Lecture 9: Organelles and Cytoskeleton

Mitochondria

sites of cellular respiration

- surrounded by two membranes

outer: covers mitochondria

inner: folded onto itself

Mitochondria Matrix

intermembrane space

Chloroplasts

found in plants and algae

- responsible for carrying out photosynthesis

- three membranes: inner, outer, thylakoids

Thylakoids

stacks of pancakes surrounded by continuous membrane

- granum

Stroma

fluid in the spaces between the granum

Cytoskeleton

network of fibers extending throughout cytoplasm

- gives shape, support, structure

microfilaments, microtubules, intermediate filaments

Microtubules

moves organelles and vesicles

- separates chromosomes during cell division

- largest

- dynamic and slightly unstable

Microfilaments (Actin Filaments)

eating, moving white blood cells, muscle contraction

- smallest; located under the cell membrane

- dynamic and slightly unstable

Intermediate Filaments

maintains structure; fixes organelles in place

- found in cells of some animals

- static and stable

Extracellular Matrix

ensures that cells that need to stay in the tissue stay in the tissue

- animal cells

Cell Wall

composed of cellulose

- only in plant cells

primary cell wall, middle lamella, secondary cell wall

Primary Cell Wall

thin and flexible

Middle Lamella

between primary walls of adjacent cells

Secondary Cell Wall

only in some cells

- added between plasma membrane and primary cell wall

Cell Junctions

cell communication to neighboring cells

plasmodesmata, tight junction, desmosomes, gap junction

Plasmodesmata

Channels that allow materials to move from one plant cell to another adjacent cell  

- only in plants

Tight Junctions

Prevent leaking of extra cellular functions  

- knitted together

- actin is dynamic therefore it can break

Desmosomes

intermediate filaments that rivet cells together

- permanent

- muscle tears

Gap Junction

animal plasmodesmata