7.1 Life is Cellular

Hooke: saw chambers (“cells”) in cork w/primtv mscope

Leeuwenhoek: saw pond “animicules” w/smple mscope

1838: Schleiden: plants made of cells

1839: Schwann: animals made of cells

1855: Virchow: cells come from other cells

B. Cell Theory All living things composed of cells

Cells: basic unit of structure & functn of life

New cells produced from existing cells

All cells:

Come in different sizes & shapes

Have DNA sometime in cell’s life

Cell (plasma) membrane: thin flexible barrier

Regulates what enters/leaves cell

Selectively permeable = semipermeable

Protects & supports cell

Flexible structure

Made up of many parts that float around in membrane

Lipid Bilayer:2 layers that has

Hydrophilic: H20-loving; heads-outside cell

Hydrophobic: H20-hating; tails-inside cell

2 types of cells based upon presence of nucleus: Prokaryotes & Eukaryotes

A. Prokaryotes

No Nucleus

Smaller than Euk

Simple

DNA in cytoplasm

Bacteria cells

B. Eukaryotes

Nucleus houses DNA

Larger & more complex

Single->Multicelld: protist, fungi, plant

anml

Cell membrane important role to reg. movt of molecules

A. Diffusion Move from HIGH to LOW conc til equilibrium reached

No NRG needed = passive transport

B. Facilitated Diffusion No NRG needed

Proteins in membrane act as channels/carriers to help ions get across

Fast & specific

High to low conc.

C. Osmosis (Ex of Facilitated Diffusion) Diffusion of H20 thru semipermeable membrane

High to low conc til equilibrium

Uses aquaporin (H20 channel protein) to pass thru membrane

Equal conc of both sugar &H2O

How Osmosis Works

Isotonic = same strength—no net change

Hypertonic = above strength—cell shrinks

Hypotonic = below strength—cell swells

Osmotic Pressure

Occurs b/c diff solute conc

Water pressure (force) required to maintain equilibrium

Mov’t against gradient (LOW to HIGH conc)

Requires NRG

A. Molecular Transport Use protein pump to transport ions/molecules across membrane

Protein (pump) changes shape to get ions across

B. Bulk Transport Large molecules & solid clumps transported by movt of membrane

1. Endocytosis: material into cell

Cell “engulfs” food & forms pocket

2. Exocytosis: release large amts of material

Ex: contractile vacuole—H20 exits cells

1. Cells as an Org. Unicellular = single-celled org

Maintains homeostasis by perfoming all life’s activities

Prokaryotic: bacteria; Eukaryotic: algae, protists, fungi (yeast_

Staphylococcus aureus

2. Multicellular Life Cells interdependent (work together)

Communicate w/others homeostasis

A. Cells Specialization

Many specialized cells w/particular functions

Nerve cells, or neurons, have many long

branches to deliver messages quickly!

Cell specialization in blood: red blood cells, platelets (yellow) and T lymphocytes (green

B. Levels of Organization Cells: smallest unit of life; skin

Tissues: similar cells doing same job; muscle

Organs: tissue grps work together; heart

Organ system: org grps work together; digestion