unit 4. discovery of cells anton van leeuwenhoek : made improvements to the simple microscope in...

Unit 4

Discovery of Cells

• Anton van Leeuwenhoek:

• Made improvements to the simple microscope in 1648

– Saw microscopic critters in pond water 1674

Discovery of Cells

• Robert Hooke

• 1st person to see cells & identify them – saw cell walls in cork 1665;

• He gave ‘cells’ their name!

2 Types of Cells

•Prokaryotic Cells

and

•Eukaryotes Cells

Prokaryotes• The cell DOES NOT

have a “true” nucleus;

Tend to be smaller than Eukaryotes

Not as many organelles as Eukaryotes

– Ex: All bacteria

Eukaryotes• The cell HAS a “true”

nucleus– Eukaryotes contain

organelles which are special structures that perform important cellular functions

– Ex: All plants, animals, fungi, & protists

Similarities and Differences in Prokaryotes and Eukaryotes

Cell membraneContain DNA

CytoplasmRibosomes

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

EukaryotesProkaryotes Both

Cell Organelles 1

• Tiny structures inside the cell that perform functions

• The organelles are to the cell as the organs are to the whole body

• Cells Tissues Organs Organ Systems Organism

NUCLEUS

• The control center of the cell

• contains DNA, chromatin, & chromosomes

• DNA contains coded instructions needed to make proteins

• Chromosomes are thread-like structures that contain genetic material

CYTOPLASM

• Gel-like material in the cell

• organelles are suspended in the cytoplasm

Ribosomes

• Makes proteins with the help of RNA and Amino Acids

Endoplasmic Reticulum• Moves materials

around the cell• Assembly of Lipids• Assists with Protein

Synthesis

• Rough ER: contains ribosomes

• Smooth ER: no ribosomes

Mitochondria:• “Power-house” of the cell

• makes ATP (energy);

found in both plants & animals

– Converts food into compounds that the cell uses for growth, development, and movement

Chloroplasts:

• Converts energy from sunlight into chemical energy by photosynthesis

–Found only in plants, bacteria, and some protists

Golgi Apparatus• Sorts &

Packages proteins from the ER

Vacuole• Stores water, salts,

protein, & carbs

– Plant cells have a single large vacuole (stores water)

– Animal cells have many small vacuoles

Lysosomes:

• Contains enzymes to digest waste

Cytoskeleton• helps the cell

maintain its shape

– Contains microfilaments & microtubules

Cell WallProvides support and protection for the cell; found in plant cells and bacteria

• Regulates what enters and leaves the cell; found in both plant & animal cells– Composed of a

Lipid bilayer (contains lipids and proteins)

Cell Membrane

Lipid BilayerOutsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Animal Cell – rounder shape; no cell wall; no chloroplasts

How a school is like a cell

Just as the Administrative assistant controls what enters and leaves the school, so the plasma membrane regulates what leaves and enters the cell.

Just as the princible directs all operations that go on in the school, so the nucleus and DNA controls all cell activities and what proteins will be made.

Just as the school floor holds all the desks and every thing that’s on it, so the cytoplasm is were all the organelles and activities are found.

Just as the cafeteria kitchen is the place were the workers do their job making food, so the ER is the place were the ribosomes do their job of assemabling proteins

Just as the janitors clean up all the trash around the school and recycles the things that can still be used, so the so the lysosomes break down the cell waste so the different parts can be reused.

Just as the support beams, walls, ceilings, floors, bricks, and cement support the school building, so the cytoskeleton supports and maintains the shape of the cell.

Just like lunch provides the students with energy to do there work, so the mitochondria are the source of ATP that is used for energy in cell processes.

Just as composting breaks down garbage from the students in the school, so the peroxisomes break down hazardous material such as hydrogen peroxide.

Just as the storage closets in the classrooms store material, so the smooth ER (edoplasmic reticulum) stores steroids and ions.

Just as the teacher directs the students into the auditorium for an assembly, so the necleolous directs the assembly of proteins with in the cell necleus.

Just as the buses drive kids to and from school, so the centrosome is were microtubes carry out transportation.