Lecture - Cells

8/3/2019 Lecture - Cells

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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for

Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

Chapter 3Chapter 3

A Tour of the Cell




DISCOVERY OF CELLS

Anton van Leeuwenhoek developed the first

microscope

his invention enabled him to see things that no

one had ever see beforeHe carefully observed the tiny living things in

pond water and called them animalcules

Robert Hooke used the microscope to look at thinslices of plant stems, wood and pieces of cork

Looking at the cork, he saw that it was

composed of thousands of tiny chambers.




Robert Brown a Scottist scientist,

discovered the nucleus

M atthias Schleiden German botanist,stated that all plants are made of

cells

Theodor Schwann discovered that aanimals are made of cells too.




J ohannes Purkinji introduced the term

protoplasm to denote the living part

of the cellRudolf Virchow a German physician, stated

that all cells arise from the division of

pre-existing cellsWalter Fleming observed that cells

undergo the process of cell division




Overview: The Importance of Cells

All organisms are made of cells

The cell is the simplest collection of matter

that can live

Cell structure is correlated to cellular function

All cells are related by their descent from ear lier

cells




CELL THEORY

a. All living things are composed of

cells.

b. Cells are the basic units of structure and function in living

things

c. All cells come from pre-existing

cells.




Eukaryotic cells have internal membranes thatcompartmentalize their functions

The basic structural and functional unit of every

organism is one of two types of cells: prokaryotic

or eukaryotic

Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells

Protists, fungi, animals, and plants all consist of

eukaryotic cells




Comparing Prokaryotic and Eukaryotic Cells

Basic features of all cells:

± Plasma membrane

± Semif luid substance called the cytosol

± Chromosomes (carry genes)

± Ribosomes (make proteins)




Prokaryotic cells have no nucleus

In a prokaryotic cell, DN A is in an unbound region

called the nucleoid

Prokaryotic cells lack membrane-bound organelles



LE 6-6

A typical

rod-shaped

bacterium

A thin section through the

bacterium Bacillus

coagulans (TEM)

0.5 µm

Pili

Nucleoid

Ribosomes

Plasma

membrane

Cell wall

Capsule

Flagella

Bacterial

chromosome




Eukaryotic cells have DN A in a nucleus that isbounded by a membranous nuclear envelope

Eukaryotic cells have membrane-bound

organelles

Eukaryotic cells are generally much larger than

prokaryotic cells

The logistics of carrying out cellular metabolismsets limits on the size of cells




Prokaryotic Cells:Domains

Lack a membrane-bound nucleus

Structurally simple

Two domains:

± Bacteria

Three Shapes

± Bacillus (rod)

± Coccus (spherical)

± Spirilla (spiral)

± Archaea

Live in extreme habitats

1




Shapes of Bacterial Cells

1




Prokaryotic Cells: Visual Summary

1




Prokaryotic Cells:The Envelope

Cell E

nvelopes

± Glycocalyx

Layer of polysaccharides outside cell wall

May be slimy and easily removed, or

Well organized and resistant to removal (capsule)

± Cell wall

± Plasma membrane

Like in eukaryotes

Form internal pouches (mesosomes)

1




Prokaryotic Cells:Cytoplasm & Appendages

Cytoplasm

± Semif luid solution

Bounded by plasma membrane

Contains inclusion bodies ± Stored granu

les of various substances

Appendages

± Flagella ± Provide motility

± Fimbriae ± small, bristle-like fibers that sprout from the

cell surface

± Sex pili ± rigid tubular structures used to pass DN A

from cell to cell

1




A Panoramic View of the Eukaryotic Cell

A eukaryotic cell has internal membranes thatpartition the cell into organelles

Plant and animal cells have most of the same

organelles



LE 6-9a

Flagellum

Centrosome

CYTOSKELETON

Microfilaments

Intermediate filaments

Microtubules

Peroxisome

Microvilli

ENDOPLASMIC RETICULUM (ER

Rough ER Smooth ER

MitochondrionLysosome

Golgi apparatus

Ribosomes:

Plasma membrane

Nuclear envelope

NUCLEUS

In animal cells but not plant cells:LysosomesCentriolesFlagella (in some plant sperm)

Nucleolus

Chromatin



LE 6-9b

Roughendoplasmicreticulum

In plant cells but not animal cells:ChloroplastsCentral vacuole and tonoplastCell wallPlasmodesmata

Smoothendoplasmicreticulum

Ribosomes(small brown dots)

Central vacuole

Microfilaments

Intermediatefilaments

Microtubules

CYTOSKELETON

Chloroplast

Plasmodesmata

Wall of adjacent cell

Cell wall

Nuclear envelope

Nucleolus

Chromatin

NUCLEUS

Centrosome

Golgiapparatus

Mitochondrion

Peroxisome

Plasma

membrane




Concept 6.3: The eukaryotic cell¶s genetic instructions arehoused in the nucleus and carried out by the ribosomes

The nucleus contains most of the DN A in a

eukaryotic cell

Ribosomes use the information from the DN A to

make proteins




The Nucleus: Genetic Library of the Cell

The nucleus contains most of the cell¶s genes andis usually the most conspicuous organelle

The nuclear envelope encloses the nucleus,

separating it from the cytoplasm



LE 6-10

Close-up of nuclear envelope

Nucleus

Nucleolus

Chromatin

Nuclear envelope:

Inner membrane

Outer membrane

Nuclear pore

Pore

complex

Ribosome

Pore complexes (TEM) Nuclear lamina (TEM)

1 µm

Rough ER

Nucleus

1 µm

0.25 µm

Surface of nuclear envelope




Ribosomes: Protein Factories in the Cell

Ribosomes are particles made of ribosomal RN A and protein

Ribosomes carry out protein synthesis in two

locations:

± In the cytosol (free ribosomes)

± On the outside of the endoplasmic reticulum

(ER) or the nuclear envelope (bound

ribosomes)




The Cell: A Living Unit Greater Than the Sum of Its Parts

Cells rely on the integration of structures andorganelles in order to function

For example, a macrophage¶s ability to destroy

bacteria involves the whole cell, coordinatingcomponents such as the cytoskeleton, lysosomes,

and plasma membrane



LE 6-32

5 µ m

Lecture - Cells

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