PARTS OF THE CELL & THEIR FUNCTIONS

Nucleus

Repository for genetic material
Directs activities of the cell
DNA synthesis

Nucleolus

Inside the nucleus
RNA synthesis
Contains RNA to build proteins

Smooth Endoplasmic Reticulum

"Smooth" (has no ribosomes)
Lipid synthesis
Carbohydrate metabolism in liver cells
Detoxification in liver cells
Calcium ion storage

Rough Endoplasmic Reticulum

"Rough" (due to presence of ribosomes)
Synthesis of membrane proteins
Secretory proteins and hydrolytic enzymes

Golgi Apparatus

Packaging house of the cell
Temporary storage and transport of macromolecules
Formation of lysosomes and transport vesicles

Ribosomes

Polypeptide (protein) synthesis

Mitochondria

Conversion of chemical energy of food to chemical energy of ATP
Double membranous
Size of a bacterium
Contains its own DNA; mDNA
Produces high energy compound ATP
"Powerhouse of the cell"

Vacuole

Sacs that help in food digestion or helping the cell maintain its water balance
Found mostly in plants and protists

Chloroplast

Conversion of light energy to chemical energy of sugars (Photosynthesis)
Larger and more complex than mitochondria
Double membrane
Center section contains grana
Thylakoid (coins) make up the grana
Found in plants and algae

Grana

Closed compartments of stacked membranes

Thylakoids

Disc shaped structure

Stroma

Fluid matrix
Gel-like material surrounding grana

Nuclear membrane

Surrounds nucleus
Made of two layers
Openings allow material to enter and leave nucleus

Plasma membrane

Allows some substances to cross more easily than others and blocks passage of some substances altogether

Takes up substances the cell needs and disposes of the cell's wastes

Forms a boundary between the living cells and its surroundings and controls the traffic molecules into and out of the cell

Like the membranes of the cell, the plasma membrane exhibits selective permeability

Phospholipid bilayer

In water, phospholipid spontaneously form a stable two-layer sheet called a _

Their hydrophilic heads face outward (exposed to the water) and their hydrophobic fatty acid tails point inward (shielded from the water)

Cytosol

Only includes the thick solution; not the organelles containing it

Cilia and Flagella

The short numerous appendages that propel protists such as Trichodina and Paramecium are called cilia (singular, cilium)

Longer, generally less numerous appendages on other protists are called flagella.

The role of cytoskeleton in movement is clearly seen in eukaryotic flagella and cilia, the locomotor appendages that protrude from certain cells.

Composed of a core microtubules wrapped in an extension of the plasma membrane

A ring of nine microtubule doubles surrounds a central pair of microtubules. This arrangement found in nearly all eukaryotic flagella and cilia is called the 9+2 pattern.

The nine doublets extend into an anchoring structure called a basal body; which has a pattern of nine microtubule triplets.

Microtubules both provide support and contribute to the locomotor mechanism underlying the whipping action of these organelles

Microtubules

Part of the cytoskeleton

Chromosomes

In nucleus
Made of DNA
Contain instructions for traits and characteristics

Endosymbiotic Theory

Can also be applied to chloroplasts

It is assumed that these organelles were primitive photosynthetic prokaryotes because they have their own DNA, RNA, and ribosomes, and can also self-replicate.

It is presumed that mitochondria were primitive aerobic prokaryotes that were engaged in mutualism with primitive anaerobic eukaryotes, receiving protection from these organisms and providing them with energy in return.

This hypothesis is called the endosymbiotic theory of the origin of mitochondria.

Fluid mosaic model

The outside surface of the plasma membrane has carbohydrates (chains of sugars) bonded to proteins and lipids in the membrane

Glycoprotein

A protein with attached sugars

Membrane proteins

Attachment of the membrane to the cytoskeleton and external fibers, providing identification tags and forming junctions to adjacent cells