biology cell structure and function

CELLS: STRUCTURE AND FUNCTIONChapter 7.1, 7.2 & 7.4

Discovery of the cell

• Robert Hooke – early microscope, thin layer of cork, “cells”

• Anton van Leeuwenhoek – observed pond water – small living world

• Schleiden – all plants are made of cells• Schwann – all animals are made of cells• Virchow – cells come from existing cells

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The cell theory1. All living things are composed of

cells.

2. Cells are the basic unit of structure and function in living things.

3. New cells are produced from existing cells.

Characteristics of all cells•Surrounded by cell membrane (plasma)

•Contain DNA – genetic material (blueprint)

•Contain cytoplasm

Examples of CellsAmoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Prokaryotic• No nucleus (nucleoid region)

• Few internal structures - have simple ribosomes

• Smaller & simpler than eukaroytic cells

• One-celled organisms

• Ex. Bacteria http://library.thinkquest.org/C004535/prokaryotic_cells.html

Prokaryotic Cells• Some use flagellum for locomotion

• threadlike structures protruding from cell surface Bacterial cell wall

Flagellin

Rotarymotor

Sheath

Eukaryotic•Have a membrane bound nucleus, control center that holds DNA (genetic material)

•Contain organelles surrounded by membranes (small organs)

•Most living organisms – lots of variety•Larger & more complex than prokaryotic cells

http://library.thinkquest.org/C004535/eukaryotic_cells.html

Diversity of Life

• Unicellular Organisms• 1 cell• Ex. Bacteria, Amoeba

• Multicellular Organisms• 2 or more cells• Ex. Plants & Animals

• Levels of Organization• Cells• Tissues• Organs• Organ Systems

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Plant Cells vs. Animal Cells• Plant Cells

• Chloroplasts• Large Central Vacuole

• Cell Wall

• Animal Cells• Lysosome• Centrioles

ORGANELLESStructure & Function

Cell Membrane / Plasma• Outer membrane of cell that controls movement in & out of the cell

• Double layer (Lipid Bilayer)

• AKA - Plasma Membrane• Selectively permeable boundary between the cell and the environment

• All cells have this!!http://library.thinkquest.org/12413/structures.html

Cell Membrane / Plasma

Nucleus• Directs cell activities• Separated from cytoplasm by nuclear membrane

• Contains genetic material - DNA

• Nuclear Membrane• Surrounds nucleus• Made of two layers• Openings allow material to

enter and leave nucleus

Chromosomes/Chromatin• In nucleus• Made of DNA & protein

• Contain instructions for traits & characteristics

• Contains instructions for making proteins

http://library.thinkquest.org/12413/structures.html

Nucleolus• Inside nucleus• Makes ribosomes which then leave the nucleus

http://library.thinkquest.org/12413/structures.html

Ribosomes• Each cell contains thousands

• Make proteins (site for protein synthesis)

• Found on Rough ER & floating throughout the cell

http://library.thinkquest.org/12413/structures.html

Endoplasmic Reticulum• A system of tubes & sacs

formed by membranes (an enclosed space)

• Moves materials around inside of the cell

• Smooth: lacks ribosomes• Lipid synthesis, drug

detoxifcation

• Rough type (pictured): ribosomes embedded in surface • Transports proteins to the Golgi

bodyhttp://library.thinkquest.org/12413/structures.html

Golgi Bodies• Protein “packaging plant”

• Modifies protein• Attach lipids & carbohydrates to the protein

http://library.thinkquest.org/12413/structures.html

Vesicles move from ER to Golgi

Mitochondria• Produces energy through chemical reactions – cellular respiration

• Converts glucose into ATP

• Cristae – inner membrane

• Matrix – inner membrane space

http://library.thinkquest.org/12413/structures.html

Lysosome• Digestive sac for proteins, fats, & carbohydrates

• Transports undigested material to cell membrane for removal

• Cell breaks down if lysosome explodes

http://library.thinkquest.org/12413/structures.html

Cytoskeleton

Actin

Microtubules

Intermediate filaments

Cytoskeleton• Network of protein fibers supporting cell shape and anchoring organelles• Microfilaments

• Actin • Cell movement• Support of cell

• Microtubules• Hollow tubes• Movement of organelles• Forms cilia, flagella, centrioles

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Michondrion

Centrioles

• Assemble microtubules during cell division

• Barrel shaped – pairs

• Found In animal cells (used during cell reproduction)

Cell Wall• Most commonly found in plant cells & bacteria

• Supports & protects cells

http://library.thinkquest.org/12413/structures.html

Chloroplast• Found in plant cells• Contains green chlorophyll

• Location where photosynthesis takes place in the cell

http://library.thinkquest.org/12413/structures.html

Vacuoles• Membrane-bound sacs for storage, digestion, and waste removal

• Contains water solution

• Help plants maintain shape- large central vacuolehttp://library.thinkquest.org/12413/structures.html

“Typical” Animal Cell

http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

“Typical” Plant Cell

Prokaryotes Eukaryotes

Cell membraneRibosomesCell wall

NucleusEndoplasmic reticulumGolgi apparatusLysosomesVacuolesMitochondriaCytoskeleton

Animal Cells Plant Cells

LysosomesCentrioles

Cell membraneRibosomesNucleusEndoplasmic reticulumGolgi apparatusVacuolesMitochondriaCytoskeleton

Cell Wall

Chloroplasts

Section 7-2

Venn Diagrams

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