Cells-Important Vocab

Exocytosis

A process used by the cell to take out its trash and to incorporate proteins into the cell membrane.

Endocytosis

Brings molecules into the cells, three types, phagocytosis, pinocytosis, and receptor-mediated.

Phagocytosis

Cell engulfs the molecule in order to move it to the interior of the cell

Pinocytosis

How cell “drinks”, engulfs dissolved ions and other solutes in liquid medium surrounding the cell.

Receptor-mediated endocytosis

Receptors embedded in CM allows molecule to enter cell similar to phagocytosis and pinocytosis.

Gap Junctions

Tubes that join two cells together to allow for the transport of water/ions to and from connecting cells, also spread electrochemical signals that are produced by action potentials.

Tight Junctions

Connections when cells are squished up against one another, cell membranes connected but contents are not. Impermeable layer between cells forming a watertight seal. Found in bladder, intestines, kidneys

Desmosomes

Cell membranes connected by thread-like substances that connect cells across space in cells, holds cells together but do not allow content exchange, attached to cytoskeleton for support. Allows water and solutes to flow without compromising the connection

Membrane Receptors

Integral protein that communicates with cell’s outside environment, three types: ligand-gated ion channels, g-protein coupled receptors, enzyme-linked receptors

Ligand-gated ion channels

Transmembrane ion channels that opens/closes in response to binding of a ligand, quick acting so found in cells like neurons.

G-protein coupled receptors

Only found in eukaryotes, noted to have 7 transmembrane alpha helices, where a signaling cascade causes a secondary messenger to accomplish the goal.

Enzyme-linked receptors

Transmembrane proteins that are unique because they also act as enzymes after the ligand binds. Causes phosphorylation, that causes signal transduction in other proteins to regulate gene transcription.

Prokaryotic

Cells without a nucleus and membrane-bound organelles.

Eukaryotic

Cells with a nucleus and membrane bound organelles.

Nucleus

Site of DNA storage and transcription in eukaryotic cells.

Nuclear Envelope

membrane surrounding the nucleus to create a room within the cell to protect genetic information and to house all molecules involved in processing and protecting that information

Nuclear pores

Protein channels that allow things in and out of the nucleus.

Nucleolus

Not bound by a membrane, contains instructions to make ribosomes.

Rough endoplasmic reticulum

Surface studded with ribosomes to become a site for protein productions, these proteins are destined to be a part of a membrane or to be secreted from the cell membrane out of the cell, post-translational modification of proteins also occurs here.

Smooth endoplasmic reticulum

Makes lipids and steroids which are important in energy storage, membrane structure and communication, also responsible for detoxifying the cell.

Golgi Apparatus

Responsible for packing proteins from RER into membrane-bound vesicles to translocate to cell membrane where it will join the cell membrane or be expelled out of the cells.

Lysosome

Spheres full of enzymes to hydrolyze contents so cells can reuse the raw materials.

Peroxisome

Spherical organelle responsible for fatty acid breakdown, protects the cell from reactive oxygen species (ROS) molecules.

Mitochondria

Produces ATP to make bulk of the energy for the cell, self-replicating and have their own DNA

Endosymboitic theory

Eukaryotes formed by large prokaryotic cells engulfing smaller cells.

Cytoskeleton

Network of protein fibers, responsible for cell movement and stability, composed of microtubules, intermediate filaments, and microfilaments.

Microtubules

Small tubes made from protein tubulin, help provide pathways for secretory vesicles to move through the cell and involved in cellular division.

Intermediate Filaments

Made of keratin/neurofilament, provide structure to nuclear envelope and anchor organelles

Microfilaments

Made of actin, useful in cell movements.

Integral Membrane Proteins

Extend completely across and remain permanently embedded in the membrane.

Peripheral proteins

Project from either side of the membrane.

Fluid mosaic model

A cell membrane is a mosaic of proteins and phospholipids, with protein molecules floating like icebergs in a lipid sea.

Isotonic solutions

Relative term for two solutions that have the same dissolved solute concentration. The net movement of water will be equal in both directions

Hypotonic solution

Relative term for a solution that has less dissolved solute than another solution, the net movement of water by osmosis will be out.

Hypertonic

Relative term for a solution that has more dissolved solute than another solution. Net movement of water by osmosis will be in.

Passive transport

Does not require any energy expenditure by the cell to transport materials across a membrane.

Simple diffusion

When the random kinetic energy causes particles to bounce randomly off one another in all direction, the net movement of particles going down a concentration gradient from high to low.

Osmosis

The movement of water across a semipermeable membrane through simple diffusion.

Osmotic pressure

The pressure generated by the presence of solutes dissolved in water.

Facilitated diffusion

Solute molecules cross the lipid bilayers through transport proteins, which act as gates or carriers.

Channel proteins

Amphipathic transmembrane molecules with a region of hydrophilic amino acids on the interior.

Carrier proteins

Bind to solutes and undergo a comformational change that physically carries the solute molecules across the membrane.

Active transport

the movement of substances across a membrane in a way that requires the expenditure of cellular energy.

Membrane potential

A net positive charge on the outside of the cell membrane and a net negative charge on the inside results in a voltage gradient.

Electrochemical gradient

Store chemical and electrical energy as potential energy that is available to do work.

Autocrine signaling

When a signal molecule produced by a cell binds to receptors on the plasma membrane of the same cell.

Juxtacrine Signaling

Occurs between cells that are in direct physical contact with each other, such as across cell junctions.

Paracrine signaling

Involves chemical messengers that send signals over short distances between nearby cells.

Endocrine signaling

Involves hormones that function in long-distance communication by traveling through the bloodstream to target cells.