Honors Bio: Cytology 2

Nucleus

membrane-bound organelle found in all eukaryotic cells that serves as protection for the cells genetic material

Structure of Nucleus

nuclear membrane, nucleoplasm, nucleolus, nuclear sap, chromatin

Nuclear membrane

double membrane with pores  passing through both membranes

connected with other membranes of the cell (E.R.).

Nucleoplasm

protoplasm of the nucleus

Nucleolus

site of rRNA synthesis

Nuclear Sap

watery fluid

Chromatin

combination of DNA and histones (proteins)

Functional DNA

“used DNA” used by that particular cell to carry out its function (loosely separated, appears light)

Nonfunctional DNA

“stored DNA”, not used by the cell (compacted, appears dark)

Ribosomes

site of protein synthesis

non-membrane bound organelles

number of them depends upon the activity or function of cell

Structure of Ribosomes

composed of rRNA and proteins, making 2 subunits that join together in the presence of mRNA

1/10^th the size of the wavelength of light

Function of Ribosomes

manufacture proteins

involved in regulating the translation of mRNA

Free ribosomes

not attached to other organelles and produce proteins for use in the cytoplasm of the cell

Attached ribosomes

attached to E.R. and produce proteins for export out of the cell

Cisternae

flattened membrane-bound sacs

Structure of E.R.

composed of cisternae with interconnecting channels

can be attached to nuclear envelope and the cell membrane itself (as part of “membrane flow”)

Function of ER

transportation system in the cytoplasm of the cell

Granular E.R.

has attached ribosomes and involved in the production of secretory proteins

Agranular E.R.

no ribosomes

functions vary and include: synthesis of lipids and steroids and detoxification of harmful substances

Function of Transport vesicles

involved in intracellular transportation and absorption

Transport vesicles are formed by

pinching off the E.R., other vacuoles or the Golgi complex

Structure of Golgi Complex

cisternae surrounded by small transport vesicles

Functions of Golgi complex

processes and concentrates materials made by the cell

packages these materials based on chemical tags into vesicles or vacuoles to be either exported or used within the cell

*sequence of events determined by using biological tracers

Endomembrane system (membrane flow)

due to similarities in plasma membrane structure, membranes can “flow” from one organelle to another

Structure of Vacuoles

membrane-bound sacs named by their function or what they contain

Functions of Vacuoles

storage, biosynthetic, secretion, excretion, contractile (osmoregulation)

Storage Vacuole

hold a variety of materials (food/water vacuole)

Biosynthetic Vacuole

contain material made by the cell

Secretion Vacuole

export materials made by the cell

Excretion Vacuole

exports metabolic waste (“waste vacuole’)

Contractile Vacuole

specialized in osmoregulation in unicellular organisms

Osmoregulation

maintaining water balance

Structure of Lysosomes

specially coated membrane-bound sacs (vacuoles) that contain digestive enzymes

Function of Lysosomes

intracellular digestion, extracellular digestion, autolysis

Intracellular Digestion

digestion occurs within cell

Extracellular Digestion

lysosome secreted outside the cell and then digested nutrients are absorbed into the cell

Autolysis

self-destruction

“Suicide-sac”

-breakdown/recycle damaged or worn-out organelles

-destruction of damaged on diseased cells

-removal of cells no longer needed by body (as in metamorphosis)

Cell Coats

non-living secretion covering the outside surface of the cell membranes

Extracellular Matrix (Slime layer/Muscus layer)

combination of water, proteins, carbohydrates, and lipids

Cell Wall (plant cell)

provides protection and support

Middle Iamella

middle layer between plant cells

Pectin

glues cells together

Primary Cell Wall

cellulose fibers that can slide past each other, flexible for growth

Secondary Cell Wall

cellulose and lignin

Lignin

binds cellulose fibers together

Structure of Cytoskeleton

a combination of solid protein filaments (“wires”) and hollow protein tubules (“pipes”) that have a supportive role

Microfilament

solid protein fibers

provides movement to the cell membrane (pinocytosis and phagocytosis).

actin

Intermediate Filaments

composed of several smaller filaments intertwined together

suspension: holding organelles in position

Microtubules

large, hollow protein tubes

gives shape to the cell

internal transport

movement of cell itself (internal structure of cilia and flagella)

Internal transport

“monorail” for vesicle movement within the cytoplasm

Cilia

short, membrane covered hair-like projections

usually many

Flagella

long, membrane covered whip-like projections

usually only a few

Structure of Cilia and Flagella

composed of a 9+2 pattern of microtubules, covered by an extension of cell the cell membrane

Functions of cilia and Flagella

both involved in cellular locomotion

cilia involved in movement of materials outside the cell either to bring materials to the cell or sweeping materials across/away from the surface of the cell

Centrosome

cell center

only found in animal cells

Structure of centrosome

a non-membrane-bound structure located in a dense region of the cytoplasm near the nucleus.

composed of two centrioles

Centrioles

each made up of a 9+0 pattern of microtubules, lying at right angles to each other

Function of Centrosome

seems to be involved in cytoskeleton formation or organization by acting as a “microtubule organizing center”

basal body

Basal body

centrioles also involved in building the structure of cilia and flagella

Cell Junctions

points of attachment between cells

Interstital Fluid

space between cells that allows materials to be transported to and from cells

Tight Junctions

form an impenetrable barrier preventing the passage of materials into the intercellular space

Snap Junctions

holds cells together to form tissues

protein fibers help anchor “snap” into the cytoplasm

intercellular material can pass around it

Gap Junctions

form direct channels from one cell to the other

rapid exchange of material or for communication

Plasmodesmata

when plant cells divide and form specialized conductive tubes for xylem and phloem through cell wall from one cell to another

Xylem

transport of water

Phloem

transport of sugar

Structure of Transport Vesicles

small membrane-bound sacs containing various materials