cells

nucleus

surrounded by a double membrane - nuclear envelope

contains pores to enable molecules to enter and leave the nucleus

contains chromatin - DNA wrapped around histone proteins

contains a nucleolus - the site of ribosome production

present in animal and plant cells, but not in prokaryotes

rough endoplasmic reticulum

3d system of membranes spreading through the cytoplasm surrounding the nuclear membrane/envelope

has ribosomes on the outer surfaces

folds and packages proteins into vesicles

provides a pathway for transport of material, especially proteins

present in animal and plant cells but not in prokaryotes

smooth endoplasmic reticulum

no ribosomes on surface, no synthesis of proteins

synthesises essential lipids

produces and secretes steroid hormones

present in plant and animal cells, but not in prokaryotes

golgi apparatus

found in almost all eukaryotic cells, not in any prokaryotes

stack of membranes (curved, cisternae) with small rounded hollow structures (vesicles)

processes and packages proteins and lipids

produces lysosomes

mitochondrion

not found in prokaryotes (they must rely on immediate environment to obtain energy), found in animal and plant cells

double membrane called the envelope which controls the entry and exit of materials

site of stages of aerobic respiration, responsible for producing ATP

the inner membrane is folded to form cristae (to increase SA)

matrix on the insane containing all the enzymes needed for respiration

centrioles

hollow cylinders containing bundles of microtubules

involved in cell division

not found in prokaryotes or plant cells, only in animal cells

ribosomes

found in eukaryotes and prokaryotes

not membrane bound

some found free in cytoplasm, others bound to rough ER

site of protein production

lysosome

not found in prokaryotes, found in plant and animal cells

membrane bound vesicles formed from the golgi apparatus

contains digestive enzymes bound by a single membrane

cytoskeleton

a network of proteins

made of microfilaments, microtubules and intermediate fibres

acts as train tracks for cell organelles, they attach and are moved to different regions of the cell

anchors the nucleus in the cytoplasm

mechanical strength provided

aids transport within cells and enables cell movement

protein transport

1. mRNA copy of the gene is made in the nucleus

2. mRNA leaves nucleus through nuclear pore

3. mRNA attaches to a ribosome (either in cytoplasm or RER), ribosome reads instructions to assemble the protein, protein is folded and processed

4. the molecules are pinched off in vesicles and are transported to the golgi apparatus in vesicles

5. the vesicle fuses with the golgi apparatus, the golgi apparatus processes and packages the molecules

6. packaged molecules pinched off in vesicles from golgi apparatus and move towards cell surface membrane, vesicle fuses with cell surface membrane and leave the cell by exocytosis