Cell

lowest level of biological organization that can perform all activities required for life; all organisms are made of cells

Name the parts of the microscope from highest to lowest

eye piece, ocular lense, nosepiece, arm,objective lenses, stage clips, stage, condenser/iris or diaphragm, coarse focus, fine focus, light source, light switch, base

Light microscopes

can magnify up about 1,000 times actual size
most subcellular structures are too small to be resolved by light microscope

Electron microscopes

Scanning electron microscopes (SEMs) focus a beam of electrons into the surface area of a specimen

Transmission electron microscopes (TEMs)focus a beam of electrons through a specimen

Basic features of all cells

Plasma (cell) membrane, cytoplasm, cytosol, chromosomes, ribosomes

Plasma membrane

selective barrier that allows passage of oxygen, nutrients and waste
constructed of phospholipid layer
surface are to volume ratio of a cell is critical for cell functions

Ribosomes

made of ribosomal RNA and protein
not membrane bound
carry out protein synthesis in the cytosol (free ribosomes)and on endoplasmic reticulum or nuclear envelope (bound ribosomes)

Prokaryotic cells

no nucleus
DNA in region called nucleoid
no membrane bound organelles

Eukaryotic cells

DNA in nucleus bond by nuclear envelope
Membrane-bound organelle
generally larger than prokaryotic cells

Organelles

membrane enclosed structures with specific functions

Parts of a plant cell

Nucleus, Nuclear Membrane, Rough ER, Smooth ER, Ribosomes, Golgi apparatus, Vesicles, Central vacuole, Mitochondrion, Chloroplasts, Cell wall

Nucleus

contains most of cell's genes

Nuclear Membrane

encloses the nucleus with double membrane

Rough ER

has bound ribosomes, distributes transport vesicles, manufactures membranes

Smooth ER

synthesizes lipids, metabolizes carbohydrates, detoxifies poisons, stores calcium

Ribosomes

carry out protein synthesis in two locations

Golgi apparatus

modifies products of ER, manufactures macromolecules, sorts and packages materials into transport vesicle, "UPS store of cell"

Vesicles

breaks down substances in a cell to smaller molecules

Central vacuole

hold organic compounds and water; common in plane cells

Mitochondria

sites of cellular respiration to generate ATP
releases free energy when phosphate bonds are hydrolyzed
have double membrane
contains own DNA

Chloroplasts

function in photosynthesis, contain green pigment (only in plant cells)found in plants and algae
have double membrane
contains own DNA

Cell wall

protects cell
maintains shape
prevents over-expansion when eater enters cell (only in plant cells)

Chromatin

the complex of DNA and proteins making up chromosomes

Nuclear Lamina

composed of protein, maintains shape of nucleus

Components of Endomembrane system

Nuclear envelope, endoplasmic reticulum, Golgi apparatus, Lysosomes, Vacuoles, Plasma membrane

Endoplasmic reticulum

accounts for more than half of the total membrane in many eukaryotic cells (smooth or rough)

Lysosomes

membrane sac of hydrolic enzymes that many eukaryotic cells use to digest macromolecules
fuses with food vacuole and digests the contents

Lysosomal enzymes

can hydrolize proteins, fats, carbohydrates and nucleic acids (macromolecules)

Phagocytosis

"cell eating" engulfing other cells or particles. Creates food vacuole and digests

Vacuole

a eukaryotic cell may have one or several vacuoles
Food vacuoles: formed by phagocytosis
Contractive vacuoles: pump excess water out of cells

Peroxisomes

remove hydrogen atoms from various substrates and transfer them to oxygen
are oxidative organelles
metabolic compartments bonded by a single membrane
produce hydrogen peroxide and convert it to water
break down molecules

Cytoskeleton

support the cell and maintain shape
Interacts with motor proteins for motility

Components of Cytoskeleton (3 types of fibers)

microtubes: thickest
intermediate filaments: middle diameter
microfilaments: thinnest components aka actin filaments

Microtubules

hollow rods
functions:
-shaping the cell
-guiding movement of organelles
-separating chromosomes during cell division
made of alpha (a) and beta (B) tubulin-
-control the beating of cilia and flagella, locomotor appendages of some cells

Centrosomes

in many cells microtubules grow out from centrosome near the nucleus
"microtubule-organizing center"
has a pair of centrioles: nine triples of microtubules arranged in a ring (animal cells)

Cilia

rowing motion locomotor
usually cover entire cell or side of cell

Flagella

swimming motion locomotor
usually 1-3 in a group

Intermediate Filaments

larger than microfilaments but smaller than microtubules
support cell shape and fix organelles in place
are ;more permanent cytoskeleton structures

Microfilaments (Actin filaments)

solid rods built as twisted double chain of actin units
role is to bear tension, resisting pulling forces within the cell cortex: network inside the plasma membrane to support cell shape
bundles make up core of microrilli intestinal cells

Pseudopodia

the way a cell crawls along a surface
they are cellular extensions that extend and contract through the reversible assembly of contraction of actin subunits into microfilaments
speeds distribution of materials within the cell

Cytoplasmic streaming

circular flow of cytoplasm within cells

Cell walls of plants

found in plant cells, NOT animal cells
prokaryotes, fungi and some protists have cell walls
made of cellulose, other polysaccharides and protein

Plasmodesmata

channels that perforate plant cell walls
water and small solutes can pass from cell to cell

Extracellular Matrix (ECM)

animal cells are covered by ECM
Functions:
-support
-adhesion
-movement
-regulation

Intercellular Junctions

neighboring cells adhere, interact, and communicate through direct physical contact
types:
-plasmodesmata
-tight junctions
-desmosomes
-gap junctions

Tight Junctions

membranes neighboring cells are pressed together, preventing leakage of extracellular fluid

Desmosomes(anchoring junctions)

fasten cells together into strong sheets

Gap junctions (communicating junctions)

provide cytoplasmic channels between adjacent cells
-similar to plasmodesmata in plant cells