Cell Energy Production, Structure and Support

Plant vs Animal Cells.

Plant Cells.  Plant cells have rigid and thick cell walls. These walls protect the plant cell and help the cell maintain its shape. (The polysaccharide cellulose is used in the construction of plant cell walls.)  Plastids such as chromoplast and photosynthetic chloroplasts are found in plant cells.  A large central vacuole is found in mature plant cells. Enzymes in the vacuole can be used for digestion or the uptake of water to increase plant cell size.

Plastids  These are the organelles that are similar to chlorophyll in their photosynthetic abilities. They can occur in bands or as a random distribution of granular masses  Not found in animals

Plastids  Plastids can function as chemical factories and storehouses for food and color pigments  Plastids are the site of photosynthesis in eukaryotic cells  A chloroplast is one form of a plastid  Other forms of plastids include chromoplasts (color pigment) and leucoplasts (white pigment or storage for starch)

Chloroplasts - Convert solar energy to chemical energy in sugar molecules. - Internal structure is much more successful than anything yet produced by human ingenuity.

Internal membranes partition a chloroplast into three major compartments: 1. Outer membrane 2. Narrow intermembrane space between outer and inner membranes of chloroplast 3. Inner membrane - space enclosed by intermembrane space contains thick fluid called stroma and a network of tubules and hollow disks formed of membranes - granum (plural grana) occurs in stacks and are the chloroplasts’ solar power packs - The individual ‘blocks’ that make up a granum are called thylakoids - The collective inner membrane space of a chloroplast is referred to as a lumen or specifically a thylakoid lumen Chloroplasts

Mitochondria  Function - make ATP energy from cellular respiration  sugar + O 2  ATP  fuels the work of life  Structure - double membrane ATP in both animal & plant cells

Mitochondria (singular – mitochondrion)  The power generators of the cell  Carry out processes of cellular respiration in which the chemical energy of foods such as sugars is converted to the chemical energy of a cellular fuel molecule called ATP (adenosine triphosphate)

Mitochondria Is enclosed by two membranes but only has two compartments: encloses the second compartment containing fluid called a inner membrane encloses the second compartment containing fluid called a mitochondrial matrix where many of the chemical reactions of cellular respiration occur folds called cristae (contain enzyme molecules that make ATP) greatly increase the membrane’s surface area and enhancing the mitochondria’s ability to produce ATP Mitochondria can self-replicate and adapt to the demands of the tissue the cell is in - has its own DNA - Scientists hypothesize that millions of years ago, free-living prokaryotes were engulfed, but not digested by larger prokaryotes

Mitochondria are in both cells!! animal cells plant cells mitochondria chloroplast Mitochondria are in both cells!!

 Mitochondria  make energy from sugar + O 2  cellular respiration  sugar + O 2  ATP  Chloroplasts  make energy + sugar from sunlight  photosynthesis  sunlight + CO 2  ATP & sugar  ATP = active energy  sugar = stored energy  build leaves & roots & fruit out of the sugars Plants make energy two ways!

Cytoskeleton

cell membrane  cell boundary  controls movement of materials in & out  recognizes signals cytoplasm  jelly-like material holding organelles in place

Structural Support of Cells comes from the Cytoskeleton  A supportive meshwork of fine fibers that extend throughout the cytoplasm  Three fibers make up the cytoskeleton: microfilaments (thinnest), microtubules (thickest), and intermediate filaments (in between thickness)

Microtubules and Microfilaments.  Microfilaments.  Intermediate Filaments  Microtubules

Microfilaments helical rods globular protein actin  Solid helical rods composed of a globular protein called actin twisted double chain  Usually forms in a twisted double chain of actin molecules change shape and move  Can help cells change shape and move by assembling at one end and disassembling at the other in a form of amoeboid crawling aid in muscle contraction  Microfilaments can interact with protein filaments such as the protein myosin in muscle cells that aid in muscle contraction

Intermediate Microfilaments  Made of fibrous proteins rather than globular ones and have a ropelike structure  Serve mainly as reinforcing rods for bearing tension  Also help anchor organelles such as the nucleolus being held in place by a ‘cage’ of intermediate filaments

Microtubules  Straight, hollow tubules that provide anchorage for organelles and to act as tracks along which organelles can move within the cytoplasm  A lysosome might move along a microtubule to reach a food vacuole  May serve as a guide for chromosomes when cells divide, and are the basis for ciliary and flagellar movement

Cilia and Flagellum Move When Microtubules Bend  Cilia and flagellum have similar structure and mechanisms of movement  Cilia are generally and occur in numbers  Cilia are generally short and occur in large numbers  Flagellum are typically and numerous  Flagellum are typically longer and less numerous  Composed of a core of microtubules wrapped in an extension of the plasma membrane

Cilia and Flagellum

Plant Cell Wall Structure Plasma membrane Secondary cell wall Primary cell wall (cellulose) Middle lamella (pectin)

Animal Cell.  Animal cells can have flagellum while plant cells (with a few exceptions) lack flagellum.  Animal cells also have that are not found in plant cells. (Centrioles are used in mitosis to help construct the mitotic spindle.)  Animal cells also have centrioles that are not found in plant cells. (Centrioles are used in mitosis to help construct the mitotic spindle.)  vacuole  Smaller vacuole

Cell Surfaces Support, Protect, and Join Cells (FYI)  Most cells have more than just a plasma membrane surrounding it to protect it from its environment  In plants, rigid cell walls not only protect the cells but provide skeletal support that keeps the plants upright on land and are typically ties thicker than plasma membranes. The cells walls are composed mainly of the polysaccharide cellulose embedded in a matrix of other polysaccharides and proteins  Some plant cell walls also contain a multilayered arrangement of polysaccharides that work to ‘glue’ adjacent cells together such as in wood  To communicate with adjacent cells, plants must have some type of cell junctions (example is plasmodesmata [singular plasmodesma] that are a small channel between adjacent plant cells and function to allow plant tissues to share water, nourishment, and chemical messages)  Animal cells are generally more flexible than plant cells and are usually covered by a sticky layer of polysaccharides and proteins that helps hold tissues together in tissues (lining of digestive tract helps prevent stomach cells from being broken apart from enzymes and acids used for digestion)

Cell Junctions  Cells are connected by cell junctions that come in three different types:  attach adjacent cells to each other or to an extracellular matrix (substance which tissue is embedded) allow materials to pass along the spaces between cells  Anchoring junctions attach adjacent cells to each other or to an extracellular matrix (substance which tissue is embedded) allow materials to pass along the spaces between cells  bind cells together forming a leak proof sheet such as in the digestive tract  Tight junctions bind cells together forming a leak proof sheet such as in the digestive tract  are channels similar to plasmodesmata in plants by allowing water and other small molecules to flow between neighboring cells (example is in embryos where communication and flow of nutrients is necessary for sustaining life)  Communicating junctions are channels similar to plasmodesmata in plants by allowing water and other small molecules to flow between neighboring cells (example is in embryos where communication and flow of nutrients is necessary for sustaining life)

Cell Surfaces  In plant cells, small openings called aid in communication with other cells and the environment  In plant cells, small openings called plasmodesmata aid in communication with other cells and the environment  and are taken through these openings and are removed  Chemicals and water are taken through these openings and wastes are removed

All Life Forms on Earth Share Fundamental Features , each enclosed by a membrane that maintains internal conditions very different from its surroundings  Life forms consist of cells, each enclosed by a membrane that maintains internal conditions very different from its surroundings  as a genetic material  Having DNA as a genetic material , which involves the interconversion of different forms of energy and of chemical materials  Carrying out metabolism, which involves the interconversion of different forms of energy and of chemical materials

Cell Communication and Relationships For Maintaining Life Overview

Categorizing Cell Structure with Function  Category 1 – Manufacture Includes not only synthesis of molecules but also transport within the cell Includes not only synthesis of molecules but also transport within the cell Structure depends heavily on a network of metabolically active membranes Structure depends heavily on a network of metabolically active membranes  Category 2 – Breakdown Includes three organelles that break down and recycle materials harmful or no longer needed to the cell Includes three organelles that break down and recycle materials harmful or no longer needed to the cell All organelles are composed of single membranous sacs, inside which materials can be broken down All organelles are composed of single membranous sacs, inside which materials can be broken down  Category 3 – Energy Processing Two organelles utilized in energy production Two organelles utilized in energy production Expanses of metabolically active membranes within the organelle make it possible to perform complex energy conversions that power the cell Expanses of metabolically active membranes within the organelle make it possible to perform complex energy conversions that power the cell  Category 4 – Support, Movement, and Communication Between Cells For movement to occur, there must be a rigid support against which a force can be applied and communication between these surfaces interact with one another, forming a communication For movement to occur, there must be a rigid support against which a force can be applied and communication between these surfaces interact with one another, forming a communication These four categories of organelles form an integrated team and the properties of life at the cellular level emerge from the coordinated functions of the team members These four categories of organelles form an integrated team and the properties of life at the cellular level emerge from the coordinated functions of the team members

End of Cell Structure and Function