AP-Bio-Unit-4-Cell-Communication-and-Cell-Cycle.pdf

Cell-Communication-and-Cell-Cycle

1. Unit 4 Cell Communication and Cell Cycle
Topic 4.1 Cell Communication
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.

(4.1 cont. next slide)
Genetic information provides for continuity of life, and, in most cases, this
information is passed from parent to offspring via DNA.

Non-heritable information transmission influences behavior within and
between cells, organisms, and populations. These behaviors are directed
by underlying genetic information, and responses to information are vital to
natural selection and evolution.

Genetic information is a repository of instructions necessary for the
survival, growth, and reproduction of the organism.

Genetic variation can be advantageous for the long-term survival and
evolution of a species.
Enduring Understanding: Cells communicate by generating,
transmitting, receiving, and responding to chemical signals.

2. Learning Objective: Describe the ways that cells can communicate with one another.
Essential Knowledge: Cells communicate with one another through direct contact with other cells or from a distance via
chemical signaling —
a. Cells communicate by cell-to-cell contact.
(4.1 cont. next slide)
Cell Communication
Direct Contact From a Distance
Long Distance
or Large Audience
Local Regulators

3. Learning Objective: Explain how cells communicate with one another over short and long distances.
Click HERE to watch Mr. Anderson’s
(Bozeman Science) video explaining the
3 types of cell communication:
1)Cell-to-Cell (Post-It Note) - Handing someone a
message.
2)Local Regulators (Email) - Sending a message a
short distance; to one person.
3)Long Distance (Facebook Status Post) - Sending
a message a long distance or to a large audience
to be acted on (Liked) or not.
Essential Knowledge: Cells communicate over short distances by using local regulators that target cells in the vicinity of
the signal-emitting cell —
a. Signals released by one cell type can travel long distances to target cells of another cell type.
(End 4.1)

4. Topic 4.2 Introduction to Signal Transduction
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Cells communicate by generating, transmitting, receiving, and responding to
chemical signals.
(4.2 cont. next slide)
1. 2. 3.Click HERE to view Mr. Anderson’s
(Bozeman Science) video on
Signal Transduction Pathways

5. Learning Objective: Describe the components of a signal transduction pathway.
Essential Knowledge: Signal transduction pathways link signal reception with cellular responses.
(4.2 cont. next slide)

6. Learning Objective: Describe the components of a signal transduction pathway.
Essential Knowledge: Many signal transduction pathways include protein modification and phosphorylation cascades.
(4.2 cont. next slide)
TRANSDUCE - to convert (something,
such as energy or a message) into
another form.

7. Learning Objective: Describe the role of components of a signal transduction pathway in producing a
cellular response.
Essential Knowledge: Signaling begins with the recognition of a chemical messenger—a ligand—by a receptor protein in
a target cell—
a. The ligand-binding domain of a receptor recognizes a specific chemical messenger, which can be a peptide
(hormone), a small chemical, or protein, in a specific one-to-one relationship.
b. G protein-coupled receptors are an example of a receptor protein in eukaryotes.
(4.2 cont. next slide)

8. (4.2 cont. next slide)
Essential Knowledge: Signaling cascades relay signals from receptors to cell targets, often amplifying the incoming
signals, resulting in the appropriate responses by the cell, which could include cell growth, secretion of molecules, or
gene expression —
a. After the ligand binds, the intracellular domain of a receptor protein changes shape initiating transduction of the
signal.
Consider:

1.What is the ligand in this diagram?
2.What are the 3 domains of the receptor? Hint: see last
slide
3.Which domain changes shape?
4.How is this transduction?

9. (4.2 cont. next slide)
Essential Knowledge: Signaling cascades relay signals from receptors to cell targets, often amplifying the incoming
signals, resulting in the appropriate responses by the cell, which could include cell growth, secretion of molecules, or
gene expression —
a. After the ligand binds, the intracellular domain of a receptor protein changes shape initiating transduction of the
signal.
b. Second messengers (such as cyclic AMP or cAMP) are (small, non-protein) molecules (or ions) that relay and
amplify the intracellular signal.
Secondary Messengers - small, non-protein intermediate
messengers molecules or ions in the pathway.

Examples: cyclic AMP/cAMP, Ca
2+
, IP
3

Advantages over protein:
●Speed - rapid diffusion
●Amplification - the preceding protein may produce 10K
secondary messengers.

Common pathways with secondary messengers :
●Insulin signaling pathway
●Apoptosis (programmed cell death)
●Fertilization of egg by sperm
Click HERE to view
Secondary Messengers in Cell Signalling
(Katherine Hubbard)

10. (End 4.2)
Ligands can open or close
ligand-gated channels.

Click HERE to view
a Walter John video
of a ligand opening
a ligand-gated channel.
Essential Knowledge: Signaling cascades relay signals from receptors to cell targets, often amplifying the incoming
signals, resulting in the appropriate responses by the cell, which could include cell growth, secretion of molecules, or
gene expression —
a. After the ligand binds, the intracellular domain of a receptor protein changes shape initiating transduction of the
signal.
b. Second messengers (such as cyclic AMP or cAMP) are (small, non-protein) molecules (or ions) that relay and
amplify the intracellular signal.
c. Binding of ligand-to-ligand-gated channels can cause the channel to open or close.

11. Pause and Reflect
on
Cell Signalling
by clicking on this
Amoeba Sisters
Intro to Cell Signaling
video.

12. Topic 4.3 Signal Transduction
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Cells communicate by generating, transmitting, receiving, and responding to
chemical signals.
(4.3 cont. next slide)
Essential Knowledge: Signal transduction pathways influence how the cell responds to its environment.
Learning Objective: Describe the role of the environment in eliciting a cellular response.
Watch this TED Archive video entitled, Quorum sensing: Bacteria talks
(with Bonnie Bassler) to learn about…

…“use of chemical messengers by microbes to communicate with other nearby
cells (microbes) and to regulate specific pathways in response to population
density (quorum sensing)...

…and how researchers are working to develop medicines to combat bacterial
infections that depend on this communication to overwhelm their host.
A MICROBE is defined as a very small organism that causes disease,
including bacteria, archaea, fungi, protists, and (non-living) viruses.

13. (4.3 cont. next slide)
Watch Mr. Anderson (Bozeman Science) explain how chemical signaling is used during the
Fight or Flight Response for communication among many organs / tissues / cells of the
body in response to environmental stimuli…

…by releasing epinephrine (adrenaline), which stimulates the breakdown (hydrolysis) of
glycogen into glucose in mammals…

… and leads to variety of beneficial responses in numerous organ systems / tissues / cells.
GLYCOGEN is a polysaccharide (large carbohydrate) storage molecule
primarily made and stored in the liver and skeletal muscle cells of animals.
We learned about glycogen in Unit 1 - Chemistry of Life. Glycogen is
broken down into glucose by hydrolysis.
Cell communication (and signal transduction) is also used for “ epinephrine stimulation of
glycogen breakdown in mammals.”
Also watch this animation of How Epinephrine Works - causes signal transduction and a
cascading phosphorylation leading to a cell response (hydrolysis of glycogen into glucose).

14. (4.3 cont. next slide)
Essential Knowledge: Signal transduction may result in changes in gene expression and cell function,
which may alter phenotype or (may) result in programmed cell death (apoptosis).
Learning Objective: Describe the different types of cellular responses elicited by a signal transduction
pathway
Big picture understanding… DNA is the instructions/code for making
proteins. A gene is a segment of DNA that codes for making one
protein, which controls one trait.
As seen in the diagram, the cell response targeted by signal transduction
pathways is sometimes the expression of genes.

The affected gene/protein can be one that determines a physical trait
(phenotype) of an organism. Likewise, it can also be the gene that
regulates apoptosis (programmed self destruction or cell death).
To understand apoptosis and how signal
transduction can affect it, watch this
(Professor Dave Explains) video entitled,
Apoptosis: Programmed Cell Death.

15. (End 4.3)
Intrigued?… Click on a link in the magnifying glass below for additional specific examples of gene expression
affected by signal transduction pathways.
Cytokines
Mating Pheromones in Yeast
SRY Genes
Ethylene Levels & and Ripening
HOX Genes & Embryo
Development

16. Topic 4.4 Changes in Signal Transduction Pathways
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Cells communicate by generating, transmitting, receiving, and responding to
chemical signals.
(4.4 cont. next slide)
Essential Knowledge: Changes in signal transduction pathways can alter
cell response —

a. Mutations in any domain of the receptor protein or in any component of the
signaling pathway may affect the downstream components (and the cell
response) by altering the subsequent transduction of the signal.
Learning Objective: Explain how a change in the structure (form) of any signaling molecule affects the activity (function) of the
signaling pathway.
MUTATION - a random error in the sequence of nucleotides in DNA or RNA.
Form = Function: Likewise, a change in form = a change in function! This
includes proteins in signal transduction pathways!
Note: Different segments of a protein serve different functions. If the mutation affects the
ligand-binding domain, then the ligand’s ability to bind will be affected. If the intracellular
domain of the receptor protein is affected, then the next step in the pathway may be affected.
CLICK HERE to view the
DNA Learning Center video entitled,
The Central Dogma of Biology.

17. (4.4 cont. next slide)
Mutations and Disease

Mutations that affect cell signal transduction pathways are
the cause of many diseases, such as those listed below.
Click on the name of a disease for information from the
CDC - Centers for Disease Control and Prevention:

●Cancer (CDC)
●Alzheimer’s (CDC - website)
●Parkinson’s (Mayo Clinic - website)
●Diabetes (CDC)
●Multiple Sclerosis (Mayo Clinic - video)
●Huntington’s (Mayo Clinic - website)

CLICK HERE - To view the WEHI website overview of
cell signaling, including the connection between
mutations and disease (Walter and Eliza Hall Institute of
Medical Research).

18. (End 4.4)
Essential Knowledge: Chemicals that interfere with any component of the signaling pathway may activate
or inhibit the pathway.
ACTIVATORS - Molecules that increase the activity of an enzyme.
WATCH THIS Khan Academy video on activation and Inhibition of signal transduction pathways.
●Enzyme activators are chemical compounds that speed-up reaction (opposite of inhibitors).
●Include small organic molecules, peptides, proteins, lipids, and ions (ex. Ca
2+
).
●The second messenger Ca
2+
is an activator of adenylyl cyclases, protein kinases, and phospholipases.
WATCH THIS Biology Dictionary video for Topic 4.4 entitled, Changes in Signal
Transduction Pathways: Genetic Diseases and Pathway Inhibitors.
INHIBITORS - Molecules that decrease the activity of an enzyme.
●Upstream (earlier) disruptions to the pathway affect cell response more.
●Competitive inhibitors can be offset by increasing substrate concentration.
●Noncompetitive inhibitors affect enzymes no matter how much substrate is added.

19. Topic 4.5 Feedback
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Timing and coordination of biological mechanisms involved in growth, reproduction, and
homeostasis depend on organisms responding to environmental cues.
(End 4.5)
Learning Objectives; Essential Knowledge:
1) Describe positive and/ or negative feedback mechanisms; Organisms use feedback
mechanisms to maintain their internal environments and respond to internal and external
environmental changes.

2) Explain how negative feedback helps to maintain homeostasis; Negative feedback mechanisms
maintain homeostasis for a particular condition by regulating physiological processes. If a system is
perturbed, negative feedback mechanisms return the system back to its target set point. These
processes operate at the molecular and cellular levels.

3) Explain how positive feedback affects homeostasis; Positive feedback mechanisms amplify
responses and processes in biological organisms. The variable initiating the response is moved
farther away from the initial set point. Amplification occurs when the stimulus is further activated,
which, in turn, initiates an additional response that produces system change.
CLICK HERE to view a Beverly Biology video entitled, Negative vs. Positive Feedback.
Negative feedback mechanisms/loops oppose change (work to maintain homeostasis).
Positive Feedback mechanisms/Loops encourage more change.

20. Topic 4.6 Cell Cycle
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Heritable information provides for continuity of life.
(4.6 cont. next slide)
Learning Objective: Describe the events that occur in the cell cycle.

Essential Knowledge:

●In eukaryotes, cells divide and transmit genetic information via two highly
regulated processes


●The cell cycle is a highly regulated series of events for the growth and
reproduction of cells—

a. The cell cycle consists of sequential stages of interphase (G1, S, G2),
mitosis, and cytokinesis.

b. A cell can enter a stage (G0) where it no longer divides, but it can
reenter the cell cycle in response to appropriate cues. Nondividing cells
may exit the cell cycle or be held at a particular stage in the cell cycle.
Click here for
Cell Cycle Video
(Nucleus Biology)

21. Topic 4.6 Cell Cycle
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Heritable information provides for continuity of life.
(End 4.6)
Learning Objective: Explain how mitosis results in the transmission of
chromosomes from one generation to the next.

Essential Knowledge:

Mitosis is a process that ensures the transfer of a complete genome from
a parent cell to two genetically identical daughter cells—

a. Mitosis plays a role in growth, tissue repair, and asexual
reproduction.

b. Mitosis alternates with interphase in the cell cycle.

c. Mitosis occurs in a sequential series of steps (PMAT =
prophase, metaphase, anaphase, telophase).
Click here for
Mitosis Video
(Nucleus Biology)

22. Topic 4.7 Regulation of the Cell Cycle
Big Idea: IST - Living systems store, retrieve, transmit, and respond to information essential to life processes.
Enduring Understanding: Heritable information provides for continuity of life.
(4.7 cont. next slide)
Learning Objective: Describe the role of checkpoints in regulating the cell cycle.

Essential Knowledge:

A number of internal controls or checkpoints regulate progression through the
cycle.

Interactions between cyclins and cyclin-dependent kinases control the cell cycle.

Exclusion Statement: Knowledge of specific cyclin - CdK pairs or growth factors
is beyond the scope of the course and the AP Exam.
Click here for a video on
Cell Cycle Control (Kahn
Academy)

23. Click here to watch a
Cancer Video
(TED Ed). (End 4.7)
Learning Objective: Describe the effects of disruptions to the cell cycle on the cell or organism.

Essential Knowledge: Disruptions to the cell cycle may result in cancer and/or programmed cell death (apoptosis).
Click here for a video on
Apoptosis
(Professor Dave Explains).
Click here for
Mr. Anderson’s video,
What is Cancer?