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AP BIOLOGY > AP BIO UNIT 4 > Flashcards

AP BIO UNIT 4 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell Communication

A

Cell-to-cell communication is critical for the function and survival of cells. It is responsible for the growth and development of multicellular organisms.

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2
Q

3 Ways Cells Communicate

A

Direct Contact
Local Signaling
Long-Distance Signaling

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3
Q

Direct Contact

A

Communication through cell junctions. Signaling substances and other materials dissolved in the cytoplasm can pass freely between adjacent cells.

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4
Q

Direct Contact in Animal Cells

A

Occurs through gap junctions

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5
Q

Direct Contact in Plant Cells

A

Occurs through plasmodesmata

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6
Q

Direct Contact in Immune Cells

A

Antigen-presenting cells (APCs) communicate to T-cells through direct contact.

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7
Q

Ligand

A

Chemical message

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8
Q

Local Regulators

A

A secreting cell will release chemical messages (local regulators/ligands) that travel a short distance through extracellular fluid. The chemical messages will cause a response in a target cell

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9
Q

2 Types of Local Regulators

A

Paracrine Signaling
Synaptic Signaling

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10
Q

Paracrine Signaling

A

Secretory cells release local regulators (ie. growth factors) via exocytosis to an adjacent cell

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11
Q

Synaptic Signaling

A

Occurs in animal nervous systems. Neurons secrete neurotransmitters. They diffuse across the synaptic cleft space between the nerve cell and the target cell.

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12
Q

Long-Distance Signaling

A

Animals and plants use hormones for long-distance signaling.

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13
Q

Long-Distance Signaling in Plants

A

Release hormones that travel in the plant vascular tissue (Xylem and phloem) or through the air to reach target tissues.

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14
Q

Long-Distance Signaling in Animals

A

Use endocrine signaling. Specialized cells release hormones into the circulatory system where they reach target cells.

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15
Q

Long-Distance Signaling Example - Insulin

A

Insulin is released by the pancreas into the bloodstream where it circulates through the body and binds to target cells.

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16
Q

What type of communication involves a cell secreting a substance to an adjacent target cell?

A

Local Regulators (Paracrine Signaling)

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17
Q

Plant cells in direct contact with each other can diffuse substances through these structures to communicate. What are they?

A

Plasmodesmata

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18
Q

Cell-to-Cell Signaling Overview

A

Reception: ligand binds to receptor
Transduction: signal is converted
Response: a cell’s response alters the cell process

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19
Q

Reception

A

The detection and receiving of a ligand by a receptor in the target cell.

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20
Q

Receptor

A

Macromolecule that binds to a signal molecule (ligand). All receptors have an area that interacts with the ligand and an area that transmits a signal to another protein. Binding between ligand and receptor is highly specific. When the ligand binds to the receptor, the receptor activates (via a conformational change). This allows the receptor to interact with other cellular molecules. Initiates transduction signal. Receptors can be in the plasma membrane or intracellular.

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21
Q

Plasma Membrane Receptors

A

Most common type of receptor involved in signal pathways. Bind to ligands that are polar, water-soluble, large.

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22
Q

Plasma Membrane Receptor Examples

A

G-protein coupled receptors (GPCRs)
Ligand-gated ion channels

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23
Q

Intracellular Receptors

A

Found in the cytoplasm of nucleus of target cells. Bind to ligands that can pass through the plasma membrane

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24
Q

Intracellular Receptors Examples

A

Hydrophobic molecules.
Steroid and thyroid hormones.
Gasses like nitric oxide.

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25
Q

Transduction

A

The conversion of an extracellular signal to an intracellular signal will bring about a cellular response. Requires a sequence of changes in a series of molecules known as a signal transduction pathway.

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26
Q

Signal Transduction Pathway

A

Regulates protein activity through phosphorylation and dephosphorylation. (Change in shape means change in function). During transduction, the signal is amplified.

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27
Q

Phosphorylation in Signal Transduction Pathway

A

Phosphorylation by the enzyme protein kinase relays signals inside the cell.

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28
Q

Dephosphorylation in Signal Transduction Pathway

A

Dephosphorylation by the enzyme protein phosphatase shuts off pathways.

29
Q

Second Messengers

A

Small, nonpolar molecules and ions help relay the message and amplify the response. Cyclic AMP (cAMP) is a common second messenger.

30
Q

Response

A

The final molecule in the signaling pathway converts the signal to a response that will alter a cellular process.

31
Q

Response Examples

A

Protein that can alter membrane permeability. Enzymes that will change a metabolic process. Protein that turns genes on or off.

32
Q

Signal Transduction Pathways can influence…

A

How a cell responds to its environment. They can result in changes in gene expression & cell function. Can alter phenotypes or result in cell death.

33
Q

Changes in Signal Transduction Pathway

A

Mutations to receptor proteins or to any component of the signaling pathway will result in a change to the transduction of the signal.

34
Q

In Eukaryotic Organisms, there are 2 main categories of cell membrane receptors

A

G protein-coupled receptors
Ion Channels

35
Q

G Protein-Coupled Receptors

A

The largest category of cell surface receptors. Important in animal sensory systems. Binds to a G protein that can bind to GTP, which is an energy molecule similar to ATP. The GPCR, enzyme, and G protein are inactive until ligand binding to GPCR on the extracellular side. Ligand binding causes cytoplasmic side to change shape. Allows for G protein to bind to GPCR. Activates the GPCR and G protein. GDP becomes GTP. Part of the activated G protein can then bind to the enzyme which activates the enzyme and amplifies the signal if needed, leading to a cellular response.

36
Q

Ion Channels

A

Ligand-gated ion channels. Located in the plasma membrane. Important in the nervous system. Receptors that act as a “gate” for ions. When a ligand binds to the receptor, the “gate” opens or closes allowing the diffusion of specific ions. Initiates a series of events that lead to a cellular response.

37
Q

Homeostatis Overview

A

The bod must be able to monitor its internal conditions at all times.

38
Q

Set Points

A

Values for physiological conditions that the body tries to maintain. This set points has a normal range for which it can fluctuate Example: body temperature (Set Point: 98.6 F, Set Range: 97-99 F)`

39
Q

Homeostasis

A

The state of relatively stable internal conditions. Organisms can detect and respond to a stimulus (balance) The body maintains homeostasis through feedback loops.

40
Q

Types of Feedback Loops

A

Positive
Negative

41
Q

Stimulus

A

A variable that will cause a response

42
Q

Receptor/Sensor

A

Sensory organs that detect a stimulus. This information is sent to the control center (brain).

43
Q

Effector

A

Muscle or gland that will respond

44
Q

Response

A

Changes (decreases or increases) the effect of the stimulus

45
Q

Negative Feedback

A

The most common feedback mechanism. This type of feedback reduces the effect of the stimulus. Examples (sweat, blood sugar, breathing rate).

46
Q

Positive Feedback

A

This type of feedback increases the effect of a stimulus. Examples (child labor, blood clotting, fruit ripening).

47
Q

Homeostatic Imbalances

A

There are many reasons fo why the body may not be able to regulate homeostasis. Examples (genetic disorders, drug or alcohol abuse, and intolerable conditions (extreme heat/cold)).

48
Q

Disease

A

When the body is unable to maintain homeostasis. Example (cancer: the body cannot regulate cell growth. Diabetes: the body cannot regulate blood sugar levels).

49
Q

Cell Signaling as a Means of Homeostasis

A

In order to maintain homeostasis, the cells ina. multicellular organisms must be able to communicate, Communication occurs through signal transduction pathways.

50
Q

Regulation of the Cell Cycle

A

Throughout the cell cycle, there are checkpoints. Control points that regulate the cell cycles. Cells receive stop/go signals.

51
Q

G1 Checkpoint

A

Most important checkpoint. Checks for cell size, growth factors, and DNA damage. “Go”: cell completes the whole cell cycle. “Stop”: the cell enters a nondividing (quiescent) state known as G0 phase.

52
Q

G0

A

Some cells stay in G0 forever (muscle/nerve cells). Some cells can be called back into the cell cycle.

53
Q

G2 Checkpoint

A

Checks for completion of DNA replication and DNA damage. “Go”: Cell proceeds to mitosis. “Stop”: Cell cycle stops and the cell will attempt to repair damage. If the damage cannot be repaired, the cell will undergo apoptosis (cell death).

54
Q

M (Spindle Checkpoint)

A

Checks for microtubule attachment to chromosomes at the kinetochores at metaphase. “Go”: Cell proceeds to anaphase and completes mitosis. “Stop”: cell will pause mitosis to allow for spindles to finish attaching to chromosomes.

55
Q

Internal Cell Cycle Regulators

A

Regulation of the cell cycle involves an internal control system that consists of proteins known as cyclins and enzymes known as cyclin-dependent kinases (CDKs).

56
Q

Cyclins

A

Concentration of cyclin varies. Cyclins are synthesized and degraded at specific stages of the cell cycle.

57
Q

Cyclin-Dependent Kinases

A

Concentration remains constant through each phase of the cell cycle. Active only when its specific cyclin is present. Each cyclin-CDK complex has a specific regulator effect. Active CDK complexes phosphorylate target proteins, which help regulate key events in the cell cycle.

58
Q

External Cell Cycle Regulators

A

Growth Factors
Contact (Density) Inhibition
Anchorage Dependence

59
Q
A
60
Q

Growth Factors

A

Hormones released by cells that stimulate cell growth. The signal transduction pathway is initiated. CDKs are activated leading to progression through the cell cycle.

61
Q

Contact (Density) Inhibition

A

Cell surface receptors recognize contact with other cells. Initiates signal transduction pathway that stops the cell cycle in G1 phase.

62
Q

Anchorage Dependence

A

Cells rely on attachment to other cells or the extracellular matrix to divide

63
Q

Cancer

A

Normal cells become cancerous through DNA mutations. DNA mutations: changes in the DNA. Cancer cells on average have accumulated 60 or more mutations on genes that regulate cell growth.

64
Q

Normal Cells

A

Follow checkpoints, divide on average 20-50 times in culture, go through apoptosis when there are significant errors.

65
Q

Cancer Cells

A

Do not follow checkpoints. Divide infinitely when in culture (consider “immortal”), evade apoptosis, and continue dividing even with errors.

66
Q

Tumor

A

A mass of tissues formed by abnormal cells

67
Q

Benign Tumor

A

Cells are abnormal, but not considered to be cancerous (yet). Cells remain at only the tumor site and are unable to spread elsewhere in the body.

68
Q

Malignant Tumor

A

Mass of cancerous cells that lose their anchorage dependency and can leave the tumor site.

69
Q

Metasis

A

When cells separate from the tumor and spread elsewhere in the body.

AP BIOLOGY (5 decks)

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