Download Eukaryotic cells

Chapter 4
A Tour of the Cell
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
• Cells were first described in 1665 by Robert Hooke.
• 200 years later, the accumulation of scientific evidence led to the
cell theory.
– All living things are composed of cells.
– All cells come from other cells.
© 2010 Pearson Education, Inc.
The electron microscope (EM) uses a beam of electrons, which results in
better resolving power than the light microscope.
The electron microscope can
Magnify up to 100,000 times
Distinguish between objects 0.2 nanometers apart
TYPES OF MICROGRAPHS
Light micrograph of a protist, Paramecium
Transmission Electron Micrograph (TEM)
(for viewing internal structures)
Colorized SEM
Colorized TEM
Scanning Electron Micrograph (SEM)
(for viewing surface features)
LM
Light Micrograph (LM)
(for viewing living cells)
Scanning electron micrograph of Paramecium
Transmission electron micrograph of Paramecium
Two kinds of electron microscopes reveal different parts of
cells.
Figure 4.1
10 m
1m
Length of some
nerve and
muscle cells
10 cm
Chicken egg
Unaided eye
Human height
1nm = 1/1,000 um
1 cm
1nm = 1/1,000,000mm
Frog eggs
1 mm
Plant and
animal cells
1mm = 1,000 um
10 um
1um = 1,000 nm
1 um
SO
100 nm
Nucleus
Most bacteria
Mitochondrion
Smallest bacteria
Viruses
Ribosomes
1 meter = 1 Billion nm
Or
1 meter = 1x109 nm
10 nm
1nm =
1/1,000,000,000m
Electron microscope
100 um
Light microscope
1 meter = 1,000 mm
Proteins
Lipids
1 nm
0.1 nm
Small molecules
Atoms
Figure 4.3
The Two Major Categories of Cells
• The countless cells on earth fall into two categories:
– Prokaryotic cells — Bacteria and Archaea
– Eukaryotic cells — protists, plants, fungi, and animals
• All cells have several basic features.
– They are all bound by a thin plasma membrane.
– All cells have DNA and ribosomes, tiny structures that build proteins.
© 2010 Pearson Education, Inc.
• Prokaryotic and eukaryotic cells have important differences.
• Prokaryotic cells are older than eukaryotic cells.
– Prokaryotes appeared about 3.5 billion years ago.
– Eukaryotes appeared about 2.1 billion years ago.
© 2010 Pearson Education, Inc.
• Prokaryotes
– Are smaller than eukaryotic cells
– Lack internal structures surrounded by membranes
– Lack a nucleus
– Have a rigid cell wall
© 2010 Pearson Education, Inc.
Prokaryotes
Plasma membrane
(encloses cytoplasm)
Cell wall (provides
Rigidity)
Capsule (sticky
coating)
Colorized TEM
Prokaryotic
flagellum
(for propulsion)
Ribosomes
(synthesize
proteins)
Nucleoid
(contains DNA)
Pili (attachment structures)
Figure 4.4
• Eukaryotes
– Only eukaryotic cells have organelles, membrane-bound structures that
perform specific functions.
– The most important organelle is the nucleus, which houses most of a
eukaryotic cell’s DNA.
© 2010 Pearson Education, Inc.
An Overview of Eukaryotic Cells
• Eukaryotic cells are fundamentally similar.
• The region between the nucleus and plasma membrane is the
cytoplasm.
• The cytoplasm consists of various organelles suspended in fluid.
© 2010 Pearson Education, Inc.
• Unlike animal cells, plant cells have
– Protective cell walls
– Chloroplasts, which convert light energy to the chemical energy of food
© 2010 Pearson Education, Inc.
Ribosomes
Cytoskeleton
Centriole
Lysosome
Flagellum
Not in most
plant cells
Plasma
membrane
Nucleus
Mitochondrion
Rough
endoplasmic
reticulum (ER)
Golgi
apparatus
Cytoskeleton
Mitochondrion
Nucleus
Rough endoplasmic
reticulum (ER)
Idealized animal cell
Smooth
endoplasmic
reticulum (ER)
Central
vacuole
Cell wall
Not in animal cells
Chloroplast
Ribosomes
Plasma
membrane
Smooth
endoplasmic
reticulum (ER)
Channels between
cells
Idealized plant cell
Golgi apparatus
Figure 4.5
MEMBRANE STRUCTURE
• The plasma membrane separates the living cell from its nonliving
surroundings.
© 2010 Pearson Education, Inc.
The Plasma Membrane: A Fluid Mosaic of
Lipids and Proteins
• The membranes of cells are composed mostly of
– Lipids
– Proteins
© 2010 Pearson Education, Inc.
Outside of cell
Hydrophilic
head
Hydrophobic
tail
Hydrophilic
region of
protein
Outside of cell
Hydrophilic
head
Proteins
Phospholipid
bilayer
Hydrophobic
tail
Phospholipid
Cytoplasm (inside of cell)
(a) Phospholipid bilayer of
membrane
Hydrophobic
regions of
protein
Cytoplasm (inside of cell)
(b) Fluid mosaic model of
membrane
Figure 4.6
• Most membranes have specific proteins embedded in the
phospholipid bilayer.
• These proteins help regulate traffic across the membrane and
perform other functions.
“selective permeability”
© 2010 Pearson Education, Inc.
Cell Surfaces
• Plant cells have rigid cell walls surrounding the membrane.
• Plant cell walls
– Are made of cellulose
– Protect the cells
– Maintain cell shape
– Keep the cells from absorbing too much water
© 2010 Pearson Education, Inc.
THE NUCLEUS AND RIBOSOMES:
GENETIC CONTROL OF THE CELL
• The nucleus is the chief executive of the cell.
– Genes in the nucleus store information necessary to produce proteins.
– Proteins do most of the work of the cell.
© 2010 Pearson Education, Inc.
Structure and Function of the Nucleus
• The nucleus is bordered by a double membrane called the nuclear
envelope.
• Pores in the envelope allow materials to move between the
nucleus and cytoplasm.
• The nucleus contains a nucleolus where ribosomes are made.
© 2010 Pearson Education, Inc.
Nuclear
envelope
Nucleolus
Pore
TEM
Chromatin
TEM
Ribosomes
Surface of nuclear envelope
Nuclear pores
Figure 4.8
• Stored in the nucleus are long DNA molecules and associated
proteins that form fibers called chromatin.
• Each long chromatin fiber constitutes one chromosome.
• The number of chromosomes in a cell depends on the species.
© 2010 Pearson Education, Inc.
DNA molecule
Proteins
Chromatin
fiber
Chromosome
Figure 4.9
Ribosomes
• Ribosomes are responsible for protein synthesis.
• Ribosome components are made in the nucleolus but assembled in
the cytoplasm.
© 2010 Pearson Education, Inc.
• Ribosomes may assemble proteins:
– Suspended in the fluid of the cytoplasm or
– Attached to the outside of an organelle called the endoplasmic reticulum
© 2010 Pearson Education, Inc.
How DNA Directs Protein Production
• DNA directs protein production by transferring its coded
information into messenger RNA (mRNA).
• Messenger RNA exits the nucleus through pores in the nuclear
envelope.
• A ribosome moves along the mRNA translating the genetic
message into a protein with a specific amino acid sequence.
© 2010 Pearson Education, Inc.
DNA
Synthesis of
mRNA in the
nucleus
mRNA
Nucleus
Cytoplasm
Movement of
mRNA into
cytoplasm
via
nuclear pore
Synthesis of
protein in the
cytoplasm
mRNA
Ribosome
Protein
Figure 4.12-3
The Endoplasmic Reticulum
• The endoplasmic reticulum (ER) is one of the main
manufacturing facilities in a cell.
• The ER
– Produces an enormous variety of molecules
– Is composed of smooth and rough ER
© 2010 Pearson Education, Inc.
Nuclear
envelope
Ribosomes
TEM
Rough ER
Smooth ER
Ribosomes
Figure 4.13
Rough ER
• The “rough” in the rough ER is due to ribosomes that stud the
outside of the ER membrane.
• These ribosomes produce membrane proteins and secretory
proteins.
• After the rough ER synthesizes a molecule, it packages the
molecule into transport vesicles.
© 2010 Pearson Education, Inc.
Proteins are
often modified in
the ER.
Secretory
proteins depart in
transport vesicles.
Ribosome
Vesicles bud off
from the ER.
Transport
vesicle
Protein
A ribosome
links amino acids
into a
polypeptide.
Rough ER
Polypeptide
Figure 4.14
Vacuoles
• Vacuoles are membranous sacs that bud from the
– ER
– Golgi
– Plasma membrane
• Contractile vacuoles of protists pump out excess water in the cell.
• Central vacuoles of plants
– Store nutrients
– Absorb water
– May contain pigments or poisons
© 2010 Pearson Education, Inc.
LM
Vacuole filling with water
LM
Vacuole contracting
Colorized TEM
(a) Contractile vacuole in Paramecium
Central vacuole
(b) Central vacuole in a plant cell
Figure 4.17
CHLOROPLASTS AND MITOCHONDRIA:
ENERGY CONVERSION
• Cells require a constant energy supply to perform the work of life.
© 2010 Pearson Education, Inc.
Chloroplasts
• Most of the living world runs on the energy provided by
photosynthesis.
• Photosynthesis is the conversion of light energy from the sun to
the chemical energy of sugar.
• Chloroplasts are the organelles that perform photosynthesis.
© 2010 Pearson Education, Inc.
Inner and outer
membranes
Space between
membranes
Granum
TEM
Stroma (fluid in chloroplast)
Figure 4.19
Mitochondria
• Mitochondria are the sites of cellular respiration, which produce
ATP from the energy of food molecules.
• Mitochondria are found in almost all eukaryotic cells.
chemical energy
© 2010 Pearson Education, Inc.
usable energy
TEM
Outer
membrane
Inner
membrane
Cristae
Matrix
Space between
membranes
Figure 4.20
Maintaining Cell Shape
• The cytoskeleton
– Provides mechanical support to the cell
– Maintains its shape
© 2010 Pearson Education, Inc.
• The cytoskeleton contains several types of fibers made from
different proteins:
– Microtubules
–
Are straight and hollow
–
Guide the movement of organelles and chromosomes
– Intermediate filaments and microfilaments are thinner and solid.
© 2010 Pearson Education, Inc.
LM
(a) Microtubules
in the cytoskeleton
LM
(b) Microtubules
and movement
Figure 4.21
Cilia and Flagella
• Cilia and flagella aid in movement.
– Flagella propel the cell in a whiplike motion.
– Cilia move in a coordinated back-and-forth motion.
– Cilia and flagella have the same basic architecture.
© 2010 Pearson Education, Inc.
Colorized SEM
(a) Flagellum of a human sperm cell
Colorized SEM
Colorized SEM
(b) Cilia on a protist
(c) Cilia lining the
respiratory tract
Figure 4.22
• Cilia may extend from nonmoving cells.
• On cells lining the human trachea, cilia help sweep mucus out of
the lungs.
© 2010 Pearson Education, Inc.
Figure 4.UN1
Plasma
membrane
© 2010 Pearson Education, Inc.
Figure 4.UN1
Figure 4.UN2
Nucleus
© 2010 Pearson Education, Inc.
Figure 4.UN2
Figure 4.UN3
Ribosome
© 2010 Pearson Education, Inc.
Figure 4.UN3
Figure 4.UN4
Endoplasmic
reticulum
© 2010 Pearson Education, Inc.
Figure 4.UN4
Figure 4.UN7
Vacuole
© 2010 Pearson Education, Inc.
Figure 4.UN7
Figure 4.UN8
Chloroplast
© 2010 Pearson Education, Inc.
Figure 4.UN8
Figure 4.UN9
Mitochondrion
© 2010 Pearson Education, Inc.
Figure 4.UN9
Figure 4.UN10
Cytoskeleton
© 2010 Pearson Education, Inc.
Figure 4.UN10
Figure 4.UN11
Cilia and
flagella
© 2010 Pearson Education, Inc.
Figure 4.UN11