CHAPTER 4 INSIDE THE CELL

Cells

Extremely diverse and specialized for a particular function in our body, require a microscope to be seen

Light microscope

-Invented in the 17th century

- limited by properties of light

Electron microscope

Invented in the 1930s overcomes limitation by using beam of electrons

The limit to cell size

Need surface areas large enough for entry and exit of materials: surface area to volume ratio

Microvilli

In the small intestine increase surface area for absorption of nutrients

Plasma membrane

- Marks boundary between outside and inside of a cell

- regulates passage in and out of a cell

Polar heads

(hydrophilic) of phospholipids face into watery medium

Nonpolar tails

(Hydrophobic) face each other

Channel proteins

Form tunnel for specific molecules

Transport proteins

Involved in passage of molecules through membrane sometimes requiring input of energy

Cell recognition proteins

Enable our body to distinguish between our own cells and cells of other organisms

Receptor proteins

Allow signal molecules to bind causing a cellular response

Enzymatic proteins

Directly participate in metabolic reactions

Junction proteins

Form junctions between cells: Cell to cell adhesion and communication

Cell theory

All organisms are composed of cells all cells come only from pre existing cells

Plasma membrane

Regulate movement of material

Cytoplasm

Where chemical reactions occur

Prokaryotic cells

Lack membrane bounded nucleus. Organisms from the domains bacteria and archaea usually smaller and simpler than eukaryotic. Reproduce very quickly

Bacteria

Well known because some cause disease some are used to manufacture chemicals, food, drugs, and so on

Eukaryotic cells

Have nucleus housing dna

Cytoplasm

Surrounded by plasma membrane and cell wall. Sometimes a capsule- protective layer.

DNA

Single circular coiled chromosome located in nucleotide region-not membrane enclosed

Ribosomes

-Site of protein synthesis

-found in prokaryotes and eukaryotes

-composed of proteins and rRNA

Flagella

Propulsion (pushing forward)

Fimbriae

Attachment to surfaces

Conjugation pili

DNA transfer

Membrane bounded nucleus

Protists, fungi, plants, and animals much larger cells than prokaryotic

Four categories of organelles

Nucleus and ribosomes, endomembrane system, energy-related, cytoskeleton

Nucleus

Stores generic information

nucleolus

Region where ribosomal RNA (rRNA) is made

Nuclear envelope-double membrane

Nuclear pores permit passage in and out

endomembrane system

-Consists of nuclear envelope, membranes of ER, Golgi apparatus and numberous vesicles

-Compartmentalizes cell

ER

System of membranous channels and accuses

Rough ER

Studded with ribosomes modifies proteins in lumen forms transport vesicles going to Golgi apparatus

Smooth ER

-continuous with rough ER no ribosomes

-Synthesizes lipids like phospholipids and sterilizes

-Produces testosterone, detoxifies drugs

Golgi app

Stack of flattened saccules, transfer station, sorts and packages for new destination (some are lysosomes)

Lysosomes

Vesicles that digest molecules or portions of the cell.

Vacuoles

-membranous sacs

-larger than vesicles

-digestion storage (plant pigments and animal adipocytes)

Mitochondria

-Found in plants and animals

-bounded by double membrane

-break down carbs to produce ATP

Cellular respiration

-needs oxygen, produces carbon dioxide

Chloroplasts

-Use solar energy to synthesize carbs through process of photosynthesis

-plants and algae

Cytoskeleton

Network of interconnected protein filaments and tubules

-extends from nucleus to plasma membrane

-only in eukaryotes

-maintains cell shape

Motor proteins

Allow cell and organelles to move

-myosin

-lines in

-dynein

Myosin

Interacts with actin

Muscle contractions

Kinesin and Dynein

Move along microtubules

Transport vesicles from Golgi app to final destination

Microtubules

Hollow cyclone era

Maintains cell shape and as a track from organelles and other materials to move

Centrioles

Made of nine sets of microtubule triplets

Two centrioles lie at right angles

In animal cells not plant

Primary cell walls

Cellulose fibrils and noncellulose substances

Wall stretches when cell is growing

Secondary walls

Forms inside primary cell wall

Woody plants

Lignin adds strength

Plasmadesmata

Plant cells connected by numerous channels that pass through cell walls

Exchange water and small solutes

Extra cellular matrix ECM

Mesh work of fibrous proteins and polysaccharides

Collagen and elastin

Cell wall

Provides support to cell in many nonanimal cells connected

-plant

-fungi

-protists

Collagen

Resists stretching

Elastin

Provides resilience

Adhesion junctions

Internal cytoplasmic plaques hounded by intercellular filaments

Tight junctions

Impermeable barrier

Adjacent plasma membraned joined

Gap junctions

Allow communication between two cells

Adjacent plasma membrane channels joined