cells

An animal cell

Plant cells

The cell Theory The cell theory states that all living organisms are made of one or more cells, cells are the basic units of structure and function , and cells come only from pre existing cells

Cells come in a shapes and sizes 1 meter = 100 cm 1cm= 10 mm 1mm= 1000 um (Micrometer) 1um=1000 nm (Nanometer)

there are two main types of cell

The are two main types of cell Prokaryotic cells do not have a nucleus and internal membrane-bound structures Most unicellular organisms are prokaryotes eg. Bacteria

Eukaryotic cells Eukaryotic Cells have a nucleus and internal membrane-bound structures. Most multicellular organisms are eukaryotes. Eg. Yeast and algae (unicellular, eukaryotes) Plant and animals

Common features of cells Cytoplasm – Gel like material that protects, supports and suspends organelles. It contains dissolved substances. It contains a cytoskeleton of microtubules and filaments to give the cell structure and allow substances to move about the cell.

Plasma membrane plasma membrane is the outer layer of the cell. It protects the cell and acts as a selective barrier, letting some materials in and keeping others out It is made of a lipid bilayer (phospholipids) and has proteins and carbohydrates through it

The fluid mosaic model is used to explain how membranes are flexible The phosphate head is hydrophilic and the fatty tail is hydrophobic so it forms a bilayer with a fatty insoluble middle.

The nucleus and nucleolus Surrounded by the nuclear membrane and contains pores to let substances in and out. It contains DNA in the form of chromosomes ( eukaryotes) The nucleolus makes ribosomes which travel out to the cytoplasm and are needed for protein synthesis

The endoplasmic reticulum comes in two types A series of folded membranes Rough endoplasmic reticulum (RER) contains ribosomes. This is where proteins are made smooth endoplasmic reticulum (SER) make and store lipids ( Fats)

ribosomes Ribosomes are made up of two subunits They can be free floating in the cytoplasm or attached to the RER. Ribosomes make proteins.

Vacuoles These are storage sacs for the temporary storage of materials such as food, enzymes, waste. Plant cells have one large vacuole surrounded by a tonoplast membrane and amyloplasts. animal cells have lots of small vesicles

Mitochondria This is where cellular respiration occurs making ATP. the number of mitochondria depends on the type of cell. Muscle cells have lots

Lysosomes Contain digestive enzymes Digest excess or worn organelles, food particles, viruses, and bacteria Surrounded by membrane that prevents it from destroying the cell Can burst causing cell death

Golgi apparatus These are tubular membranes which ‘nip’ off at the ends to make vesicles The golgi apparatus sorts, modifies, packages and transports proteins so they can move around the cell.

Centrioles (Animal Cells) They are micro-tubules These help with cell reproduction by making spindle fibres.

Chloroplasts ( plant cells) Chloroplast – Located in plant cells, some bacteria, and protists. Photosynthesis-Capture light energy to produce and store food Contain chlorophyll-green pigment that traps light

Flagella and cilia are made of microtubules Whip like projections Hair like projections that wave around

Cell wall ( plants only) Rigid outer covering made of cellulose. Located outside the cell membrane Provides support and protection Helps produce turgor pressure Contains holes called plasmodesmata to allow stuff in and out of cells

Intercellular junctions Animal cells Tight junctions join cells together to make tissue. Desmosomes act like rivets joining cells together Gap junctions are channels to allow substances in and out