THE CELL “The smallest unit that can carry out all the processes of life.” Why are they important? Click the pic

Scientists Who Discovered the Cell Click the RBC

Discovery of the Cell  ROBERT HOOKE  First to observe cells.  He examined cork cells.  “These little boxes reminded him of the small rooms in which monks lived, so he called them cells.”

Discovery of the Cell  Anton van Leeuwenhoek – First person to examine living cells & father of microscopy  Matthias Schleiden – “All plants are composed of cells.”  Theodore Schwann – “All animals are composed of cells.”  Rudolf Virchow – “All cells come from existing cells.”

The Cell Theory  Schleiden, Schwann, & Virchow  All living things are composed of one or more cells.  Cells are organisms’ basic units of structure & function.  Cells come from existing cells.

CELL DIVERSITY 1. Size  Cells range in size from.2 um to 2 m.  Average plant & animal cells are 10 to 50 um in diameter. 2. Shape  Cuboidal & spherical. 3. Internal Organization  Different Organelles

TYPES OF CELLS  Eukaryotes  Eukaryotes – Contains a nucleus and membrane-bound organelles.  Prokaryotes  Prokaryotes – Lacks a nucleus. (bacteria)  Organelle  Organelle – A cell component that performs specific functions in the cell.

ORGANELLES  Nucleus  Cell Membrane  Cytoplasm  Ribosomes  Rough Endoplasmic Reticulum  Smooth Endoplasmic Reticulum  Golgi Apparatus  Mitochondria  Lysosomes  Cytoskeleton - Microtubules & Microfilaments  Cilia  Flagella

The Nucleus  Directs activities of the cell.  Contains DNA.  Nucleolus – synthesis of ribosomes.  Nuclear pores  Nuclear envelope  Nucleoplasm

DNA  Deoxyribonucleic acid  Encodes information important for the synthesis of proteins.

CYTOPLASM  Contains various organs in the cell  Gelatin-like fluid called cytosol which has dissolved salts, minerals, and organic molecules

CELL MEMBRANE  Made of lipids & proteins.  Provides shape & flexibility.  Selectively Permeable - a complex barrier that keeps out some molecules & allows others through.

RIBOSOMES  Carry out protein synthesis.  Attached ribosomes - attached to Rough ER; produce proteins to be exported by the cell.  Free ribosomes - produce proteins for the cell.

ENDOPLASMIC RETICULUM  Rough Endoplasmic Reticulum - (ER) - A membrane system covered with ribosomes; aids in protein synthesis.  Smooth ER - Few or no ribosomes; intracellular pathway for proteins.

GOLGI APPARATUS  System of membranes.  Processing, packaging, & secreting organelle of the cell.

MITOCHONDRIA  “Powerhouse of the cell.”  Carries out cellular respiration.

LYSOSOMES  Contains digestive enzymes.  Digests food & disease-causing bacteria.

CYTOSKELETON  Provides a structural framework for the cell.  Microtubules - long, slender protein tubes  Microfilaments - fine protein threads.

CILIA & FLAGELLA  Function in movement.  Composed of proteins.  Cilia - small & hair-like; covers entire surface of the cell.  Flagella - long & slender; found singly or in pairs.

VACUOLES  Store substances inside the cell.  Plant cells have large central vacuoles.

CENTRIOLES  Structure that appears during animal cell division

CELL WALL  Only in plant cells  Lies outside the cell membrane  Supports and protects the plant

PLASTIDS  Convert solar energy into chemical energy.  Chloroplast - contain green pigments  Leucoplast - store food, such as starches.  Chromoplast - synthesize & store other pigments.  Plant cells only!!

CHLOROPLASTS  Found in plant cells only  Where the energy of sunlight is converted into chemical energy during photosynthesis  Contain green pigment called chlorophyll

DIFFERENCES BETWEEN PLANT & ANIMAL CELLS  ANIMAL CELLS  Centrioles  Small vacuoles  PLANT CELLS  Plastids  Large central vacuole  Cell Wall