Multiple Choice Questions for Modules 8 & 9

Signal transduction pathway

A series of molecular events and interactions that lead to a cellular response following the binding of a signaling molecule to a receptor.

Local regulator

A signaling molecule that diffuses a short distance to stimulate nearby cells.

Paracrine signaling

A form of cell signaling in which a cell produces a signal to induce changes in nearby cells.

Ligand-gated ion channel

A type of receptor that opens an ion channel in response to the binding of a ligand.

Protein kinase A (PKA)

An enzyme that is activated by cyclic AMP (cAMP) and phosphorylates target proteins.

G protein-coupled receptors (GPCRs)

A large family of receptors that detect molecules outside the cell and activate internal signal transduction pathways.

Receptor tyrosine kinase (RTK)

A type of receptor that, upon binding with a ligand, dimerizes and autophosphorylates to activate signaling pathways.

Phosphatases

Enzymes that remove phosphate groups from proteins.

cAMP

Cyclic adenosine monophosphate, a second messenger that is produced by adenylyl cyclase.

Apoptosis

Programmed cell death that occurs in multicellular organisms.

Amplification of the signal

The process in a signal transduction pathway where a single signal leads to the activation of multiple downstream proteins.

Cell division

The process by which a parent cell divides into two or more daughter cells.

Eukaryotic cells

Cells that contain a nucleus and other organelles enclosed within membranes.

Chromosomes

Structures within cells that contain DNA and carry genetic information.

S phase

The phase of the cell cycle in which DNA is replicated.

Mitosis

A process of cell division that results in two genetically identical daughter cells.

Genetically identical cells

Cells that have the same genetic material as the parent cell.

Phases of mitosis

The stages of mitosis include prophase, metaphase, anaphase, and telophase.

Centromere

The region of a chromosome where the two sister chromatids are joined.

Kinetochore

A protein structure on the chromosome that attaches to the spindle fibers during cell division.

Sister chromatid

One of the two identical halves of a duplicated chromosome.

Chromatin

The material of which the chromosomes of organisms are composed, consisting of protein, RNA, and DNA.

Genetic variation

Differences in DNA sequences among individuals.

Cell specialization

The process by which generic cells change into specific cells meant to do certain tasks.

Plasmids

Small, circular DNA molecules found in bacteria that are separate from chromosomal DNA.

Metaphase

During metaphase, chromosomes are aligned at the metaphase plate.

Separation of sister chromatids

The separation of sister chromatids occurs during anaphase.

Cytokinesis in animal cells

Cytokinesis in animal cells involves the formation of a cleavage furrow.

Mitotic spindle

The mitotic spindle is composed of microtubules.

Cell cycle checkpoints

Cell cycle checkpoints are important because they ensure the accuracy of DNA replication and chromosome segregation.

MPF

MPF, a key regulator of the cell cycle, is composed of cyclin and a protein kinase.

Cancer cells

Cancer cells differ from normal cells in that cancer cells may continue to divide even when tightly packed.

G1 phase

A cell that is metabolically active but not preparing to divide is in G1 phase.

Signal transduction

The process of signal transduction usually begins when a cell receives a signal.

Characteristic feature of cancer cells

A characteristic feature of cancer cells is metastasis.

Cell cycle phase labeled 'X'

In the figure, the phase labeled 'X' represents G1 phase.

Molecules involved in cell signaling

The molecules commonly involved in both cell signaling and the regulation of the cell cycle are protein kinases.

Relation of cell cycle and cancer

Cancer is the uncontrolled cell cycle.

Primary role of mitosis

The primary role of mitosis is to produce diploid cells.

Chromosome duplication

Chromosomes duplicate during S phase.

Proteins attached to centromeres

The proteins attached to centromeres are kinetochores.

Division of cytoplasm

The division of cytoplasm is called cytokinesis.

Structure that divides plant cells

The structure that divides the cell in plant cells is called the cell plate.

Main steps of cell division

The two main steps of cell division are mitosis and cytokinesis.

Longest phase of the cell cycle

The longest phase of the cell cycle is interphase.

Non-dividing phase of the cell cycle

The non-dividing phase of the cell cycle is called G0 phase.

S phase

A phase of the cell cycle where DNA is replicated.

G0 phase

A resting phase where the cell is not actively preparing to divide.

M phase

The phase of the cell cycle where mitosis occurs.

G2 phase

The phase of the cell cycle where the cell prepares for mitosis.

Cell cycle checkpoints

To ensure the accuracy of cell division.

Major component of organic molecules

Carbon (C).

Type of chemical bond in water

Covalent bond.

Characteristic of a buffer solution

It resists changes in pH.

Krebs cycle location

mitochondrial matrix in eukaryotes

Acetyl CoA and oxaloacetate

Combine to form citrate.

Produced during the Krebs cycle

ATP.

Main purpose of the Krebs cycle

Oxidize glucose to CO2.

NOT directly involved in the Krebs cycle

DNA.

ATP produced by one glucose in Krebs cycle

2 ATP.

Ultimate fate of carbons in glucose

Released as CO2.

Role of oxygen in cellular respiration

To accept electrons at the end of the electron transport chain.

Most ATP produced in cellular respiration

Oxidative phosphorylation.

Processes occurring in the cytoplasm

Glycolysis.

Energy released during Krebs cycle

Carried by NADH and FADH2.

Lack of cellular respiration

ATP.

Example of potential energy

A molecule of glucose.

Enzymes function as

Catalysts.

NOT a characteristic of enzymes

They are consumed in the reaction.

Location where substrate binds to enzyme

Active site.

Energy required to start a chemical reaction

Activation energy.

Reaction that releases energy

Exergonic.

Represents an exergonic reaction

Cellular respiration.