Ch 4 CELL STRUCTURE AND FUNCTION The Cell

Ch 4 CELL STRUCTURE AND FUNCTION

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

Chapter 4 Section 2 Introduction to Cells Cellular Organization

Discoveries Leading to The Cell Theory • Robert Hooke – 1665 -observed cork through a light microscope. • Anton Van Leewenhoek – 1675 -observed LIVING cells. • Matthias Schleiden – 1883 –plants are made of cells. • Theodor Schwann – 1839 –animals 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, and cells come only from pre-existing cells.

Two Basic Types of Cells

Prokaryotic Cell • Prokaryotic-cells that do not have a nucleus and internal membrane-bound structures – Most unicellular organisms are prokaryotes. – Bacteria

Eukaryotic Cell • Eukaryotic-Cells that do have a nucleus and internal membrane -bound structures. – Most multicellular organisms are eukaryotes. – Yeast and algae (unicellular, eukaryotes) – Plant and animal

Features Common to Cells: • Cytoplasm – Gel like material that protects, supports and suspends organelles. All cells have either DNA or RNA or both.

Features Common to Cells: • Cell membrane – Semi-permeable allows some materials in and keeps others out. 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 modelmembrane is flexible • Cholesterol-keeps fatty acid tails from sticking together • Transport proteins-allow needed substances to move through the membrane

Chapter 4 Parts of the Cell

Nucleus • “Command center” • Surrounded by a nuclear envelope • Contains genetic material: – chromatin – chromosomes • Nucleolus-makes ribosomes – Ribosomes-site where proteins are made • Can be found floating in the cytoplasm or attached to endoplasmic reticulum

Endoplasmic Reticulum (ER) • 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 • Smooth Endoplasmic Reticulum (SER) – Produce and store lipids

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

VACUOLES • Storage sacs Temporary storage of materials – Store food, enzymes, waste • 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

Chapter 4 Mitochondria • Cellular respiration -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

Plastids – Color pigments of cells • Examples: – 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. – Microfilament- thin and tubular…support the cell membrane. – Microtubule- thick and tubular also branched. Act as “rails” on which materials move through the cell.

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

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 • – – Animal Cell vs. Plant cell • • Animal Cell DO contain centrioles. DO NOT contain a cell wall or plastids. Plant Cell DO contain a cell wall, plastids, and a large central vacuole. DO NOT contain centrioles