Cell Bio Midterm #1

Cell

The smallest unit of life that can carry out all life processes

Plasma Membrane

A thin barrier surrounding the cell that separates the inside of the cell from the outside environment

Eukaryotic Cell

A cell with a nucleus and membrane-bound organelles

Prokaryotic Cell

A cell without a nucleus or membrane-bound organelles

Organelle

A specialized structure inside the cell that performs a specific function

Cytoplasm

The material inside the cell excluding the nucleus

Compartmentalization

Division of the cell into separate regions with specific functions

Macromolecule

A large biological molecule made from smaller subunits

Monomer

A small repeating subunit that forms larger molecules

Polymer

A large molecule made of repeating monomers

Protein

A macromolecule made of amino acids that performs many cellular functions

Amino acid

The monomer of proteins

Nucleic Acid

A macromolecule made of nucleotides that stores genetic information

Nucleotide

The monomer of nucleic acids

DNA

A nucleic acid that stores genetic information

RNA

A nucleic acid involved in protein synthesis and gene expression

Polysaccharide

A carbohydrate made of sugar molecules linked together

Primary Structure

The sequence of amino acids in a protein

Secondary Structure

Local folding of a protein into structures like alpha helices and beta sheets

Alpha helix

A coiled secondary protein structure stabilized by hydrogen bonds

Beta Sheet

A folded secondary protein structure stabilized by hydrogen bonds between peptide strands

Tertiary Structure

The overall 3D shape of a single polypeptide chain

Quaternary Structure

The arrangement of multiple polypeptide chains in a protein

Polypeptide

A chain of amino acids linked by peptide bonds

Peptide Bond

A covalent bond between amino acids

Protein Folding

The process where a protein forms its functional protein 3D shape

Denaturation

Loss of a protein’s normal structure and function

Conformation

The 3D shape of a protein

Ligand

A molecule that binds to a protein

Binding Site

The region of a protein where a ligand binds

Affinity

The strength of binding between a ligand and a protein

Polar amino acid

An amino acid with hydrophilic side chains that interact with water

Nonpolar amino acid

An amino acid with hydrophobic side chains that avoid water

Hydrophilic

Attracted to water

Hydrophobic

Repelled by water

Hydrogen Bond

A weak attraction between partially charged atoms

Ionic bond / electrostatic interaction

An attraction between positively and negatively charged groups

Van der Waals Interactions

Weak attractions between nearby atoms

Non-covalent interactions

Weak interactions that help stabilize protein structure

Phosphorylation

The addition of a phosphate group to a protein

Dephosphorylation

The removal of a phosphate group from a protein

Kinase

An enzyme that adds phosphate groups to proteins

Phosphatase

An enzyme that removes phosphate groups from proteins

Cell Culture

The growth of cells outside an organism in controlled conditions

In vitro

Experiments performed outside a living organism “in glass”

In vivo

Experiments performed inside a living organism

Cell Line

Cells grown in the lab that can continue dividing

Transformed Cell Line

A cancer-derived cell line that grows continuously

Homogenate

A mixture made by breaking open cells

Ultracentrifuge

A machine that separates cell components by size and density using high-speed spinning

Pellet

Material collected at the bottom of a centrifuge tube

Supernatant

The liquid remaining above the pellet after centrifugation

Chromatography

A method used to separate molecules

Column Chromatography

A technique where molecules move through a column and separate based on their interactions

Matrix

The material inside a chromatography column used for seperation

Ion-exchange chromatography

Seperates proteins based on charge

Hydrophobic Chromatography

Separates proteins based on hydrophobicity

Gel-filtration Chromatography

Separates proteins based on size

Affinity Chromatography

Separates proteins based on specific binding interactions

Epitope Tag

A short amino acid sequence added to a protein for detection or purification

Monoclonal Antibody

An antibody that recognizes one specific target molecule

Microscope

An instrument used to magnify small objects

Magnification

The enlargement of an image

Resolution

The ability to distinguish two close objects as separate

Detection

The spreading of light waves as they pass around edges

Interference

The interactions of light waves that can increase or decrease intensity

Objective Lens

The lens closest to the specimen that magnifies the image

Condenser

A lens that focuses light onto the specimen

Fluorescence Microscopy

A microscopy technique using fluorescent molecules to visualize structures

Fluorophore

A molecule that absorbs light and emits light at a longer wavelength

Excitation

Absorption of high-energy light by a flurophore

Emission

Release of lower-energy light from a flurophore

Fluorescent Dye

A fluorescent molecule used to label structures in cellls

Out-of-focus light

blurred light coming from regions outside the focal plane

Confocal microscope

A microscope that removes out-of-focus light to create sharper images

Pinhole

A small opening in a confocal microscope that blocks out-of-focus light

3D Reconstruction

Combining many microscope images to create a 3D image

Membrane Bilayer

A double layer of phospholipids forming biological membranes

Fluid Mosaic Model

Model describing membranes as fluid lipid bilayers with moving proteins

Selective Permeability

The membrane allows some substances through while blocking others

Phospholipid

An amphiphilic lipid with a hydrophilic head and hydrophobic tails

Glycerophospholipid

A phospholipid with a glycerol backbone

Sphingolipid

A phospholipid with a sphingosine backbone

Amphiphilic

Containing both hydrophilic and hydrophobic regions

Fatty Acid

A hydrocarbon chain found in lipids

Unsaturated Fatty Acid

A fatty acid containing double bonds that create kinks

Cis-unsaturated Fatty Acid

A fatty acid with a cis double bond that bends the chain

Saturated Fatty Acid

A fatty acid without double bonds

Cholesterol

A membrane lipid that affects membrane fluidity and stiffness

Membrane Fluidity

The flexibility and movement of molecules with a membrane

Antibody

A protein produced by B-cells that specifically binds a target molecule

Antigen

A molecule recognized by an antibody

B-Cell

An immune cell that produces antibodies