Cell Unit Learning Goal 2: Describe cell organelles and their functions within the cell.

Prokaryotic Cells  Believed to be the first cells to evolve.  Lack a membrane bound nucleus and organelles.  Genetic material is naked in the cytoplasm  Ribosomes are only organelle.

Eukaryotic Cells “True nucleus”; contained in a membrane bound structure. Membrane bound organelles. Thought to have evolved from prokaryotic cells.

Prokaryotic vs. Eukaryotic

Cell Size of the Cell nt/begin/cells/scale/ Cell Structure nt/begin/cells/insideacell/

Cell Wall The main function of the cell wall is to provide support and protection for the cell. Found in plant and prokaryotic cells. Formed from cellulose molecules.

Cytoplasm Location of growth, metabolism, and replication. Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures.

Ribosomes Translate the genetic code to assemble proteins. Found attached to the Rough endoplasmic reticulum or free in the cytoplasm.

Ribosome

Rough Endoplasmic Reticulum Rough E.R.  Network of continuous tubes, studded with ribosomes.  Manufactures, processes, and transports proteins for export from cell.  Continuous with nuclear envelope.

Endoplasmic Reticulum

Smooth Endoplasmic Reticulum Smooth E.R. Similar in appearance to rough ER, but without the ribosomes. Contains a collection of enzymes that perform specialized tasks.

Lysosome Single membrane bound structure. Found mostly in animal cells. Contains digestive enzymes that break down cellular waste, old cell parts, and nutrients for use by the cell.

Lysosome

Golgi Apparatus (Complex) Modifies, sort, and package proteins and lipids made by the ER.

Golgi Apparatus

Mitochondria Membrane bound organelles that are the site of cellular respiration (ATP production) Powerhouse of the cell.

Mitochondria

Nucleus Double membrane- bound control center of cell. Brain of the cell. Contains nearly all of the cell’s DNA.

Nucleus

Parts of the nucleus:  Chromatin - genetic material of cell in its non-dividing state.  Chromosomes – Condensed chromatin ready for cell division.  Figure 2: Different levels of DNA condensation. (1) Double-strand DNA. (2) Chromatin strand (DNA with histones). (3) Chromatin during interphase with centromere. (4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (5) Chromosome during metaphase. interphaseprophasemetaphase

Parts of the nucleus:  Nucleolus - dark- staining structure in the nucleus that plays a role in making ribosomes  Nuclear envelope - double membrane structure that separates nucleus from cytoplasm.

Centrioles Found only in animal cells. Self-replicating Made of bundles of microtubules. Help in organizing cell division.

Cytoskeleton  Solid rods of globular proteins.  cytoskeleton offers support to cell structure.

Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion Section 7-2 Figure 7-11 Cytoskeleton

Chloroplast  Site of photosynthesis  Membrane bound structure.  Contains chlorophyll

Chloroplast

Vacuole Store water and nutrients needed by the cell. Help support the shape of the cell. Plants have a large central vacuole. Other types of cells have a much smaller vacuole.

Animal Vacuole

Plant Cell Vacuole

Cell Membrane

Plasma (Cell) Membrane Is a Fluid Mosaic The plasma membrane is a selectively semipermeable barrier – controls the passage of substances into and out of the cell. Fluid Mosaic composed of Phospholipids, Proteins, Cholesterol, Glycolipids, and Glycoproteins.

Phospholipid Bilayer Phopholipids are the main components of membranes. They arrange themselves in a bilayer, with their water-hating tails facing each other, and their water-loving heads facing the outside of the cell on one side, and the inside of the cell on the other side. Phospholipid Phospholipid Bilayer

Membrane Proteins Roles of membrane proteins include : Structural Enzyme Transport Cell- recognition

Types of Transport

Transport Across the Membrane Diffusion a substance moving from an area of high concentration of the substance to a region of low concentration of the substance until it reaches equilibrium. – This is a passive process that does not require an energy input.

Diffusion

Diffusion

Facilitated Diffusion Transport Proteins – channels for substances to enter or exit the cell through passive diffusion. – No Energy Required

Active Transport – Substances move from a region of low concentration on one side of the membrane to a region of high concentration on the other side. Active Transport Requires Energy

Osmosis: Diffusion of Water Osmosis is the diffusion of water, across a semipermeable membrane. – from a region of high concentration of water to a region of low concentration of water, until equilibrium of water on both sides of the membrane is reached.

Osmosis

Osmoregulation: Control of H 2 O Balance in Cells Tonicity: the movement of water into and out of cells in response to the water concentration on the outside of the cell. – Water moves from where it is in high concentration to where it is in low concentration until an equilibrium of the water concentration is reached.

Transport of Large Molecules Across the Membrane Endocytosis – Large substances enter the cell through phagocytosis, cell “eating” or pinocytosis, cell “drinking”. Exocytosis – vesicles fuse with the plasma membrane and its contents are ejected from the cell

Animal Cell Centrioles Nucleolus Nucleus Nuclear envelope Rough endoplasmic reticulum Golgi apparatus Smooth endoplasmic reticulum Mitochondrion Cell Membrane Ribosome (free) Ribosome (attached) Section 7-2 Figure 7-5 Plant and Animal Cells

Plant Cell Nuclear envelope Ribosome (attached) Ribosome (free) Smooth endoplasmic reticulum Nucleus Rough endoplasmic reticulum Nucleolus Golgi apparatus Mitochondrion Cell wall Cell Membrane Chloroplast Vacuole Section 7-2 Figure 7-5 Plant and Animal Cells

ProkaryotesEukaryotes Cell membrane Contain DNA Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Animal CellsPlant Cells Centrioles Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts Section 7-2 Venn Diagrams

Animal Cell vs. Plant Cell