Section 1Cell Structures

and Ultrastructures

Cell Compartmentalization

Organelles of an Animal CellStructure- parts of a cell visible through a

light microscope

Ultrastructure- parts of a cell visible through

only an electron microscope

Plasma Membrane- “wall and gate” of the

cell; 7nm wide

•Selective permeability - allows some

molecules to pass through while keeping

others out.

•Transport proteins- special tunnels or

doors that only let in specific molecules

The Nucleus

•The “brain” of the cell; contains

loosely coiled DNA (Chromatin)

• Nucleolus- Compact, largely

inactive DNA in chromosome

form

•Makes ribosomes

• Nuclear envelope- two

membrane outer layer

•Nuclear pores- small openings

to allow exchange of materials

The ERsEndoplasmic Reticulum- system of membrane sacs (cristernea) branching off of the nucleus; does various of chemical reactions

Smooth ER- no ribosomes; makes lipids and hormones

Rough ER- ribosomes; makes proteins

Ribosomes- take copy of DNA’s information (mRNA) and use it as a guide to create proteins

ER ribosomes- proteins move on to Golgi apparatus

Free ribosomes- proteins move to cytoplasm

Golgi ApparatusGolgi Apparatus- membrane sacs (cisternae) that put proteins into small membrane-bound packages called vesicles which are sent out or around the cell; makes lysosomes

Lysosomes- sacs of hydrolytic enzymes that digest old organelles, food, and viruses/bacteria

The Mitochondria• power house of the cell; produces ATP(energy unit for cells) by breaking down sugars and other organic compounds (aerobic respiration)•Two membranes with inner one folded into cristae•Matrix (inner area) produces ATP and lipids

Organelles for Support

Cytoplasm- clear gel-like fluid inside cells; help holds organelles in place

Cytoskeleton- “Bones” of the cell; crossing rods, filaments, and tubes, that hold the cells shape. Also act at a

“train” system to move things around the cell

Cilia and Flagella

Flagella- long, wipe-like tail that pushes and rolls the cell

Cilia- short, hair-like paddles that push the cell along

Both made from microtubules that form a basal body

Basal body- cylinder shape of 9 pairs of tubules + 2 central tubes•9 + 2 formation

Centrioles

• two 9+2 cylinders stuck at 90o from each other• move chromosomes during cell division by growing spindle fibers• animal cells only

Organelles of a Plant Cell•The organelles already covered (except centrioles, cilia, and flagella) can also be found in plant cells•Plants have a few extra organelles

Cell wall- thick, rigid wall made of cellulose that gives the plant cell a definite shape

Plasmodesmata- small connecting points between the cells walls of neighboring plant cells; allow exchange

Photosynthesis CentersChloroplasts- perform photosynthesis to make energy from

sunlight in planets and some unicellular organisms

Chlorophyll- chemical that absorbs wavelengths of sunlight, expect green

Grana- stacks of membranes containing chlorophyll

Vacuoles- Both Large and Small

Vacuoles- storage compartments for food, enzymes, etc.• In plant cells- they are very large and hold lots of water

and nutrients; tonoplast membrane controls exchange; also holds pigments the give flowers color• In animal cells- very small; transport things inside the

cell

Animal Cells Vs. Plant CellsOrganelle Plants only Animals only Both

Plasma Membrane

X

Cell Wall X

Nucleus X

Ribosomes X

Endoplasmic Reticulum

X

Gogi Apparatus X

Cilia/Flagella (Extremely Rare)

X

Lysosome X

Vacuole (large) (small) X

Centrioles X

Mitochondria X

Chloroplasts X

Homework• Review

Section 1 for a quiz next Tuesday• Cell Analogy

worksheet