Biology Unit 2

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  • Created by: xisx
  • Created on: 31-05-17 15:40

Prokaryotes and Eukaryotes.

Organisms (living things) can be divided into 2groups :

1) Prokaryotes.

- Made up of prokaryotic cells which are smaller and simpler.

E.g. Bacteria.

2) Eukaryotes.

- Made up of eukaryotic cells which are more complex.

E.g. All animals and plants.

Both types of cells have organelles (parts of a cell) which have a specific function and can be examined under an electron microscope to view its ultrastructure (the organelles and the cell's internal structure).

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Organelles of a Eukaryotic Cell.

Animal cells are eukaryotic (more complex).

To remember all the organelles you can use this mnemonic -

N-N-Nightmare - Nucleus (Nuclear envelope, Nuclear Pore and Nucleolus).

Lingers - Lysosome.

Really - Ribosome.

Really - Rough endoplasmic reticulum.

Strangely, - Smooth endoplasmic reticulum.

Getting - Golgi apparatus.

More - Mitochondrion (mitochondria = plural).

Creepy - Centrioles.

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`The Nucleus.

The Nucleus is a large organelle (part of the cell) which is surrounded by a double membrane (inner and outer membrane) known as the nuclear envelope. The nuclear envelope contains many pores called the nuclear pores.

The nucleus also contains chromatin (made from DNA and proteins) and a structure called the nucleolus

The nucleus' function is to control the cell's activities. It controls the cell's activities by controlling transcription of DNA. DNA contains instructions to make proteins. 

The nuclear pores allow substances to move between the nucleus and the cytoplasm (e.g. mRNA after transcription must move out to the ribosomes to be translated).

The nucleolus makes ribosomes (which synthesises proteins).

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Lysosome.

The lysosome is a round organelle and surrounded by a membrane. 

It contains digestive enzymes.

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