Cells

All living things are made up of one or more cells Cells are the basic units of life Unicellular organism Multicellular organism

Organisms Organ systems Organs Tissues Cells Molecules Atoms tree human Organ systems Organs leaf stem brain heart Tissues leaf tissues cardiac tissue Cells nerve cell Molecules DNA molecules Atoms Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Most cells are between 10 and 100 microns Cells = 10,000 to 100,000 times smaller than us Atoms = 100,000 to 1,000,000 times smaller than cells

Every cell has: Cell membrane layer that surrounds the cell Cytoplasm semi-fluid substance inside the cell Organelles small structures or compartments inside the cell

Cell Membrane Functions: Characteristics: Controls what enters and leaves the cell Protects the cell from the environment Maintains an internal environment different than that outside the cell. Characteristics: Selectively – permeable: only some substances can pass through Made of a bi-layer of phospholipids embedded with proteins

Some proteins act as channels through which certain molecules can pass Phospholipid bilayer

Fluid mosaic model of the cell membrane: The phospholipids can flow around each other in most parts of the cell membrane

Organelles are divided into two groups: Membranous Nucleus Endoplasmic reticulum Golgi apparatus Vesicles, vacuoles Lysosomes Mitochondria Chloroplasts Non Membranous: Ribosomes Cytoskeleton (microtubules, filaments) Centrioles Cilia and flagella

Membranous Organelles The nucleus Functions: Controls the activities of the cell Stores hereditary material (DNA) that is passed on to the next generation

Parts of the Nucleus: Nuclear envelope: double membrane separates the nucleoplasm from the cytoplasm has nuclear pores (openings) that control what leaves and enters the nucleus

Parts of the Nucleus: Chromatin Nucleolus: long, threadlike form of chromosomes Made of DNA and proteins wound together Carries genetic information Contains the instructions for the cell activities Nucleolus: dark region of chromatin Site of ribosome production

Electron micrograph of a cell

Endoplasmic reticulum Sets of membranes connected to nuclear and plasma membranes Functions: Site of synthesis of organic molecules (esp. proteins) Transport of materials around the cytoplasm

Endoplasmic reticulum Two types: Rough ER – ribosomes attached Smooth ER – no ribosomes attached Ribosomes: Structures made of RNA found on rough ER and in cytoplasm Function: Site of protein synthesis

Golgi apparatus: Stack of membranes that package newly-synthesized molecules [from ER] and distributes to other parts of cell or out of cell 

Vesicle: membrane bound sac used for transportation of molecules into and out of a cell

Membrane bound sac used for storage Vacuole: Membrane bound sac used for storage -enzymes -water -starch -wastes -lipids

Lysosomes: Specialized vesicle containing hydrolytic enzymes to digest large molecules Usually double walled to protect cell Important part of programmed cell death called apoptosis

Intracellular conversion: Information and products flow from : Nuclear membrane  ER  Golgi  Vesicle  Plasma membrane

Getting molecules out: Vesicles carrying products of the cell fuse with the cell membrane

Mitochondria: Function: site of aerobic respiration (breaking down of food molecules to release energy) Also called the “powerhouse” of the cell

Structure of a Mitochondria:

Chloroplasts: Function: site of photosynthesis (process in which light energy is used to make food) Found in plants, algae and some protists

Structure of Chloroplast:

Non-membranous Cytoskeleton Provides internal structural support and allows the cell and organelles to move Includes protein filaments (rods) and microtubules (small hollow tubes)

Organizes the chromosomes during cell division Centrioles: Non-membranous Two structures found close to the nucleus at right angles to each other Organizes the chromosomes during cell division Not found in plant cells  

Cilia and flagella: Used to move fluids across the cell surface or move the entire cell Cilia are short and cover more of the cell membrane Flagella are long whip-like structures

What are the three parts all cells have? Plasma membrane or cell membrane Cytoplasm Organelles What are the two groups of organelles? Membranous Organelles: Non-membranous Organelles:

Name the Membranous Organelles: Nucleus Endoplasmic reticulum Golgi apparatus Vesicles, vacuoles Lysosomes Mitochondria Chloroplasts Name the Non-membranous Organelles: Ribosomes Cytoskeleton (microtubules, filaments) Centrioles Cilia and flagella

Cellular Organelles vacuole Nucleus centrioles mitochondrium Rough ER Smooth ER lysosomes Golgi

There are three large groups of living organisms called Domains Bacteria Archaea Eukarya Kingdoms Animals Plants Protists Fungi

There are three domains of living organisms They are differentiated by their cell type, organelles and biochemistry Bacteria Archaea Eukarya Prokaryotic cells Animals Plants Protists Fungi Eukaryotic cells

Prokaryotic vs. Eukaryotic Cells Nucleus – DNA contained within a membrane Membranous and non membranous Organelles Large (10 – 100 μm) Can be unicellular or multicellular Some with cell walls, some without Prokaryotic (bacteria) No nucleus- DNA in cytoplasm (nucleoid) Few organelles (cell membrane, ribosomes, flagella Small [same size of organelles; 1 – 10 μm ] Unicellular Cell wall

Prokaryotic & Eukaryotic Cells Prokaryotic cell

The four kingdoms of Eukarya (Cells contain nucleus) Protista Fungi Animalia Plantae

Domain Eukaryota Kingdom Plantae Multicellular Autotrophic (chloroplasts) Cell wall (cellulose)

Domain Eukaryota Kingdom Animalia Multicellular (cells are held together by collagen) Heterotrophic No cell wall

Domain Eukaryota Kingdom Fungi Multicellular Multinucleated (several nuclei) Cell wall (Chitin) Heterotrophic Spores used for reproduction

Domain Eukaryota Kingdom Protista Artificial Group Unicellular, Colonial or multicellular Auto/Heterotrophic Variable cell walls (silica, cellulose, chitin, no cell wall)