Download 3 - Riverside City College

PowerPoint® Lecture Slides
prepared by
Janice Meeking,
Mount Royal College
CHAPTER
3
Cells: The
Living Units:
Part A
Copyright © 2010 Pearson Education, Inc.
Generalized Cell
• All cells have some common structures and
functions
• Human cells have three basic parts:
• Plasma membrane—flexible outer boundary
• Cytoplasm—intracellular fluid containing
organelles
• Nucleus—control center
Copyright © 2010 Pearson Education, Inc.
Chromatin
Nucleolus
Nuclear envelope
Nucleus
Smooth endoplasmic
reticulum
Mitochondrion
Cytosol
Lysosome
Centrioles
Centrosome
matrix
Cytoskeletal
elements
• Microtubule
• Intermediate
filaments
Copyright © 2010 Pearson Education, Inc.
Plasma
membrane
Rough
endoplasmic
reticulum
Ribosomes
Golgi apparatus
Secretion being
released from cell
by exocytosis
Peroxisome
Figure 3.2
Plasma Membrane
• The plasma membrane separates the
intracellular fluid (ICF) from extracellular fluid
(ECF)
• The plasma membrane is semi-permeable
which means that some things can cross the
membrane and some things cannot
Copyright © 2010 Pearson Education, Inc.
Extracellular fluid
Intracellular fluid
Copyright © 2010 Pearson Education, Inc.
Figure 3.3
Types of Membrane Transport
• Passive Transport
• No cellular energy (ATP) required
• Substance moves down its concentration
gradient
• Active Transport
• Energy (ATP) required
• Substances are moved or“pumped” against
their gradient
Copyright © 2010 Pearson Education, Inc.
Passive Transport
•
What determines whether or not a
substance can passively permeate (cross)
a membrane?
1. Lipid solubility of substance
2. Size of the molecule that is passing
PLAY
http://www.youtube.com/watch?v=JShwXBWGMyY
Copyright © 2010 Pearson Education, Inc.
Passive Transport
• Simple diffusion
• Facilitated diffusion
• Osmosis
Copyright © 2010 Pearson Education, Inc.
Passive Transport: Simple Diffusion
• Small, nonpolar, hydrophobic substances
diffuse directly through phospholipid bilayer
Copyright © 2010 Pearson Education, Inc.
Extracellular fluid
Lipidsoluble
solutes
Cytoplasm
Copyright © 2010 Pearson Education, Inc.
Figure 3.7a
Passive Transport: Facilitated Diffusion
• Larger, hydrophilic molecules (glucose,
amino acids, ions) use carrier proteins or
channel proteins to pass through the plasma
membrane
Copyright © 2010 Pearson Education, Inc.
Hydrophilic
molecules
Copyright © 2010 Pearson Education, Inc.
Figure 3.7b
Passive Transport: Osmosis
• Movement of solvent (water) across a
selectively permeable membrane from where
it is most concentrated to where it is less
concentrated
• Water diffuses through plasma membranes:
• Through lipid bilayer
• Through channels (aquaporins)
Copyright © 2010 Pearson Education, Inc.
Water
molecules
Lipid
billayer
Aquaporin
Copyright © 2010 Pearson Education, Inc.
Figure 3.7d
Passive Transport: Osmosis
• Osmolarity: The measure of total
concentration of solute particles
• When solutions of different osmolarity are
separated by a membrane, osmosis occurs
until equilibrium is reached
Copyright © 2010 Pearson Education, Inc.
(a)
Membrane permeable to both solutes and water
Solute and water molecules move down their concentration gradients
in opposite directions.
Both solutions have the
same osmolarity: volume
unchanged
H2O
Solute
Membrane
Copyright © 2010 Pearson Education, Inc.
Solute
(sugar)
Figure 3.8a
(b)
Membrane permeable to water, impermeable to solutes
Solute molecules are prevented from moving but water moves by osmosis.
Volume increases in the compartment with the higher osmolarity.
Left
compartment
Right
compartment
Both solutions have identical
osmolarity, increases on the right
because only water is
free to move
H2O
Membrane
Copyright © 2010 Pearson Education, Inc.
Solute
(sugar)
Figure 3.8b
Importance of Osmosis
• When osmosis occurs, water enters or leaves
a cell
• A change in cell volume disrupts cell function
Copyright © 2010 Pearson Education, Inc.
Tonicity
• Defined as: The ability of a solution to cause a
cell to shrink or swell
• Isotonic: A solution that does not cause a
change in cell volume
• Hypertonic: A solution that causes a cell to
shrink
• Hypotonic: A solution that causes a cell to
swell.
Copyright © 2010 Pearson Education, Inc.
(a)
Isotonic solutions
Copyright © 2010 Pearson Education, Inc.
(b)
Hypertonic solutions
(c)
Hypotonic solutions
Figure 3.9
Active Transport
• The Sodium-potassium pump (Na+-K+ ATPase) is a
specific example of active transport
• Located in all plasma membranes
• Maintains electrochemical gradients essential for
functions of muscle and nerve tissues
Copyright © 2010 Pearson Education, Inc.
Vesicular Transport
• Transports large particles, macromolecules, &
fluids across plasma membranes
• Is active transport = requires energy ATP
• Examples:
• Exocytosis—moves substances out of cell
• Endocytosis—moves substances into cell
Copyright © 2010 Pearson Education, Inc.
ECF
Cytoplasm
Transport
vesicle
Endosome
Lysosome
(a)
Copyright © 2010 Pearson Education, Inc.
Other Organelles
• Membranous structures
• Nucleus with chromatin• Mitochondria –
• Endoplasmic Reticulum (ER) (rough and
smooth) –
• Golgi Apparatus• Lysosomes-
Copyright © 2010 Pearson Education, Inc.
Nucleus
Nuclear envelope
Smooth ER
Rough ER
Vesicle
Plasma
membrane
Lysosome
Copyright © 2010 Pearson Education, Inc.
Golgi
apparatus
Transport
vesicle
Figure 3.22
Smooth ER
Nuclear
envelope
Rough ER
Ribosomes
Copyright © 2010 Pearson Education, Inc.
Figure 3.18a
Rough ER
Phagosome
ER
membrane
Plasma
membrane
Vesicle becomes
lysosome
Golgi
apparatus
Secretory
vesicle
Secretion by
exocytosis
Copyright © 2010 Pearson Education, Inc.
Extracellular fluid
Figure 3.20
Mitochondria
• Organelle with shelflike
folds called cristae
• Provide most of cell’s
ATP (enzymes for this
process are located on
cristae)
Copyright © 2010 Pearson Education, Inc.
Other Organelles
• Non-Membranous structures
• Centrioles- involved in cell division
• Cytoskeleton- includes
microfilaments, intermediate
filaments and microtubules
Copyright © 2010 Pearson Education, Inc.
Centrosome matrix
Centrioles
(a)
Copyright © 2010 Pearson Education, Inc.
Microtubules
Figure 3.25a
Microfilaments
• Function in cell
motility and aid
in cell shape
Copyright © 2010 Pearson Education, Inc.
(a) Microfilaments
Intermediate Filaments
(b) Intermediate filaments
• Resist pulling forces
on the cell and
attach to
desmosomes
Copyright © 2010 Pearson Education, Inc.
Microtubules
• Most radiate from
centrosome
• Determine overall
shape of cell and
distribution of
organelles
Copyright © 2010 Pearson Education, Inc.
(c) Microtubules
Extensions of the plasma membrane
• Cilia are: short, hairlike structures that move
substances across cell surfaces
• Flagella are: Whiplike, tails that move entire
cell
• Microvilli are: fingerlike extensions found on
absorptive cells
Copyright © 2010 Pearson Education, Inc.
Power, or
propulsive,
stroke
1
2
3
4
Recovery stroke, when
cilium is returning to its
initial position
5
6
7
(a) Phases of ciliary motion.
Layer of mucus
Cell surface
(b) Traveling wave created by the activity of
many cilia acting together propels mucus
across cell surfaces.
Copyright © 2010 Pearson Education, Inc.
Figure 3.27
Microvillus
Actin
filaments
Terminal
web
Copyright © 2010 Pearson Education, Inc.
Figure 3.28
The Cell Cycle
• Includes:
• Interphase
• Period from cell formation to cell division
• Three sub phases of Interphase:
• G1 (gap 1)—growth and metabolism
• S (synthetic)—DNA replication
• G2 (gap 2)—preparation for division
• Cell division (mitotic phase)
Copyright © 2010 Pearson Education, Inc.
S
Growth and DNA
synthesis
G1
Growth
Copyright © 2010 Pearson Education, Inc.
M
G2
Growth and final
preparations for
division
Figure 3.31
DNA Replication
• Helicase untwists the double helix and
exposes complementary chains
• Each nucleotide strand serves as a template
for building a new complementary strand
• DNA polymerase forms new DNA strand
Copyright © 2010 Pearson Education, Inc.
DNA Replication
• End result: two DNA molecules formed from
the original
• This process is called semiconservative
replication
Copyright © 2010 Pearson Education, Inc.
Chromosome
Free nucleotides
DNA polymerase
Template for synthesis
of new strand
Leading strand
Old DNA
Helicase unwinds
the double helix and
Exposes bases
Replication
fork
Adenine
Thymine
Cytosine
Guanine
Copyright © 2010 Pearson Education, Inc.
Lleading and lagging strands are
synthesized in opposite directions
Lagging
strand
DNA polymerase Old (template) strand
Figure 3.32
Cell Division
• Mitotic (M) phase of the cell cycle
• Essential for body growth and tissue repair
• Does not occur in most mature cells of
nervous tissue, skeletal and cardiac muscle
Copyright © 2010 Pearson Education, Inc.
Cell Division
•
Includes two distinct events:
1. Mitosis—four stages of nuclear division:
•
Prophase
•
Metaphase
•
Anaphase
•
Telophase
2. Cytokinesis—division of cytoplasm by
cleavage furrow
Copyright © 2010 Pearson Education, Inc.
S
Growth and DNA
synthesis
G1
Growth
Copyright © 2010 Pearson Education, Inc.
G2
Growth
M
Figure 3.31
Prophase
• Chromosomes condense and become visible
• Mitotic spindle form
• Nuclear envelope fragments
Copyright © 2010 Pearson Education, Inc.
Early Prophase
Early mitotic
spindle
Aster
Early Prophase
Copyright © 2010 Pearson Education, Inc.
Chromosome
consisting of two
sister chromatids
Centromere
Figure 3.33
Microtubule
Late Prophase
Late Prophase
Copyright © 2010 Pearson Education, Inc.
Fragments
of nuclear
envelope
Microtubule
Figure 3.33
Metaphase
• Chromosomes are aligned at the equator
• Metaphase plate = The plane midway
between the poles of the cell
Copyright © 2010 Pearson Education, Inc.
Metaphase
Spindle
Metaphase
Copyright © 2010 Pearson Education, Inc.
Metaphase
plate
Figure 3.33
Anaphase
• Shortest phase
• Chromosomes are pulled to opposite poles by
microtubules
Copyright © 2010 Pearson Education, Inc.
Anaphase
Anaphase
Copyright © 2010 Pearson Education, Inc.
Daughter
chromosomes
Figure 3.33
Telophase
• Begins when chromosome movement stops
• Nuclear membrane forms around each
chromatin mass
• Spindle disappears
Copyright © 2010 Pearson Education, Inc.
Cytokinesis
• Begins during late anaphase
• Ring of actin microfilaments contracts to form
a cleavage furrow
• Two daughter cells are pinched apart, each
containing a nucleus identical to the original
Copyright © 2010 Pearson Education, Inc.
Nuclear
envelope
forming
Nucleolus
forming
Contractile
ring at
cleavage
furrow
Telophase and Cytokinesis
Telophase
Copyright © 2010 Pearson Education, Inc.
Figure 3.33
PROTEIN SYNTHESIS
Copyright © 2010 Pearson Education, Inc.
Protein Synthesis
• DNA is the master blueprint for protein
synthesis
• Gene: Segment of DNA with blueprint for one
polypeptide
• Each triplet (3 base sequence) in DNA
specifies an amino acid
Copyright © 2010 Pearson Education, Inc.
Nuclear
envelope
Transcription
RNA Processing
DNA
Pre-mRNA
mRNA
Translation
Nuclear
pores
Ribosome
Polypeptide
Copyright © 2010 Pearson Education, Inc.
Figure 3.34
Roles of the Three Main Types of RNA
• Messenger RNA (mRNA)
• Carries instructions for building a polypeptide,
from a gene in DNA to ribosomes in cytoplasm
Copyright © 2010 Pearson Education, Inc.
Roles of the Three Main Types of RNA
• Ribosomal RNA (rRNA)
• Helps form ribosome
Copyright © 2010 Pearson Education, Inc.
Roles of the Three Main Types of RNA
• Transfer RNAs (tRNAs)
• Transfer amino acids from cytoplasm to
mRNA attached to ribosome to begin process
of protein synthesis
Copyright © 2010 Pearson Education, Inc.
Transcription
• Transfers triplet code into a complementary
base sequence in mRNA
Copyright © 2010 Pearson Education, Inc.
Transcription
• RNA polymerase
• Enzyme that oversees synthesis of mRNA
• Unwinds DNA
• Adds complementary RNA nucleotides using a
DNA template and joins them together
• Stops when it reaches termination signal
Copyright © 2010 Pearson Education, Inc.
RNA polymerase
Coding strand
DNA
Promoter
region
1
Template strand
Termination
signal
Initiation: Once transcription factors are bound to promoter, RNA
pol binds promoter, unwinds DNA strands,
and initiates mRNA synthesis .
Copyright © 2010 Pearson Education, Inc.
Figure 3.35 step 1
mRNA
Template strand
2 Elongation: RNA pol moves along the template
strand, elongating the mRNA transcript one base at a time.
mRNA transcript
Copyright © 2010 Pearson Education, Inc.
Figure 3.35 step 2
3 Termination: mRNA synthesis ends when the termination signal
is reached. RNA poly and mRNA transcript are released.
Completed mRNA transcript
Copyright © 2010 Pearson Education, Inc.
RNA
polymerase
Figure 3.35 step 3
Steps of Translation
• Converts base sequence of nucleic acids into
the amino acid sequence of proteins
• Involves mRNAs, tRNAs, and rRNAs
Copyright © 2010 Pearson Education, Inc.
Genetic Code
• Each three-base sequence on DNA (triplet) is
represented by a codon
• Codon—complementary three-base sequence
on mRNA
Copyright © 2010 Pearson Education, Inc.
SECOND BASE
C
A
U
UUU
U
UUC
UUA
UUG
Phe
Leu
CUU
C
CUC
CUA
A
Leu
UCC
UAC
UCA
Ser
UAA
UCG
UAG
CCU
CAU
CCC
CCA
Pro
CAC
CAA
CCG
CAG
AUU
ACU
AAU
ACC
AAC
AUC
Ile
ACA
Thr
AAA
Met or
AUG Start ACG
AAG
GUU
GCU
GAU
GUC
GCC
GAC
GUA
GUG
Copyright © 2010 Pearson Education, Inc.
UAU
CUG
AUA
G
UCU
Val
GCA
GCG
Ala
GAA
GAG
G
Tyr
UGU
UGC
U
Cys
C
Stop UGA Stop A
Stop UGG
Trp G
His
Gln
Asn
Lys
Asp
Glu
U
CGU
CGC
CGA
C
Arg
A
CGG
G
AGU
U
AGC
AGA
AGG
Ser
C
A
Arg
G
GGU
U
GGC
C
GGA
GGG
Gly
A
G
Figure 3.36
Translation
• mRNA attaches to a small ribosomal subunit that
moves along the mRNA to the start codon (AUG)
• Large ribosomal unit attaches, forming a functional
ribosome
• Anticodon of tRNA binds to complementary codon
and adds its amino acid to the forming protein chain
• New amino acids are added by other tRNAs as
ribosome moves along mRNA, until stop codon is
reached
Copyright © 2010 Pearson Education, Inc.
Nucleus
RNA polymerase
mRNA
Leu
Template
strand of
DNA
1 After mRNA synthesis in the
nucleus, mRNA leaves the nucleus
and attaches to a ribosome.
Energized by ATP, the correct amino
acid is attached to each species of
tRNA by aminoacyl-tRNA synthetase
enzyme.
Amino acid
Nuclear pore
tRNA
Nuclear
membrane
G A A
2 Translation begins as incoming
aminoacyl-tRNA recognizes the
complementary codon calling for
it at the A site on the ribosome. It
hydrogen-bonds to the codon via
its anticodon.
Released mRNA
Aminoacyl-tRNA
synthetase
Leu
3 As the ribosome moves along
the mRNA, and each codon is
read in sequence, a new amino
acid is added to the growing
protein chain and the tRNA in
the A site is translocated to the
P site.
Ile
tRNA “head”
bearing
anticodon
Pro
4 Once its amino acid is released
from the P site, tRNA is ratcheted
to the E site and then released to
reenter the cytoplasmic pool,
ready to be recharged with a new
amino acid. The polypeptide is
released when the stop codon is
read.
E
site
P
site
G G C
A
site
A U A C C G
C U U
Codon
15
Codon
17
Codon
16
Large
ribosomal
subunit
Small
ribosomal
subunit
Direction of
Portion of mRNA ribosome advance
already translated
Copyright © 2010 Pearson Education, Inc.
Figure 3.37
Nucleus
mRNA
RNA polymerase
Template
strand of
DNA
1
mRNA leaves the
nucleus and attaches to a
ribosome.
Leu
Amino acid
Nuclear pore
tRNA
Nuclear
membrane
GAA
Released mRNA
Aminoacyl-tRNA
synthetase
Copyright © 2010 Pearson Education, Inc.
Figure 3.37 step 1
Leu
2 Translation begins;.
Ile
tRNA “head”
bearing
anticodon
Pro
E
site
P
site
G G C
A
site
Large
ribosomal
subunit
A U A C C G C U U
Codon Codon
15
16
Codon
17
Small
ribosomal
subunit
Direction of
Portion of
ribosome advance
mRNA already
translated
Copyright © 2010 Pearson Education, Inc.
Figure 3.37 step 2
Leu
3
The ribosome moves
along the mRNA, and each
codon is read in sequence. a
new amino acid is added to
the growing protein chain .
Ile
tRNA “head”
bearing
anticodon
Pro
E
site
P
site
G G C
A
site
Large
ribosomal
subunit
A U A C C G C U U
Codon Codon
15
16
Codon
17
Small
ribosomal
subunit
Direction of
Portion of
ribosome advance
mRNA already
translated
Copyright © 2010 Pearson Education, Inc.
Figure 3.37 step 3
Leu
3
2
Ile
tRNA “head”
bearing
anticodon
Pro
4 tRNA is released to reenter the
cytoplasmic pool, ready to be
recharged with a new amino
acid. The polypeptide is
released when the stop
codon is read.
E
site
P
site
G G C
A
site
Large
ribosomal
subunit
A U A C C G C U U
Codon Codon
15
16
Codon
17
Small
ribosomal
subunit
Direction of
Portion of
ribosome advance
mRNA already
translated
Copyright © 2010 Pearson Education, Inc.
Figure 3.37 step 4
Nucleus
RNA polymerase
mRNA
Leu
Template
strand of
DNA
1
Energized by ATP, the correct amino
acid is attached to each species of
tRNA by aminoacyl-tRNA synthetase
enzyme.
Amino acid
Nuclear pore
tRNA
Nuclear
membrane
G A A
2
Released mRNA
Aminoacyl-tRNA
synthetase
Leu
3
Ile
tRNA “head”
bearing
anticodon
Pro
4
E
site
P
site
G G C
A
site
A U A C C G
C U U
Codon
15
Codon
17
Codon
16
Large
ribosomal
subunit
Small
ribosomal
subunit
Direction of
Portion of mRNA ribosome advance
already translated
Copyright © 2010 Pearson Education, Inc.
Figure 3.37