Cell Ultrastructure Flashcards
Cytoskeleton
• provides mechanical strength to the cell
• aids transport within cells
• enables cell movement
•allows movement of cilia or flagella
•changes shape of cell(cytokinesis, pseudopodia, endomcytosis etc)
Microfilaments
-fibres made up of the protein actin. They are responsible for movement of the cell and cytoplasm during cytokinesis
Microtubleals
-formed by the globular protein tubulin. They polymerise to determine the shape of the cell.
Intermediate fibres
Gives strength to the cells and helps maintain cell integrity.
Nucleus
Double nuclear envelope- a double membrane which compartmentalises the nucleus and prevents damage.
Nuclear pores- allows molecules to enter and leave the cell e.g. mRNA
Nucleolus- site of ribosome production composed of RNA and proteins
Chromatin- is the DNA (with assorted histon proteins) contains the genetic code which controls the activities of the cell. Is assorted to make chromosomes.
Rough ER(rough endoplasmic reticulum)
-stacks of membrane bound fluid filled sacs called cisternea
-attached to the nucleus and covered in ribosomes
-site of protein synthesis
Smooth ER(smooth endoplasmic reticulum)
- similar to rough ER but does not have ribosomes jotted on the surface
-site of lipid synthesis
Ribosomes
-not membrane bound made from RNA and protein found floating in the cytoplasm or attached to the rough ER.
-where proteins are made. arranges amino acids into protein chains using mRNA.
Golgi apparatus
-stacks of flattened membrane bound sacs called cisternae
-bud of as Golgi vesicles
-modifies the protein and restructures them e.g. adds a carbohydrate
-makes lysosomes
Lysosomes
-spherical sacs surrounded by a single membrane
-contains powerful hydro lyric digestive enzymes called lysozymes
-break down worn out components of the cell or digest invading cells.
Centrioles
-A component of the cytoskeleton composed of many microtubules.
-small hollow cylinders that occur in pairs next to the nucleus in animal cells only.
-forms spindle fibres during cytokinesis
Cilia
-hair like extensions that petrude from some animal cell types
-sensory function creates a beat to move/ waft the fluids/mucous or other objects
-for locomotion
Flagella
-Similar to cilia but longer
-they pretrude from the cell surface and are surrounded by a plasma membrane
-9+2 arrangement
-enables cell movement(propels cells forward e.g. sperm cell)
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Chloroplasts
-double membrane which encloses the stroma (liquid that makes up the cytoplasm)
-stroma contains starch grains, lipids, DNA, RNA, ribosomes
-series of flattened membrane bound sacs called thylakoids thylakoids stacked together are called grana.
Site of photosynthesis
Cell surface membrane
-a membrane found on the surface of animals cells and under the cell wall in a plant cell
-phospholipid bilayer
-regulates the movement of substances in and out the cell
Cellulose cell wall
-made of b-cellulose microfibrils
-fully permeable to substances
-gives the plant mechanical strength
-gives the cell support and its shape
- contents of the cell can become turgid the cell wall keeps the cell sturdy
Large permanent vacuole
-Single membrane bound (membrane is called the tonoplast)
-selectively permeable
-contains cell sap (solution of amino acids, mineral salts, sugars etc)
-cell sap can act as a temporary food store
-helps herbaceous plants by making cells turgid.
