Cells Chapter 7

The size range of cells

Why are cells so small? Small cells have a high surface area to volume ratio which allows more stuff to move in and out of the cell

CELL THEORY Living organisms are composed of one or more cells Cells are the smallest unit of life Cells come from other cells

ALL CELLS HAVE Plasma membrane –Outer layer Cytoplasm –Watery stuff inside DNA –Genetic material Ribosomes –Make proteins

TWO BASIC CELL TYPES

Prokaryotic Cells DNA in nucleoid region No membrane-bound organelles No nucleus Small Bacteria

Plasma Membrane aka: The Gate-keeper

Overview of an Animal Cell

Overview of a Plant Cell

Nucleus & Nuclear Envelope

Ribosomes

Endoplasmic Reticulum (ER)

Golgi Apparatus

Lysosomes Sac of hydrolytic enzymes Digests macromolecules Breaks down dead organelles pH ~ 5

Formation & Function of Lysosomes

The Endomembrane System

Mitochondria Site of Cellular Respiration, Makes ATP

Chloroplast Site of Photosynthesis Converts energy from sunlight to chemical energy stored in sugar

Central Vacuole: Plant Cells Stores Water Waste Nutrients Makes plant cell turgid

Peroxisomes Produce and break down H 2 O 2

Cytoskeleton Network of fibers throughout cytoplasm Gives cell shape Holds organelles in place Involved in movement & changing shape

Motor Molecules & Cytoskeleton Changing shape Cilia movement Flagella movement Organelles move along microtubule or microfilament Ex: Vesicle transport

Centrioles Centriole: 9x3 ring of microtubules Involved in cell division

Structure of Eukaryotic Cilia/ Flagella 9x2 + 2 ring of microtubules Covered in plasma membrane Basal Body Anchors cilia/ flagella to cell 9x3 ring of microtubules

Wave Back and forth

Dynein “walking” moves Cilia and Flagella Powered by ATP Dynein arms grip adjacent microtubule Grip, pull, release – repeat Results in bending of microtubules

Microfilaments (actin filaments) Pulling force –Muscle contraction –Cytoplasmic streaming –Pseudopodia Part of Extracellular Matrix –Support cell membrane –Inside of cell membrane

Extracellular Matrix

Plant Cell Walls Protects cell Gives cell shape Prevents excessive uptake of H20 Primary, secondary walls Plasmodesmata –Cell to cell communication –Cytoplasm continuous from one cell to other Middle lamella cements cells together

Cell Junctions in Animal Cells Fuses membranes Strong sheets Pass ions and small molecules