Cell Structure and Organelles: Microscope Techniques and Functions

cell

simplest collection of matter that can be considered a living entity

light microscope

a type of microscope where light is passed through the specimen and then through a lens that refracts the light

magnification

the ratio of an object's image size to its real size

resolution

a measure of the clarity of the image; the minimum distance two points can be separated by and still be distinguished as two distinct objects

contrast

difference in brightness between the light and dark areas of an image

organelles

the membrane-enclosed structures within eukaryotic cells

electron microscope

focuses a beam of electrons through the specimen or onto its surface

resolution formula

resolution = 1/wavelength

scanning electron microscope (SEM)

useful for topography; electron beam scans the surface (typically coated in gold) and creates a 3D looking image

transmission electron microscope (TEM)

studies internal structure of cells; electron beams shoot through a very small section of sample stained with heavy metal atoms; image is based on the different electron densities in the sample

cytology

the study of cell structure

biochemistry

study of chemical processes of the cells

cell fractionation

taking cells apart and separating organelles and other sub-cellular structures from another to understand the cell structure and function

centrifuge

a device used to separate components based on density; faster spins create smaller blobs at the bottom, slower spins create larger blobs

prokaryotic cells

cells that do not have a membrane-bound nucleus; includes bacteria and archaea

eukaryotic cells

cells that have a membrane-bound nucleus; includes protists, fungi, animals, and plants

cytosol

jellylike substance where components are suspended

chromosomes

carry genes via DNA

ribosomes

tiny complexes that make proteins according to instructions from the genes

cytoplasm

interior of the cell in prokaryotic and eukaryotic cells

plasma membrane

a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the whole cell

nucleus

an organelle bounded by a double membrane where eukaryotic DNA is found

nucleoid

the region in prokaryotic cells where DNA is located, which is not membrane enclosed

phospholipid bilayer

layer of bilipids that have proteins embedded or attached to them

nuclear envelope

encloses the nucleus and separates it from the cytoplasm; this is a DOUBLE MEMBRANE

nuclear lamina

a netlike array of protein filaments that maintain the shape of the nucleus by supporting the envelope; help with organization

nuclear matrix

a framework of protein fibers extending throughout the nuclear interior; can help organize genes

chromatin

complex of DNA and proteins that make up the chromosome

nucleolus

mass of densely stained granules and fibers; RNA (ribosomal) is synthesized here via DNA instruction

free ribosomes

suspended in the cytosol

bound ribosome

attached to the outside of the ER

endomembrane system

made up of the nuclear envelope, ER, golgi apparatus, lysosome, vesicles and vacuoles, and membrane; synthesizes proteins, transportation, metabolism and moving lipids, detoxing

ER

an extensive network of membranes of tubules and sacs called cisternae; membrane separates the ER lumen from cytosol- internal compartment

smooth ER

no ribosomes; sometimes will synthesize lipids, metabolize carbs, detox drugs, store Ca+; pumps Ca+ from cytosol into ER lumen

rough ER

ribosomes on the walls; create proteins

glycoproteins

secretory proteins with carbs covalently bonded

transport vesicles

transmit things from one part of the cell to the other, made from the membrane

golgi apparatus

a warehouse for receiving, storing, shipping, and some manufacturing; ER products are modified, stored, and shipped off

cisternal maturation model

cisternae of golgi progress towards the trans (from cis); suggested that central doesn't move as much. The edges move more.

Molecular identification tags

Tells proteins where to go.

Vesicles

Small membrane-bound sacs that transport substances within a cell.

Lysosomes

Membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest macromolecules.

Acidic environment

The optimal condition for lysosomes to work best.

Rough Endoplasmic Reticulum (RER)

Where the membrane and enzymes of lysosomes are made.

Phagocytosis

The process by which lysosomes carry out digestion by eating smaller organisms.

Macrophages

A type of cell in humans that performs phagocytosis.

Autophagy

A process in which lysosomes recycle enzymes by becoming surrounded by a double membrane.

Vacuoles

Large vesicles derived from the ER and GA, part of the endomembrane system.

Selective vacuolar membrane

The membrane of vacuoles that allows specific solutions inside, differing from cytosol.

Food vacuoles

A specific type of vacuole that stores nutrients.

Contractile vacuoles

Pumps that expel excess water from the cell to maintain equilibrium.

Central vacuole

A large vacuole in mature plant cells that holds reserves of organic compounds.

Cell sap

Fluid inside the vacuole that increases in volume when more water is absorbed.

Mitochondria

The site of cellular respiration in animals.

Chloroplasts

The site of cellular respiration in plants.

Endosymbiont theory

The theory that an early form of P consumed an oxygen-using non-photosynthetic P cell.

Endosymbiont

Cell living within another cell, which then merged into the mitochondria we know today.

Cristae

Infoldings in the inner membrane of the mitochondria.

Intermembrane space

Narrow region between inner and outer membranes of mitochondria.

Mitochondrial matrix

Structure within both membranes that carries enzymes and DNA.

Thylakoids

Interconnected sacks found within chloroplasts.

Granum

Stack of three thylakoids.

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Stroma

Fluid outside the thylakoids that contains the DNA.

Plastids

Larger family of plant organelles.

Amyloplast

Colorless organelle that stores starch.

Chromoplast

Contains pigments that give fruit orange and yellow colors.

Peroxisomes

Specialized metabolic compartments bounded by a single membrane that remove hydrogen from toxins and combine them with H2 to create H2O2.

Glyoxysomes

Special peroxisomes found in plant seeds to kick start fatty acid conversion to sugar.

Cytoskeleton

A network of fibers extending throughout the cytoplasm that organizes the structures and activities found in a cell.

Cell motility

Changes in cell location and movement of cell parts.

Motor proteins

Proteins that need to interact with the cytoskeleton to enable cell motility, allowing organelles and other objects to 'walk.'

Microtubules

Hollow rods constructed from globular proteins called tubulins. - known as a dimer

Dimer

A molecule made up of two sub-units.

Plus end

The side of a microtubule where most dimers are being added and dropped.

Centrosome

A region often located by the nucleus that contains centrioles.

Centrioles

Composed of 9 sets of triplet microtubules in a ring.

Cilia

Microtubule containing extensions that can pass fluid when anchored down. (oar like movement)

Flagella

Microtubule containing extensions that undulate for propulsion.

Primary cilium

The main cilia that function like an antennae to trigger actions.

Basal body

Similar to a centriole, sometimes becomes the centriole in sperm.

Dyenins

Motor proteins that allow for bending and movement of microtubules.

what features do cilia and flagella share

a group of microtubules shathed in a nextension of the plasma membrane, basal body, and dyeins

Microfilaments (actin)

Thin solid rods made of globular protein actin, forming structural networks.

Cortex

A network of microfilaments that gives the cell shape.

Myosin

A protein that causes the contraction of muscle cells.

Pseudopodia

Cellular extensions that help cells crawl.

Cytoplasmic streaming

A circular flow of cytoplasm within cells that speeds the movement of organelles.

Intermediate filaments

Larger than microfilaments, made from keratin, providing strong support.

-only foundin some animals, made from keratin that are more permanents structures that support the cell

Cell wall

Extracellular structure of plant cells that protects and maintains shape.

Primary cell wall

A thin and flexible wall that a young plant first creates.

Middle lamella

Thin layer rich in sticky polysaccharides called pectins that glues cells together.

Secondary cell wall

A strong and durable matrix that affords the cell protection and support.

-sometimes plants take the primary cell wall and turn it into the secondary wall

Extracellular Matrix (ECM)

Made of glycoproteins and carbs, similar to the cell wall.

Collagen

Forms strong fibers outside cells embedded in a network of proteoglycans.

Fibronectin

An ECM glycoprotein that binds to cell-surface receptors called integrins.

Plasmodesmata (plant cells)

Holes in the plant wall that allow cytosol to pass through and connect cells.

Tight junctions

Plasma membranes tightly pressed against each other to prevent leakage.

Desmosomes

Function like rivets to fasten cells into strong sheets.

Gap junctions

Provide cytoplasmic junctions from one cell to another in animal cells.