Cells & Cell Transport

Cells

Cell Membrane

Cell membrane (plasma

membrane): a

phospholipid bilayer

surrounding the cell

Each phospholipid has a

polar phosphate head

and lipid tails

Selectively permeable:

allows only certain

substance into the cell,

like a screen door, only

some things can come

through

Cytoplasm

The watery

environment of the

cell where all cell

activity takes place

Made up of mostly

water, with ions,

proteins, and other

compounds

Cytoskeleton

A network of fibers throughout the cytoplasm called microfilaments and microtubules

They provide structure to the cell, points of attachment for organelles (MT), and are used in cell movement (MF)

Spindle fibers are used for movement of chromosomes during cell division

Nucleus

Surrounded by a nuclear

membrane (nuclear

envelope) which is a

bilayer like the cell

membrane

Contains nuclear pores

for transport in and out of

the nucleus

Stores most of the

genetic information in the

form of chromosomes

Directs most activities of

the cell.

Chromatin

Made up of sections

of DNA called genes

and also proteins

Uncurled: chromatin

Curled up for

transport:

chromosomes (these

are stained & visible

under a microscope)

They do not leave the

nucleus

Nucleolus

Found inside the nucleus

A mass of RNA, not an official membrane bound organelle like the rest described here

‘Disappears’ during cell division

RNA can leave the nucleus for protein synthesis (ribosome synthesis)

Centrioles

(AKA centrosomes)

Lay just outside the nucleus, made up of microtubules Involved in cell division (although they are not present in plant cells)

Replicate into two centrioles before cell division and migrate to opposite ends of nucleus

Ribosome

Can be free (in the cytoplasm) or bound (found on the rough ER)

Made up of two subunits (large & small), 40% protein & 60% RNA (rRNA)

The location of protein production (the site of protein synthesis)

No membrane

Endoplasmic Reticulum Can be rough (with

ribosomes attached) or

smooth (no ribosomes)

Two types of ER:

Rough ER:

transportation of proteins,

Smooth ER: toxin

breakdown, regulation of

calcium and production of

steroids when in glad

cells (smooth ER)

Intracellular highway –

moves proteins from one

part of the cell to another

Golgi Apparatus (Body)

Responsible for protein processing which includes:

*marking proteins with their destination location

*preparing proteins to become active and able to do their job (ex: enzyme folding)

* Modifies proteins for export

System of flattended sacs (pancakes of membrane)

Mitochondria Often called the ‘powerhouse’ of the cell, has a 2nd inside membrane that folds to increase surface area (cristae, where chemical reactions take place)

It generates ATP (cellular energy) from glucose molecules

Contains its own DNA unlike every other organelle in the cell

Is thought to have once lived on its own

Vacuole Used for storage for a variety of things including food, waste, and proteins to be transported out/around the cell

A moving vacuole is called a vesicle

Plants have a large central vacuole for water storage to keep the shape of the plant cell

Lysosome A small, spherical vacuole containing digestive enzymes

They fuse with vacuoles containing substances to be broken down (food, waste, invading bacteria)

Digest protein, carbs, lipids, DNA, RNA and sometimes old organelles, viruses, bacteria that the cells ingested

Rare in plant cells

Cell Wall

Found in bacteria, fungus, plant, and some protists

Made up of cellulose in plant cells

Adds extra security/protection and/or provides structure (shape) for cells

Flagella and Cilia

Used for movement in some protist and animal cells, made of microtubules

Flagella are whip like tails (one or more) for movement much like a tail is used for swimming by fish

Cilia are hair like extensions (circular movement is like that of a bullet)

Video comparing flagella and cilia movement:

http://www.youtube.com/watch?v=QGAm6hMysTA

Chloroplasts

Contain chlorophyll (green, yellow, red color)

Only found in cells that do photosynthesis (plants, some protists, some bacteria)

Like mitochondria, they contain their own DNA and are thought to have lived as single celled organisms at one time

Plant vs. Animal Cells

No centrioles for cell division

A large central vacuole

Cell wall of cellulose to help maintain square shape

Chloroplasts containing chlorophyll for photosynthesis

Use centrioles for cell division

No central vacuole

No cell wall

No chloroplasts, no chlorophyll, no photosynthesis