AP Biology Test 12-3-2020

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What are cytokines?

A category of small signlaing proteins that regulate immunity, inflammation, and formation and differentiation of blood cells.

What are cytokines role in the hematopoiesis?

to regulate the formation and differentiation and determine the cells fate.

Explain how so many different cell types are generated from the multipotent hematopoietic stem cell.

they give rise to any cell types of a particular tissue. This helps with creating more cells like the Lymphoid progenitor.

What are the three stages of signal transduction?

Reception\>Transduction\>Response

What happens in the reception stage of signal transduction?

an extra cellular signal molecule binds to its receptor on a target cell.

What happens in the transduction stage of signal transduction?

the activates receptor triggers a chain of biochemical events within the cell. Many different enzymes are involved and the entire reaction is often called a signaling cascade.

What happens in the reaction stage of signal transduction?

the signal cascade results in a specific cellular response.

Why doesn't every cell respond to a signal molecule?

because only cytokines are triggered.

Why is it important that not all cells react to every signal molecule?

some may promote a signal transduction which shouldn't be conducted... or not related to the cell in question

why would signal transduction pathways be under strong selection pressure?

Because failure can result in death of an organism.

Compare how hormones are transported in plants and animals

Hormones are transported around in plants but are not usually transported in animals

what role do plasmodesmata play in cell signaling between plant cells?

They are the tiny cells that the hormones are transferred through.

identify a type of long lasting chemical signal.

Hormones

identify a type of short lasting chemical signal.

Neurotransmitter

How do pheromones differ from the other types of chemical signals?

They are aggressive, they reproduce, and they are territorial.

Explain what is meant by Quorum sensing and describe its biological role.

It is communication between cells through bacteria cells. It helps the bacteria reproduce. It issues the resources and energy well so that they won't be wasted in other parts of the cell.

Briefly outline the process of cell to cell signaling resulting in luminescence in bacteria.

It is controlled by auto inducer that travels between bacteria. Then more auto diver is produced and proteins get involved. Then when the level of autoducer is high enough it activates proteins which stimulates the expression of the genes responsible for producing the proteins involved.

(a)Explain how the autoinducer molecule in luminescent bacteria signals when to luminesce. (b)Explain how this enables the bacterium to detect the population density. (c) how might this information be of survival advantage to the bacterium.

(a)When the level of autoinducer reaches a critical value that the density of the bacteria is high (b) it turns them into proteins (c)Transport messages that don't show high densities of bacteria

Explain how the Che molecules allow a bacterium to move towards or away from a chemical source.

When two Che come together they attach to each other and attach to a flagellum motor that caused clockwise rotation away

Define autocrine cell signaling

happens during growth and development

cell-to-cell communication

Cells interact directly with each other. Special channels bind them together or their complementary proteins on the surface

Local regulation

Binds receptors on nearby cells causing a response

endocrine signaling

Signal that connects cells that are some distance away. May involve hormones or cytokines

Communication by pheromones

Chemical signals that are produced to cause a response in other organisms. Signal molecules are called pheromones and they affect the physiology or behavior of members of the same species

Cytokines and hormones are both involved with endocrine signaling. How do they differ?

Cytokines are for regulating immunity and inflammation. Hormones are for growth and development

Compare direct cell-to-cell communication between animal cells of the immune system and adjacent plant cells.

In cell to cell communication the cells are connected by microscopic tunnels. In adjacent plant cells the cells just have to be adjacent from each other

How could plants regulate the level of cell signaling occurring through plasmodesmata?

They wouldn't have to go through other cells they would just communicate directly with each other.

Contrast the two mechanisms of transcellular transport in plants.

One is over a short distance without use of the plasmodesmata. the other is a long distance with use of the plasmodesmata.

describe a similarity in cell signaling involving local regulation in plants and animals

Both take place between cells. Both cause channels to open and close. Both cells involve are directly connected.

Why must blood glucose levels be tightly regulated?

Because it could result in death it is too high or too low

describe the process by which insulin signaling causes the uptake of glucose into cells

Two molecules of insulin come together to activate the insulin receptor. Phosphate groups are added to the receptor in a process called autophosphorylation. Then the auto phosphorylation of the receptor begins a signal cascade and other proteins come into sequence. Each activate other proteins. The cascade sequence results in the activation of GLU24 secretory vesicles which produce GLU24 glucose transporters.

How does the signal cascade increase the response of the insulin receptor?

it sends more glucose transporters

describe the metabolic effects of growth hormone

Growth deficiencies and abnormal tissue growth resulting in tumors or giantism

describe the two main mechanisms through which the secretion of growth hormone is regulated

It's a peptide bromine that stimulates growth, cell reproduction through endocrine signaling. It's released form the pituitary gland and binds to two adjacent receptors on the liver cells and stimulates a production of proteins called insulin-like growth factor.

predict the effects of low GH levels during infancy

Dwarfism. One small body part one large body part. Body parts that don't fit together and work like they should.

Describe the differences between an intracellular receptor and an extracellular receptor

Intercellular bind signal molecules that have passed into the cell directly across the plasma membrane. Extra cellular bing signal molecules outside of the cell that don't cross the plasma membrane.

what must a signal molecule do in order to activate a receptor?

They have to bind with another molecule

In terms of their ability to cross the plasma membrane, describe the difference between a hydrophobic signal molecule and a hydrophilic signal molecule.

Hydrophilic cannot cross the membrane but the hydrophobic can freely cross the membrane into cytoplasm

outline the process when signal transduction occurs via an extracellular receptor

The first messenger binds to the receptor protein. Protein subunit form the receptor protein and activated the enzyme. Active enzyme produces a second messenger. The second messenger triggers a cascade of phosphorylation that leads to a cellular response.

describe the difference between the first messenger and the second messenger in signal transduction

The whole process begins with the first messenger. The second messenger has to be produced by a triggered active enzyme

Outline the process when signal transduction occurs via an intercellular receptor

It occurs in the plasma membrane and not outside of the cell. Cells travel through the membrane and cytoplasm.

describe how methylation of MCP proteins influences the signal transduction pathway responsible for flagellar rotation in the bacteria

The different receptors are responsible for the chemotaxis and the methylation determines which protein is used and which way it rotates

describe how DNA is repair is signaled in cells

It requires an initiator. It begins a cascade of chemical reactions within the cell that activated the required molecules and transmits the signal to the correct area of the cell.

Explain why a signal cascade can be useful in certain cell processes

It can activate molecules that participate in DNA repair, arrest the cell cycle, or bring about apoptosis.

use the example of DNA damage to explain why there is a strong selection pressure for the correct functioning of signal transduction pathways

Because the DNA can not be wrong but it has to have an initiator to fix the dna.

explain the link between signal transduction and disease

The failure of correct cell signaling can lead to many serious diseases like cancer. Failure to operate properly causes significant detrimental effects.

describe the action of a universal signal transduction inhibitor

They work by affecting the signaling of nerve cells by either blocking uptake of singalong molecules or facilitating the uptake of far greater amounts than normal.

explain how antihistamines prevent hayfever

Some block the histamine receptor of cells to block the signal for the inflammatory response so there is no reaction

Signal molecule

a molecule that relays signals from receptors on the cell surface to target molecules inside the cell

pheromones

These chemical signals are secreted externally by one organism and cause a response in other organisms (usually of the same species

hormone

a signal molecule that is carried in the bloodstream to target cells, often a considerable distance away

ligand

A molecule that binds to another

Cell signaling

the process by which cells use signals (chemical messengers) to communicate and to gather information about, and respond to, changes in their cellular environment

cyclic AMP

a second messenger important in many biological processes

signal transduction

the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events to cause a specific cellular response

Quorum sensing

a process of cell to cell communication between bacterial cells

Phosphorylation cascade

a sequence of events where one enzyme phosphorylates another, causing a chain reaction leading to the phosphorylation of many proteins

receptors

a specific protein molecule that a signal molecule binds to.

second messenger

a molecule that relays signals from receptors on the cell surface to target molecules inside the cell

protein kinase

a kinase enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation)

what is the opposite reaction to condensation?

hydrolysis

signal transduction pathways may be regulated by:

second messengers, transcription factors, and protein methylation

hormones are relatively long lived signals that travel through the bloodstream. This type of signaling is called:

endocrine signaling

what type of signal molecule is used in synaptic signaling?

Neurotransmitters

What prevents other signal molecules from binding to the same receptor?

they do not have complementary shapes to the same receptor

What class of organic molecules does cellulose belong?

carbohydrates

where is the molecule cellulose found?

cell walls

what is the monomer from which cellulose is made?

Glucose

What are the stages of Mitosis?

Prophase, Metaphase, Ananphase, and Telophase

what is the special growth region that forming new cells is restricted to?

meristems

interphase

nondivision portion of the cell

prophase

DNA condenses into chromosomes

metaphase

chromosomes line up in the middle of the cell

Anaphase

chromosomes pull apart to seperate poles

telophase

reform the nucleus

paracrine signals

occurs between cells that are close together.

example of paracrine signals

Synaptic signals between neurotransmitters

Hormones only act on what type of cells?

target cells

example of hormones helping maintain homeostasis

maintaining temperature & blood glucose levels

How do hormones help maintain homeostasis?

by returning the body to a set point (negative feedback)

example of positive feedback

oxytocin increasing uterine contractions in response to cervix stimulation & climate change

direct signaling

gap junctions between plant cells share small molecules via connectors

Autocrine signaling

signaling and target cell are the same or similar

what is an example of autocrine signaling

a cell that is infected with a virus can signal apoptosis (cell death) in itself and neighboring cells

what are the largest and most diverse group of membrane receptors in eukaryotess?

G protein-coupled receptors (GPCR)

What are the two types of receptors?

cell-surface receptors, Ligand Gated Ion channels

what are the steps of intercellular communication

signaling molecule released by one cell binds to a receptor on another cell, signal converted to a form that affects the signal-receiving cell, receiving cell changes in some way as a result of the signal

cephalization

evolutionary process that concentrated neurons that detect and process information at the head

nerve

bundle of neuron fibers wrapped in connective tissue

central nervous system

invertebrates, consists of the brain and spinal cord

peripheral nervous system

nerves that extend from the central nervous system to the rest of the body

sensory neurons

detect a stimulus such as light and touch

interneurons

send and receive signals from other neurons

motor neurons

controls muscles and glands

Glial Cells

act as a framework that holds neurons in place

action potential

a brief reversal in the electric gradient polarity across the membrane

myelin sheath

a discontinuous covering of glial cells that wrap around the axon

synapse

region where an axon terminal signals another cell

synaptic cleft

fluid-filled region between the axon terminal and the receiving (postsynpatic) cell

example of a neurotransmitter

motor neuron releases acetylcholine