Biology 109 Exam Iii Study Guide

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Allowed multi and unicellular organisms to grow very large

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Increased atmospheric oxygen levels

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Zygote

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Diploid cell which is created when a sperm fertilizes an egg

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Blastula

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Early stage of embryonic development, consists of a hollow sphere of cells

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Gastrula

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Early embryonic stage consisting of inner and outer cell layers, results from folding in of blastula

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Nuclear Equivalence

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all of the genetic information necessary to produce the various tissues is found in (essentially) all cells of a developing, multicellular organism

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Somatic Cell

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All cells of an organism except the gametes

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Differentiation

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The determination of cell fates, results from differences in gene expression. Can be caused either by segregation of cytoplasmic determinants or induction by other cells

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Cytoplasmic segregation

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Unequal distribution of a component in the cytoplasm of the cell. Results in unequal distribution in daughter cells and leads to cell differentiation

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Embryonic Induction

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The actions of nearby cells induce changes in cells around them, can result in the formation of organs.

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Determination

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sets the developmental fate of a cell even before unique characteristics of to be cell type are observable

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Morphogenesis

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spacial distribution of differentiated cells in the multicellular body. Caused by : cell division, cell expansion, cell movement, apoptosis

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Totipotent

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a cell that is capable of giving rise to any other type of cell

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Genetic Equivalence

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all information in nucleus of a cell is preserved as the cell passes through early stages of embryonic development

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Multipotent

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cells able to differentiate into a limited number of different cells

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iPS

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induced pluripotent stem cells. Produced by virally injecting genes active in embryonic cells back into adult cells

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ES Cell

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Embryonic Stem Cell. Can be mimicked by nuclear transfusion

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Morphogen Gradient

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signal concentration varies over space, leading to a whole series of different induction events depending on position

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Pattern Formation

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process by which cells acquire positional information. Occurs by Sequential Segregation & Induction and Morphogen Gradient

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Gap Genes

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organize broad areas along the anterior-posterior axis

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Pair Rule Genes

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divide the embryo into units of two segments each

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Segment polarity Genes

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determine the boundaries and anterior-posterior organization of the individual segments

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Hox Genes

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encode a family of transcription factors that are expressed in different combinations along the length of the embryo, and help determine cell fate within each segment

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Maternal Effect Genes

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determine the anterior-posterior axis and induce three classes of segmentation genes

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Evo-Devo

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Many animals and plants share similar molecular mechanisms of morphogenesis
molecular pathways that determine different developmental processes act independently of each other
changes in location and timing of expression of certain genes important in evolution of new structures
much of evolution occurs through modification of existing structures
mechanisms of development are often responsive to environmental conditions

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Modularity

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The molecular pathways that determine different developmental processes operate independently from one another

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developmental plasticity

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the ability of an organism to alter its development to suit its environment

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Endocrine Glands

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Secrete chemical signals into the blood in order to communicate with other cells

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Hormonal Communication

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Slow acting, long lasting

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Axon

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conducts cell away from the cell body of a neuron towards the synapses

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Synapse

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junction between a neuron and another cell across which chemical signals are passed

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Dendrites

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conduct signals into the cell body of a neuron

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Resting Potential

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Charge difference across the membrane of a neuron at rest

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Action Potential

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rapid change of charge distribution that travels down the neuron undiminished

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Saltatory Conduction

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conduction of an action potential along a myelinated axon between nodes of Ranvier.

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Glia

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cells which support neurons physically, immunologically, and metabolically

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Astrocytes

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glia which insulate blood vessels in the brain, protecting it from harmful chemicals in the blood

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Inhibitory synapse

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decrease likelihood of an action potential, generally by causing hyperpolarization, e.g. open K+ channels

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Spatial summation

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adds up different stimuli at different sites on a post-synaptic membrane

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Temporal summation

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adds up signals generated at the same site in rapid succession

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Neurotransmitters

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Endogenous chemicals that relay, amplify, and modulate signals between a neuron and another cell

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Excitatory Synapse

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increase likelihood of an action potential, generally by causing depolarization, e.g. open Na+ channels

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Mechanoreceptor

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pressure opens an ion channel

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Thermoreceptor

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Temperature influences a membrane protein that is a cation channel or is closely associated with the channel

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Electroreceptor

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An electrical charge opens an ion channel

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Chemoreceptor

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A molecule binds to a receptro, initiating a signal that controls the ion channel via second messenger cascade

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Photoreceptor

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light alters a receptor protein, initiating a signaling cascade that controls an ion channel