history, types and general characteristics of cells packet #10 chapter #3 wednesday, october 21,...

History, Types and General Characteristics of Cells

Packet #10Chapter #3

Thursday, April 20, 20231

Cytology


Cytology is the study of cells.

Cell Theory

Various scientists arrived at three major thoughts All living things are composed of cells Cells are the basic units of structure and

function in living things All cells come from preexisting cells

These three thoughts became known as the cell theory.


The Discovery


Cells discovered by Robert Hooke in 1665 However the subcellular

structures could not be seen--the organelles

It wasn’t until the 1950’s, with the invention of the electron microscope that cell biology really took off

Isolation of OrganellesCell Fractionation

Cell fractionation allowed scientists to study cell components and involves a process known as centrifugation The centrifuge is an instrument that

is used to fractionize cells Spins fast as much as 80,000

revolutions per minute and apply forces on particles up to 500,000 times the force of gravity

Differential centrifugation separate cellular components based on size and density.

Density gradient centrifugation allows further purification.


Micromanipulation Another technique for the removal of parts of

the cell Can also insert material into a living cell Done while looking through a microscope

In-Vitro Fertilization In-Vivo Fertilization

Cell Cultures** Isolate one type of cell and you grow it in

large numbers--bacteria for exampleThursday, April 20, 20236

Isolation of Organelles IIMicromanipulation & Cell

Cultures

SIZE OF ATOMS, MOLECULES, MACROMOLECULES,

ORGANELLES, CELLS AND ORGANISMS

The Hierarchy Revisited


Hierarchy Revisited


Why do you think that the size of a cell is significant? What makes the

cell’s size special? The small cell size

allows maximum cell surface area. HW

Introduction of Prokaryotic & Eukaryotic Cells

The discovery of cells, and their components, led to the distinction between prokaryotic cells and eukaryotic cells.


Prokaryotic vs. Eukaryotic


Prokaryotic Cells Prokaryotes are structurally

simpler than eukaryotic cells. Prokaryotic cells lack membrane-

bound organelles and are typically smaller than eukaryotic cells.

Prokaryotic cells have a plasma membrane and typically a cell wall.

In prokaryotes, DNA is located in the nuclear area or nucleoid.

Prokaryotes have smaller ribosomes.

Chlorophyll may be present but no chloroplasts.

Mitosis, nor meiosis, does not occur Cells reproduce by other asexual

means

Prokaryotic versus Eukaryotic II


Eukaryotic Cells Membrane bound

organelles are present Nucleus and nuclear

membrane are present Chlorophyll, when

present, is contained in chloroplasts

Ribosomes are larger Cell wall is present in

some eukaryotic cells Mitosis and meiosis

occurs

Prokaryotic Cells Eukaryotic Cells

No distinct nucleus No chromosomes

Circular strands of DNA known as plastids

No membrane bound organelles

Ribosomes are smaller No mitosis or meiosis occurs

Distinct, membrane-bounded nucleus

Chromosomes present on which DNA is located

Chloroplasts and mitochondria may be present

Ribosomes are larger Mitosis and/or meiosis

occurs

Prokaryotes vs. Eukaryotes


TYPES OF EUKARYOTIC CELLS

Plant cells vs. Animal Cells


Eukaryotic Cells


Most organisms are eukaryotes and are composed of eukaryotic cells.

There are two basic types of eukaryotic cells Plant cells Animal cells

Plant Cells


Have cell walls Contain cellulose

Large vacuole filled with cell sap

Larger than animal cells Shape

Different from animal cells Cilia and flagella absent in

higher plants What kingdom(s) are the

higher plants found? What kingdom(s) are the

lower plants found?

Animal Cells


No cellulose cell wall in MOST animal cells Plasma membrane

Some vacuoles but they are usually small and numerous

Cytoplasm throughout the cell

Nucleus may be found anywhere in the cell Is normally in the center

of the cell Cilia is common in animal

cells of higher animals

Animal Cell IICell Specialization


In animals, cells are often uniquely suited to perform a particular function within the organism Nerve Cells Muscle Cells Rods and Cones in the eye Sex cells

These specialized cells are determined by complex processes of turning on and off genes.


Plant Cell


Animal Cell

Plant Cell vs. Animal Cell

Similarities

Both Eukaryotic Cells Have membrane bound

organelles

Differences Plant cells are “generally”

larger than animal cells Plant cells have a cell wall

of cellulose Adds stability and

protection to the plant cell Plant cells have vacuoles

That are used as space fillers

Fulfills digestive functions in plants--similar to lysosomes that are also found in animal cells.

Animal cells have centrioles


Review


history, types and general characteristics of cells packet #10 chapter #3 wednesday, october 21,...

Documents

study of cells

animal cells

cells size special

living thingsall cells

eukaryotic cellsmitosis

cell biology

type of cell

small cell size