Eukaryotes

Selective permeability

Some substances pass more easily than others

Fluid mosaic model

Constantly moving boundary separating the living cell form the external environment

Functions

transport and cell-to-cell communication

Microtubules

cell shape maintenance and change

Microfilaments

cell organisation

Intermediate filaments

cell motility

Accessory proteins

organelles motility

Smooth ER - ribosome free

SER provides a detox from drugs, proliferation of SER in response to drugs - tolerance.

Other functions of SER

Synthesis of lipids, carbohydrates metabolism and storage of ca2+ to regulate responses

Rough ER - ribosome bound

RER - protein synthesis, folding and modification. ER-bound ribosomes synthesize proteins into the ER where they can be folded and modified by the addition of sugar side chains

Ribosome and protein synthesis

Ribosomes read the nucleotide letter code of mRNA. Each triplet of nucleotides can be read by a molecule of tRNA. tRNA determines the amino acid to assembled on the growing protein.

Golgi Apparatus (GA)

A series of flattened membrane sacs called cisternae. Following folding into the ER proteins are transported to GA. GA modifies proteins - primarily by changing sugar chains

Lysosomes

Membranous sac of hydrolytic enzymes. There are 40 types of hydrolytic enzymes. They are the digestive system of a cell - by degrading macromolecules

Mitochondria

2 compartments separated by 2 membranes. The inner membrane is highly folded meaning more surface for enzymes of respiration - more efficient. Convert energy contained in food to forms that cells can use

Site of cellular respiration

Respiration generates ATP by extracting energy from sugars, fats and other fuels with the help of oxygen

Nucleus

The nucleus controls storage and maintenance of the cells genome (DNA). It controls gene expression through transcription.

Plant cell wall

Walls consist of a meshwork of cellulose microfibrils embedded in a gelatinous matrix of hemicellulose and pectins. Walls contain a range of proteins - mainly structural function. Some involved in interaction with environment and organ formation, some are important for altering wall properties during growth

Main functions of cell wall

Shape, mechanical stability, build-up of cell turgor pressure, protection from bursting, transport path and interaction

Chloroplast

Highly specialised member of plastids family. Enclosed by 2 membranes. Inside the chloroplast is another membrane system - flattened and interconnected sacs called thylakoids

Chloroplast functions

Site of photosynthesis [light energy -> chemical energy]. Converted energy - stored in bonds of sugar molecules

Vacuoles

Mature plant cells generally contain 1 large central vacuole enclosed by a membrane (tonoplast/vacuole membrane). Fusion of smaller vacuoles from ER-GA and contain hydrolytic enzymes

Vacuoles functions

Multifunctional in plant cells. Storage function - a storage organelle. Digestive function - degradative compartment. Structural function - control of turgor pressure.