The CellThe CellCell Theory/HistoryCell Theory/HistoryStructuresStructuresTransport Transport Differentiation Differentiation Levels of Organization Levels of Organization

Robert Hooke

• English physicist• 1665• Saw a slice of

cork tree tissue– Tiny chambers– Termed them

“cells”(looked like monks’ cells in monastery)

Robert Hooke

• Published his book Micrographia– Contained

drawings of cork cells

– Used early microscope

Anton Van Leeuwenhoek

• Dutch businessman

• 1674• Perfected

microscope(about 300x)

• Saw living things in pond water– “Animalcules”– Observed

bacteria (on wood teeth) and protozoa

Matthias Schleiden

• German botanist

• 1838• Concludes that

all plants are made up of cells

Theodor Schwann

• German zoologist

• 1839• Concluded that

all animals are made up of cells

Rudolph Virchow

• German physician/pathologist

• 1855• Worked with eggs

from various organisms

• Proposes that all cells come from existing cells

Cell Theory•All living things are

composed of cells.

•Cells are the basic units of structure and function in living things.

•New cells are produced from existing cells.

Janet Plowe

• 1931• Demonstrates that the cell

membrane is a physical structure, not an interface between two liquids.

Lynn Margulis

• 1970• Proposes a

theory that certain organelles were once free-living cells themselves

Singer - Nicholson

• 1972• Fluid Mosaic Model

– Membranes are phospholipid bilayers with globular proteins embedded in them

– Membrane is always moving– Made up of smaller pieces

(mosaic)

Prokaryote cells

Very simple (bacteria)

Eukarote cells

Larger, complex

Cell Structures

Barriers…

Cell WallPlants & prok. (not animals)Structural (plant support) & protective roleCelluloseFreely permeable

Cell walls of onion skin…

Barriers…

Cell Membrane (plasma membrane)In ALL cellsSupport/protection Regulates movement in/out of:

○ Water○ Nutrients○ Waste products

Cell Membrane...

Barriers…

Nuclear Envelope (nuclear membrane)Surrounds nucleusThousands of pores

○ Material move in/out, incl. RNA

Nuclear envelope

Fluids…

Cytoplasm (cytosol)Bet. cell mem. and nuclear env.,

site of most chemical activity

NucleoplasmSemi-fluid medium of nucleus

ProtoplasmTerm used for all substances inside cell

The Nucleus

The Nucleus…

Controls most cell processes Contains Chromatin

DNA bound to proteinsDuring cell division, condenses to

Chromosomes…

Has a NucleolusSmall, dense regionAssembly of Ribosomes

Nuclear Envelope (or membrane)

Organelles of the cytoplasm

Cytoskeleton…

Protein filaments Maintains cell shape Involved in cell movement

Cytoskeleton

Ribosomes…

Small,made of RNA Assembly of proteins Free in cytoplasm or att. to ER

Endoplasmic Reticulum… Called “ER” Two types:

Rough ER○ Ribosomes stud surface○ Aids in synthesis and modif. of proteins○ Found wrapped around nucleus

Smooth ER○ No ribosomes○ Special tasks with certain enzymes

(such as making lipids)

Mitochondrion…

Uses energy from food Makes high-energy compounds (ATP)

needed for Rx elsewhere. The POWERHOUSE of the cell

Golgi Apparatus…

Receives proteins from rough ER Enzymes attach carbs and lipids to the

proteins Can store proteins until needed Proteins then sent to final destination PACKAGING and SHIPPING

Golgi Apparatus

Vacuoles…

Saclike structure Stores water, salts, proteins, carbs Can be large in plant cells

Helps in plant support by keeping turgor pressure high

Vacuoles

Vacuoles

Korotnovella, an amoeba. Inside this cell we can see a nucleus near the center with a rather angular dark nucleolus, various food vacuoles, and a clear round contractile vacuole at about 10 o'clock.

Lysosomes…

Filled with enzymes Breaks down

lipids, carbs, and proteins from foodold organellesdebris and harmful invaders

Video

Plastid 1: Chloroplasts…

In plants, not animals or fungi Uses sunlight to make energy rich food

mol. thru photosynthesis

Chloroplasts…

Chloroplast

Plastid 2: Leucoplast

Sometimes called amyloplast; stores starch (amylose = starch)

Plastid 3: Chromoplast

Stores pigments in plants

Centrioles

Cylindrical; group of microtubules In animal cells, used in cell division As “basal bodies,” form cilia and flagella

The Cell Membrane

Is composed of a phospholipid bilayer

A barrier; reg. what passes in/out Supports and protects Selectively permeable – only certain things pass through. About 5 nanometers thick (1 nm = 1 Billionth of a meter)

Cell membrane - Structure

A phospholipid contains-

one head; negatively charged phosphate group that is hydrophilic (water-loving)

two tails of fatty acid chains that are hydrophobic (water fearing)

Cell membrane features

The fluid mosaic modelit is fluid in nature allowing cell mobilityScattered in the membrane are various

proteins which perform various functions:

○ enzyme activity,○ cell attachment,○ communicating with other cells, ○ Trans. of substances in and out

Passive transportDiffusion: net movement of sub. (liquid or gas) from an area

of higher conc. to area of lower conc. Example: perfume

Passive transportOsmosis: diffusion of water across a

semi-permeable or selectively perm. membrane.○ Hypertonic: Solution having a high conc. of solute. ○ Hypotonic:  Solution having a low conc. of solute. ○ Isotonic:  Both solutions have equal solute conc.

○ This difference (Δ) of conc. of molecules across a space is called a Concentration Gradient

Lysis Equilibrium Plasmolysis

Turgid Flaccid Plasmolysis

An

imal P

lan

t

Passive transport

Facilitated diffusion = trans. of materials across membranes by transport proteins

Active transport

Active transport - Trans. of molecules against a concentration gradient (from regions of low conc. to regions of high conc.) with the aid of proteins in the cell mem. and energy from ATP

Other types of active transport Other types of active transport

Endocytosis – import of materials into cell by infoldings of the cell membrane. A. phagocytosis – “cell eating”; extensions of the cell membrane surround the food and make a vacuole. Lysosomes then secrete enzymes into vacuole to digest food.B. pinocytosis – “cell drinking”; smaller infoldings allowing droplets of liquid to enter cell.

Endocytosis in general

Exocytosis – reverse of endocytosisDumping of excretions or wastes outside by

discharging them from waste vacuoles.Also can result in secretion of substances

(ex: gland cells secreting hormones into the bloodstream)

Cell Differentiation

And hierarchy of organisms’ tissues

Cell differentiation

The process by which unspecialized cells develop into their mature forms and functions

Embryonic Stem CellsUndifferentiated (unspecialized)

○ Totipotent – can develop into ANY type tissue

Adult Stem Cells○ Pluripotent or multipotent – can develop into

certain types of tissues.

Levels of organization

Level one = cells -basic unit of life; examples are blood cells

○ Red (RBC, or erythrocytes)○ White (leukocytes)

nerve cells (neurons),bone cells (osteoblasts)

Levels of organization Level two -tissues= Made up of cells that are similar in

structure and function and which work together to perform a specific activity

-Humans have 4 basic tissues: connective, epithelial, muscle, and nerve. Connective tissue

○ include bones, ligaments, cartilage, blood, tendonsEpithelial tissue-

○ skin, the mucosa, and the serosa (lines body cavities and internal organs)

Muscle tissue-○ skeletal muscle, smooth muscle, and cardiac muscle

Nerve tissue- ○ brain, spinal cord, and nerves

Levels of organization

LEVEL 3 – Organs -Made up of tissues that work together to perform a specific activity heart, brain, skin, etc.

LEVEL4 - Organ Systems -Groups of two or more organs that work together to perform a specific function for the organism.The Human body has 11 organ systems - circulatory,

digestive, endocrine (hormonal), excretory (urinary), lymphatic (immune), integumentary (skin), muscular, nervous, reproductive, respiratory, and skeletal.

Levels of organization

LEVEL 5 - Organisms -Entire living things that can carry out all basic life processes.

Meaning they can take in materials, release energy from food, release wastes, grow, respond to the environment, and reproduce.

Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria or protist.

Examples - bacteria, amoeba, mushroom, sunflower, human

Cell Regulation

What makes a cell divide?Internal signal: Enzymes produced by cellExt. signal: like growth factor produced

elsewhereWhen cells packed close, NO divisionNot packed, division starts

Checkpoints: where stop/go signals reg. division

Uncontrolled division

Too many cells form a tumorDisrupts normal

cell activityTakes nutrientsIf one area only:

benignIf spreading:

malignant

The staging of a carcinoma has to do with the size of the tumor, and the degree to which it has penetrated. When the tumor is small and has not penetrated the mucosal layer, it is said to be stage I cancer. Stage II tumors are into the muscle wall, and stage III involves nearby lymph nodes. The rare stage IV cancer has spread (metastasized) to remote organs.

http://www.nytimes.com/imagepages/2007/08/01/health/adam/19222Stagesofcancer.html