Exam 3 Material Summary

Bio 212 SI
Exam 3
Chapter 9 (sections 1-3) Cell Communication
Cell communication is the process of sending a signal to induce a specific cellular
response on a target cell.
To receive the signal and the target cell must have the appropriate receptor.
Be able to list a few reasons cell-to-cell communication is necessary in an
organism and understand the phototropism example on page 178.
Compare, contrast and think of an example for each of the following:
-Direct intercellular signaling- signals being passed through gap junctions in
adjacent cells.
-Contact-dependent signaling- adjacent cells communicating via outermembranous signal and receptor
-Autocrine signaling- a cell releasing a signal that will affect surrounding target
cells as well as itself
-Paracrine signaling- a cell releasing a signal to affect surrounding target cells only
-Endocrine signaling- a cell sending a signal long range (through bloodstream) to
target cell
An overview of the three stages of cellular response, be able to diagram the general
1. Receptor Activation- ligand binds to receptor (lock and key) alters shape of
“activated” receptor protein inside the cell.
2. Signal Transduction- change in activated receptor protein transmits signal
across various proteins inside the cell (usually via phosphorylation)
3. Cellular Response- Intracellular target (enzyme, structural proteins or
transcription factors) are affected and produce the intended response. Understand
what response is being called for with each of the previous listed possible targets.
Know how steroid hormones and peptide hormones affect a cell differently.
Which ones can penetrate the phospholipid membrane directly? What’s an
Diagram a ligand-gated ion channel.
Understand the epidermal growth factor (EGF) example of cell signal transduction.
Understand that secondary messengers not only transmit a signal, but also can
amplify it and speed it up. What would the benefits of that be?
Chapter 36 (section 1-3) Plant Behavior
Behavior is a response in an organism to any stimuli (touch, light, gravity,
chemicals, pathogens). Stimuli can be internal or external, be able to identify
examples from each category.
Tropism is a growth response that is dependent on a stimulus, which favors a
direction. So be able to identify phototropism, gravitropism, and thigmotropism.
Auxin is an example of an important plant chemical that can affect the structure,
development and behavior of a plant, make sure you understand that example.
Other plant hormones include cytokinin and gibberellin.
Chapter 10 (sections 1-3) Muliticellularity
An ExtraCellular Matrix (ECM) is a network of material formed outside a cell from
its own cellular secretions. It is made of proteins and polysaccharides and play roles
involving strength, structural support, organization and cell signaling.
What are the functions of adhesive and structural proteins of the ECM in animals? In
what tissues of the human body would you expect to find them?
The primary cell wall of plants is made of mostly cellulose with cross-linking
glycan and pectin fibers; it is somewhat flexible to allow cell growth. The optional
secondary cell wall layers are composed of only cellulose. Primary and secondary
cell walls are named in the order that they are produced.
Instead of cell walls animals use cellular junctions for support. There are various
types of these linkages.
- Anchoring junctions bind adjacent cells or a cell to the ECM. Include four types
(Adherins, desmosomes, hemidesmosomes, and focal adhesions)
- Tight Junctions bind adjacent cells, do not allow material passage.
- Gap junctions allow ions and small molecules to pass between adjacent cells.
Think of direct-intercellular signaling.
-Plasmodesmata (plant specific) provide a passageway between adjacent cells,
which can open or close.
Cellular Adhesion Molecule (CAM) can be a cadherin or integrin. Cadherins create
cell to cell bonds. Integrins create connections between cells and the extracellular
matrix. Integrin mutations are related to mobility of cancerous cells.
From cell to tissue to organ, an animal must undergo cell division, cell growth,
differentiation, migration, apoptosis, and form cell connections. Understand the
processes and their order, it should be evident.
Animals have many types of tissues.
-Epithelial (skin, top layer and intestinal linings)
-Nervous (brain and other nerve tissues)
-Muscle (cardiac, skeletal, and smooth)
-Connective (cartilage, tendon, fat, bone)
Plants have multiple types of tissue as well.
-Dermal (outer covering of leaves and root)
-Ground (parenchyma, collenchyma, and sclerenchyma) which photosynthesize,
store carbohydrates and provide support.
-Vascular (xylem and phloem) transport water and minerals as well as nutrients,
Chapter 19 (sections 1-3) Development
Development- series of changes to a cell, tissue, organ or organism.
Morphology- the form of an organism.
Morphogen- a chemical that promotes developmental changes at a certain position
on the cellular level.
A Zygote is a fertilized egg and a singular cell. The zygote grows, divides and
develops into a multicellular embryo. Determination is when a cell has
committed to a specific path of development and it will make itself different than
other cells to perform a specific function (Differentiation).
Understand the characteristics and uses of a model organism; be able to explain
experimentally how they are used to track cell determination and organism
Pattern formation occurs in both animal and plants. Animals organize along a
dorsoventral axis, anteroposterior axis and left-right axis. Know how each of
these planes dissect the body. Plants organize along a root-shoot axis (vertical) as
well as in a radial pattern (spiral around stem).
Differential gene regulation is a hierarchy of transcription factor control on
whether or not certain genes are expressed. Remember that all of our cells have the
same DNA, and thus the same potential, yet we have such highly differentiated cells!
The fate of a cell is its ultimate morphology at maturity.
Homeobox genes affect pattern formation and activate the transcription of certain
genes. Hox genes or homeobox containing organisms can be analyzed across
multiple organisms (page 401).
Totipotent > Pluripotent > Multipotent > Unipotent I assume you can dissect
the meaning of each prefix and potent= potential. Know an example of each. What
is a meristem an example of?
Sufficient= the organism could survive/expression of a gene can occur on this
substance ALONE.
Necessary= organism cannot survive without it, but other factors are also needed.
Understand the MyoD experiment and the ideas of loss-of-function and gain-offunction.
Chapter 35 (section 2) Plants Form and Function
Plants develop in four general steps
- development and maintenance of characteristic architecture throughout life
- increase in length by the activity of apical meristems
- maintenance of a population of youthful stem cells in meristems
- expansion of cells in controlled directions by water intake
Expansins unzip cross-linked cell walls of cellulose so cell wall can stretch and cell
can grow.
Compare and contrast fibrous root system, taproot system and adventitious