Cytology 3.1, 3.2 22 September 2014

Compound microscope allowed for discovery of cells Compound microscope allowed for discovery of cells. Cells are microscopic. Cyto- means “cell”. –ology means “study of”.

Cell theory principles All organisms are made of cells. All cells come from preexisting cells. The cell is the basic unit of life.

All cells have cytoplasm: a jelly-like substance that contains molecular building blocks. Cytoplasm fills space between nucleus & membrane

All cells have a membrane: a barrier made up of phospholipids All cells have a membrane: a barrier made up of phospholipids. Separates cytoplasm and organelles from the outside.

Cell-Membrane

Some cells have organelles – structures specialized to perform distinct functions.

Two Basic Cell Types – Prokaryotes and Eukaryotes

Prokaryotes do not possess a nucleus or membrane-bound organelles Prokaryotes do not possess a nucleus or membrane-bound organelles. DNA is suspended within cytoplasm.

Eukaryotes possess a nucleus and membrane-bound organelles Eukaryotes possess a nucleus and membrane-bound organelles. DNA is within the nucleus

Eukaryote cells have a cytoskeleton – a network of proteins that give the cell shape and strength.

The nucleus stores and protects DNA (genes) The nucleus stores and protects DNA (genes). The nucleus also contains the nucleolus.

The endoplasmic reticulum (ER) – network of thin, folded membranes The endoplasmic reticulum (ER) – network of thin, folded membranes. Will be close to the nucleus usually.

Ribosomes – tiny organelles on the ER Ribosomes – tiny organelles on the ER. They link amino acids together to form ____________. Similar to sleeping bag with many folds.

Ribosomes – tiny organelles on the ER Ribosomes – tiny organelles on the ER. They link amino acids together to form proteins. Smooth ER – no ribosomes – makes lipids Rough ER – ribosomes – makes proteins

Golgi apparatus – processes, sorts, and delivers proteins Golgi apparatus – processes, sorts, and delivers proteins. Much like the post office within a county.

Vesicles are sacs (with membrane) that separate, hold, and transport some materials intracellularly. intra- means “within”. inter- means “between.”

The mitochondrion converts food into energy. Site of ATP production The mitochondrion converts food into energy. Site of ATP production. Mitochondria is plural for mitochondrion.

vacuole – fluid-filled sac (no membrane) used to store materials needed by the cell.

Lysosomes – organelles containing enzymes Lysosomes – organelles containing enzymes. Defends cell from invaders and breaks down worn out cell parts. More like a water tank.

Cell Wall – rigid layer that gives support, shape, and protection to some cells. Cell wall – animals? no – plants, fungi, most bacteria? yes

Made of cellulose Made of chitin Made of peptidoglycan Plant Cell Wall Fungi Cell Wall Bacterial Cell Wall Made of cellulose Made of chitin Made of peptidoglycan

Chloroplasts carry out photosynthesis. Photo- means “light” Chloroplasts carry out photosynthesis. Photo- means “light”. Synthesis- means “production”.