B2.2 Organelles and Compartmentalisation

Organelles

Discrete structures in cells that are adapted to perform a specific function

Advantage of separation of the nucleus & cytoplasm into separate compartments

• (in eukaryotes) keeping chromosomes in nucleus protects DNA

• Gene expression is regulated by controlling what enters and exits the cell

• Cell cycle control increases

Post-transcriptional modification of RNA

Process of changing & improving RNA molecules

Compartmentalisation

Organisation and separation of different functions/processes within specific areas within cells

Lysosomes contain:

High concentrations of enzymes

Phagocytosis

Plasma membrane engulfs a large particle

Phagocyte

Cells that perform phagocytosis

What does mitochondria produce?

ATP

Adaptations of mitochondria

• Double membrane with a small volume of intermembrane space

• Large surface area of cristae

• Compartmentalisation of enzymes and substrates of Krebs cycle in the matrix

Adaptations of chloroplast

• Outer membrane- Exchange sions and metabolites

• Inner membrane- Allows specific directions for molecules to go in and out of chloroplast

• Stroma

• Matrix- Citric Acid Cycle happens

Stroma in chloroplast

Colourless fluid around thylakoids

Nucleus

Info-processing organelle of cell

Parts of nucleus

• Chromatin

• Nucleus

• Nuclear envelope

• Nuclear pore

• Nucleoplasm

Nucleus _________ and _________ each time most cells divide

disassembles, re-forms

rRNA

ribosomal RNA

Function of ribosomes

In eukaryotes

• “Free ribosomes” In cytoplasm, synthesis proteins used within cell

• “Bound ribosomes“ Attached to rER, synthesis proteins secreted from cell

Endomembrane System

System of compartmentalised sacs within eukaryotic cells

Cisternae

Flattened membrane-enclosed sacs in Golgi Apparatus

Role of Golgi Apparatus

Modifications of proteins & lipids

Name of entry face of Golgi Apparatus

Cis face

Name of exit face of Golgi Apparatus

Trans face

Clathrin

Protein that plays an important role in the formation of vesicles in cells

Function of Transport Vesicles

Transports proteins & lipids from one location to another in cell

Function of Secretory Vesicles

Transports proteins & lipids inside the cell to the plasma membrane

Endocytic Vesicles

Formed by invagination of the plasma membrane

Vesicle Fusion

Merging of vesicle and another organelle