Ch 4 (Honors Bio) Ch 3 (Bio) CELL STRUCTURE AND FUNCTION

The Cell The cell is the smallest unit of life smallest unit 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. Matthias Schleiden – 1883 –all plants are made of cells. Theodor Schwann – 1839 –all animals are made of cells Rudolph Virchow-1855- all cells must come from other cells

The Cell Theory 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.

Two Basic Types of Cells

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

Eukaryotic Cell Cells that do have a nucleus. They do have organelles. 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.

Common Features cont…. All cells have DNA. (DeoxyriboNucleic Acid) Chromosomes vs Chromatin

Common Features cont…. Cell (plasma) membrane – Semi-permeable- allows some materials in and keeps others out. This helps to maintain cellular homeostasis. SELECTIVE PERMEABILITY

Structure of the Plasma Membrane 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. Phospholipid Bilayer -2 layers of phospholipids. Phospholipid- phosphate head attached to two lipids (fatty acid tails).

Cell membrane Structure 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 “Command center” Surrounded by a nuclear envelope Contains genetic material: chromatin chromosomes

Chromatin vs Chromosomes When the cell is not actively dividing CHROMOSOMES When the cell is dividing

Nucleolus and Ribosomes Nucleolus-makes ribosomes Ribosomes- build proteins 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) Has Ribosomes attached Protein synthesis

Smooth ER Produce and store lipids

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

VACUOLES Storage sacs Animal cells have many small vesicles. Store food, enzymes, waste Animal cells have many small vesicles.

LYSOSOMES Full of 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 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

Cytoskeleton 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 Flagella-long, whip-like projections Cilia-short, numerous hair-like projections that move in a wavelike motion

Centriole Help with cell reproduction Only found in animal cells

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

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

Large Central Vacuole Plant cells Storage-stores food, enzymes, wastes, etc

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