AP Bio Chapter 4

Ap Bio review

signal

A transmitter of information or stimulus.

target cell

A cell that is acted on selectively by a specific agent.

ligands

Any molecule or atom that binds reversibly to a protein.

autocrine

Pertaining to a signal or a signaling molecule that is generated by a cell and that affects that same cell.

gap junctions

Specialized intercellular connections between a multitude of animal cell-types. They directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells.

paracrine

Relating to or denoting a hormone or a secretion which has an effect on nearby cells.

endocrine

Relating to glands which secrete hormones or other products directly into the blood.

receptor

A structure on the surface of a cell or inside a cell that selectively receives and binds a specific substance, which changes the shape of the structure. Important part of cell signaling.

hormone

In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body, changing the target cells' functioning. Important in long-distance signaling.

reception

The action or process of receiving something sent, given, or inflicted.

transduction

The process by which foreign DNA is introduced into a cell by a virus or viral vector.

response

A reaction to something.

conformational change

Change in the shape of a macromolecule, often induced by environmental factors or binding of a ligand.

signal transduction

A series of steps linking a mechanical, chemical or electrical signal on the cell's exterior to changes within the cell. This process ultimately triggers a specific cellular response.

amplification

The act or result of increasing in size or effect, often by production of multiple copies of a molecule.

phosphorylation

The addition of a phosphate group to a molecule.

apoptosis

The death of cells which occurs as a normal and controlled part of an organism's growth or development.

G-protein-coupled receptors

A large protein family of receptors that sense molecules outside the cell and activate signal transduction pathways and, ultimately, cellular responses.

transmembrane

Extending or occurring across a cell membrane.

cyclic AMP (cAMP)

A second messenger important in many biological processes.

second messenger

A substance whose release within a cell is promoted by a hormone and that brings about a response by the cell.

feedback

The control of a biological reaction by a product of that reaction.

downstream

Events that take place at a later stage in a sequence of reactions. Also refers to portions of dna or rna that are more remote from the initiation sites and that will therefore be translated or transcribed later.

upstream

Events that take place at an earlier stage in a sequence of reactions. Also refers to portions of dna or rna that are less remote from the initiation sites and that will therefore be translated or transcribed earlier.

negative feedback

The counteraction of an effect by its own influence on the process giving rise to it.

positive feedback

The enhancement or amplification of an effect by its own influence on the process that gives rise to it.

cascade

A series of sequential events where one event triggers the next, leading to a significant outcome

proliferation

The process by which a cell or organism produces others of its kind.

differentiation

The process by which a cell or group of cells becomes specialized in structure and function.

stem cell

An undifferentiated cell of a multicellular organism that is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.

cell cycle

The series of events that take place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells.

interphase

The period in the cell cycle when the cell is not dividing. Cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Accounts for about 90% of the cell cycle.

G1

The first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis.

S phase

The part of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase.

chromatid

Each of the two threadlike strands into which a chromosome divides longitudinally during cell division. Each contains a double helix of DNA.

centromere

The region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

G2 phase

The third and final subphase of Interphase in the cell cycle directly preceding mitosis.

mitosis

A type of cell division that results in two daughter cells identical to one another and to the parent cell. Used for organism growth and cell replacement.

chromosome

A thread-like structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

prophase

The first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears.

mitotic spindle

The structure that separates chromosomes into the daughter cells during cell division.

condense

To undergo condensation.

histone

Any of a group of basic proteins found in chromatin.

chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, this exists in its dispersed form as a mass of very long, thin fibers. When the cell is dividing, this condenses and chromosomes become visible with a light microscope.

metaphase

The stage of cell division in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned.

anaphase

The stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle. Sister chromatids are separated during this stage in mitosis and meiosis II.

telophase

The final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

cytokinesis

The division of the cytoplasm to form two separate daughter cells immediately after mitosis.

G0 phase

A period in the cell cycle in which cells exist in a quiescent state.

somatic cells

Any cell of a living organism other than the reproductive cells.

diploid (2n)

Containing two complete sets of chromosomes, one from each parent.

gamete

A mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

haploid (n)

Having a single set of unpaired chromosomes.

cell cycle checkpoint

A control point in the cell cycle where stop and go-ahead signals can regulate the cycle.

kinases

An enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.

cyclin dependent kinases (CDKs)

A family of kinases that help regulate the cell cycle.