BIO EXAM 4 CH 7,11 & 12

selective permeability

the property of a cellular membrane that allows certain molecules or ions to pass through it while restricting others

amphipathic

molecules containing both hydrophilic and hydrophobic regions

fluid mosaic model

protein molecules bobbing in a fluid phospholipid bilayer

integral proteins

proteins that penetrate the hydrophobic interior of the lipid bilayer

transmembrane proteins

integral proteins that span the entire membrane

peripheral proteins

proteins that are loosely bound to the surface of the membrane, not embedded in the lipid bilayer

CD4 proteins

protein that helps HIV infect immune system cells

CCR5 protein

co-receptor that HIV uses to enter immune cells, facilitating infection.

glycolipids

carbohydrates bound to lipids

glycoproteins

carbohydrates bound to proteins

transport proteins

proteins that assist in the movement of ions and molecules across cell membranes.

aquaporins

transport proteins that facilitate the passage of water across cell membranes.

carrier proteins

Transport proteins that bind to specific molecules and change shape to shuttle them across the membrane.

diffusion

the movement of particles so that they spread out into the available space

concentration gradient

the region where the density of a chemical substance increases or decreases

passive transport

the movement of substances across a cell membrane without the use of energy

osmosis

the diffusion of water molecules across a selectively permeable membrane

isotonic

solution where the concentration of solutes is equal inside and outside of the cell

hypertonic

solution where the concentration of solutes is greater outside the cell than inside

hypotonic

solution where the concentration of solutes is less outside the cell than inside

osmoregulation

the control of solute concentration and water balance

turgid

when a plant cell is swollen due to the uptake of water, causing pressure against the cell wall.

flaccid

a state where a plant cell is limp due to loss of water, resulting in reduced pressure against the cell wall.

plasmolysis

the process in which a plant cell loses water in a hypertonic solution, causing the cell membrane to separate from the cell wall.

facilitated diffusion

the process by which molecules pass through a cell membrane via specific transmembrane proteins

ion channels

channel proteins that transport ions

gates channels

ion channel that opens or closes in response to a specific stimulus

active transport

molecules transported against their concentration gradient, requires energy

sodium-potassium pump

a type of active transport that moves sodium ions out of the cell and potassium ions into the cell, using ATP.

membrane potential

the voltage across a membrane

electro chemical gradient

the difference in ion concentration and electric charge across a membrane, which affects the movement of ions.

electrogenic pump

a transport proteins that generates voltage across a membrane

proton pump

the main electrogenic pump in plant, bacterial, and fungal cells

cotransport

a transport protein that can couple the “down hill” diffusion of a solute and the “up hill” transport of a second substance against its concentration gradient.

endocytosis

the process by which cells internalize substances by engulfing them in a membrane-bound vesicle.

exocytosis

the process by which cells expel substances by fusing a vesicle with the plasma membrane, releasing its contents outside the cell.

phagocytosis

a type of endocytosis where large particles or cells are engulfed by the cell membrane to form a phagosome.

pinocytosis

a type of endocytosis where the cell engulfs small particles and liquids, forming a vesicle to internalize them.

receptor-mediated endocytosis

a specialized form of endocytosis where cells take in specific substances through receptors on their surface, forming vesicles.

signal reception

target cells detection of a signaling molecule coming from outside the cell

signal transduction

the binding of the signaling molecule changes the receptor protein, initiating a response

cellular response

the transduced signal triggers specific cellular activities or changes in behavior.

quorum sensing

a process by which bacteria communicate and coordinate behavior based on population density.

biofilm

an aggression of bacterial cells attached to the surface by molecules secreted by the cells

cell junctions

directly connects the cytoplasm of the adjacent cells

cell-surface molecules

cell molecules that interact with each other

paracrine signaling

secreting cell acts on nearby target cell by secreting molecules of a local regulator

growth factors

compounds that stimulate nearby target cells to grow and divide

synaptic signaling

nervous system signaling where an electrical signal in a nerve cell triggers the release of neurotransmitters that diffuse across a synapse to affect a target cell.

endocrine signaling

chemical messengers produced by glands that travel through the bloodstream to distant target cells, regulating various physiological processes.

ligand

a molecule that binds to a specific receptor to initiate a biological response.

G-protein

a protein that binds the energy-rich GTP

protein kinase

an enzyme that catalyzes the transfer of phosphate groups from ATP to another protein

protein phosphates

enzymes that can rapidly remove phosphate groups from proteins

second messengers

small molecules that relay signals received at receptors on the cell surface to target molecules inside the cell.

cyclic AMP (cAMP)

a small molecule produced from ATPthat acts as a second messenger

adenyly cyclase

an enzyme that converts ATP to cyclic AMP (cAMP) in response to an extracellular signal.

scaffolding proteins

large relay proteins that organize multiple signaling pathways by providing a framework for specific interactions between various signaling molecules.

apoptosis

programmed cell death

cell division

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

genome

the complete set of genetic material in an organism, including all of its genes and non-coding sequences.

chromosomes

structures within cells that contain DNA and are visible during cell division, consisting of long strands of DNA wrapped around proteins.

chromatin

the material that makes up chromosomes, consisting of DNA and proteins

somatic cells

any cells of the body that are not reproductive cells

gametes

the reproductive cells involved in sexual reproduction, specifically sperm and eggs.

sister chromatids

joined copies of the original chromosome

centromere

the region made up of repetitive sequences in the chromosomal DNA where the chromatid is attached to its sister chromatid

mitosis

the division of the genetic material in the nucleus

cytokinesis

the division of cytoplasm after mitosis or meiosis, resulting in two separate daughter cells.

cell cycle

the life of a cell from the time it is formed during division of a parent cell until its own division into daughter cells

M phase

mitosis and cytokinesis

interphase

accounts for 90% of the cell cycle and is the phase where the cell prepares for mitosis, including DNA replication and growth.

G1 phase

the first phase of interphase, where the cell grows and synthesizes proteins necessary for DNA replication.

G2 phase

the second gap phase in the cell cycle that follows the S phase, where the cell continues to grow and prepares for mitosis.

S phase

the phase of interphase where DNA replication occurs, resulting in the duplication of chromosomes in preparation for cell division.

G2 phase

the cell undergoes further growth and ensures all DNA is replicated correctly before proceeding to mitosis.

G0 phase

phase where cells are in a state of metabolic activity but do not actively prepare to divide, often exiting the cell cycle.

prophase

the first stage of cell division where cells condense into chromosomes

prometaphase

the stage of mitosis following prophase during which the nuclear envelope breaks down and spindle fibers attach to chromosomes.

metaphase

the stage of mitosis where chromosomes are aligned at the cell's equatorial plane before being separated into daughter cells.

anaphase

the stage of mitosis during which sister chromatids are pulled apart toward opposite poles of the cell.

telophase

the final stage of mitosis where the separated chromatids reach the poles, the nuclear envelope re-forms around each set of chromosomes, and the cell begins to split.

cytokinesis

the process that follows mitosis, where the cytoplasm divides, forming two separate daughter cells.

mitotic spindle

consists of fibers made of microtubules and associated proteins that help separate sister chromatids during cell division.

centrosome

a subcellular region containing material that functions throughout the cell to organize the microtubule cytoskeleton and regulate cell division.

kinetochore

a structure made up of proteins that have assembled on specific sections of DNA at each chromosome's centromere, serving as the attachment site for spindle fibers during cell division.

metaphase plate

imaginary plate where chromosomes align during metaphase.

cleavage furrow

the indentation that forms in the cell membrane during cytokinesis, helping to separate the two daughter cells.

binary fission

a method of asexual reproduction where a single organism divides into two identical daughter cells

origin of replication

the specific location on a DNA molecule where replication begins.

cell cycle control system

a set of molecules in the cell that triggers and coordinates events in the cell cycle

checkpoint

control point in the cell where stop and go signals regulate the cycle

cyclin

a protein that has cyclically fluctuates levels in the cell

cyclin-dependent kinases (CDK)

enzyme proteins that regulate the cell cycle by activating or inactivating target proteins when bound to cyclins.

M-phase promoting factor (MPF)

a complex of cyclin and cyclin-dependent kinase that triggers the cell's progression into the M phase of the cell cycle.

growth factor

a protein released by certain cells that stimulates other cells to divide

density-dependent inhibition

a regulatory mechanism in which cell division is halted when cells become crowded

anchorage dependence

a condition in which cells must be attached to a substrate in order to divide

transformation

a normal cell converted to a cancerous cell

malignant tumor

a cancerous growth that invades surrounding tissues and can metastasize to other parts of the body