HL Biology - Organelles and Compartmentalisation

Organelle

specialized structure that performs important cellular functions within a cell

cell structures that are NOT organelles

- cell wall
- cytoskeleton
- cytoplasm

Prokaryotes + organelles

- no membrane bound organelles

Which organelles do not have membranes?

- ribosomes
- centrioles
- microtubules

Which organelles have single membranes?

- Golgi apparatus
- vacuoles
- vesicles
- lysosome
- ER

Which organelles have double membranes

- nucleus
- mitochondria
- chloroplasts

Compartmentalised

Membrane bound

advantages of compartmentalization

- nucleus: prtoecting the DNA
- mRNA editing: when DNA is transcribed into mRNA in the nucleus, it can be edited before leaving the membrane to be translated
- concentrating enzymes if necessary
- maintaining pH, solute concentration
- storing damaging substances

Draw a diagram of a mitochondria

including:
- inner membrane
- outer membrane
- cristae
- matrix
- intermembrane space

Outer membrane function

Separation from the rest of the cell

Inner membrane function

Contains proteins for the ETC

Cristae function

Increase surface area for more ATP producing proteins

Matrix functions

- link reaction and krebs cycle takes place there
- conentrates enzymes, high concentration where we need it

Inter-membrane space function

- small space allows a high concentration of protons or hydrogen ions
- pumped from the matrix to the inter-membrane space in less time

Draw a chloroplast

including
- outer membrane
- inner membrane
- thylakoid
- granum/a (stacks)
- stroma (fluid)

Thylakoid function

- chlorophyll absorbs light to produce ATP in the small thylakoid space

Stroma function

Closed space to contain all the enzymes necessary for the Calvin cycle

The double membrane surrounding the nucleus has...

Large pores

Importance of the double membrane's pores

- created by integral proteins to allow large molecules to pass through as bigger pores can be formed
- easier to break down and reform during mitosis to allow chromosomes to be moved

Which molecules pass through the pores of the double membrane (nucleus)

- mRNA: synthesized in the nucleus during transcription --> needs to leave, requires a large pore
- Ribosomes produced in the nucleolus go to the cytoplasm or the rER

Nucleolus

the site of ribosome production within the nucleus of eukaryotic cells

Does a ribosome have a membrane?

No

Where to find ribosomes in eukaryotes

- free-floating in the cytoplasm
- attached to the rER

What do free ribosomes do and where?

cytoplasm: produce proteins needed in the rest of the cell
rER: produce proteins for excretion, exported from the cell to be sent elsewhere

Draw the golgi apparatus.

- mention vescicles

Function of the golgi

- Receives a ribosome from the ER, which fuses with the golgi
- releases its contents into the golgi
- golgi processes it
- repackages it into another vesicle and exports it via exocytosis

When are vesicles formed

Endocytosis

Specific function of vesicles

- moving things around in cells
--> need to move specific contents to a specific location (neurotransmitter)
--> cell membrane growth (vesicles added to membrane)