BIol final

In a eukaryote, transcription factors called activators may stimulate gene expression by binding to DNA sites called \__________.

enhancers

IP3 (inositol triphosphate) is produced as a result of \__________.

the cleavage of a specific phospholipid in the plasma membrane

What is the correct order of the neural pathways that light travels after hitting the retina?

photoreceptors, bipolar cells, ganglion cells, optic nerve

What is a natural pain reliever?

endorphins

What is a correct pairing of a synapse and its characteristic?

electrical synapses and gap junctions

chemical synapses match up with

ligand gated ion channels

enhancers characteristics

1. increases the rate of transcriptions

2. may be located thousands of base pairs away from the promoter

3. are found in eukaryotic genomes

4. may be located upstream or downstream from the genes they regulate

What kind of receptors consists of neurons with naked dendrites?

nociceptors; pain receptors in the epidermis of the skin

Post-transcriptional controls of gene expression \__________

1. can include changes in mRNA stability
2. may involve changes to the rate at which an mRNA is translated
3. may involve regulation of mRNA splicing
4. can include translational controls

Example of the role of the local regulator nitric oxide

When oxygen levels fall, nitric oxide activates an enzyme that relaxes smooth muscle. This dilates blood vessels and improves blood flow.

Which hormones have ANTAGONISTIC effects?

insulin and glucagon; these hormones decrease and increase blood sugar respectively

The binding of a signal molecule to a ligand-gated ion channel \__________.

affects the membrane potential

As a young girl, Maria suffered a head injury that damaged her pituitary. An injury to the pituitary is particularly serious because of all the functions controlled by this gland. As Maria got older, she and her doctors found that all of the following EXCEPT her \__________ were affected.

blood sugar level; water regulation, menstrual cycle, growth, and metabolic rate were affected

A high rate of gene transcription in eukaryotic cells is usually dependent on \__________.

specific binding of activator molecules to enhancers and protein-protein interactions that are promoted by the activation domains of activator proteins

the endocrine system relies on \____________ that \______________ all of the cells in the body

hormones ..... reach

How are neurons structurally adapted to chemically transmit impulses to neighboring neurons?

axon terminals contain neurotransmitter within synaptic vesicles

Although the number of genes in the human genome is surprisingly low compared to less complex organisms, the number of possible products from those genes is greatly amplified by \__________.

alternate arrangements of exons from a primary transcript

A cancer cell \_________

does not respond to the chemical signals that control cell division

In what way can cancer be hereditary?

One or two of several mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer.

Action potentials are generated along a neuron because \__________.

depolarization of the membrane at one point causes an increase of permeability to sodium at the next point

Incapacitating the muscles of a mammalian eye would result in an inability \__________.

to focus light onto the retina

The BRCA1 and BRCA2 genes are thought to be what type of genes?

tumor-supressor genes

The regulation of water volume in the blood involves which hormone?

Antidiuretic hormone (ADH)

What is an increase in the magnitude of the membrane potential called?

hyperpolarization

A drug that causes potassium to leak out of a neuron, increasing the positive charge on the outside, would \__________.

inhibit transmission of nerve signals by the neuron

The interplay of multiple excitatory and inhibitory inputs most affects what part of a neuron?

axon hillock

What did Sutherland discover about glycogen metabolism in liver cells?

The hormone epinephrine binds to a specific receptor on the plasma membrane of the liver cell.

The cellular response of a signal pathway that terminates at a transcription factor would be \__________.

the synthesis of mRNA

In insects, ecdysteroid is released \__________.

in response to prothoracicotropic hormone

Both repressible and inducible operons control gene expression at the level of \__________.

transcription

Gene expression in bacteria is regulated primarily by \__________.

controlling the transcription of genes into mRNA

Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?

Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell's nucleus.

Phosphorylation \________

can either activate or inactivate a protein

Correct focusing of the image on the retina in humans is achieved by changing the \__________.

shape of the lens of the eye

What is true about muscle contraction?

Neither thin nor thick filaments change in size, although the area of overlap between them increases.

What is the role of a second messenger in hormone action?

It relays a hormone's message inside a target cell.

The period in which an axon membrane CANNOT generate an action potential is called \__________.

the refractory period

Cytoplasmic determinants \__________.

are coded for by maternal genes

What characterizes our current understanding of cancer development?

In order for a cell to become fully cancerous, it typically must have at least one active oncogene and the mutation or loss of several tumor-suppressor genes.

Receptors for signal molecules \__________.

may be found embedded in the plasma membrane, or found within the cytoplasm or nucleus

Nitric oxide is unusual among animal signal molecules in that it \__________.

is a gas

A G protein is active when \__________.

GTP is bound to it

Domoic acid is a neurotoxin produced by some species of alga. Domoic acid binds to the kainate receptor on neurons in parts of the brain. The kainate receptor facilitates the movement of calcium into the cell. Excess domoic acid-induced stimulation of the neural kainate receptors causes neural damage and short-term memory loss. Based on this, which of the following is likely true?

The kainate receptor is a ligand-gated ion channel and domoic acid is a ligand.

During the transduction of a signal, one molecule or ion may be closely associated with the activity of another. What pairs correctly combines two associated molecules?

1. DAG, IP3
2. cAMP, adenylyl cyclase
3. calcium, IP3
4. cAMP, protein kinase A

A difference between the mechanisms of cAMP and Ca2+ in signal transduction is that cAMP \__________ and Ca2+ \__________.

is synthesized by an enzyme in response to a signal ... is released from intracellular stores

In liver cells, epinephrine stimulates the breakdown of glycogen. As the signal-transduction pathway progresses, \__________.

the signal is amplified

Which of the following statements about apoptosis is true?

Apoptosis is essential for normal development of the nervous system.

Evidence that cell signaling evolved early in the history of life comes from \__________.

the similarity of cell-signaling mechanisms in organisms that have a very distant common ancestor

Certain yeast cells secrete a molecule called the α factor. The purpose of this molecule is to \__________.

stimulate cells of the opposite mating type, a yeast cells, to grow toward the α cell

Second messengers tend to be water-soluble and small. This accounts for their ability to \__________.

rapidly move throughout the cell by diffusion

In an inducible operon, the inducer is often the \__________ in the pathway being regulated; the inducer binds to the \__________, which then becomes \__________.

substrate ... repressor ... inactive

The control of gene expression is more complex in multicellular eukaryotes than in prokaryotes because \__________.

in a multicellular eukaryote, different cells are specialized for different functions

Dioxin, produced as a by-product of various industrial chemical processes, is suspected of causing cancer and birth defects in animals and humans. It apparently acts by entering cells and binding to specific proteins, which then enter the nucleus and alter the pattern of gene expression. Therefore, dioxin acts by mimicking the action of \__________.

steroid hormones

What is involved in controlling eukaryotic gene expression?

1. transcriptional regulation
2. mRNA processing
3. DNA packing
4. methylation of DNA

Specific cells that appear undifferentiated under the microscope but are already fated to become muscle cells are called \__________.

myoblasts

Most human cancers are \__________.

caused by the accumulation of somatic mutations

Why is cancer more prevalent in older people?

Cancer involves an accumulation of mutations, and older people have had more time to accumulate mutations in their DNA.

A scientist clones a regulatory gene that is involved in controlling the expression of other genes, and discovers that the regulatory gene encodes an enzyme that acetylates histones. It is likely that this enzyme regulates gene expression by \__________.

causing looser packing of the chromatin at the target gene, thereby enhancing transcription

What is the evolutionary significance of alternative RNA splicing?

It expands the number of proteins that can be coded for by one gene, increasing an organism's ability to produce novel proteins.

The expression of a gene located in a tightly coiled region of DNA can be promoted by \__________.

histone acetylation

A cell releases a cytokine, which binds to, and acts on, a neighboring cell. This represents an example of \__________.

paracrine signaling

Because most chemical signals are UNABLE to pass through the plasma membrane, the cellular action they initiate results from \__________.

the activation of a signal transduction pathway

What result would you expect following the binding of epinephrine to an α-type epinephrine receptor?

Blood flow to the intestines decreases.

Which of the following hormones is thought to act at the cellular level by inducing a change in gene expression?

estrogen

Hyperthyroidism, typically characterized by a high metabolic rate and high blood pressure, might be expected when \__________.

thyroid-stimulating hormone (TSH) concentration is high

A goiter may form because \__________.

low blood levels of T3 and T4 inhibit the negative feedback loop, and an overload of TSH causes enlargement of the gland

What endocrine organ only stores hormones produced by the hypothalamus?

posterior pituitary

What neurohormone is secreted by the posterior pituitary?

oxytocin

FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are tropic hormones that are also known as \__________.

gonadotropins

WhAT hormones specifically act(s) to trigger secretion of hormones by another endocrine gland? (Concept 45.3) (Chapter 45)

adrenocorticotropic hormone (ACTH)

What are ganglia?

cluster of nerve cell bodies

A neuron that transmits an impulse to the central nervous system after the neuron is stimulated by the environment is called a(n) \__________.

sensory neuron

Which of the following is specifically a part or a function of the central nervous system?

integration

If your fingers touch a hot stove and you suddenly pull back, you have experienced a reflex. What is the correct order of the information processing in this reflex?

sensory input, integration, motor output

Blocking potassium ion channels in a mammalian cell membrane would \__________.

decrease the magnitude of the membrane potential

Threshold is of great significance in the physiology of neurons. What happens if threshold is NOT reached?

positive-feedback depolarization will not occur

An action potential is \__________.

a traveling wave of depolarization in the neuron membrane

Saltatory conduction means that the membrane potential changes \__________.

only at the nodes of Ranvier

Acetylcholinesterase is the enzyme that degrades acetylcholine. What effect on nerve transmission would occur following the administration of a chemical that inhibited acetylcholinesterase?

Continuous excitatory postsynaptic potentials would occur in the postsynaptic neuron.

In humans, making more serotonin available to brain cells typically \__________.

produce an affect on mood

A fish detects vibrations in the water around it by means of its lateral lines, rows of sensory receptors along each side of the body. Based on what you know about sensory receptors, the lateral line receptors are probably which of the following?

mechanoreceptors

If we wait too long between meals, our blood glucose levels drop. Which receptors will respond to this decrease in blood glucose?

chemoreceptors

Organs in the inner ear of mammals are the cochlea, semicircular canals, and vestibule (saccule and utricle). Match them to their functions.

cochlea - hearing

cochlea

hearing

semicircular canals

hearing

saccule

equilibrium

utricle

equilibrium

The brain determines the loudness of a sound from the \__________.

rate of nerve impulses received

A person born without otoliths in the ears would be \__________.

unable to determine the position of the head with respect to gravity

Compound eyes are advantageous for small prey species to detect a potential predator because \__________.

they permit sensitive motion detection

Which of the following correctly traces the path of light into your eyes?

cornea, pupil, lens, retina

What is the fluid in the anterior chamber of the eye?

aqueous humor

The greatest concentration of cone receptors is found at the \__________.

fovea

Which of the following occurs when you move from a bright area into a darkened room?

The iris dilates, increasing the size of the pupil.

A human born with nonfunctional rhodopsin would \__________.

be unable to see in dim light

Difficulty in distinguishing red from green is most likely due to a defect in which cells?

cone cells

Taste and smell are two distinct senses in animals living in terrestrial environments. Animals living in aquatic environments, however, have no distinction between taste and smell. Which response might explain this difference?

The equivalent of air in the terrestrial environment does not exist in an aqueous environment.