria

Is a membrane enclosed organelle (has a double membrane) where the inner membrane is folded in a matrix to form cristae that increase SA:V for the attachment of ATP needed in aerobic respiration.

What are thykaloids?

Internal system of flattened sacs that contain photosynthetic pigments (chlorophyll) and are stored as stacks called grana.

What does chlorophyll do?

It traps light energy to convert it into chemical energy.

What are the two types of metabolic pathways?

Aerobic respiration and photosynthesis.

What is aerobic respiration?

Breaking down complex molecules into simpler ones.

What is photosynthesis?

Chemically build complex molecules from simple ones.

3 things cells can carry out as a result of metabolic pathways:

1. Mechanical work (contraction of muscles)

2. Transport work (active transport)

3. Chemical work (creating proteins in transcription and translation)

In metabolic pathways there are…

1. Many small regulated steps that allow for more control.

2. Each step loses some energy.

3. Many different enzymes can be involved in a single pathway called ‘energy coupling’ where one reaction drives the next.

5 environmental factors that can influence biochemical processes are:

1. Temperature

2. Light intensity

3. pH

4. Water availability

5. Substrate and enzyme availability

4 chemicals that can interfere with cell metabolism:

1. Pesticides

2. Fertiliser

3. Antibiotics

4. Other pharmaceuticals

Effect of cyanide on eukaryotes

Prevents the cell from binding to oxygen at the active site during aerobic respiration leading to death.