Topic 4 Cells and Transport

Light Microscope

An optical instrument with lenses that refract visible light to magnify images of specimens

Electron Microscope

A microscope that focuses an electron beam through a specimen, resulting great resolving power

Cell Fractionation

The disruption of a cell and separation of its organelles by homogenization and centrifugation

Organelle

Structure found within a cell that performs a specific task

Centrifugation

A technique that uses spinning force to separate particles from a suspension

Pellet

Fraction of cell components that settles at the bottom of a tube after centrifugation

Supernatant

Liquid that collects above the pellet in a tube after centrifugation

Scanning electron microscope

A microscope that uses electrons to show the surface of a sample. Useful for studying the topography of a specimen

Transmission electron microscope

A microscope that uses electrons to study a thin specimen of a specimen. Used to study the ultrastructure of cells.

Eukaryotic cell

A cell that contains a nucleus and other structures (organelles) enclosed within membranes.

Prokaryotic cell

A cell that has no membrane bound organelles.

Cytosol

The semifluid portion of the cytoplasm

Nucleoid

A dense region of DNA that is found in a prokaryotic cell

Cytoplasm

The entire contents of the cell, exclusive of the nucleus, and bounded by the plasma membrane

Plasma Membrane

The membrane at the boundary of every cell that acts as a selective barrier.

Nuclear Envelope

The membrane structure in eukaryotes that encloses the nucleus, separating it from the cytoplasm

Nuclear Lamina

A netlike array of protein filaments that maintains the shape of the nucleus.

Chromosome

A threadlike, gene-carrying structure found in the nucleus or nucleoid. Each consists of one very long coiled DNA molecule

Chromatin

The complex of DNA and proteins that makes up a eukaryotic chromosome when it is not coiled.

Nucleolus

A specialized structure in the nucleus that is active in the synthesis of ribosomes

Endomembrane System

The collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles

Smooth endoplasmic reticulum

Endoplasmic reticulum that lacks ribosomes.

Rough endoplasmic reticulum

Endoplasmic reticulum that contains ribosomes. Manufactures membranes and secretory proteins.

Vesicle

A small sac surround by a membrane inside of cells.

Glycoproteins

Proteins that have carbohydrates covalently bonded to them.

Transport Vesicle

A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell

Golgi apparatus

An organelle that modifies products of the endoplasmic reticulum, such as proteins and sends them to other destinations in the cell

Lysosome

A sac of hydrolytic enzymes that is used to digest macromolecules or cellular debris.

Phagocytosis

A method used by cells for engulfing large particles by surrounding them with the plasma membrane.

Autophagy

A process when lysosomes use their hydrolytic enzymes to recycle the cell's own organic material.

Vacuoles

Large vesicles derived from the endoplasmic reticulum and Golgi apparatus. Mostly used to store molecules or waste.

Endosymbiotic (Endosymbiont) Theory

Explanation for how the early ancestor of eukaryotic cells engulfed prokaryotic cells that eventually evolved into the mitochondria and chloroplasts.

Cristae

Infoldings of the inner membrane of a mitochondrion.

Mitochondrion

Organelle that is site of cellular respiration.

Mitochondrial Matrix

The compartment of the mitochondrion enclosed by the inner membrane.

Thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.

Granum

A stack of thylakoids found in the chloroplast.

Stroma

The fluid outside the thylakoid found inside a chloroplast

Plastid

Members of a family of closely related plant organelles that contain pigments or reserve materials such as starch.

Photosynthesis

A process used by plants and other organisms to convert light energy, carbon dioxide and water into chemical energy

Peroxisome

An organelle containing enzymes that degrade hydrogen peroxide into water and oxygen.

Microtubule

A hollow rod of tubulin protein in eukaryotic cells that forms part of cilia, flagella, and the cytoskeleton

Centrosome

The microtubule organizing center, present in the cytoplasm of all eukaryotic cells. It is involved in cell division.

Centrioles

Structures found in an animal cells composed of cylinders of microtubule triplets. An animal cell usually has a pair of them that are involved in cell division.

Flagella

Long cellular appendages specialized for locomotion.

Cilia

Short cellular appendages specialized for locomotion.

Basal Body

A eukaryotic cell structure made out of microtubule triplets. The are part of cilia and flagella.

Microfilament

A solid rod of actin protein in the cytoplasm of eukaryotic cells, making up part of the cytoskeleton.

Actin

A globular protein that links into chains, forming microfilaments in muscle and other contractile elements in cells.

Myosin

The contractile protein that makes up the thick filaments of muscle fibers.