Cells

Cells 3 Major Parts of Cell Plasma Membrane  controls passage of materials in/out of cell Nuclear Region  Controls cell’s activities; contains DNA & RNA Cytoplasm  Organelles and cytosol Plasma Membrane Nucleus

How Big is a Cell? How Big is a Cell? Not big (diameter = 0.000008in) 20,000 bacterial cells = 1 cm

Why Are Cells So Small? High surface to Volume ratio!! Greater the SURFACE, more stuff gets in and out of cell Greater the VOLUME, less stuff gets in or out; cell starves or is poisoned

Characteristics of Cells Size Size varies Bacteria cell  small Nerve cells large Spinal Neuron-Over 3 feet long Sperm Cell- 25 Micrometers

Internal Organization & Types of Cells Each cell contains miniature organs called organelles Each organelle performs specific functions for the cell Eukaryotic Cells  Cells with a nucleus and outer cell membrane which allows molecules to pass in and out Prokaryotic Cells  Cells without a nucleus or other organelles

Organization of Cells Tissue Groups of cells performing the same task Exp. Nerve Tissue  transmits nerve impulses Epithelial Tissue  protective outer layer Organ  Groups of tissues performing the same task Exp. Heart  Circulate blood through body System  Group of organs working together Exp. Circulatory System Digestive system Organism  Groups of systems working together

Plant & Animal Cell Organelles Cytoplasm All the area between the cell membrane and the nucleus and contains all of the organelles within the cell Ribosomes  Make proteins from AA; found on ER or in cytosol Rough ER  Makes proteins and transports them to other parts of the cell via vesicles (little packages) Smooth ER  transports proteins Golgi Apparatus  Found close to ER. Takes proteins from ER and modifies them to make them work; then sends them on their way (mailroom of the cell) Mitochondrion  Powerhouse of the cell. Takes in food; Converts it to ATP, which is broken down for energy. Some cells have more mitochondria than others Cristae  folds in the inner membrane of mitochondria to increase surface area Nucleus  Controls and coordinates cell’s activities. Contains chromatin (DNA). DNA converted to RNA and stored in nucleolus. RNA sent out to cell as a messenger Surrounded by nuclear envelope Nuclear pores allow RNA to leave nucleus

Plant & Animal Cell Organelles Cytoskeleton  Scaffolding that gives cell shape Microfilaments  Used for muscle contraction Microtubules  Thicker,move organelles Cilia and Flagella  Help some cells move around Lining of respiratory tract Lysosomes  Contain Digestive Enzymes; breaks down glucose; can rupture and kill cell Nuclear Membrane Surrounds genetic material CentriolesSet of microtubules that move chromosomes during mitosis Plasma Membrane  Selective Transport of molecules and communication

Pictures of Cell Organelles You already have this information in your notes! Do not write this down!

Cytoplasm All of the area between the cell membrane and the nucleus Contains all of the organelles within the cell.

Ribosomes Make proteins from amino acids (AA); Found on ER or in cytosol.

Rough Endoplasmic Reticulum(ER) Makes proteins and transports them to other parts of the cells via vesicles (little packages).

Smooth Endoplasmic Reticulum Transports proteins

Golgi Apparatus Found close to ER. Takes proteins from ER and modifies them to make them work; then sends them on their way (mailroom of the cell).

Mitochondrion Powerhouse of the cell. Takes in food (glucose) and converts it to ATP, which is broken down for energy Some cells have more mitochondrion than others.

Cristae Folds in the inner membrane of the mitochondria to increase the surface area

Nucleus Controls and coordinates cell activities. Contains chromatin (DNA). DNA converted to RNA and stored in nucleolus. RNA sent out to cell as a messenger.

Nucleus Surrounded by nuclear envelope. Nuclear pores allow RNA to leave nucleus.

Cytoskeleton Scaffolding that gives cell shape. Microfilaments -used for cell movement Microtubules -thicker, used for support

Cilia and Flagella Help some cells move around Some found in the lining of respiratory tract.

Lysosomes Contain digestive enzymes Breaks down glucose Can rupture and kill cell.

Nuclear Membrane Surrounds genetic material

Centrioles Set of microtubules that move chomosomes during mitosis

Organelles only in Plant Cells Cell Wall Protects Cell and gives cell shape Vacuoles Storage for food, water, gives plant cells shape Chloroplasts  Found only in plant cells. Used to trap the sun’s energy

Structure of Plasma Membrane Selectively Permeable  allows some molecules in; keeps others out Phospholipid Bilayer Polar heads on outside and inside of cell; nonpolar tails on inside of membrane Polar = Hydrophilic = water loving Nonpolar = hydrophobic = water hating Why is there this arrangement of lipids? Cytoplasm and outside of cell is watery

Molecules on the Plasma Membrane Carbohydrates  Act as receptors; molecules attach to cell; tell it what to do Cholesterol  Gives membrane shape; rigidity Receptor Proteins  bind hormones & other substances coming in from outside the cell Recognition Proteins  proteins on membrane that are used for recognition by extra-cellular substances Adhesion Proteins  help cells of a certain type stick together to form tissues Protein Receptors coming out of plasma membrane

What gets in and out of the cell membrane? How do some substances pass through the membrane while others stay out? Materials moves across the membrane in two ways 1. Passive Transport 2. Active Transport

Passive Transport Diffusion  movement of molecules from high to low concentration Oxygen, CO2, fat soluble molecules, and water pass through the membrane by diffusion

Active Transport Active Transport  Using energy to transport large molecules into the cell against their concentration gradients 1. Cell Membrane Pumps  carrier proteins pump ions against their concentration gradient 2. Endocytosis  Engulfing of large particles or liquids by plasma membrane Cells take in cholesterol by endocytosis from bloodstream Pinocytosis  Endocytosis of liquid 3. Exocytosis  vesicle contents expelled by cell Proteins are transported by exocytosis

Exocytosis Animation

Endocytosis Animation

Osmosis Osmosis  diffusion of water Isotonic Solution Cells are at equilibrium; no NET movement of water Hypertonic solution  Cell is in a solution that has lots of salts or other ions in it; water rushes out of the cell and the cell shrinks Hypotonic solution Cell is in a solution that has little or no salts or other ions in it; water rushes into the cell and the cell swells

Tonicity in Red Blood Cells