Cell Type and Organelles

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  • Created by: yott33
  • Created on: 08-02-16 09:29

Eukaryotic Cells

  • Cell membrane
  • RER (Rough Endoplasmic Reticulum)
  • Nucleolus
  • Nucleus
  • SER (Smooth Endoplasmic Reticulum)
  • Lysosome
  • Ribosome
  • Nuclear envelope
  • Golgi Apparatus
  • Cytoplasm
  • Mitochondrion

Plant Cell Extras

Chloroplasts. Cell wall with plasmodesmata ('channels' for exchanging substances). Vacuole. 

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Prokaryotic Cells

  • Extremely small cells
  • Circular DNA
  • No Nucleus
  • DNA free in cytoplasm
  • Cell wall made fo polysaccharide not cellulose or chitin
  • Few organelles - no membrane-bound organelles (e.g. no mitochondria)
  • Flagella made of protein flagellin arranged in a helix
  • Smal ribosomes
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Cell Membrane

Description

The membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells. Made of lipids and protein.

Function

Regulates movement of substances in and out of the cell. Has receptor molecules on it, so it can respond to chemicals like hormones.

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Cell Wall

Description

Rigid structure surrounding plant cells. Made mainly of cellulose.

Function

Supports plant cells.

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Nucleus

Description

A large organelle surrounded by a nuclear envelope (double membrane) which contains many pores. The nucleus contains chromatin (which is made from DNA and proteins) and the nucleolus.

Function

Controls the cell's activities. DNA contains instructions to make proteins. The pores allow substances to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.

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Lysosome

Description

Round organelle. Surrounded by a membrane. No clear internal structure.

Function

Contains digestive enzymes which are kept separate from the cytoplasm by the surrounding membrane. Can be used to digest invading cells or break down worn-out components of the cell. 

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Ribosome

Description

Very small organelle. Floats free in cytoplasm or is attached to RER. Made of proteins and RNA. No membrane.

Function

Site where proteins are made.

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RER

Description

System of membranes enclosing fluid-filled space. Surface covered with ribosomes.

Function

Folds and processes proteins that have been made at the ribosomes.

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SER

Description

Similar to RER but no ribosomes.

Function

Synthesises and processes lipids.

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Vesicle

Description

Small. Fluid-filled sac in cytoplasm, surrounded by a membrane.

Function

Transports substances in and out of the cell (via the plasma membrane) and between organelles. Some formed by Golgi Apparatus or Endoplasmic Reticuluum. Some formed at cell surface.

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Golgi Apparatus

Description

A group of fluid-filled, membrane-bound, flattened sacs. Vesicles often seen at edges of sacs.

Function

Processes and packages new lipids and proteins. Makes lysosomes. 

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Mitochondrion

Description

Usually oval-shaped. Have a double membrane - inner one is folded to form cristae. Inside is the matrix, which contains enzymes involved in respiration.

Function

Site of aerobic respiration, where ATP is produced. Found in large numbers in cells that are v. active. Require a lot of energy.

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Chloroplast

Description

Small, flattened structure. Found in plant cells. Surrounded by a double membrane. Has membranes inside called thylakoid membranes. These membranes are stacked up in some parts of the chloroplast to form grana. Grana are linked together by lamellae - thin, flat pieces of thylakoid membrane.

Function

Where photosynthesis occurs. Some parts of photosynthesis happen in the grana and other parts happen in the stroma (thick fluid found in chloroplasts). 

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Centriole

Description

Small, hollow cylinders. Made of microtubules (tiny protein cylinders). Found in animal cells, but only some plant cells.

Function

Involved with the separation of chromosomes during cell division.

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Cilia

Description

Small, hair-like structures. Found on the surface membrane of some animal cells. In cross-section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, wiht two microtubules in the middle.

Function

Microtubules allow the cilia to move. This movement is used by the cell to move substances along the cell surface.

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Flagellum

Description

Flagella on eukaryotic cells are like cilia but longer. They stick out from the cell surface. Surrounded by plasma membrane. Two microtubules in the middle, nine pairs round the edge.

Function

Microtubules contract to make the flagellum move. Used like outboard motors to propel cells forward e.g. when a sperm cell swims.

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Protein Production

1. Proteins made at the ribosomes

2. Ribosomes on RER make proteins that are excreted or attached to the cell membrane. Free ribosomes in the cytoplasm make proteins that stay in the cytoplasm.

3. New proteins produced at the RER are folded and processed in the RER.

4. Transported to the SER in vesicles

5. At the Golgi Apparatus, the proteins may undergo further processing.

6. Proteins enter more vesicles to be transported around the cell.

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Cytoskeleton

The organelles in cells are surrounded by cytoplasm - it has a network of protein threads running through it called the cytoskeleton.

In eukaryotic cells, the protein threads are arranged as microfilaments and microtubules

Functions

  • Support the cell's organelles, keeping them in position
  • Help to strengthen the cell and maintain its shape
  • Responsible for movement of materials within the cell e.g. movement of chromosomes when they separate during cell division depends on contraction of microtubules in the spindle
  • Proteins of the cytoskeleton cause the cell to move e.g. cilia and flagella
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