Cells

Functions of centrioles

Associated with cell division Forms the spindle fibres

The function of the vacuoles and toniplasts

A large cell-sap filled cavity. The tonoplast membrane surrounds the vacuole. It contains a number of dissolved minerals, hormones, glucose. Stores water, food, ions and waste products. The vacuole isolates materials that are harmful to the cell. The vacuole maintains the cell turgur. And maintains the cell's Ph. Supports the cell structure.

Functions of lysosomes

Breakdown imported food vacuoles Cause self-digestion of broken-down organelles

Structure of the Golgi apparatus

Consist of stacks of flattened membranes - dictyosomes Membranes are fluid-filled Small vesicles/sacs form at the end of the membranes

Functions of the nucleus

Controls the structure, functions and activities of the cell Contains genetic material within the chromatids Passes on genetic information to new cells Regulates the production of all proteins Site of transcription (genetics) Nucleolus - site of ribosome synthesis

Structure of the mithrochondria

Cylindrical, rod-shaped organelle Surrounded by double membrane Outer membrane is smooth and selectively permeable Inner membrane is folded to form cristae where energy is produced Contains a matrix consisting of metabolites and enzymes

Structure of the cell walls

Membrane made of cellulose Cellulose is a carbohydrate

Structure of the nucleus

Largest organelle Surrounded by a double membrane - nuclear envelope Membrane is perforated allowing exchange of substances between nucleus and cytoplasm Contains nucleolus, nucleoplasm, and chromatids

Function of cytoplasm

Metabolic pathways are constructed in it Fluid in which cellular activities take place

Structure of the Endoplasmic Reticulum

Network of folded membranes forming interconnected sheets, tubes or sacs Originates from the outer membrane of the nucleus Two types exist: Smooth ER Rough ER

Structure of cell membrane

Phospholipid bilayer Hydrophobic lipid tails (water hating) Hydrophilic phosphate heads (water loving) Glycoproteins stretch through the bilayer Carbohydrate chain Protein molecule It aids in recognising molecules that need to enter the cell

Function of the chloroplasts

Produces glucose and O2 during photosynthesis Starch granules act as temporary food storage compartments

Function of the mithrochondria

Releases energy while breaking down glucose during the process of aerobic respiration Krebs cycle takes place inside the inner membrane NB: The amount of mitochondria in a cell is determined by activities and energy requirements of the cell

Functions of the ribosomes

Responsible for proteinsynthesis (making of proteins)

Structure of centrioles

Short cylinders of microtubules

Structure of ribosomes

Small bead-like structures May be free OR attached to the ER

Functions of ER

Smooth ER Functions: Not covered with ribosomes Synthesizes hormones, steroids, lipids and oils Transports lipids and steroids, therefore producing transport vesicles Aids with drug detoxification Rough ER Functions: Covered with ribosomes for proteinsynthesis Modifies and transports proteins, therefore producing transport vesicles

Structure of lysosomes

Spherical vesicles Contain digestive enzymes produced in the Golgi apparatus or ER

Function of the Golgi apparatus

Stores lipids and proteins Produces secretory vesicles to transport them Produces lysosomes in animal cells Produces secretory materials e.g. enzymes

Functions of the cell wall

Strength Protection Support Prevents the cell bursting Fully permeable (it allows substances to pass through)

Structure of the vacuoles and tonoplasts

Structure: A large cell sap filled cavity Cell sap contains dissolved solutes such as glucose, amino acids, hormones and salts In young plant cells, small vacuoles untie themselves to form one large one Tonoplast membrane surrounds the vacuole and controls entry and exit of substances

Structure of chloroplasts

Surrounded by a double membrane Outer, smooth membrane is selectively permeable for H2O and CO2 into the cell and for glucose and O2 out of the cell Inner membrane gives rise to strands called thylakoids These are arranged to form flattened, circular granum (grana) Liquid inside is known as matrix and contains starch granules.

Functions of the cell membrane

Surrounds cell content Maintains a constant internal environment Controls the entry and exit of substances into and out of the cell Cell surface receptors aid in allowing substances passage into and out of the cell Selectively permeable - only certain substances are passed through

Structure of cytoplasm

Watery solution containing dissolved substances, enzymes (proteins) and organelles