Microscopes & Cells

California State Standards:1.a Students know cells are enclosed within semi-permeable membranes that regulate their interaction with their surroundings.

1.c. Students know how prokaryotic cells, eukaryotic cells (including those from plants and animals), and viruses differ in complexity and general structure.

1.e. Students know the role of the endoplasmic reticulum and Golgi apparatus in the secretion of proteins.

*1.j. Students know how eukaryotic cells are given shape and internal organization by a cytoskeleton or cell wall or both.

Microscopes and Cells: History

• In 1663, __________ coined the term “cells”

• 10 years later, _________________ observed bacteria and protozoa

• In 1833, __________ observed and coined the term “nucleus”

Robert HookeRobert Hooke

Anton van LeeuwenhoekAnton van Leeuwenhoek

Robert BrowneRobert Browne

Cell Theory: History

• In 1838 (and 1839) German scientists, ________________ & ________________ independently came up with the “Cell Theory”

Matthias SchleidenMatthias Schleiden

Theodore SchwannTheodore Schwann

Guten Tag, Dr. Shwann

Guten Tag, Dr. Schleiden

It appears we have come up with a very similar

theory…

What shall we call this theory?

Cell Theory

1. All living things are composed of one or more cells.

2. Cells are organisms' basic units of structure and function.

3. Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation).

• In 1855, German physician Rudolph Virchow discovered that…

I do believe that all cells must come from pre-

existing cells.

How big are cells?• Eukaryotic cells include

_______ & _______ cells.

• Most eukaryotic cells are between __ and ___ m.

• What is the limit of the light microscope?

• Why?

• What is used to see smaller objects? __________________

plant animal

10 100

Electron Microscopes

0.2 m

Electron Microscopy

• ___________ Electron Microscopes (TEM) emit light through a thin piece of heavy metal ion stained tissue

• ________ Electron Microscopes (SEM) reflect light off of a piece of heavy metal ion stained tissue

Transmission

Scanning

Prokaryotic Cells

DNA (Nucleoid)

Ribosomes

Plasma Membrane

FlagellumFlagella

Cytoplasm

TEM of a bacterium

CiliumCilia

Differences and similarities between Prokaryotes and EukaryotesDifferences

Prokaryotes lack:

1. True nucleus

2. Membrane bound organelles

Prokaryotes are much smaller than eukaryotes (prokaryotes are about 1 – 10 m)

Similarities

Both have:

1. DNA

2. Cytoplasm

3. Ribosomes

4. Plasma Membrane

The Plasma Membrane

TEM of a red blood cell

Hydrophilic Region

Hydrophilic Region

Hydrophobic Region

Phospholipid

Proteins

Carbohydrate side chains

The Plasma Membrane

• It is a semi-permeable barrier that allows for the passage of certain things based upon ______.

• What are the forms of transport across a cell membrane?

H2O produced by cell during respiration

size

Plant and Animal Cells

Comparing and Contrasting

Organelles in Eukaryotic Cells

Nucleus

• Ribosomes are made here:

• In non-dividingcells, DNA andproteins are here:

• Openings in thenuclear membrane

SEM of a freeze-fractured nuclear membrane

TEM of nuclear pores

nucleolus

chromatin

Nuclear pores

Ribosomes:Function in

TEM of ribosomes

Free ribosomes

Attached ribosomes(on ER)

protein synthesis

Ribosome unit

1.Proteins made by free ribosomesfree ribosomes stay in the cell

2.Proteins made by attached ribosomesattached ribosomes are shipped out of the cell or sent to the membrane

Endoplasmic Reticulum

There are two types:1. ER has

ribosomes attached.• Modifies & transports

proteins

2. ER does not have ribosomes on it.

• Synthesizes • Metabolizes carbohydrates• Detoxifies drugs & poisons

Rough

Smooth

lipids

Golgi ApparatusER products move here in

It is the center of Manufacturing, Warehousing, Sorting and Shipping

vesicles

Mitochondria

takes place in this organelle.

It is often called the “ “ of the cell.

Cellular Respirationpowerhouse

The Cytoskeleton

• A network of fibers that extend throughout the cytoplasm

• Three types:Microtubules

Microfilaments

Intermediate

Filaments

Cytoskeleton: Functions

1. Provides shape and support

2. Moves the cell and organelles

3. Regulates biochemical activities in cell

Organelle

Centrosome

• Microtubules grow out of this structure

• In animal cells, a pair of structures called that are involved in cell

division.centrioles

centrioles

centrosome

Cilia and Flagella

• Cellular projections that aide in movement

• Flagella are longer & move in a snake-like motion.

• Cilia are shorter, more numerous and move back & forth

Microvilli

• Projections from the cell’s surface that increase the surface area.

Microvilli

Intermediate Filaments

Microfilaments

Lysosomes

• Membrane-bound organelle that contains

enzymesdigestive

Lysosome engulfing a peroxisome and a

mitochondria

Vacuoles

• Large, central organelle

• Stores water and waste products

• In animals, it stores food

• Protists have a Contractile Vacuole

Chloroplasts

• An organelle that converts energy from the sun into chemical energy

The process is called:Photosynthesis

Cell Wall

• Found in plant and bacterial cells.

• Surrounding the , this feature does the following for plant cells:

1. Provides Support

2. Provides Protection

cell membrane