Cell Structure & Function

The Cell The cell is the smallest unit of life that can carry out life processes.

Cellular Organization Section 2 Introduction to Cells Chapter 4 Cellular Organization

Discoveries Leading to The Cell Theory Robert Hooke – 1665 -observed cork through a light microscope. Anton Van Leewenhoek – 1675 -observed LIVING cells. Theodor Schwann – 1839 –animals are made of cells Rudolf Virchow – 1855 – all cells come from other cells. Matthias Schleiden – 1883 –plants are made of cells.

The Cell Theory The cell theory states that: all living organisms are made of one or more cells cells are the basic units of structure and function cells come only from pre-existing cells

Prokaryotic Cell Prokaryotic- Do not have a nucleus Do not have internal membrane-bound structures Most unicellular organisms are prokaryotes. Bacteria

Eukaryotic Cell Eukaryotic- Has a nucleus Has internal membrane-bound structures Most multicellular organisms are eukaryotes. Yeast and algae (unicellular, eukaryotes) Plant and animal

Cilia and Flagella Flagella-long, whip-like projections Aid in movement and feeding Composed of microtubules Cilia-short, numerous hair-like projections that move in a wavelike motion

Organelles “little organs” Specialized parts within a cell that has a specific function

Features Common to Cells: Cytoplasm – Gel like material that protects, supports and suspends organelles.

Features Common to Cells: Cell membrane – Semi-permeable Controls what enters and leaves the cell. This helps to maintain cellular homeostasis.

Structure of the Plasma Membrane Phospholipid Bilayer -2 layers ofphospholipids. Phospholipid- phosphate head attached to two lipids (fattyacid tails). Polar phosphate group allows membrane to interact with its environment. Fatty acid tails create a water-insoluble layer in the middle which is non-polar. Fluid mosaic model-membrane is flexible Cholesterol-keeps fatty acid tails from sticking together Transport proteins-allow needed substances to move through the membrane

Parts of the Cell Chapter 4

Nucleus Nucleolus-makes ribosomes “Command center” Ribosomes-site where proteins are made Can be found floating in the cytoplasm or attached to endoplasmic reticulum “Command center” Contains genetic material: Chromosomes DNA

Endoplasmic Reticulum (ER) Smooth Endoplasmic Reticulum (SER) No ribosomes Produce and store lipids Series of folded membranes allow a large amount of work to be done in a small amount of space Transportation unit for the cell Rough Endoplasmic Reticulum (RER) Ribosomes attached Protein synthesis

Golgi Apparatus Vesicles Flattened tubular membranes Packaging plant Modify, sort, package, and transport proteins throughout the cell

VACUOLES Storage areas Temporary storage of materials Store food, enzymes, waste, water Plant cells have one large vacuole. Animal cells have many small vesicles.

LYSOSOMES Contain digestive enzymes Digest excess or worn organelles, food particles, viruses, and bacteria Surrounded by membrane that prevents it from destroying the cell Can burst causing cell death

Mitochondria Chapter 4 converts food into energy Cell “Powerhouse” Number of mitochondria depends upon the function of the cell Ex: muscles cells have more mitochondria than fat cells

Centriole Help with cell reproduction Only found in animal cells

Chloroplast Located in plant cells, some bacteria, and protists. Capture light energy to produce and store food Contain chlorophyll-green pigment that traps light energy

Features Common to Cells: Cytoskeleton – tiny fibers that give structure and support to the cell.

Cell wall Rigid outer covering PLANT CELLS Located outside the cell membrane Provides support and protection Helps produce turgor pressure

Animal Cell Plant Cell

Plant cell vs. Animal Cell

Plant vs. Animal Cells Plant Animal Has chloroplasts Large central vacuole Has cell wall No centrioles No chloroplasts or cell wall Small vacuoles Has centrioles