CELL COMMUNICATION Figure 11.1 Figure 11.1 How does cell signaling trigger the desperate flight of this gazelle? CELL COMMUNICATION

Yeast cell, mating type a Yeast cell, mating type  Figure 11.2  factor Receptor 1 Exchange of mating factors a  a factor Yeast cell, mating type a Yeast cell, mating type  2 Mating a  Figure 11.2 Communication between mating yeast cells. 3 New a/ cell a/

Individual rod-shaped cells Figure 11.3 1 Individual rod-shaped cells 2 Aggregation in progress 0.5 mm 3 Spore-forming structure (fruiting body) 2.5 mm Figure 11.3 Communication among bacteria. Fruiting bodies

Gap junctions between animal cells Plasmodesmata between plant cells Figure 11.4 Plasma membranes Gap junctions between animal cells Plasmodesmata between plant cells (a) Cell junctions Figure 11.4 Communication by direct contact between cells. (b) Cell-cell recognition

Neurotransmitter diffuses across synapse. Secreting cell Figure 11.5a Local signaling Target cell Electrical signal along nerve cell triggers release of neurotransmitter. Neurotransmitter diffuses across synapse. Secreting cell Secretory vesicle Figure 11.5 Local and long-distance cell signaling by secreted molecules in animals. Local regulator diffuses through extracellular fluid. Target cell is stimulated. (a) Paracrine signaling (b) Synaptic signaling

Long-distance signaling Figure 11.5b Long-distance signaling Endocrine cell Blood vessel Hormone travels in bloodstream. Target cell specifically binds hormone. Figure 11.5 Local and long-distance cell signaling by secreted molecules in animals. (c) Endocrine (hormonal) signaling

EXTRACELLULAR FLUID CYTOPLASM Plasma membrane 1 Reception Receptor Figure 11.6-1 EXTRACELLULAR FLUID CYTOPLASM Plasma membrane 1 Reception Receptor Figure 11.6 Overview of cell signaling. Signaling molecule

Relay molecules in a signal transduction pathway Figure 11.6-2 EXTRACELLULAR FLUID CYTOPLASM Plasma membrane 1 Reception 2 Transduction Receptor Relay molecules in a signal transduction pathway Figure 11.6 Overview of cell signaling. Signaling molecule

Relay molecules in a signal transduction pathway Figure 11.6-3 EXTRACELLULAR FLUID CYTOPLASM Plasma membrane 1 Reception 2 Transduction 3 Response Receptor Activation of cellular response Relay molecules in a signal transduction pathway Figure 11.6 Overview of cell signaling. Signaling molecule

G protein-coupled receptor Plasma membrane Activated receptor Figure 11.7b G protein-coupled receptor Plasma membrane Activated receptor Signaling molecule Inactive enzyme GTP GDP GDP CYTOPLASM G protein (inactive) Enzyme GTP 1 2 GDP Activated enzyme Figure 11.7 Exploring: Cell-Surface Transmembrane Receptors GTP GDP P i 3 Cellular response 4

Signaling molecule (ligand) Ligand-binding site Figure 11.7c Signaling molecule (ligand) Ligand-binding site  helix in the membrane Signaling molecule Tyrosines Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr Tyr CYTOPLASM Receptor tyrosine kinase proteins (inactive monomers) Dimer 1 2 Activated relay proteins Figure 11.7 Exploring: Cell-Surface Transmembrane Receptors Cellular response 1 Tyr Tyr P Tyr Tyr P Tyr Tyr P P Tyr Tyr P Tyr Tyr P Tyr Tyr P P Cellular response 2 Tyr Tyr P Tyr Tyr P Tyr Tyr P 6 ATP 6 ADP P Activated tyrosine kinase regions (unphosphorylated dimer) Fully activated receptor tyrosine kinase (phosphorylated dimer) Inactive relay proteins 3 4

Signaling molecule (ligand) Figure 11.7d 1 2 3 Gate closed Ions Gate open Gate closed Signaling molecule (ligand) Plasma membrane Ligand-gated ion channel receptor Cellular response Figure 11.7 Exploring: Cell-Surface Transmembrane Receptors

Hormone (testosterone) EXTRACELLULAR FLUID Figure 11.9-1 Hormone (testosterone) EXTRACELLULAR FLUID Plasma membrane Receptor protein DNA Figure 11.9 Steroid hormone interacting with an intracellular receptor. NUCLEUS CYTOPLASM

Hormone (testosterone) EXTRACELLULAR FLUID Figure 11.9-2 Hormone (testosterone) EXTRACELLULAR FLUID Plasma membrane Receptor protein Hormone- receptor complex DNA Figure 11.9 Steroid hormone interacting with an intracellular receptor. NUCLEUS CYTOPLASM

Hormone (testosterone) EXTRACELLULAR FLUID Figure 11.9-3 Hormone (testosterone) EXTRACELLULAR FLUID Plasma membrane Receptor protein Hormone- receptor complex DNA Figure 11.9 Steroid hormone interacting with an intracellular receptor. NUCLEUS CYTOPLASM

Hormone (testosterone) EXTRACELLULAR FLUID Figure 11.9-4 Hormone (testosterone) EXTRACELLULAR FLUID Plasma membrane Receptor protein Hormone- receptor complex DNA Figure 11.9 Steroid hormone interacting with an intracellular receptor. mRNA NUCLEUS CYTOPLASM

Hormone (testosterone) EXTRACELLULAR FLUID Figure 11.9-5 Hormone (testosterone) EXTRACELLULAR FLUID Plasma membrane Receptor protein Hormone- receptor complex DNA Figure 11.9 Steroid hormone interacting with an intracellular receptor. mRNA NUCLEUS New protein CYTOPLASM

Activated relay molecule Figure 11.10 Signaling molecule Receptor Activated relay molecule Inactive protein kinase 1 Active protein kinase 1 Inactive protein kinase 2 ATP Phosphorylation cascade ADP Active protein kinase 2 P PP P i Figure 11.10 A phosphorylation cascade. Inactive protein kinase 3 ATP ADP P Active protein kinase 3 PP P i Inactive protein ATP ADP P Active protein Cellular response PP P i

First messenger (signaling molecule such as epinephrine) Figure 11.12 First messenger (signaling molecule such as epinephrine) Adenylyl cyclase G protein G protein-coupled receptor GTP ATP Second messenger cAMP Figure 11.12 cAMP as a second messenger in a G protein signaling pathway. Protein kinase A Cellular responses

Signaling molecule (first messenger) Figure 11.14-1 EXTRA- CELLULAR FLUID Signaling molecule (first messenger) G protein DAG GTP G protein-coupled receptor PIP2 Phospholipase C IP3 (second messenger) IP3-gated calcium channel Figure 11.14 Calcium and IP3 in signaling pathways. Endoplasmic reticulum (ER) Ca2 CYTOSOL

Signaling molecule (first messenger) Figure 11.14-2 EXTRA- CELLULAR FLUID Signaling molecule (first messenger) G protein DAG GTP G protein-coupled receptor PIP2 Phospholipase C IP3 (second messenger) IP3-gated calcium channel Figure 11.14 Calcium and IP3 in signaling pathways. Endoplasmic reticulum (ER) Ca2 Ca2 (second messenger) CYTOSOL

Signaling molecule (first messenger) Figure 11.14-3 EXTRA- CELLULAR FLUID Signaling molecule (first messenger) G protein DAG GTP G protein-coupled receptor PIP2 Phospholipase C IP3 (second messenger) IP3-gated calcium channel Figure 11.14 Calcium and IP3 in signaling pathways. Various proteins activated Cellular responses Endoplasmic reticulum (ER) Ca2 Ca2 (second messenger) CYTOSOL

Inactive transcription factor Active transcription factor Figure 11.15 Growth factor Reception Receptor Phosphorylation cascade Transduction CYTOPLASM Inactive transcription factor Active transcription factor Figure 11.15 Nuclear responses to a signal: the activation of a specific gene by a growth factor. Response P DNA Gene NUCLEUS mRNA

Figure 11.18 Signaling molecule Receptor Relay molecules Activation or inhibition Figure 11.18 The specificity of cell signaling. Response 1 Response 2 Response 3 Response 4 Response 5 Cell A. Pathway leads to a single response. Cell B. Pathway branches, leading to two responses. Cell C. Cross-talk occurs between two pathways. Cell D. Different receptor leads to a different response.

Ced-9 protein (active) inhibits Ced-4 activity Figure 11.21a Ced-9 protein (active) inhibits Ced-4 activity Mitochondrion Figure 11.21 Molecular basis of apoptosis in C. elegans. Ced-4 Ced-3 Receptor for death- signaling molecule Inactive proteins (a) No death signal

Death- signaling molecule Figure 11.21b Ced-9 (inactive) Cell forms blebs Death- signaling molecule Active Ced-4 Active Ced-3 Other proteases Figure 11.21 Molecular basis of apoptosis in C. elegans. Nucleases Activation cascade (b) Death signal

Cells undergoing apoptosis Figure 11.22 Cells undergoing apoptosis Space between digits 1 mm Interdigital tissue Figure 11.22 Effect of apoptosis during paw development in the mouse.

Chapter 12 The Cell Cycle

(b) Growth and development Figure 12.2 100 m (a) Reproduction 200 m (b) Growth and development Figure 12.2 The functions of cell division. 20 m (c) Tissue renewal

Sister chromatids Centromere 0.5 m Figure 12.4 Figure 12.4 A highly condensed, duplicated human chromosome (SEM).

Chromosomal DNA molecules Figure 12.5-3 Chromosomal DNA molecules Chromosomes 1 Centromere Chromosome arm Chromosome duplication (including DNA replication) and condensation 2 Sister chromatids Figure 12.5 Chromosome duplication and distribution during cell division. Separation of sister chromatids into two chromosomes 3

INTERPHASE S (DNA synthesis) G1 Cytokinesis G2 Mitosis Figure 12.6 INTERPHASE S (DNA synthesis) G1 Cytokinesis G2 Mitosis Figure 12.6 The cell cycle. MITOTIC (M) PHASE

Chromosome, consisting of two sister chromatids Figure 12.7a G2 of Interphase Prophase Prometaphase Centrosomes (with centriole pairs) Fragments of nuclear envelope Chromatin (duplicated) Early mitotic spindle Aster Nonkinetochore microtubules Centromere Figure 12.7 Exploring: Mitosis in an Animal Cell Plasma membrane Nucleolus Kinetochore Kinetochore microtubule Chromosome, consisting of two sister chromatids Nuclear envelope

Metaphase plate (imaginary) Sister chromatids Microtubules Figure 12.8 Centrosome Aster Metaphase plate (imaginary) Sister chromatids Microtubules Chromosomes Kineto- chores Centrosome 1 m Overlapping nonkinetochore microtubules Figure 12.8 The mitotic spindle at metaphase. Kinetochore microtubules 0.5 m

CONCLUSION Chromosome movement Kinetochore Microtubule Figure 12.9b CONCLUSION Chromosome movement Kinetochore Microtubule Tubulin subunits Motor protein Figure 12.9 Inquiry: At which end do kinetochore microtubules shorten during anaphase? Chromosome

Metaphase Anaphase Telophase and Cytokinesis Metaphase plate Figure 12.7b Metaphase Anaphase Telophase and Cytokinesis Metaphase plate Cleavage furrow Nucleolus forming Figure 12.7 Exploring: Mitosis in an Animal Cell Nuclear envelope forming Spindle Centrosome at one spindle pole Daughter chromosomes

Chromatin condensing Nucleus 10 m Nucleolus Chromosomes Cell plate 1 Figure 12.11 Chromatin condensing Nucleus 10 m Nucleolus Chromosomes Cell plate Figure 12.11 Mitosis in a plant cell. 1 Prophase 2 Prometaphase 3 Metaphase 4 Anaphase 5 Telophase

Chromatin condensing Nucleus Nucleolus 10 m 1 Prophase Figure 12.11a Figure 12.11 Mitosis in a plant cell. 10 m 1 Prophase

Chromosomes 10 m 2 Prometaphase Figure 12.11b Figure 12.11 Mitosis in a plant cell. 10 m 2 Prometaphase

Figure 12.11c 10 m Figure 12.11 Mitosis in a plant cell. 3 Metaphase

Figure 12.11d 10 m Figure 12.11 Mitosis in a plant cell. 4 Anaphase

10 m Cell plate 5 Telophase Figure 12.11e Figure 12.11 Mitosis in a plant cell. 5 Telophase

Figure 12.UN02 Figure 12.UN02 Test Your Understanding, question 7

(a) Cleavage of an animal cell (SEM) Figure 12.10 (a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (TEM) 100 m Cleavage furrow Vesicles forming cell plate Wall of parent cell 1 m Cell plate New cell wall Figure 12.10 Cytokinesis in animal and plant cells. Contractile ring of microfilaments Daughter cells Daughter cells

Chromosome replication begins. Two copies of origin Figure 12.12-4 Origin of replication Cell wall Plasma membrane E. coli cell Bacterial chromosome 1 Chromosome replication begins. Two copies of origin 2 Replication continues. Origin Origin 3 Figure 12.12 Bacterial cell division by binary fission. Replication finishes. 4 Two daughter cells result.

Intact nuclear envelope Figure 12.13 Bacterial chromosome (a) Bacteria Chromosomes Microtubules (b) Dinoflagellates Intact nuclear envelope Kinetochore microtubule (c) Diatoms and some yeasts Intact nuclear envelope Figure 12.13 Mechanisms of cell division in several groups of organisms. Kinetochore microtubule (d) Most eukaryotes Fragments of nuclear envelope

G1 checkpoint Control system S G1 G2 M M checkpoint G2 checkpoint Figure 12.15 G1 checkpoint Control system S G1 G2 M Figure 12.15 Mechanical analogy for the cell cycle control system. M checkpoint G2 checkpoint

(a) Cell receives a go-ahead signal. Figure 12.16 G0 G1 checkpoint G1 Figure 12.16 The G1 checkpoint. G1 (a) Cell receives a go-ahead signal. (b) Cell does not receive a go-ahead signal.

(b) Molecular mechanisms that help regulate the cell cycle Figure 12.17b G1 S Cdk Cyclin accumulation M G2 Degraded cyclin G2 checkpoint Cdk Figure 12.17 Molecular control of the cell cycle at the G2 checkpoint. Cyclin is degraded Cyclin MPF (b) Molecular mechanisms that help regulate the cell cycle

M G1 S G2 M G1 S G2 M G1 MPF activity Cyclin concentration Time Figure 12.17a M G1 S G2 M G1 S G2 M G1 MPF activity Cyclin concentration Figure 12.17 Molecular control of the cell cycle at the G2 checkpoint. Time (a) Fluctuation of MPF activity and cyclin concentration during the cell cycle

A tumor grows from a single cancer cell. Figure 12.20 Lymph vessel Tumor Blood vessel Cancer cell Glandular tissue Metastatic tumor 1 A tumor grows from a single cancer cell. Cancer cells invade neighboring tissue. Figure 12.20 The growth and metastasis of a malignant breast tumor. 2 3 Cancer cells spread through lymph and blood vessels to other parts of the body. 4 Cancer cells may survive and establish a new tumor in another part of the body.