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Unit 4 of AP Biology: Cell Communications and Cell Cycle study guide
G1
G1 is the first phase of interphase where the cell grows and prepares for DNA replication.
Prophase
The first stage of mitosis, where chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the mitotic spindle begins to form.
Cellular division
The process by which a parent cell divides into two or more daughter cells, including mitosis and meiosis.
DNA
The molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known living organisms and many viruses.
Single chromosome
a structure consisting of a single DNA molecule and associated proteins, representing the condensed form of genetic material during cell division. (interphase)
G protein
A molecular switch that transmits signals from outside the cell to its interior, playing a crucial role in various cellular processes.
Centromere
The region of a chromosome where the two sister chromatids are joined together, playing a key role in the separation of chromosomes during cell division.
telophase
The final stage of mitosis, during which the chromosomes decondense, the nuclear envelope re-forms, and the cell prepares to divide into two daughter cells.
mutated genes
Genes that have undergone a change in their nucleotide sequence, potentially leading to altered protein function and various genetic disorders.
CDKs and Cyclins
Cyclin-dependent kinases (CDKs) and cyclins are crucial regulators of the cell cycle, where CDKs are enzymes that, when activated by binding to cyclins, phosphorylate target proteins to drive cell cycle progression.
End product
of cellular processes such as metabolism or signaling, resulting in specific molecules or structures necessary for cell function.
Signal transduction
The process by which a cell converts an extracellular signal into a functional response, involving a series of molecular events including receptor activation, signal amplification, and cellular response.
Tumor suppressor genes
genes that help prevent uncontrolled cell growth by regulating the cell cycle and repairing DNA damage.
Signal transduction cascades
are sequences of biochemical events that amplify a signal and lead to a cellular response, often involving multiple proteins and second messengers.
Interphase
The phase of the cell cycle during which a cell prepares for division, confine G1, S, and G2 phases.
receptor
a protein that binds to signaling molecules and initiates a cellular response.
DNA damage
refers to alterations in the DNA structure that can lead to mutations or cell cycle arrest, often triggering repair mechanisms or apoptosis.
ion channels
proteins that allow ions to pass through the cell membrane, playing a critical role in cellular signaling and homeostasis.
Positive feedback pathway
a biological process where the output of a system enhances or amplifies the initial stimulus, leading to an increased response.
Plasma membrane receptors
are proteins located on the cell surface that bind to signaling molecules, initiating cellular responses and communication.
cell cycle
the series of events that take place in a cell leading to its division and duplication, consisting of phases such as interphase and mitosis.
symbiosis
a close and long-term interaction between two different biological species, which can be mutualistic, commensalistic, or parasitic.
G- protein
a family of proteins that act as molecular switches inside cells, involved in transmitting signals from various stimuli outside a cell to its interior.
cancer
a disease caused by uncontrolled cell division, leading to the formation of tumors and the potential spread of malignant cells throughout the body.
cellular differentiation
the process by which a less specialized cell becomes a more specialized cell type, allowing for the development of distinct cell functions and structures.
centrioles
cylindrical structures found in animal cells that play a key role in cell division by organizing the mitotic spindle.
Explain how cells communicate with one another over short and long distances
Cells communicate over short distances by using local regulators that target cells in the vicinity of the signal-emitting cell –
Signals released by one cell type can travel long distances to target cells of another cell type.
Describe the ways that cells can communicate with one another
Cells communicate with one another through direct contact with other cells or from a distance via chemical signaling –
Cells communicate by cell-to-cell contact
Describe the components of a signal transduction pathway
Signal Transduction pathways link signal reception with cellular responses.
Many signal transduction pathways include protein modification and phosphorylation cascades.
Describe the role of components of a signal transduction pathway in producing a cellular response
Signaling begins with the recognition of a chemical messenger – a ligand – by a receptor protein in a target cell-
The ligand-bonding domain of a receptor recognizes a specific chemical messenger, which can be a peptide, a small chemical, or protein, in a specific one-to-one relationship.
G protein-coupled receptors are an example of a receptor protein in eukaryotes.
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 –
After the ligand binds, the intracellular domain of a receptor protein changes shape, initiate a transduction of the signal.
Second messengers (such as cyclic AMP) are molecules that relay and amplify the intracellular signal.
Binding of ligand-to-ligand-gated channels can cause the channel to open or close.
Describe the role of the environment in eliciting a cellular response
Signal transduction pathways influence how the cell responds to its environment
Describe the different types of cellular responses elicited by a signal transduction pathway
Signal transduction may result in changes in gene expression and cell function, which may alter phenotype or result in programmed cell death (apoptosis).
Explain how a change in the structure of any signaling molecule affects the activity of the signaling pathway
Changes in signal transduction pathways can alter cellular response –
Mutations in any domain of the receptor protein or in any component of the signaling pathway may affect the downstream components by altering the subsequent transduction of the signal.
Chemicals that interfere with any component of the signaling pathway may activate or inhibit the pathway.
Describe positive and/or negative feedback mechanisms
Organisms use feedback mechanisms to maintain their internal environments and respond to internal and external environmental changes.
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.
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.
Describe the events that occur in the cell cycle
In eukaryotes, cells divide and transmit genetic information via two highly regulated processes.
The cell cycle is a highly regulated series of events of the growth and reproduction of cells –
The cell cycle consists of sequential stages of interphase (G1, S, G2), mitosis, and cytokinesis.
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.
Explain how mitosis results from the transmission of chromosomes from one generation to the next
Mitosis is a process that ensures the transfer of a complete genome from a parent cell to two genetically identical daughter cells –
Mitosis plays a role in growth, tissue repair, and asexual reproduction.
Mitosis alternates with interphase in the cell cycle.
Mitosis occurs in a sequential series of steps (prophase, metaphase, anaphase, telophase).
Describe the role of checkpoints in regulating the cell cycle
A number of internal controls or checkpoints regulate progression through the cycle.
Interactions between cyclins and cyclin-dependent kinases control the cell cycle
Describe the effects of disruptions to the cell cycle on the cell or organism
Disruptions to the cell cycle may result in cancer and/or programmed cell death (apoptosis
Prophase
DNA condenses into visible chromosomes and mitotic spindle begins to form.
Metaphase
The nucleus dissolves and the cells chromosomes condense and move together aligning in the center of the cell (the metaphase plate).
Anaphase
Sister chromatids separate from each other and are pulled towards opposite ends of the cell.
Telophase
The duplicated genetic material is moved to opposite ends of the poles (ends of cell) and cell begins to seperate
cytokinesis
separates cell into two daughter cells with genetically identical DNA
