Cell Structure - Cell Ultrastructure

Front 1

Features of Prokaryotes

Back 1

•No nucleus.

•Only one membrane.

•No membrane-bound organelles.

•Cell wall is made of peptidoglycan.

•Smaller ribosomes than eukaryotes.

•DNA is a single loop called a circular or bacterial chromosome.

•DNA is "naked" - not associated with histone proteins.

•Smaller loops of DNA called plasmids carry additional genes.

•ATP production occurs in infolded parts of the membrane called mesosomes.

•Some species have flagella for movement.

Front 2

Bacterial Cell Structure

Back 2

1. Cell Wall - physical barrier which protects against mechanical damage.

2. Capsule - protects bacterium from White Blood Cell and helps groups of bacteria stick together.

3. Plasma Membrane - acts as a partially permeable layer to control entry/exit of substances.

4. Pilus - helps cells stick to one another, or to other surfaces.

5. Flagellum - aids movement through fluids by rotation.

Front 3

Features of an Animal Cell

Back 3

•Surrounded by a plasma membrane.

•Jelly-like cytoplasm contains these organelles:

1. Nucleus

2. Mitochondria

3. Ribosomes

4. Endoplasmic Reticulum

5. Golgi Apparatus

6. Centrioles

7. Lysosomes

8. Cytoskeleton

Front 4

Features of a Plant Cell

Back 4

Same organelles as animal cells plus:

1. Cellulose cell wall for strength and support.

2. Large, permanent fluid-filled vacuole surrounded by a membrane called a tornoplast.

3. Chloroplasts for photosynthesis.

4. Plasmodesmata to link adjacent cells together.

Front 5

Cytoplasm

Back 5

Jelly-like material containing all of the organelles.

Front 6

Cytosol

Back 6

Water with dissolved substances in it - what would be left if the organelles were removed.

Front 7

Cytoskeleton

Back 7

Network of protein filaments used for transport within the cell and providing strength and support.

Front 8

Nucleus

Back 8

•Largest organelle.

•Contains all genetic information in the form of DNA.

•Nucleolus - darker region where ribosomes and RNA are made.

•Nuclear Envelope - double membrane surrounding nucleus that is perforated by nuclear pores for exchange of materials between the nucleus and cytoplasm.

Front 9

Plasma Membrane

Back 9

•Outer boundary of animal cells. Found inside cell wall in plants.

•Defines animal cell's perimiter.

•Controls what enters and leaves the cell.

•Place of communication with environment and other cells.

Front 10

Endoplasmic Reticulum

Back 10

•Series of folded membranes that form interconnected sacs or tubes called cistarnae.

•Rough ER has ribosomes attached and is continuous with the nuclear envelope - involved in protein synthesis and transport.

•Smooth ER has no ribosomes - site of lipid synthesis.

Front 11

Ribosomes

Back 11

•Made of two protein sub-units - smalles organelle (22nm).

•The site of protein synthesis in cells.

•May be found free in the cytoplasm or attached to RER.

•Proteins are vital to life - all cells must produce them.

Front 12

Mitochondria

Back 12

•Site of respiration.

•Where the molecule ATP is produced.

•Long and thin.

•Double membrane.

•May also contain mitochondrial DNA.

•Many mitochondria have muscle and live cells.

Front 13

Golgi Apparatus

Back 13

•Stack of sac-like membranes, usually located near the nucleus.

•Transport vesicles pinch off from the sides.

•Process, package and distribute proteins made within cell.

•Involved in secretion - cells that make hormones, enzymes, antibodies, saliva or mucus have many Golgi Bodies.

Front 14

Lysosomes

Back 14

•A spherical sac, bounded by a single membrane.

•Contains digestive enzymes.

•Intracellular digestion of food materials.

•Help white blood cells to destroy bacteria in the process of phagocytosis.

•Destroy the worn-out organelles inside cells.

•For self-destruction of cells in developmental processes.

Front 15

Centrioles

Back 15

•Two short bundles of nine microtubules, arranged at right angles to each other.

•Located just outside the nucleus in a clear area of cytoplasm called the centrosome.

•Migrate to opposite ends of cell during cell division to form spindle fibres to pull chromosomes to the poles of the cell.

Front 16

Cilia and Undulipodia

Back 16

•Hair-like extensions from cells.

•Allow movement.

•Cilia - short, many found on one cell. Found in the trachea and bronchi and fallopian tubes.

•Undipodia - long, only one or two found on each cell.

•Both have a similar structure.

Front 17

Cell Wall

Back 17

•Found in plant cells but not animal cells.

•Provides strength and support.

•Made of cellulose.

•Allows water and dissolved molecules to pass through.

•Pores called plasmodesmata connect the cytoplasm of adjacent cells for more rapid exchange of molecules.

Front 18

Chloroplasts

Back 18

•Only found in plants and algae.

•Chloroplasts contain the pigment chlorophyll and accessory pigments, which absorb light energy for photosynthesis.

•Double membrane.

•Grana - a stack of thylakoid discs that contain chlorophyll molecules.

•Stroma - fluid containing photosynthetic enzymes.

Front 19

Vesicles and Vacuoles

Back 19

•Stores food, water, or waste materials.

•Vesicles are small membrane-bound sacs used for transport within cells.

•Plant cells have large permanent vacuoles. The surrounding membrane is called a tornoplast.

•In plant cells, the vacuole maintains turgor for support.

•Vacuoles may be small or absent in animal cells.