Section 2.1Section 2.1Cell Structures Cell Structures

andandTypes of CellsTypes of Cells

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

RibosomesRibosomes- • Factories of the Cell•Take copy of DNA’s information (mRNA) and use it as a guide to create proteins from amino acids• ER ribosomes- proteins move on to Golgi apparatus• Free ribosomes- proteins

move to cytoplasm

Golgi ApparatusGolgi Apparatus- membrane sacs that put proteins into small 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•Two membranes with inner one folded many times•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• Move in long strokes

Cilia- short, hair-like paddles that push the cell along• Move in short fast beats all at same time

Organelles of a Plant Cell•The organelles already covered 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

• Creates turgid pressure to keep plant up right• 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

Gogi Apparatus X

Cilia/Flagella (Extremely Rare)

X

Lysosome X

Vacuole (large) (small) X

Mitochondria X

Chloroplasts X

Specialization of Cells• Specialized Cells cells with physical features that allow them to do specific jobs • Ciliated cells • found in your throat and lungs• cilia on one side push material in certain direction• cilia + mucus = dust trapper

•Root hair cells• found on the roots of plants• increase surface area of cell so it can absorb more water/minerals

• Major theme in biology!• mitochondria, root cells, intestine, brains… all have many folds!

Specialization of Cells• Xylem vessels• empty waterproof tubes that allow movement of water/minerals through out the plant

•Muscle cells• long, thin fibers that can shrink (contract) and expand (relax)• Allow all movement and support for skeleton

•Red blood cells • contain haemoglobin; protein with Fe2+ ions that can transport O2 and some CO2• Reason blood is red• Flat round discs allow for movement in body and exchange of gasses

Limits of LightLimits of LightEye Piece

MagObjective

Mag

10x 4x

10x

40x

100x (oil emmersio

n)

Mag and Res PracticeMag and Res Practice

700nm line between VL/Infrared Resolution = ½ radiation used0.5 * 700nm 350nm

9mm 9000μm 9000 μm / 75,000 = 0.12 μm (120nm)

120nm = 0.5 x wavelength of radiationWavelength= 240 nm (UV light)

Homeostasis: Happy Cells• In single-celled organisms this is

not very difficult• In multi-celled, complex organisms

there are many levels to organize:• Cells Single unit of life; can be

specialized for a specific job (muscle cell)

• Tissue Groups of the same cells working together to do a specific job (muscle tissue)

• Organ Tissues grouped together to do a specific job (heart)

• System Organs and extra parts working together for a specific job (Circulatory system)

Tissues Working Tissues Working TogetherTogether

•Plant tissue:Plant tissue:

•Upper epidermisUpper epidermis water proof outer water proof outer

covering; covered with cuticlecovering; covered with cuticle

•Palisade mesophyllPalisade mesophyll photosynthetic cells photosynthetic cells

•Spongy mesophyllSpongy mesophyll space for CO space for CO22

circulationcirculation

•PhloemPhloem transport solutes transport solutes

•XylemXylem transport water and salts transport water and salts

•Lower epidermisLower epidermis stomata for gas stomata for gas

exchangeexchange

Homework• Read all of Unit 2• Unit 2 Vocab is due

on Sunday (Friday schedule)

• Questions on p. 19 and p. 23

• Organelle Worksheet