Lecture 8: Organelles

All cells contain

cytoplasm, DNA genome, plasma membrane, ribosomes

Prokaryotic Cells

bacteria and archaea

- no nucleus

- DNA is an unbound region called nucleoid

- no membrane

Eukaryotic Cells

protists, animal, fungi, plants

- most DNA is found in nucleus and is bounded by double membrane

Nucleus

houses DNA in eukaryotic cells; bound by membrane that has nuclear pores

- DNA is organized into chromosomes

- pores regulate entry and exit of the nucleus

- nuclear membrane consists of lipid bilayer

- nuclear envelope

Nuclear Envelope

encloses nucleus and separates it from the cytoplasm

Chromatin

DNA wrapped around proteins

Endomembrane System

the path a substance takes out of the cell

- everything but mitochondria

- components are either continuous or connected through by vesicles

- ER > Golgi > vesicle > exocytosis

ER

continuous membrane with nuclear envelope

- Smooth ER: lacks ribosomes

- Rough ER: studded with ribosomes

Ribosomes

make proteins in cytosol or ER

Function of Smooth ER

- synthesizes lipids

- metabolizes carbohydrates

- detoxifies dugs and poisons

- stores calcium ions

Functions of Rough ER

- has bound ribosomes, secretes glycoproteins

- distributes transport vesicles

- membrane factory

Golgi

series of flattened membranous sacs

- sorts and packages material into transport vesicles

Transport Vesicle

protein surrounded by membranes

Lysosome

digests macromolecules

- phagocytosis, autotrophy

Phagocytosis

cellular eating

- lysosome fuses with food vacuole and its enzymes to digest the molecule

- forms food vacuole

- sold particle

Autotrophy

process when cell has an organelle that is not functioning properly

- lysosome uses enzymes to recycle the organelle/macromolecule

Endocytosis

bringing into the cell

- takes in liquid or solid

- phagocytosis, pinocytosis, receptor-mediated endocytosis

Pinocytosis

cellular drinking

- solute/fluid

Receptor Mediated Endocytosis

bringing in specific molecule that is bound to a receptor

Contractile Vacuoles

pump excess water out of cells

- found in freshwater protists

Central Vacuoles

Storage for ions and other things

- found in mature plant cells