CELLSCELLS Cytology - the study of cellsCytology - the study of cells

Cells are the basic Cells are the basic unit of life.unit of life.

I. Cell organization I. Cell organization

• Organization is similar in all cellsOrganization is similar in all cells

All cells haveAll cells have::

1) DNA1) DNA

2) a membrane to protect the cell2) a membrane to protect the cell

3) organelles with special functions3) organelles with special functions

II. II. HistoryHistory A) THE CELL THEORYA) THE CELL THEORY

- - proposed by Schleiden and Schwann

1. All organisms are made of cells.

- Virchow later added…

2. All cells come from other cells. ……………Now, let’s see a video

about the Cell Theory

II. II. HistoryHistory B) MicroscopyB) Microscopy

Robert HookeRobert Hooke 11stst person to call them “cells” person to call them “cells”

(1665)(1665) observed cork cells (he was observed cork cells (he was

observing dead cell walls)observing dead cell walls)

Anton Van LeewenhoekAnton Van Leewenhoek made made superiorsuperior microscopes microscopes

((c.c.1670)1670) Observed “animicules” in water Observed “animicules” in water

(they were Protists!)(they were Protists!)

III.Study Techniques III.Study Techniques include:include: A. A. Cell fractionationCell fractionation 1. chop up cells in a blender1. chop up cells in a blender

2. “spin out” different types of 2. “spin out” different types of organelles based on size organelles based on size and density in a and density in a centrifugecentrifuge..

III. MicroscopesIII. MicroscopesA.A. Related terms Related terms::

a)a) MagnificationMagnification – how large the image – how large the image appears compared to what it seen appears compared to what it seen with the naked eye.with the naked eye.

b)b) ResolutionResolution (focus) – how clear the (focus) – how clear the image appearsimage appears

c)c) MicrographMicrograph – a photo taken of a – a photo taken of a microscopic imagemicroscopic image

B) B) 3 kinds3 kinds

1)1) Compound (light) Compound (light) microscopemicroscope

- magnification/resolution to magnification/resolution to 2,000x2,000x

- advantageadvantage: can view : can view livelive cells/processescells/processes

2) 2) Scanning electron Scanning electron microscope (SEM)microscope (SEM)- uses electron beam- uses electron beam

- views cell surfaces- views cell surfaces

3) 3) Transmission Transmission electron microscope electron microscope (TEM)(TEM)

- views internal cell - views internal cell structuresstructures

A view of a cell with ciliaA view of a cell with cilia compound microscopecompound microscope

A view of the cilia of a A view of the cilia of a cellcelltransmission electron microsope transmission electron microsope

vs. scanning electron microscopevs. scanning electron microscope

TEM (inside)TEM (inside) SEM (outside) SEM (outside)

Practice:Practice:What microscope would be used to What microscope would be used to

observe…observe…

1. A cell that is engulfing large bits of 1. A cell that is engulfing large bits of food?food?

2. A cell that is dividing (reproducing)?2. A cell that is dividing (reproducing)?

3. An external view of the cell wall of a 3. An external view of the cell wall of a plant cell?plant cell?

4. The folds of the endoplasmic reticulum?4. The folds of the endoplasmic reticulum?

5. The inside of a chloroplast?5. The inside of a chloroplast?