Cell Structure and Function

• What is the smallest unit of matter that can carry on all of the processes of life?– Cell

• What is an organism with only one cell?– Unicellular

• What is an organism with more than one cell?– Multicellular

• All living things are made up of cells• What led to the discovery of cells?

– Microscopes

Discovery of the Cell

• 1665 Robert Hooke discovered dead plant cells in a slice of cork using a very simple microscope

• Anton van Leeuwenhoek discovered living organisms in 1673

• Matthias Schleiden discovered living plant cells

• Theodor Schwann found animal cells

Cell Theory

• What is the cell theory?– The observations that Hooke and

Leeuwenhoek made 150 years earlier led to the theory that follows

1. All living things are composed of one or more cells

2. Cells are the basic units of structure and function in living things

3. Cells come only from the existing cells

The Cell

• What characteristics do all cells share?– Cell membranes and contain DNA

• What is the difference between prokaryotes and eukaryotes?– Pros lack a nucleus and euks contain a nucleus

• What is a nucleus?– Organelle that directs most of the activities of the cell

and contains the cell’s DNA

Prokaryotes

• Have genetic material that is not contained in a nucleus

• Generally smaller and simpler than eukaryotes- not all the time though

• Carry out every activity other living things do as well

• Examples- bacteria

Eukaryotes

• Generally larger and more complex

• Many are highly specialized, many structures within cell

• Contain nucleus in which their genetic material is separated from the rest of cell

• Display great variety, may be displayed as unicellular organism or multicellular such as- protists, fungi, animals and plants

Sec 2- Eukaryotic Cell Structure

• Organelles- specialized organs found within the cell

• Cytoplasm contains the various organelles, cytosol is the gelatin like fluid, surrounds nucleus

• Nucleus- contains nearly all the cell’s DNA and with it the coded instructions for making proteins and other important molecules

Parts of the Nucleus

• Nuclear envelope- membrane that surrounds nucleus, dotted with pores that allows materials to move in and out

• Nuclear matrix maintains the shape of the nucleus• Chromatin are strands of DNA and protein

– Chromosomes- threadlike structures that contain genetic information that is passed on from generation to generation

• Nucleolus is a small dense region that controls protein synthesis and is the site of ribosome synthesis

Eukaryotic Cell

• Mitochondria is where energy is transferred from organic compounds to ATP

• Ribosomes is the site of protein synthesis• Endoplasmic Reticulum or ER serves as an

intracellular highway- where lipid components of cell membrane are assembled

• 2 Types of ER– Smooth ER and Rough ER

• Rough ER is covered with ribosomes, where synthesis of proteins takes place

• Smooth ER is not, collections of enzymes that perform specialized tasks

Eukaryotic Cell

• Golgi Apparatus, appears as a stack of closely apposed membranes, is the processes, packages, and secretes substances. Also prepares proteins for export

• Lysosomes, filled with enzymes, are organelles that digest viruses, bacteria, and old organelles. Also break down lipids, carbs, and proteins

• Vacuoles- saclike structures that store materials- water, salts, proteins, carbs

• Mitochondria- organelles that convert the chemical energy stored in food into compounds that the cell can use

• Chloroplasts- organelles that convert sunlike energy into chemical energy- photosynthesis

Cytoskeleton

• Cytoskeleton is made up of protein strands that give the cell its shape and support, also aids in movement– 2 major components include microtubules and microfilaments

• Microtubules are larger and hollow, assist in the movement of chromosomes during cell division

– Centrioles- help organize cell division– Cilia are short, in large numbers and assist with movement– Flagella are long, less numbers and assist with movement

• Microfilaments are smaller and contribute to cell movement and the contraction of muscle cells

– Made of protein-actin

Sec 3- Cell Boundaries

• Cell membrane- controls what goes in and out of the cell, provides protection and support

• Made up of lipid bilayer- gives membrane flexible structure that forms strong barrier

• A selectively permeable membrane allows certain substances in while not allowing other substances

• Cell walls- lie outside of cell membranes, provides support and protection for cell– Found in plants, algae, fungi, and many prokaryotes– Made from fibers of carbohydrates and proteins– Cellulose makes up cell walls in plants

Diffusion through Cell Boundaries

• Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration– Equilibrium- concentration of solute is same

throughout

• No energy needed

• Osmosis is the diffusion of water through a selectively permeable membrane

Effects of Osmosis on Cells

• Isotonic- concentration of solutes is same inside and outside the cell– Water moving in and out of cell

• Hypertonic- solution has higher solute concentration than the cell– Water moving out of cell

• Hypotonic- solution has a lower solute concentration than the cell– Water moving into cell

Facilitated Diffusion

• Cell membrane channels help move molecules across the membrane

• Fast and specific- only happens if there is higher concentration on one side of membrane

• Does not require energy

Active Transport

• Transportation of materials against concentration difference

• Requires energy

• Molecules generally transported by transport proteins

• Endocytosis and exocytosis- processes that carry larger molecules and clumps of materials across

Endocytosis and Exocytosis

• Endocytosis and Exocytosis

• Endo- taking material into the cell by means of infoldings, or pockets of the cell membrane– Phagocytosis- extensions of cytoplasm surrounds

particle and cell engulfs it– Pinocytosis- tiny pockets form around liquid

• Exo- membrane of vacuole surrounding the material fuses with the cell membrane, forcing contents out of cell

Sec 4- The Diversity of Cellular Life

• Compare multicellular organisms to unicellular organisms?

• Cell specialization- cells throughout an organism can develop in different ways to perform different tasks

• Examples

Levels of Organization

• Levels include; individual cells, tissues, organs, and organ systems

• Tissue-group of similar cells that perform a particular function– Examples

• Organ- group of tissues that perform a particular function– Examples

• Organ system- group of organs that work together to perform a specific function– Examples