Prokaryotic and Eukaryotic Cells Structural Complexity

Life’s Three Domains 1.Bacteria 2.Archaea 3.Eukarya Prokaryotes Eukaryotes

There are two different types of cells Over time both types have evolved into two structurally different cells Bacteria and archaea consist of prokaryotic cells. All other forms of life are composed of eukaryotic cells Prokaryotic CellsEukaryotic Cells

Structure of Prokaryotic Cells They are small and relatively simple (one- tenth the size of a eukaryotic cell) Does not contain a nucleus DNA is coiled into a nucleoid region rather than being surrounded by a membrane

A prokaryotic cell is enclosed by a plasma membrane and is usually encased in a rigid cell wall  The cell wall may be covered by a sticky capsule  Inside the cell are its DNA and other parts Plasma membrane Cell wall Capsule Ribosomes Prokaryotic flagella Nucleoid region (DNA) Pili

Function of Cell Wall Helps cell maintain its shape Protects the cell

Function of Capsule Surrounds the cell wall and protects the surface Helps to glue prokaryotes to surfaces

Function of Pili Short projections that also help attach prokaryotes to surfaces

Function of Flagella These longer projections propel the prokaryotic cell through its liquid environment

Prokaryotic Reproduction They reproduce asexually through a process binary fission DNA is copied and cell splits down the center to produce to new cells with identical DNA

Prokaryotic cells, Bacillus polymyxa

Prokaryotic cell, E. coli

Pili on a prokaryotic cell

Prokaryotic flagella

Prokaryotic and eukaryotic cells compared

Structure of Eukaryotic Cells They are a lot larger than prokaryotic cells They are more complex than prokaryotic cells They contain a nucleus with membrane bound organelles

Cell Membrane Surrounds the cell and controls the flow of material into and out of the cell Porous but selectively permeable Found in all eukaryotic cells

Cytoplasm The fluid-filled region between the nucleus and the cell membrane

Organelle Structure within a cell that performs a specific function Most are bounded by membranes Endomembrane system

Reason for having membranes They allow processes that require different conditions to take place simultaneously in a single cell without effecting each other

Organelles of the Endomembrane System

What does a factory need in order to run successfully? 1)Control center or main office 2)Packaging department 3)Shipping department 4)Assembling department 5)Power or energy source 6)Clean-up crew 7)Storage

The nucleus is the cell’s genetic control center The largest organelle is usually the nucleus The nucleus is separated from the cytoplasm by the nuclear envelope The nucleus is the cellular control center  It contains the DNA that directs the cell’s activities

Chromatin Nucleolus Pore Ribosomes ROUGH ENDOPLASMIC RETICULUM NUCLEUS Two membranes of nuclear envelope

Ribosomes Small specks found throughout the cytoplasm of the cell and are used for protein synthesis

Nucleolus Structure found within the nucleus Consists of a mass of DNA, RNA, and proteins Function is to make the ribosomes

Nucleolus

Endoplasmic Reticulum Network or membranes throughout the cell used to process molecules needed by the cell such as proteins, lipids, and carbohydrates. Two Types: Rough ER Smooth ER

Rough Endoplasmic Reticulum Contains ribosomes on its surface which gives it its rough appearance. Used to manufacture proteins and more membrane Transport vesicle buds off Ribosome Sugar chain Glycoprotei n Secretory (glyco-) protein inside transport vesicle ROUGH ER Polypeptide Transport vesicles are used to transport molecules to other parts of the cell.

Smooth Endoplasmic Reticulum Lacks ribosomes Functions to synthesize lipids Helps to regulation carbohydrate metabolism and breaks down toxins and drugs

Golgi Apparatus Discovered by Camillo Golgi with a compound light microscope Consists of stacks of membranous sacs Receives and modifies products from the ER and then sends them to other parts of the cell (Considered the finishing factory)

The Golgi apparatus

Lysosome Sacs of digestive enzymes These organelles digest the cell’s food and wastes A defect in this organelle can result in an accumulation of unwanted substances in the body, which can lead to fatality.

Lysosomal enzymes  digest food  destroy bacteria  recycle damaged organelles  function in embryonic development in animals

LYSOSOMES “Food” Digestion Lysosome engulfing damaged organelle

Vacuole Organelle used to store vital chemicals, water, and waste products. In plants, vacuoles can store substances that attract pollinating insects, and also contain poisons against plant-eating animals.

Nucleus Contractile vacuoles Protist Plant Central Vacuole

Mitochondria and Chloroplast Mitochondria – Organelles that make energy from food Chloroplast – Organelle found only in plants and used to convert sunlight into usable energy (Photosynthesis)

Cytoskeleton Fibers in the cytoplasm of eukaryotic cells that serve as a supportive framework Made up of three types of fibers 1.Microfilaments – Thinnest 2.Intermediate Filaments – In between thickness 3.Microtubules - Thickest

Can a cell be related to a factory? Office Shipping Department Processing Center Custodial Crew Storage Assembling Department Power Source

1. Main Office Nucleus

2. Packaging Department Golgi Apparatus

3. Shipping Department Endoplasmic Reticulum

4. Assembling Department Ribosomes Nucleuolus

5. Clean-up Crew Lysosome

6. Storage Department Vacuole

7. Power Supply Mitochondria Chloroplast