BSB 113 Lecture 4 Energy Organelles 2020 - Phoenix PDF

# BSB 113 Lecture 4 Cell structure, Lct7 ## Objectives - Energy Organelles - Describe structures and functions of Chloroplasts and other Plastids - Structure and function of Mitochondria description ## Energy making organelles - Note: A cell makes molecules and uses them for: - Growth -...

# BSB 113 Lecture 4 Cell structure, Lct7 ## Objectives - Energy Organelles - Describe structures and functions of Chloroplasts and other Plastids - Structure and function of Mitochondria description ## Energy making organelles - Note: A cell makes molecules and uses them for: - Growth - Reproduction - Movement - Responsiveness  - It requires energy to produce them. - The energy producing organelles are Mitochondria and chloroplast. ## Plastids (Plast = form) - These are membrane bound organelles that are mostly pigmented. - They are found in plants and some protists (e.g. green algae) - They all develop from proplastids (undifferentiated) - Proplastids are found in meristematic cells of plants. **Note:** Plastids are classified according to the type of pigment they have. They may change from one form to another. ## Plastids Diagram A diagram showing the various types of plastids, branching out from proplastids, is shown. The diagram goes as follows: - **Proplastid** - **Etioplast** - **Leucoplast** - **Amyloplast** - **Elaioplast**  - **Proteinoplast** - **Chloroplast**  - **Amyloplast - forms/stores starch** - **Elaioplast - stores lipids** - **Proteinoplast - stores proteins** ## Chloroplast structure A diagram of a chloroplast is shown. The diagram is labelled as follows: - **Chloroplast** - **Outer membrane** - **Intermembrane space** - **Inner membrane** - **Thylakoid membrane** - **Thylakoid lumen** - **Thylakoid** - **Granum** - **Lamella** ## Chloroplast: Plast = form, Chloros = green - 4 to 6 µm in diameter, Variable in size and shape. - Has outer membrane and inner one that forms thylakoids (flat disks) - Thylakoids are in stacks called granum, (grana - plural). - Grana are joined together by lamellae membrane. All these are embedded in gel like matrix called stroma. - Stroma has starch grains, oil bodies, DNA, enzymes, ribosomes, etc. - Thylakoids contain chlorophylls and caretonoids (carotene, xanthophyll). - Function: photosynthesize. ## Chromoplast: chroma = colour - Spherical, elongated, lobed in shape. - They contain betacyanin, anthocyanin, carotene. May also form from other plastids. They have oil bodies where pigments are stored. - Chromoplasts found in fruits, flowers, roots: carrots, beetroot. ## Leucoplasts - No pigments, no elaborate membranes like of chloroplast. - Contains oil bodies, starch grains, protein bodies. - Found mostly in storage cells usually not exposed to the sun. ## Chromoplast Diagram A diagram is shown of a chromoplast. It is labelled as follows: - **Circular DNA** - **Membranous sac** - **Double-layered membrane** - **Plastoglobule**  - **Stroma** - **Carotenoid crystal** ## Amyloplast Diagram A diagram shows an Amyloplast. It is labelled as follows: - **Synthesis and storage of starch granules** - **Amyloplast envelope**  - **Amyloplast**  - **Starch granules** - **Plant cell** ## Mitochondria (-drion, for singular) - Vary in size and shape (sausage, spiral or spherical shapes). About 1µm in diameter. - Bound by double membranes. - Inner membrane is folded into projections called crista or crystae (plural) - Cristae is in a gel like matrix with enzymes, DNA, RNA, proteins, ribosomes (70s)  - **Function:** Respiration. ## Mitochondria Diagram A diagram is shown showing a mitochondrion. It is labelled as follows: - **F F1 complexes** - **DNA** - **Ribosomes** - **Crista** - **Inner membrane** - **Outer membrane** - **Matrix** - **Intermembrane space** Another diagram is shown with side-by-side diagrams of a Chloroplast and Mitochondrion. ## Endosymbiotic origin theory of energy organelles - Mitochondria/chloroplast originated by one cell ingesting another. - The two organelles were believed to be prokaryotes that were ingested by other cells and they were not digested. - The ingested and its host developed a symbiotic relationship. ## Why prokaryotes? - They have circular DNA without histones - Have one or more nucleiods - Antibiotics like chloromphile, streptomycin inhibits their protein synthesis like they do in bacteria. - They reproduce by fission like bacteria - Ribosomes are of 70s - Produce proteins