Transcript Introduction to Biology

Cellular Life
PowerPoint Lectures for
Biology: Concepts & Connections, Sixth Edition
Campbell, Reece, Taylor, Simon, and Dickey
Copyright © 2009 Pearson Education, Inc.
Objectives
1. Origin of Cellular Life
2. Prokaryotic Cell Structure
3. Eukaryotic Cell Structure
4. Energy Converting Organelles
5. Cytoskeleton
6. Central Dogma
7. Cell Cycle and Mitosis
Origin of Cellular Life
Elements
in Periodic 
Table

Organic Molecules and the
Origin of Life on Earth
EXPERIMENT
“Atmosphere”
CH4
Water vapor
Electrode
• Stanley Miller’s classic
experiment
demonstrated the
abiotic synthesis of
organic compounds.
• Experiments support the
idea that abiotic
synthesis of organic
compounds, perhaps
near volcanoes, could
have been a stage in
the origin of life.
Condenser
Cooled “rain”
containing
organic
molecules
H2O
“sea”
Sample for chemical analysis
Cold
water
4.5 The structure of membranes correlates with their functions

The plasma membrane
Hydrophilic
controls the movement of
heads
molecules into and out of the
cell, a trait called selective
Hydrophobic
tails
permeability
Outside cell
Hydrophobic
region of
protein
Inside cell

Phospholipids form a twolayer sheet called a
phospholipid bilayer
– Hydrophilic heads face
outward, and
hydrophobic tails point
inward
– Thus, hydrophilic heads
are exposed to water,
while hydrophobic tails
are shielded from water
Proteins
Hydrophilic
region of
protein
4.3 Prokaryotic cells are structurally simpler
than eukaryotic cells
 Bacteria and archaea are prokaryotic cells
 All other forms of life are eukaryotic cells
– Both prokaryotic and eukaryotic cells have a plasma
membrane and one or more chromosomes and
ribosomes
– Eukaryotic cells have a membrane-bound nucleus and a
number of other organelles, whereas prokaryotes have
a nucleoid and no true organelles
Prokaryotic Cells
Pili
Nucleoid
Ribosomes
Plasma membrane
Bacterial
chromosome
Cell wall
Capsule
A typical rod-shaped
bacterium
Flagella
A thin section through the
bacterium Bacillus coagulans
(TEM)
Eukaryotic cells are partitioned into functional
compartments
– Manufacturing - nucleus, ribosomes, endoplasmic
reticulum, and Golgi apparatus
– Breakdown of molecules - involves lysosomes, vacuoles,
and peroxisomes
– Energy production - mitochondria
– Structural support, movement, and communication cytoskeleton, plasma membrane, and cell wall
Eukaryotic cell Structure
Smooth endoplasmic
reticulum
NUCLEUS:
Nuclear envelope
Chromosomes
Nucleolus
Rough
endoplasmic
reticulum
Lysosome
Centriole
Peroxisome
CYTOSKELETON:
Microtubule
Intermediate
filament
Microfilament
Ribosomes
Golgi
apparatus
Plasma membrane
Mitochondrion
Manufacturing and Breakdown Organelle Path
– Nuclear envelope: DNA storage replication
– Ribosomes: Protein Synthesis
– Endoplasmic reticulum: rough=Proteins, smooth=Lipids
– Golgi Apparatus: Protein Finishing and Packaging
– Transport Vesicles: Protein Delivery=ER to Golgi to Cell
– Lysosomes=Protein Breakdown
4.6 The nucleus is the cell’s
genetic control center

The nucleus controls
the cell’s activities
and DNA is
responsible for
inheritance
– DNA is copied
within the nucleus
prior to cell
division
The nuclear envelope
is a double membrane
with pores that allow
material to flow in and
out of the nucleus.
Nucleus
Two membranes of
nuclear envelope
Nucleus
Nucleolus
Chromatin
Pore
Endoplasmic
reticulum
Ribosomes
Ribosomes - cell’s protein synthesis
Ribosomes
ER
Cytoplasm
Endoplasmic reticulum (ER)
Free ribosomes
Bound ribosomes
Large
subunit
TEM showing ER
and ribosomes
Diagram of
a ribosome
Small
subunit
Endoplasmic Reticulum
Nuclear
envelope
Smooth ER
Ribosomes
Rough ER
Endomembrane Transport
Transport vesicle
buds off
4
Ribosome
Secretory
protein
inside transport vesicle
3
Sugar
chain
1
2 Glycoprotein
Polypeptide
Rough ER
Golgi Apparatus
“Receiving” side of
Golgi apparatus
Golgi
apparatus
Transport
vesicle
from ER
New vesicle
forming
“Shipping” side
of Golgi apparatus
Transport
vesicle from
the Golgi
Golgi apparatus
Lysosomes
Lysosome
Digestion
Vesicle containing
damaged mitochondrion
Lysosomes are cellular organelles that contain acid hydrolase enzymes
to break down waste materials and cellular debris.
Mitochondria harvest chemical energy from food
– Cellular respiration involves
conversion of chemical
energy in foods to chemical
energy in ATP (adenosine
triphosphate)
– Mitochondria were once
independent bacteria that
were came to live inside
larger cells. The process of
endosymbiosis occurred 2.5
billion years ago. contributing
to the evolution of
multicellular organisms.
Mitochondrion
Outer
membrane
Intermembrane
space
Inner
membrane
Cristae
Matrix
4.17 The cell’s internal skeleton helps organize
its structure and activities
 The cytoskeleton is composed of three kinds of
fibers
– Microfilaments (actin filaments) support the cell’s
shape and are involved in motility
– Intermediate filaments reinforce cell shape and
anchor organelles
– Microtubules (made of tubulin) shape the cell and act
as tracks for motor protein
Cytoskeleton
Nucleus
Nucleus
Actin subunit
Fibrous subunits
7 nm
Microfilament
Tubulin subunit
10 nm
25 nm
Intermediate filament
Microtubule
The cell’s internal skeleton helps organize its
structure and activities

Cells cytoskeleton, that
functions in cell structural
support and intracellular
transport.
– Motility and cellular
regulation result
when the
cytoskeleton interacts
with proteins called
motor proteins
ATP
Vesicle
Receptor for
motor protein
Motor protein (ATP Microtubule
powered)
of cytoskeleton
(a)
Microtubule
(b)
Vesicles
0.25 µm
4.20 Cell Support - Extracellular Matrix
 Cells synthesize and secrete the extracellular
matrix that is essential to cell function
– Composed of strong fibers of collagen, which holds
cells together and protects the plasma membrane
– Attaches through connecting proteins that bind to
membrane proteins called integrins
Extracellular Matrix
Glycoprotein
complex with long
polysaccharide
EXTRACELLULAR FLUID
Collagen fiber
Connecting
glycoprotein
Integrin
Plasma
membrane
Microfilaments
CYTOPLASM
4.21 Cell Support - Junctions

Adjacent cells communicate,
interact, and adhere through
specialized junctions between
them
Tight junctions
– Tight junctions prevent
leakage of extracellular fluid
across a layer of epithelial
cells
Anchoring junction
– Anchoring junctions fasten
cells together into sheets
Gap junctions
– Gap junctions are channels
that allow molecules to flow
between cells
Plasma membranes
of adjacent cells
Extracellular matrix
The Double Helix - Nobel Prize 1953
Rosalind Franklin
James Watson,
Francis Crick
Maurice Wilkins
DNA Structure
Nitrogenous base
Sugarphosphate
backbone
Phosphate
group
Sugar
Nucleotide
Nitrogenous
base
Sugar
DNA
Polynucleotide
A, Adenine. C, Cytosine.
G, Guanine. T (or U),
Thymine (or Uracil)
DNA
RNA
C
G
A
T
C
G
A
U
DeoxyRibose
ribose
The DNA in one human cell contains about
30,000 genes, located on 46 chromosomes.
DNA REPLICATION
Nucleotides
Parental
molecule
of DNA
Both parental
strands serve
as templates
Two identical
daughter
molecules of DNA
RNA STRUCTURE
RNA polymerase
DNA of gene
Promoter
DNA
Terminator
DNA
1
Initiation
2
Elongation
Approximately 360000 mRNA
molecules are present in a
single mammalian cell
Area shown
in Figure 10.9A
Uracil
Adenine
Guanine
Cytosine
3
Termination
Phosphate
Ribose
Completed
RNA
Growing
RNA
RNA
polymerase
mRNA PostTranscriptional DNA
Modifications
Exon Intron
Cap
RNA
transcript
with cap
and tail
Exon
Intron Exon
Transcription
Addition of cap and tail
Introns removed
Tail
Exons spliced together
mRNA
Coding sequence
Nucleus
Cytoplasm
Proteins interacting with DNA turn genes on or off in
response to environmental changes
 Regulatory proteins that bind to control sequences
– Transcription factors promote RNA polymerase binding to the
DNA promoter
– Promoter sequence where RNA polymerase binds
– Activator transcription factor that binds DNA and enhances
transcription
– Repressor transcription factor that inhibit transcription
 An operon is a group of genes under control of the same
transcription factor.
Enhancers
Promoter
Gene
DNA
Activator
proteins
Transcription
factors
Other
proteins
RNA polymerase
Bending
of DNA
Transcription
Transcription and Translation
DNA
Transcription
RNA
Nucleus
Cytoplasm
Translation
Protein
Transcription and Translation
Strand to be transcribed
DNA
Transcription
RNA
Start
codon
Polypeptide Met
Translation
Lys
Phe
Stop
codon
Protein Translation
There are 20 different amino acids. Their order
in the protein molecule determines its structure
and function.
Amino
acid
Polypeptide
A site
P site
Anticodon
mRNA
Codons
1 Codon recognition
mRNA
movement
Stop
codon
2 Peptide bond
formation
We can calculate the total
number of protein molecules per
liver cell as about 8 × 109
New
peptide
bond
3 Translocation
Transcription and Translation (Video)
The Cell Cycle
Interphase: duplication of cell
contents
G1—growth, increase in
cytoplasm
S —duplication of
chromosomes
G2—growth, preparation for
division
Mitosis—division of nucleus
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis—division of
cytoplasm
INTERPHASE
G1
S
(DNA synthesis)
G2
Cell Cycle Control System
Cell cycle control factors:
a. Growth Factors
b. Nutrients
c. Genes
Control
system
G0
M
G1
S
Checkpoints control cell cycle:
a. G1 checkpoint allows entry into
the S phase or causes the cell to
leave the cycle, entering a
nondividing G0 phase
b. G2 checkpoint
c. M checkpoint
G1 checkpoint
G2
M checkpoint
G2 checkpoint
INTERPHASE
Chromatin
Centrosomes
(with centriole pairs)
PROPHASE
Early mitotic Centrosome
spindle
PROMETAPHASE
Fragments
of nuclear
envelope
Centromere
Plasma
Nuclear
envelope membrane Chromosome, consisting
of two sister chromatids
Nucleolus
Kinetochore
Spindle
microtubules
METAPHASE
ANAPHASE
Metaphase
plate
Spindle
Daughter
chromosomes
TELOPHASE AND CYTOKINESIS
Cleavage
furrow
Nuclear
envelope
forming
Nucleolus
forming
Cytokinesis Animal Cell
a. A cleavage furrow forms
from a contracting ring of
microfilaments, interacting
with myosin.
b. The cleavage furrow
deepens to separate the
contents into two cells.
Cleavage
furrow
Cleavage furrow Contracting ring of
microfilaments
Daughter cells