Cell Structure and Function

Definition of a Cell A cell is the smallest unit that is capable of performing life functions. Shape = function Nerve Cell Skin Cell White Blood Cell

Two types of Cells Prokaryotic – do not have membrane bound organelles (Unicellular) Eukaryotic – contain membrane bound organelles (Multicellular)

Prokaryotic Do not have structures surrounded by membranes. Few internal structures One-celled organisms Example: Bacteria

Eukaryotic Contain organelles surrounded by membranes Most living organisms

Examples of Cells Red Blood Cell Plant Stem Amoeba Proteus Bacteria Nerve Cell

Cell Parts Organelles

Cell Membrane Outer boundary of the cell Selectively Permeable Membrane – controls what can and cannot pass through it.

Cell Membrane Structure Phospholipid Bilayer Proteins – create special passages for specific molecules. Carbohydrate markers – identification tag for proteins

Functions of the Cell Membrane Keeps things in Keeps things out Regulates what passes through: Nutrients and Food Gases Water

Ribosomes Ribosomes floating in the cytoplasm produce proteins that are going to be use for THAT cell Ribosomes that attach to the ER produce proteins that are going to leave the cell. Ribosomes floating in cell ---- protein for THAT cell Ribosome on ER ---- protein for ANOTHER cell

Function of Ribosomes Organelles which make proteins from RNA. Made up of RNA

Nucleus DNA and RNA are made Surrounded by nuclear envelope Nuclear Pores – holes in the nuclear envelope which allows things to enter and leave the nucleus

Nuclear Membrane Surrounds nucleus Made of two layers Openings allow material to enter and leave nucleus

Function of Nucleus Organelle which contains the genetic information of the cell that directs all activities of the cell

Nucleolus Inside nucleus Where ribosomes are formed

Lysosome One cell may contain several lysosomes Each lysosome may contain up to 40 different enzymes

Function of Lysosomes Organelles which contain the digestive enzymes of the cell used for recycling Lysosomes perform “Apoptosis” – which is “cell suicide” – the Lysosome breaks open, spilling out the digestive enzyme, and kills the whole cell. All organelles in the cell get reused and a new cell is formed.

Endoplasmic Reticulum Rough Endoplasmic Reticulum (RER) – has ribosomes attached to it Smooth Endoplasmic Reticulum (SER) – does NOT have ribosomes attached to it

Functions of the ER Rough ER Smooth ER Membrane that is an extension from the nuclear envelope which creates a pathway for the proteins. Rough ER Smooth ER Holds the ribosomes Stores compounds such as lipids and carbohydrates Stores proteins Detoxify poisons or toxins Puts proteins in bubbles called vesicles to send them to other cells

Golgi Bodies/Apparatus Processing, packaging, and secreting organelle of the cell Made of flattened sacs

Function of Golgi Apparatus “The Post Office” 1.) Prepares proteins that are going to be secreted. 2.) Wraps these proteins in a vesicle 3.) Sends the proteins to the cell membrane.

Pathway of Proteins 1.) Protein is made by the ribosomes 2.) Stored inside RER 3.) Protein is put into a vesicle 4.) Vesicles travels to Golgi 5.) Vesicles fuses with Golgi and releases protein 6.) Proteins are changed in the Golgi 7.) Proteins are repackaged into new vesicle 8.) Vesicle fuses with cell membrane and protein is released

Mitochondria – Powerhouse of the Cell Converts food into energy (Function) Smooth outer membrane Folded inner membrane Cristae – folds in the inner membrane (more folds, more energy)

Cytoplasm Gel-like mixture Surrounded by cell membrane Function: Organelles float in it Contain the nutrients and chemicals of the cell

Cell Movement Cilia – tiny hairlike structures that provide movement. Lines inner membranes of organisms to move fluids Flagellum – a long whip like tail

Cell Wall (Plants) Thick outer covering surrounding the membrane Made of Cellulose

Vacuoles Fluid filled sac Function: Animal – small vacuoles Stores extra nutrients and water Stores waste Animal – small vacuoles Plant – one large vacuole

Chloroplast Round green disks Function: Organelle which is the site of photosynthesis

“Typical” Plant Cell

“Typical” Animal Cell