The Cell

Cells are the basic unit of life!

Viewed cork samples and observed hollow boxes which he called cells. Robert Hooke

Anton von Leeuwenhoek First to describe microorganisms as seen through a simple microscope

Matthais Schleiden - Botanist All plants are made of cells.

Theodor Schwann - Physiologist All animals are made of cells.

The studies of Schleiden and Schwann, along with others, led to the development of the cell theory.

All organisms are composed of one or more cells.

The cell is the basic unit of organization for organisms.

All cells come from pre-existing cells. (Cell reproduction makes exact copies of existing cells.)

Basic Cell Types Prokaryote vs. Eukaryote Pro = Before Eu = True Kary = Nucleus; Kernel

Prokaryote Lacks internal structures surrounded by membranes Lacks a true nucleus DNA is contained in the nucleoid Most are single celled organisms.

Eukaryote Has membrane bound structures Has a true nucleus Allows cell parts to specialize in particular function

Eukaryote Can be unicellular or multi-cellular The membrane bound structures are called organelles Allows different chemical reactions to take place within the cell Eukaryotic plant cell

Bacteria & Viruses

A. Prokaryotic organisms B. Divided into 2 kingdoms 1.Eubacteria a.Very diverse; live almost anywhere b.Surrounded by a cell wall 2.Archaebacteria a.Live in harsh conditions b.Possible ancestor to eukaryotes Bacteria

C.Identified by specific characteristics 1.Shape a.Rod: bacilli b.Round/spherical: cocci c.Spiral: spirrilla 2.Cell Wall (thick or thin) 3. Movement a.Sessile b.Flagella c.Snake or spiral forward d.Glide along a slime-like material

D. Metabolic Processes 1.Mostly heterotrophs 2.Some autotroughs 3.All need energy E. Growth and reproduction 1.Binary Fission 2.Conjugation 3.Spore formation

1.Environment a.Decomposers b.Nitrogen fixers 2.Human uses a.Food production b.Industrial Uses c.Genetic Engineering d.Produce vitamins within our bodies F. Purpose: Vital to the maintenance of the living world

Viruses A.Characteristics 1.Considered abiotic; does not have all the characteristics of life 2. Composed of a core of DNA or a RNA surrounded by a protein coat (capsid) 3. The capsid enable the virus to enter the host cell 4. Highly specific to the type of cell they infect

B. Need host cell to reproduce; parasitic C. May have evolved from the genetic material from living cells; viruses continue to evolve and adapt to their changing environment

Cellular Structure and Function

Boundary Organelles

Plasma Membrane Location: Surrounds the cell Function: boundary between cell and environment Controls what goes into and out of the cell. * Also called: cell membrane or phospholipid bilayer

Cell Wall Location: surrounds the plasma membrane in plant cells Function: support Inflexible barrier

Nuclear Envelope (membrane) Location: surround the nucleus Function: controls what goes into and out of the nucleus * The nuclear membrane is 4 layers thick

Control Organelles

Nucleus (largest organelle) Location: center of the cell Function: manage cell functions

Chromatin/Chromosomes Location: in the nucleus Function: form chromosomes during cell reproduction * Formed from DNA

DNA Location: in the nucleus, on the chromosomes Function: carries the codes for protein synthesis; carries genetic information

Assembly, Transport and Storage Organelles

Cytoplasm/Cytosol Location: from the nuclear envelope to the cell membrane, surrounding the organelles Function: a clear, jelly-like fluid that holds the organelles in place

Nucleolus Location: in the nucleus Function: produce ribosomes

Ribosomes Location: nucleolus, endoplasmic reticulum, cytoplasm Function: assembles enzymes and proteins for protein synthesis * Not surrounded by membranes *

Endoplasmic Reticulum (smooth/rough) Location: within the cytoplasm Function: site of lipid & protein synthesis Cell’s delivery system; network of canals

Rough ER - studded with ribosomes Attached to nuclear membrane site of protein synthesis and processing Smooth ER - lacks ribosomes site of synthesis of phospholipids and the packaging of proteins into vesicles

Golgi Apparatus Location: within the cytoplasm Function: Receives and distributes the new proteins and lipids from the ER and distributes substances from the vesicles

Vacuole Location: within the cytoplasm Function: temporary storage of material (food, water, waste, enzymes) One large vacuole in plants Many small vacuoles in animals

Lysosomes Location: within the cytoplasm (animals only) Function: digests worn out or extra cell parts, food, virus/bacteria

Energy Transformers

Mitochondria “power house” Location: within cytoplasm Function: breaks down food to release energy; cellular respiration

Chloroplasts Location: Within the cytoplasm Function: Change light energy into usable chemical energy Chloroplasts are larger and more complex than mitochondria Contain green pigment called chlorophyll that absorbs sunlight in the first step of photosynthesis Found ONLY in PLANTS Chloroplast structure includes Thylakoids, membranous sacs, stacked to form a granum Stroma, the internal fluid

Chlorophyll: green pigment that gives plants their color and traps light energy Belongs to a group of plant organelles called plastids which are used for storage. They store starches (carbohydrates), lipids and pigments

Support and Locomotion Organelles

Cytoskeleton Location: Within the cytoplasm Function: provides support for organelles

Composed of microtubules and microfilaments Microtubules: thin, hollow cylinders made of proteins Microfilaments: solid protein fibers Intermediate filaments: have a diameter between microtubules and microfilaments

Centrioles Location: Within the cytoplasm Function: Aids in cellular reproduction Found only in animal cells Small clusters of microtubules; found in pairs

Cilia Location: outside of the cell Function: move the cell * tiny, hair-like projections

Flagella Location: outside the cell Function: move the cell *Tail-like structure