bio2

cell

most basic unit of life

characteristics of cell

1. Microscopic

2. Membrane

3. Cytoplasm 

Eukaryotic cells

-has a nucleus and other membrane bound organelles. 

-may be single or multicellular organisms.

-has a cytoskeleton.

Cytoplasm

-important contributor to cell structure

-made up of mostly water

-many chemical reactions

Mitochondria

-cells “powerhouse”

-supplies energy to cell

-chemical reactions converts food into usable energy

Chloroplasts

-carries out photosynthesis

-highly compartmentalized

-contains thylakoids (disc-shaped sacs)

Cell Membrane

-forms boundary between cell and outside

-controls passage of materials

-selectively permeable - some methods of transport require energy, some do not

-double layer of phospholipids

-receptors made of proteins. when bind make ligands and change shape. affects how receptor interacts with other molecules.

Phospholipids

-molecule composed of 2 basic parts

-phosphate and glycerol form “head” (loves water)

-fatty acid forms “tail” (hates water)

Molecules embedded in membrane

-cholesterol - support

-proteins - gates

-carbohydrates - “identification tags”

Fluid Mosaic Model

describes arrangement of molecules in cell membrane.

Passive transport

no energy needed to pass

Diffusion

-high concentration to region of low concentration

-plays important role in movement of carbon dioxide and oxygen molecules

-facilitated diffusion - larger molecules can still diffuse through opens formed by transport proteins (still passive)

When concentration is equal in a concentration gradient

reaches dynamic equilibrium

Osmosis

diffusion of water molecul,es

Active Transport

-requires energy by cell to move materials in or out of cell

-uses energy from ATP molecule

Endocytosis

movement of liquids or large molecules into a cell by engulfing them in a membrane

Phagocytosis

-“cell eating”

-key role in immune system (white blood cells)

Exocytosis

-releases substances from cell

-vesicle moves to cell membrane, fuses, and then lets go of its contents out the cell

-occurs constantly in body

Nucleus

-storehouse for genetic material

-2 demands: protects DNA and must be available for use at proper time

-encased in nuclear envelope with pores that allow molecules to go in

Nucleolus

makes ribosomes

Rough ER

-studded with ribosomes

-makes proteins and lipids

Smooth ER

-makes lipids

-helps break down drugs and alcohol

Ribosomes

-composed of RNA and proteins

-site of protein production

Golgi Apparatus

-cells “post office”

-packages/stores/delivers proteins

Vesicles

-stores separate reactants for various chemical reactions

-membrane bound sacs

-transports materials

Vacuole

-fluid-filled storage sacs

-stores water, food, inorganic ions, enzymes

Lysosomes

-”destruction” sacs

-defends cell from invading viruses and bacteria

-breaks down damaged and worn-out cell parts

-not in plant cells

Centrosome

-small region of cytoplasm that produces microtubules

-in animal cells, contains two centrioles; cylinder-shaped organelles made of microtubules

-helps cell division in animal cells

Cilia and flagella

made of microtubles