CHAPTER 7 CELL STRUCTURE AND

FUNCTION“You are a metropolis of 50 trillion citizens. Each of the cells in your body can be considered a sentient being in its own right. They all act together as a community, performing an ongoing act of prodigious collaboration.”

Dr. Bruce LiptonBiologist

CHAPTER 7: CELL STRUCTURE AND FUNCTIONSection 1. Discovery of CellsSection 2. Cell StructureSection 3. Cell BoundariesSection 4. Diversity of Cellular Life

Go to Section:

CELL = THE BASIC UNIT OF LIFE

nm = 10-3 µm 10-9 m

µm = 10-3 mm 10-6 m

Nanometer:

Micrometer:

0.001 mm

0.000001 mm0.000000001 m

Cell Size

10 fold decrease

PERIMICIUM

Anton Von LEEUWENHOEK

Early 1600’s Discovered living “cells”

“Simple” MicroscopeBlood cells and Bacteria from teeth

ROBERT HOOKE1665Termed the word “Cell”

Matthias Schleiden = plants“Botanist”

1830’s

Theodor Schwann = Animals“Zoologist”

Rudolf Virchow (1855)= “cells come from other cells”

CELL THEORY1. All organisms are composed of cells.2. Cells are the basic units of structure and function in living things.3. New cells are produced from existing cells.

TEM SEM

ElectronMicroscopes

“Transmission” “Scanning”

Rabbit Trachea (cilia)

1940’s2 million x

Control of Cell Size

Blood Cell

Streptococcus

Bacteria 1-10 microns

(1 micron = 0.001 mm)

High surface to volume ratio facilitates the exchange of materials in/out of cells

Eukaryotic 10 -100 microns

As a cell increases in size, its volume increases faster than its surface area.

Smaller objects have a greater ratio of surface area to volume.

Larger organisms have “more” cells not “larger” cells

“Bacteria” Organism is a single cell (unicellular)PROKARYOTIC CELLS“No True Nucleus”

= a cell that lacks internal structures surrounded by membranes

EUKARYOTIC CELLS“True Nucleus”

= cells containing internal, membrane bound structures

Protists, Fungi, Plants, Animals Organism can be unicellular or multicellular

Escherichia coli

Advantages of being multicellular?

Eukaryotic Cells

Animal Cell

Cytoplasm = entire region between the nucleus and plasma membrane

Cytosol = semifluid substance within the cytoplasm

Plant Cell

Plasma Membrane (Cell Membrane)= a selective barrier controlling the transport of material in/out of the cell

Nucleus

Nuclear Envelope = double lipid bilayer enclosing the nucleus (outer and inner)

Nuclear Pores = openings within the envelope

Nucleolus = synthesis of ribosomes

Chromatin = protein/DNA complex

Ribosome= synthesize proteins (protein synthesis)

Composed of ribosomal RNA (rRNA) and two sub units (proteins)

Free ribosomes = suspended in the cytosol

Bound ribosomes = attached to endoplasmic reticulum Proteins function in the cytosol

Proteins are transported around/in/out of cell

Free and Bound are structurally identical and can alternate between the two roles (cell adjusts)

Endomembrane SystemMembranes that are related either through direct physical continuity or by the transfer of membrane segments as tiny vesicles (sacs made of membrane)

-Nuclear envelope-Endoplasmic Reticulum-Golgi Apparatus-Lysosomes-Vacuoules (various kinds)-Plasma Membrane

Endoplasmic Reticulum (ER)endoplasmic = “within the cytoplasm”reticulum = “little net”

Cisternae = network of membranous tubules and sacs

ER membrane is continuous with the Nuclear Envelope

Smooth ER = lacks ribosomes on surface

Rough ER = contains ribosomes on the surface

metabolic processes (synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons)

synthesize sex hormones

-provide surface area for ribosomes-helps package and sort proteins-forms transport vesicles

Golgi Apparatus= modifies, stores, targets, and ships products from the ERespecially extensive in cells specialized for secretion

Transport vesicles “Cis” face “Trans” face Transport vesicle

Proteins can be modified along the passage (by enzymes)The Golgi can also manufacture certain macromolecules itself

“budding”

cis/ trans = opposite polarity

Lysosomes

= a membrane-bounded sac of hydrolytic enzymes that the cell uses to digest macromoleculesinternal pH = ~5 (if burst, enzymes are relatively inactive)

Lysosome formation and function

The lysosome and enzymes are produced by the ER Golgi Lysosome

Phagocytosis = feeding by engulfing smaller organisms or food particles

Lysosome digests the food products become cellular nutrients

Autophagy = recycling of organic material (worn out organelles)

Apoptosis = Programmed destruction of own cells (tadpole tails, human webbed fingers)

Central Vacuole

Vacuoles

Food Vacuole = formed from phagocytosisContractile Vacuole = pump excess water out of the cell (protists)

-Plant Cells-Endomembrane System-Hold reserves of organic compounds-Pigments for color (flower petals)-Poisonous/unpalatable compounds (protection)-Absorb water (growth)

ParameciumOsmoregulation

Mitochondria

= site of cellular respiration (ATP synthesis from organic compounds)Contain ribosomes and own DNAGrow and reproduce on their ownMobile

Energy transformation

Number of mitochondria is correlated with the cell’s level of metabolic activity

2 membranes (both phospholipid bilyers)

Inner membrane has folds (cristae)

Chloroplast

Energy transformation

“Plastid”Amyloplasts (store starch/ amylose)Chromoplasts (have pigments that give fruits and flowers orange/yellow colors)

Photosynthetic production of sugar

-Own DNA-Grow and reproduce on own-Mobile-Chlorophyll – pigment-2 membranes

Cytoskeleton

= a network of fibers (protein) extending throughout the cytoplasmGives mechanical support to the cell and maintains its shapeEspecially important to animal cells (no cell wall)

Provides anchorage for many organellesCan be disassembled and reassembled in a different part of the cell (changing cells shape)

Microtubules

Cellular functions arise from cellular orderA cell is a living unit greater than the sum of its parts

Crawls and reaches with pseudopodiaEngulfs bacteriaDigests by lysosome (produced by endomembrane system)Ribosomes synthesize the enzymesDNA genetic programmingProcess requires ATPMitochondria

Macrophage – defends against bacteria

• YouTube - 3D sperm fertilization project

Egeria densa

Homo sapiens

Euglena

Volvex“colonial”

Amoeba

Paramecium

Daphnia“animal”

Spirogyra“algae”

Actinophrys

DO NOT SEEK TO FOLLOW IN THEFOOTSTEPS OF THE MEN OF OLD;

SEEK WHAT THEY SOUGHT.- BASHO