cell organelles

CELL STRUCTURE AND FUNCTION : 6&7(CH4) 1 CELL STRUCTURE AND FUNCTION CHAPTER- 4 LECTURE NUMBER:6 & 7

OUTLINE: CELL STRUCTURE AND FUNCTION : 6&7(CH4) 2 OUTLINE: CELL STRUCTURE AND FUNCTION The Cell Theory Cell Membranes Getting through Membranes Cell Size Organelles composed of Membranes Nonmembranous Organelles Nuclear Components Major Cell Types

Lecture Numbers: Six & Seven : 6&7(CH4) 3 Lecture Numbers: Six & Seven Organelles composed of Membranes Nonmembranous Organelles Nuclear Components Major Cell Types

Organelles composed of membranes : 6&7(CH4) 4 Organelles composed of membranes Plasma membrane (cell membrane) Endoplasmic reticulum Golgi apparatus Lysosomes Peroxisomes Vacuoles and vesicles Nuclear membrane

The plasma membrane : 6&7(CH4) 5 The plasma membrane Composed of a single phospholipid bilayer Separates the contents of the cell from the external environment Important features Metabolic activities Moving molecules across the membrane Structurally different inside and outside Identification: Self vs. nonself Attachment sites Signal transduction

CELL ORGANELLES : 6&7(CH4) 6 CELL ORGANELLES Cells are complex structures and have many subunits called organelles. Each one of the organelles has its function, shape, and structure.

The endoplasmic reticulum : 6&7(CH4) 7 The endoplasmic reticulum A set of folded membranes and tubes throughout the cell. Provides a large surface area for important chemical reactions. Because it is folded, it fits into a small space. Two types of ER Rough Has ribosomes on its surface Sites of protein synthesis Smooth Lacks ribosomes Metabolizes fats Detoxifies damaging chemicals

The Golgi apparatus : 6&7(CH4) 8 The Golgi apparatus Stacks of flattened membrane sacs. Functions Modifies molecules that were made in other places. Manufactures some polysaccharides and lipids. Packages and ships molecules.

Traffic through the Golgi : 6&7(CH4) 9 Traffic through the Golgi Vesicles bring molecules from the ER that contain proteins. Vesicles fuse with the Golgi apparatus. The Golgi finishes the molecules and ships them out in other vesicles. Some are transported to other membrane structures. Some are transported to the plasma membrane. Some vesicles become lysosomes.

Lysosomes : 6&7(CH4) 10 Lysosomes Vesicles containing enzymes that digest macromolecules. Carbohydrates Proteins Lipids Nucleic acids Interior contains low pH These enzymes only work at pH=5. The cytoplasm is pH=7. If the lysosome breaks open, these enzymes will inactivate and will not damage the cell.

Functions of lysosomes : 6&7(CH4) 11 Functions of lysosomes Digestion of food taken into the cell Destruction Disease-causing organisms Old organelles

Peroxisomes : 6&7(CH4) 12 Peroxisomes Contain the enzyme catalase Breaks down hydrogen peroxide Breaks down long-chain fatty acids Synthesizes cholesterol and bile salts Synthesizes some lipids

Vacuoles and vesicles : 6&7(CH4) 13 Vacuoles and vesicles Membrane-enclosed sacs Vacuoles Larger sacs Contractile vacuoles Forcefully expel excess water from the cytoplasm Vesicles Smaller vesicles

The nuclear membrane : 6&7(CH4) 14 The nuclear membrane Separates the genetic material from the rest of the cell Filled with nucleoplasm Composed of two bilayers Contains holes called nuclear pore complexes Allow large molecules like RNA to pass through the membrane into the cytoplasm

Interconversion of membranes : 6&7(CH4) 15 Interconversion of membranes Membranes are converted from one membranous organelle to another.

Energy converting organelles : 6&7(CH4) 16 Energy converting organelles Mitochondrion A small bag with a large bag stuffed inside. Larger internal bag is folded into cristae. Cristae contain proteins for cellular respiration. Releases the energy from food Requires oxygen Uses the energy to make ATP

Energy converting organelles : 6&7(CH4) 17 Energy converting organelles Chloroplasts Sac-like organelle Contain chlorophyll Perform photosynthesis Uses the energy in light to make sugar Contain folded membranes called thylakoids Thylakoids stacked into grana Thylakoids contain chlorophyll and other photosynthetic proteins. Thylakoids surrounded by stroma

Nonmembranous organelles : 6&7(CH4) 18 Nonmembranous organelles Ribosomes Cytoskeleton Centrioles Cilia flagella Inclusions

Ribosomes : 6&7(CH4) 19 Ribosomes Made of RNA and proteins Composed of two subunits Large Small Are the sites of protein production Found in two places Free floating in the cytoplasm Attached to endoplasmic reticulum

Cytoskeleton : 6&7(CH4) 20 Cytoskeleton Provides shape, support and movement Made up of Microtubules Microfilaments Intermediate filaments

CELL ORGANELLES : 6&7(CH4) 21 CELL ORGANELLES

CELL ORGANELLES : 6&7(CH4) 22 CELL ORGANELLES

Centrioles : 6&7(CH4) 23 Centrioles Two sets of microtubules arranged at right angles to each other. Located in a region called the centrosome. Microtubule-organizing center near nucleus. Organize microtubules into spindles used in cell division.

Cilia and Flagella : 6&7(CH4) 24 Cilia and Flagella Hair-like projections extending from the cell. Flagella Long and few in number Move the cell through its environment Cilia Small and numerous Move the environment past the cell 9 + 2 arrangement of microtubules

CELL ORGANELLES : 6&7(CH4) 25 CELL ORGANELLES

Inclusions : 6&7(CH4) 26 Inclusions Collections of miscellaneous materials Can be called granules Temporary sites for the storage of nutrients and waste

Nuclear components : 6&7(CH4) 27 Nuclear components Contains chromatin DNA + proteins Becomes condensed during cell division into chromosomes. Surrounded by nuclear membrane Contains one or more nucleoli Site of ribosome synthesis Contains nucleoplasm Water, nucleic acids, etc.

Prokaryotic cells : 6&7(CH4) 28 Prokaryotic cells Two different types of prokaryotes Domain eubacteria Contains bacteria Domain archaea Contains prokaryotes that live in extreme environments

Prokaryotic cell structure : 6&7(CH4) 29 Prokaryotic cell structure Contain DNA and enzymes Able to reproduce Engage in metabolism Surrounded by a plasma membrane Plasma membrane surrounded by a cell wall Maintains the shape of the cell Cell wall surrounded by a capsule Helps them adhere to hosts Protects them from destruction Contain ribosomes May contain flagella Facilitates movement

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Summary of cell organelles and their functions : 6&7(CH4) 32 Summary of cell organelles and their functions