Chapter 7 Cell Structure and Function. 7.1 The Discovery of Cells Robert Hooke –Discovered 1 st cell –Observed dead cork cells –Named the cell: basic.

Chapter 7Chapter 7

Cell Structure and Cell Structure and FunctionFunction

7.1 The Discovery of Cells7.1 The Discovery of Cells Robert Hooke Robert Hooke

– Discovered 1Discovered 1stst cell cell– Observed dead Observed dead

cork cellscork cells– Named the Named the cellcell: :

basic unit of living basic unit of living organismsorganisms

Anton van LeeuwenhoekAnton van LeeuwenhoekLooked at & described the 1Looked at & described the 1stst living cell living cell

The Cell TheoryThe Cell Theory

Matthias Schleiden & Thomas SchwannMatthias Schleiden & Thomas Schwann– Schleiden Schleiden Botanist Botanist– Schwann Schwann Zoologist Zoologist

Developed the Developed the cell theorycell theory::

1.1. All life forms are made from one or more All life forms are made from one or more cells. cells.

2.2. Cells only arise from pre-existing cells. Cells only arise from pre-existing cells.

3.3. The cell is the smallest form of life. The cell is the smallest form of life.

Two basic cell types:Two basic cell types:

1.1. ProkaryoteProkaryoteo Before a nucleus (NO Nucleus)Before a nucleus (NO Nucleus)o Single-celledSingle-celled

2.2. EukaryoteEukaryoteo Has a nucleusHas a nucleuso Unicellular or multicellularUnicellular or multicellularo Contained Contained organellesorganelles (membrane bound (membrane bound

structures)structures)

Which one is a prokaryotic cell?

Is B. a plant or an animal cell?

A. B.

7-2 Eukaryotic Cell Structure7-2 Eukaryotic Cell Structure

Contain Contain OrganellesOrganelles which means “little which means “little organs”.organs”.

Each cell contains Each cell contains CytoplasmCytoplasm which holds which holds all of the organelles.all of the organelles.

NucleusNucleus: : Control center of the cellControl center of the cell Contains DNA Contains DNA

Has a nuclear envelope & Nucleolus Has a nuclear envelope & Nucleolus

RibosomesRibosomes: : make proteinsmake proteins most numerous organelle in the cell most numerous organelle in the cell Found on and off of ER Found on and off of ER

Endoplasmic ReticulumEndoplasmic Reticulum: : Two types of ERTwo types of ER:: Smooth (no ribosomes) Smooth (no ribosomes)

Rough (has ribosomes) Rough (has ribosomes)

Smooth makes and transports lipids

Rough transports proteins

Golgi ApparatusGolgi Apparatus: Stores and : Stores and packages packages chemicalschemicals

LysosomeLysosome: “Stomach of the cell”: “Stomach of the cell” Vacuole that contains Vacuole that contains

digestive enzymes digestive enzymes

MitochondriaMitochondria: “Powerhouse of the : “Powerhouse of the cell” cell”

ChloroplastChloroplast: : Capture sunlight and convert it into Capture sunlight and convert it into chemical energy in a process called photosynthesischemical energy in a process called photosynthesis

7-3 Cell Boundaries7-3 Cell Boundaries

All cells are surrounded by a All cells are surrounded by a cell cell membranemembrane (also called a plasma (also called a plasma membrane).membrane).

Some cells are surrounded by a Some cells are surrounded by a cell wallcell wall (especially plant cells).(especially plant cells).

Both serve as a boundary between the cell Both serve as a boundary between the cell and its environment.and its environment.

The Cell membrane is semi-permeable.The Cell membrane is semi-permeable.

The Plasma MembraneThe Plasma Membrane

FUNCTIONSFUNCTIONS::1)1) Controls what enters and leaves the cell Controls what enters and leaves the cell

(maintaining homeostasis with selective (maintaining homeostasis with selective permeability)permeability)

2)2) Protects the cellProtects the cell Also the Also the cell wall’scell wall’s main function!! main function!!

PM continued…PM continued…

PM is made of a PM is made of a bilayer of bilayer of phospholipids!!phospholipids!!

Two ends to a Two ends to a phospholipid:phospholipid:– Hydrophilic Hydrophilic – HydrophobicHydrophobic

Two types:Two types:– SaturatedSaturated– UnsaturatedUnsaturated

Fluid Mosaic Model Fluid Mosaic Model (PG. 182)(PG. 182)

Random movement of MoleculesRandom movement of Molecules

Robert Brown – Brownian MotionRobert Brown – Brownian Motion Molecules are in a constant state of motionMolecules are in a constant state of motion

– Gas = fast movementGas = fast movement– Liquid = medium movementLiquid = medium movement– Solid = slow movementSolid = slow movement

Molecules move from high concentrations to Molecules move from high concentrations to low concentrations because of a low concentrations because of a concentration gradientconcentration gradient..

Diffusion Through Cell BoundariesDiffusion Through Cell Boundaries

DiffusionDiffusion: the movement of particles : the movement of particles from and area of high concentration to from and area of high concentration to low concentrationlow concentration

OsmosisOsmosis is the diffusion of wateris the diffusion of water

Diffusion

Three types of solutions (Pg. 186)Three types of solutions (Pg. 186)

1)1) IsotonicIsotonic: concentrations on both sides of the : concentrations on both sides of the plasma membrane are equalplasma membrane are equal

No net movementNo net movement

2)2) HypertonicHypertonic: concentration of dissolved : concentration of dissolved substances outside the cell are higher than substances outside the cell are higher than insideinside

Water moves out Water moves out Cell Shrinks Cell Shrinks

3)3) HypotonicHypotonic: concentration of dissolved : concentration of dissolved substances inside the cell are higher than substances inside the cell are higher than outsideoutside

Water moves in Water moves in Cell Swells Cell Swells

Two types of transportTwo types of transport Passive TransportPassive Transport Move with the Move with the

concentration concentration gradientgradient

NO energy NO energy requiredrequired

1.1. Simple DiffusionSimple Diffusion

2.2. OsmosisOsmosis

3.3. Facilitated Facilitated DiffusionDiffusion

Active TransportActive Transport Move against the Move against the

concentration concentration gradientgradient

Energy Energy REQUIREDREQUIRED

1.1. EndocytosisEndocytosisa)a) Pinocytosis Pinocytosis

(drinking)(drinking)b)b) Receptor-Receptor-

mediated mediated endocytosisendocytosis

c)c) Phagocytosis Phagocytosis (Eating)(Eating)

2.2. ExocytosisExocytosis