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Cells and Tissues
Part 1: Cells
Chapter 3
1
Outline
•
•
The Cell Theory
Cellular Organization (The Parts of a Cell)
–
Plasma Membrane

–
Cytoplasm


–
•
•
Transport across the plasma membrane
Cytosol
Organelles
Nucleus
Protein Synthesis
Cell Division
–
Mitosis
2
The Cell Theory
•
•
Let’s face it, life is totally cellular (this does
not refer to the mobile phone)
The cell theory states:
1.
Cells are the basic unit of life
2.
All living things are made up of cells
3.
New cells arise only from preexisting
cells
3
Table 3.1 Parts of the Cell: Structure and Function (1 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (2 of 5).
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Table 3.1 Parts of the Cell: Structure and Function (3 of 5).
© 2015 Pearson Education, Inc.
Table 3.1 Parts of the Cell: Structure and Function (4 of 5).
© 2015 Pearson Education, Inc.
Table 3.1 Parts of the Cell: Structure and Function (5 of 5).
© 2015 Pearson Education, Inc.
Cellular Organization
•
Plasma membrane surrounds the cell and
regulates entrance and exit of substances
–
–
–
•
Selective barrier
Key role in communication between cells
Key role in communication of cells with the external
environment
Cytoplasm is the portion of the cell between the
nucleus and plasma membrane
–
Cytosol: fluid portion of cytoplasm

–
•
Consistency: semifluid gel, like wet Jello
Organelles: small membranous structures each with a
specific function
The Nucleus- storage of genetic information
9
Cellular Organization (Cont.)
–
Nucleus is the centrally located organelle
containing chromosomes and is the control
center of the cell
10
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
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Secretion being
released from cell
by exocytosis
Plasma Membrane
•
Plasma membrane is a phospholipid bilayer with
attached or embedded proteins
–
Fluid mosaic model


Sea of fluid lipids with mosaic of different proteins
Phospholipids: polar head and non-polar tails




Form spherical bilayer when placed in water
Cholesterol
Glycolipids
Membrane Fluidity: critical for interactions of membrane
proteins and allows cellular process e.g. movement,
growth, division, secretion
 Dependent on
 Number of double bonds in the fatty acid tails of
the lipids
 Amount of cholesterol
12
Figure 3.2 Structure of the plasma membrane.
Hydrophilic: Love water
Extracellular fluid
(watery environment)
Glycoprotein Glycolipid
Cholesterol
Sugar
group
Polar heads
of phospholipid
molecules
Bimolecular
lipid layer
containing
proteins
Nonpolar tails
of phospholipid
molecules
Hydrophobic: Hate water
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Channel
Proteins Filaments of
cytoskeleton
Cytoplasm
(watery environment)
Plasma Membrane (Cont.)
•
•
Plasma membrane is selectively permeable, and
regulates movement of molecules and ions across
the cell membrane due to nature of the
phospholipids
Plasma membrane proteins form receptors,
conductors, or enzymes in metabolic reactions
14
Plasma Membrane (Cont.)
15
Figure 3.2 Structure of the plasma membrane.
Extracellular fluid
(watery environment)
Glycoprotein Glycolipid
Cholesterol
Sugar
group
Polar heads
of phospholipid
molecules
Bimolecular
lipid layer
containing
proteins
Nonpolar tails
of phospholipid
molecules
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Channel
Proteins Filaments of
cytoskeleton
Cytoplasm
(watery environment)
The Plasma Membrane
Examples of different membrane proteins include
 Ion channels
 Carriers
 Receptors
Copyright © John Wiley & Sons, Inc. All rights reserved.
The Plasma Membrane
Examples of different membrane proteins include
 Enzymes
 Linkers
 Cell identity markers
Copyright © John Wiley & Sons, Inc. All rights reserved.
Plasma Membrane (Cont.)
•
Transport across the plasma membrane- Two Types
2.
Passive Processes- don’t require ATP
Active Processes- require ATP
–
Passive processes
1.


Simple diffusion: movement of molecule down
concentration gradient
Facilitated diffusion
Channel-mediated
 Carrier-mediated
Osmosis: diffusion of water down it’s concentration gradient
 Water moves through bilayer
 Water moves through aquaporins
Concept of Tonicity
 Must have balance of solutes and water due to selective
permeability of membrane to solutes



19
Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Passive Processes (Cont.)

Simple Diffusion is the random movement of molecules
from an area of higher concentration to an area of lower
concentration until they are equally distributed
20
Figure 3.9 Diffusion.
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Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Passive Processes (Cont.)

Facilitated diffusion

Channel-mediated
 Carrier-mediated
Osmosis: diffusion of water down it’s concentration gradient
 Water moves through bilayer
 Water moves through aquaporins

22
Figure 3.10 Diffusion through the plasma membrane.
Extracellular
fluid
Lipidsoluble
solutes
Lipidinsoluble
solutes
Small lipidinsoluble
solutes
Water
molecules
Lipid
bilayer
Cytoplasm
(a) Simple
diffusion
of fat-soluble
molecules
directly
through the
phospholipid
bilayer
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(b) Carrier-mediated
(c)
facilitated diffusion via
protein carrier specific for
one chemical; binding of
substrate causes shape
change in transport protein
Channel(d) Osmosis, diffusion
mediated
of water through a
facilitated
specific channel
diffusion
protein (aquaporin)
through a
or through the lipid
channel protein;
bilayer
mostly ions,
selected on
basis of
size and charge
Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Passive Processes (Cont.)

Osmosis: diffusion of water down it’s concentration gradient
 Water moves through bilayer
 Water moves through aquaporins
 Osmosis is the random movement of water from an area of
higher concentration of water to an area of lower
concentration of water
 Important due to the selective permeability of membrane to
solutes
 Leads to the concept of tonicity
 Tonicity: the ability of a solution to change the water content
of a cell due to selective permeability of the membrane and
solutes in the solution
24
Principle of Osmosis
Left arm
Applied pressure =
osmotic pressure
Right arm
Volumes
equal
Water
molecule
Osmosis
Selectively
Solute
permeable
molecule
membrane
(a) Starting conditions
Osmosis
Movement due
to hydrostatic pressure
(b) Equilibrium
(c) Restoring starting conditions
Isotonic solution
Hypotonic solution
Hypertonic solution
(a) Illustrations showing direction of water movement
SEM
Normal RBC shape
RBC undergoes
hemolysis
RBC undergoes
crenation
(b) Scanning electron micrographs (all 15,000x)
Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Active processes: need to utilize ATP to drive molecular
movement against concentration gradient


Active Transport: Carrier-mediated transport of molecules
by proteins in plasma membrane
Vesicular Transport: transport in vesicles, moving
substances into or out of the cell
 Exocytosis: vesicular transport out of the cell
 Endocytosis: vesicular transport into the cell
 Phagocytosis- uptake of bacteria or dead cells
 Receptor-mediated- specific binding to cell surface
protein before uptake
 Pinocytosis- uptake of fluid (cell drinking)
27
Figure 3.11 Operation of the sodium-potassium pump, a solute pump.
Extracellular fluid
Na+
Na+
Na+-K+ pump
K+
Na+
Na+
Na+
K+
P
K+
P
ATP
Na+
1
2
3
K+
ADP
1 Binding of cytoplasmic Na+
to the pump protein stimulates
phosphorylation by ATP, which
causes the pump protein to
change its shape.
2 The shape change expels
Na+
to the outside. Extracellular
binds, causing release of the
phosphate group.
K+
Sodium-Potassium Pump
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3 Loss of phosphate
restores the original
conformation of the pump
protein. K+ is released to the
cytoplasm, and Na+ sites are
ready to bind Na+ again; the
cycle repeats.
Cytoplasm
Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Active processes (Cont.)

Vesicular Transport: transport in vesicles, moving
substances into or out of the cell
 Exocytosis: vesicular transport out of the cell
29
Figure 3.12 Exocytosis.
Extracellular Plasma
membrane
fluid
SNARE
(t-SNARE)
Secretory
vesicle
1 The membranebound vesicle
Vesicle
migrates to the
SNARE
(v-SNARE) plasma membrane.
Molecule
to be
secreted
Cytoplasm
Fusion pore formed
Fused
SNAREs
2 There, v-SNAREs
bind with t-SNAREs,
the vesicle and
plasma membrane
fuse, and a pore
opens up.
3 Vesicle contents
are released to the
cell exterior.
(a) The process of exocytosis
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(b) Electron micrograph of a
secretory vesicle in
exocytosis (190,000×)
Plasma Membrane (Cont.)
•
Transport across the plasma membrane (Cont.)
–
Active processes (Cont.)

Vesicular Transport: transport in vesicles, moving
substances into or out of the cell
 Endocytosis: vesicular transport into the cell
 Phagocytosis- uptake of bacteria or dead cells
 Receptor-mediated- specific binding to cell surface
protein before uptake
 Pinocytosis- uptake of fluid (cell drinking)
31
Figure 3.13 Events and types of endocytosis.
Extracellular
fluid
Cytosol
Vesicle
1 Vesicle fusing
with lysosome
for digestion
Plasma
membrane
Lysosome
Release of
contents to
cytosol
2 Transport to plasma
membrane and exocytosis
of vesicle contents
Extracellular
fluid
Cytoplasm
Bacterium
or other
particle
Pseudopod
(b)
Phagocytosis
Detached vesicle
Ingested
substance
Membrane
receptor
3 Membranes and receptors
Pit
(a)
Pinocytosis
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(if present) recycled to plasma
membrane
(c)
Receptor-mediated
Cellular Organization
•
Plasma membrane surrounds the cell and
regulates entrance and exit of substances
–
–
–
•
Selective barrier
Key role in communication between cells
Key role in communication of cells with the external
environment
Cytoplasm is the portion of the cell between the
nucleus and plasma membrane
–
Cytosol: fluid portion of cytoplasm

–
•
Consistency: semifluid gel, like wet Jello
Organelles: small membranous structures each with a
specific function
The Nucleus- storage of genetic information
33
Cytoplasm
•
Cytoplasm is the portion of the cell between the
nucleus and plasma membrane
–
Cytosol: fluid portion of cytoplasm


–
Consistency: semifluid gel, like wet Jello
The Cytoskeleton
Organelles: small membranous structures each with a
specific function







Centrosome- contains two centrioles
Cilia & Flagella
Ribosomes
Endoplasmic Reticulum
Golgi Complex
Lysosomes
Mitochondria
34
The Cytosol
•
Cytoskeleton is a network of interconnected
filaments and microtubules in the cytoplasm that
maintain cell shape
–
The cytoskeleton is formed of several types of
filamentous structures that give the cell its shape and
organelles the ability to move about the cell
 Microfilaments: actin & myosin; provide movement,
mechanical support
 Intermediate filaments: keratin; stabilize organelles,
attach cells to one another
 Microtubules: tubulin; movement of organelles, cilia &
flagella
35
Figure 3.7 Cytoskeletal elements support the cell and help to generate movement.
(a) Microfilaments
(b) Intermediate filaments
(c) Microtubules
Tubulin subunits
Fibrous subunits
Actin subunit
7 nm
Microfilaments form the blue
batlike network.
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10 nm
Intermediate filaments form
the purple network
surrounding the pink nucleus.
25 nm
Microtubules appear as gold
networks surrounding the
cells’ pink nuclei.
Organelles
•
•
Centrosomes: contains two centrioles made of
tubulin; organizing center for mitotic spindle during
cell division & for microtubule formation in nondividing cells
Cilia & Flagella
–
–
Cilia: microtubules; move fluids along a cell’s surface
Flagella: microtubules; moves an entire cell, e.g. sperm
37
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
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Secretion being
released from cell
by exocytosis
Organelles

Centrosome - located near the nucleus, consists of two
centrioles and pericentriolar material
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Organelles


Cilia - short, hairlike projections from
the cell surface,
move fluids along a
cell surface
Flagella - longer
than cilia, move an
entire cell; only
example is the sperm
cell’s tail
Copyright © John Wiley & Sons, Inc. All rights reserved.
Organelles
Copyright © John Wiley & Sons, Inc. All rights reserved.
Organelles (Cont.)
•
Ribosomes
–
–
Composed of multiple proteins and ribosomal RNA
(rRNA)
Function in protein synthesis
 Ribosomes on endoplasmic reticulum: synthesize
proteins destined for insertion into plasma membrane
or secretion from cell
 Ribosomes free in cytosol: synthesize proteins used
in the cytosol
42
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
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Secretion being
released from cell
by exocytosis
Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
mRNA
Rough ER
2
1
3
Protein
Transport
vesicle buds off
4
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
3 The protein is packaged in a tiny
membranous sac called a transport vesicle.
4 The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
Protein inside
transport vesicle
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Organelles (Cont.)
•
Endoplasmic Reticulum (ER)
–
System of membranous channels and saccules
 Rough ER: studded with ribosomes


Synthesizes glycoproteins, phospholipids, to be
transferred into organelles, plasma membrane, or
secreted
Smooth ER: no ribosomes

Synthesizes fatty acids, steroids, stores calcium for
muscle contraction in muscle cells
45
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
© 2015 Pearson Education, Inc.
Secretion being
released from cell
by exocytosis
Figure 3.5 Synthesis and export of a protein by the rough ER.
Ribosome
mRNA
Rough ER
2
1
3
Protein
Transport
vesicle buds off
4
1 As the protein is synthesized on the
ribosome, it migrates into the rough ER
cistern.
2 In the cistern, the protein folds into its
functional shape. Short sugar chains may be
attached to the protein (forming a
glycoprotein).
3 The protein is packaged in a tiny
membranous sac called a transport vesicle.
4 The transport vesicle buds from the
rough ER and travels to the Golgi apparatus
for further processing.
Protein inside
transport vesicle
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Organelles (Cont.)
•
The Golgi Complex
–
Consists of a stack of three to twenty curved cisternae,
along with vesicles
 Modifies, sorts, packages, transports proteins that
bud from the rough ER
 Forms secretory vesicles for ferrying molecules
 Destined for exocytosis
 Destined for plasma membrane
 Destined for other organelles; e.g. lysosomes
48
Figure 3.6 Role of the Golgi apparatus in packaging the products of the rough ER.
Rough ER
Cisterns
Proteins in cisterns
Membrane
Transport
vesicle
Lysosome fuses
with ingested
substances.
Golgi vesicle containing
digestive enzymes
becomes a lysosome.
Pathway 3
Golgi
apparatus
Pathway 2
Pathway 1
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
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Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
Synthesized
protein
Ribosome
1
Entry face cisterna
Transport vesicle
2
Medial cisterna
3
Exit face cisterna
9
4
8
Rough ER
Transport vesicle
(to lysosome)
6
Transfer vesicle
4
7
5
Transfer vesicle
Membrane
vesicle
Secretory vesicle
Plasma membrane
Proteins in vesicle
membrane merge
with plasma
membrane
Proteins exported from
cell by exocytosis
Organelles (Cont.)
•
Lysosomes
–
–
Membranous sacs produced by the Golgi Complex that
contain hydrolytic digestive enzymes
Interior pH 5.0
 Digest substances entering cell via endocytosis
 Digest worn-out organelles
51
Figure 3.6 Role of the Golgi apparatus in packaging the products of the rough ER.
Rough ER
Cisterns
Proteins in cisterns
Membrane
Transport
vesicle
Lysosome fuses
with ingested
substances.
Golgi vesicle containing
digestive enzymes
becomes a lysosome.
Pathway 3
Golgi
apparatus
Pathway 2
Pathway 1
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle.
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Secretory vesicles
Proteins
Secretion by
exocytosis
Golgi vesicle containing
membrane components
fuses with the plasma
membrane and is
incorporated into it.
Plasma membrane
Extracellular fluid
Organelles (Cont.)
•
Mitochondria are double-membrane organelles
involved in cellular respiration
–
Site of ATP production; cell powerhouses
53
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
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Secretion being
released from cell
by exocytosis
•
The Nucleus
The nucleus stores genetic information that
determines body cell characteristics and
metabolic functioning.
– Contains nucleolus: site of ribosome
formation
– Contains chromatin: uncoiled DNA
– Nucleus is separated from the cytoplasm
by a nuclear envelope
 Contains nuclear pores to permit
passage of proteins and ribosomal
subunits
55
Figure 3.1 Anatomy of the generalized animal cell nucleus.
Nuclear envelope
Chromatin
Nucleolus
Nucleus
Nuclear
pores
Cytoplasm
(a)
Plasma
membrane
Rough ER
(b)
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Nucleus
Figure 3.4 Structure of the generalized cell.
Smooth
endoplasmic
reticulum
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Plasma
membrane
Cytosol
Lysosome
Mitochondrion
Rough
endoplasmic
reticulum
Centrioles
Ribosomes
Golgi
apparatus
Microtubule
Peroxisome
Intermediate
filaments
© 2015 Pearson Education, Inc.
Secretion being
released from cell
by exocytosis
Protein Synthesis
•
DNA and RNA Structure and Function
– DNA is the genetic material found
principally in chromosomes
 In between cell divisions, chromosomes
exist in long fine threads of chromatin
 When a cell is about to divide,
chromosomes coil and condense
58
DNA double helix
Chromatin
fiber
Histones
(proteins)
Nucleosome
Chromatin
Linker DNA
Chromatid
Centromere
Loop
(a) Illustration
Chromosome
Chromatid
Protein Synthesis
•
DNA is a sequential series of joined
nucleotides
– Sugar (deoxyribose), phosphate, and base
 Adenine (A)
 Thymine (T)
 Cytosine (C)
 Guanine (G)
60
•
Protein Synthesis
DNA is a double helix with a sugarphosphate backbone and bases projecting
between the backbones
– Exhibits complementary base pairing
 A-T
 G-C
61
Protein Synthesis
•
Structure and
Function of Proteins
– Proteins are
composed of amino
acids
 Proteins differ
because the
number and order
of their amino
acids differ
62
Protein Synthesis
•
Definition of a Gene
–
–
–
–
–
A specific area of DNA that codes for a specific
protein
Each protein in a cell has a specific area of
DNA that codes for it
Each DNA code for a specific protein is called a
gene
DNA represents the blueprint for all the proteins
in the cell
DNA is the information storage system for the
cell
63
Protein Synthesis
•
Structure and Function of RNA
– RNA is made up of nucleotides containing
the sugar ribose and the base uracil in
place of thymine
 Single stranded
 RNA is a helper to DNA allowing
protein synthesis
64
Protein Synthesis
•
Types of RNA
–
–
–
Ribosomal RNA (rRNA)
 Joins with proteins in the nucleolus to form
the subunits of ribosomes
Messenger RNA (mRNA)
 Carries genetic information from DNA to the
ribosomes in the cytoplasm where protein
synthesis occurs
Transfer RNA (tRNA)
 Transfers amino acids to the ribosomes
where amino acids are joined
65
Protein Synthesis
•
Gene Expression: Making a Protein
–
Two Processes Involved
1.
2.
–
Transcription
Translation
Transcription
Strand of mRNA forms that is complementary to a
portion of DNA
 Process under control of an enzyme, RNA
polymerase

66
mRNA Synthesis
67
Protein Synthesis
•
Gene Expression: Making a Protein (Cont.)
– Translation is the synthesis of a polypeptide
under the direction of an mRNA molecule
 tRNA molecules bring amino acids to the
ribosomes




Genetic (DNA) code is a triplet code
Every three bases represents one amino acid
Each three base code in RNA is a codon
Anticodon is a triplet code in tRNA
complementary to an mRNA codon
68
Nucleus
DNA
Step 1:
Transcription
Nuclear pore
RNA
Plasma membrane
Cytoplasm
RNA
Step 2:
Translation
Ribosome
Protein
Figure 3.16 Protein synthesis.
Nucleus
(site of transcription)
Cytoplasm
(site of translation)
DNA
1 mRNA specifying one
polypeptide is made on
DNA template.
Amino
acids
mRNA
Nuclear pore
Nuclear membrane
Protein
Synthesis
Correct amino
acid attached to
each species of
tRNA by an
enzyme
4 As the ribosome
moves along the mRNA,
a new amino acid is
added to the growing
protein chain.
Met
Gly
Growing
polypeptide
chain
Ser
Phe
Ala
5 Released tRNA
reenters the
cytoplasmic pool,
ready to be recharged
with a new amino
acid.
Peptide bond
2 mRNA leaves
nucleus and attaches
to ribosome, and
translation begins.
Synthetase
enzyme
3 Incoming tRNA
recognizes a
complementary
mRNA codon calling
for its amino acid by
binding via its anticodon
to the codon.
tRNA “head”
bearing anticodon
Large ribosomal subunit
Direction of
ribosome advance;
ribosome moves the
Portion of
mRNA strand along
mRNA already
sequentially as each
translated
codon is read.
Small ribosomal subunit
Codon
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71
Protein Synthesis
•
Gene Expression Review
–
–
–
–
–
DNA triplet codes for a specific amino acid
During transcription, a segment of DNA serves as a
template for mRNA
mRNA carries a sequence of codons to the ribosomes
tRNA molecules have anticodons complementary to
mRNA codons
Linear sequence of mRNA codons determines order
amino acids are incorporated into a protein
72
Cell Division
•
Somatic cell division
–
The Cell Cycle: one round of division


Interphase
Mitotic Phase
73
The Cell Cycle
•
•
How new cells are created
Cell Cycle
–
Interphase: growth & duplication of organelles;
replication of DNA



–
Mitotic Phase: nucleus divides; cell divides


–
G1 phase: active growth duplication of organelles
S phase: DNA replication occurs
G2 phase: cell growth continues
Mitosis: DNA divided into two sets; nucleus divides
Cytokinesis: cytoplasm divides; result two daughter cells
Nondividing Cells

G0 phase: can remain in this phase for it’s entire life
74
The Cell Cycle
Copyright © John Wiley & Sons, Inc. All rights reserved.
DNA Replication
•
Replication Steps
– Hydrogen bonds between strands break
and the molecule unzips
– New nucleotides fit beside parental strand
– DNA polymerase joins new nucleotides
– Two complete molecules present, each
with one old strand and one new strand
 Semi-conservative replication
76
DNA Replication
77
Histones
(proteins)
DNA double helix
Chromatin
fiber
Nucleosome
Chromatin
Linker DNA
Chromatid
Centromere
Loop
(a) Illustration
Chromosome
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Chromatid
DNA Replication & The Cell Cycle
79
Somatic Cell Division
•
•
To understand this process follow the sister
chromatids!!!!!
Mitosis: results in 2 cells identical to parent cell
–
–
–
–
•
Prophase: replicated DNA condenses & coils, produces
chromatid sisters held together at centromere
Metaphase: chromosomes aligned in center plane of cell
Anaphase: chromatid sisters separate to opposites sides of
the cell
Telophase: chromatids have arrive at opposite poles
Cytokinesis: contractile ring of protein filaments
pinches the cell in two
80
Figure 3.15 Stages of mitosis.
Centrioles
Chromatin
Centrioles
Forming
mitotic
spindle
Plasma
membrane
Interphase
Nuclear
Chromosome,
envelope consisting of two
Nucleolus sister chromatids
Early prophase
Metaphase
plate
Spindle
microtubules
Centromere
Centromere
Fragments of
nuclear envelope
Spindle
pole
Late prophase
Nucleolus
forming
Cleavage
furrow
Spindle
Metaphase
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Sister
chromatids
Daughter
chromosomes
Anaphase
Nuclear
envelope
forming
Telophase and cytokinesis
1.
Need to Know
Cell Theory- Understand the three parts of
the theory:
A.
B.
C.
2.
Cell: Basic unit of life
Living things are made of cells
New cells only come from other cells
General cellular organization
A.
B.
C.
D.
Plasma membrane
Cytoplasm
Organelles
Nucleus
82
Need to Know (Cont.)
Plasma membrane structure & function
3.
Fluid mosaic model; phospholipid bilayer; membrane fluidity
Embedded proteins- functions
Selectively permeable- regulates molecules movements across
bilayer
Mechanisms of transport
1.
Diffusion- free movement across plasma membrane
2.
Osmosis- refers to movement of water
3.
Facilitated- carrier-mediated; channel-mediated; no ATP
4.
Active- energy required
5.
Endocytosis- engulf, bring in big things
6.
Exocytosis- release cell product to outside
A.
B.
C.
D.
4.
Cytoskeleton- provides structural support
A.
B.
C.
Microfilaments
Intermediate filaments
Microtubules
83
Need to Know (Cont.)
Organelles
5.
A.
B.
C.
D.
E.
F.
G.
6.
Centrosome: mitotic spindle movement
Cilia & Flagella: movement of fluid on cell; movement of cell
Ribosomes: protein synthesis in cytosol & on rough ER
Endoplasmic reticulum: rough & smooth; functions
Golgi Complex: functions
Lysosomes: functions
Mitochondria: functions
Nucleus
A.
Control center for the cell
B.
DNA resides there
C.
Surrounded by nuclear envelope
D.
Nucleolus: Site of ribosome formation
84
Need to Know (Cont.)
7.
8.
Understand what a gene is
RNA Structure & Function
A.
Bases:
1.
Adenine (A)
2.
Uracil (U)
3.
Cytosine (C)
4.
Guanine (G)
B.
Function: Helper to DNA to allow protein
synthesis.
85
Need to Know (Cont.)
9.
10.
Types of RNA
A.
Ribosomal RNA: helps form ribosomes
B.
Messenger RNA: Carries genetic
information to the cytoplasm for protein
synthesis.
C.
Transfer RNA: Transports amino acids
to ribosomes where protein synthesis
takes place.
Understand gene expression
A.
Transcription: make mRNA
86
Need to Know (Cont.)
Understand gene expression
10.
Understand translation
1.
Switch DNA information (in mRNA from transcription)
into a new language- language of protein synthesisfrom nucleotides into proteins
2.
Nucleotides in DNA

Bases:
 Adenine (A)
 Thymine (T)
 Cytosine (C)
 Guanine (G)
Understand the concept of the genetic code
A.
Every three bases represents one amino acid
B.
11.
87
Need to Know (Cont.)
12.
Cell Division: understand how DNA is replicated
A.
The cell cycle: understand what happens in the
phases
B.
Somatic Cell Division
1.
Mitosis: understand about the separation of sister
chromatids
88