Transcript Cell Wall
The Cell
Cell Theory
• 1-All living things are made of cells • 2-Cells are the basic unit of life • 3-All cells come from preexisting cells
• Hooke • Leeuwenhoek • Schleiden • Schwann • Virchow
Scientists
Microscopes
• Light microscope- resolves to about .2 um – magnification • Electron microscope- resolves to about .2 nm – Scanning (SEM)-cell surfaces – Transmission(TEM)-Internal contents – **what is the disdavantage?
– (note the newer STM, scanning tunneling, enables 3-D images and can be used w/ living)
Cell Size Limit
• Cells must divide when volume exceeds surface area (Mader text: p. 59; Glencoe text: section 9.1) • Cells vary in size from about 1 um (bacteria) to about 1m (sciatic neuron-nerve cell)
Prokaryotic Cells
• Lack membrane bound nucleus • DNA found in nucleoid region • Like many eukaryotic cells, these cells have cell walls, plasma membranes, flagella and ribosomes • Unlike eukaryotic cells, they may have a capsule and pili
The prokaryotic cell
Cellular Organelles
Nucleus
• controls all functioning of the cell • “Brain” of the cell • contains the hereditary information of DNA • DNA holds the coded instructions for making proteins and other important molecules • Nucleus is important because making proteins is one of the main functions of the cell • Chromatin is the granular material seen within the nucleus (DNA bound to protein)
2. Nucleolus: dark regions within the nucleus a. produces ribosome's B. In animal & plant cells
3. Ribosomes: organelle that carries out protein synthesis/interprets code from RNA. Made of rRNA and protein •Can be attached to ER or floating •In plants & animal cells
Cell Wall
• Found in plants, algae,
fungi, and almost all prokaryotes. Not in animals
• Made from
carbohydrates (cellulose in plant cells)
• Provides support,
protection and excessive uptake of H2O
• Outside the cell
membrane.
Cell Membrane
• Thin flexible
barrier around the cell.
• Selectively
permeable. Made of
– lipid bilayer – proteins – carbohydrate
chains
– Scattered
cholesterol
Endoplasmic Reticulum
• Endoplasmic Reticulum • •
Rough ER envelope
• Covered in ribosomes • Makes proteins and cell membrane
Smooth ER – Membranous maze connected to nuclear – no ribosomes present
– Also a membranous maze – Lipid synthesis – Detoxifies harmful substances – Cells in liver have a lot of smooth ER
Golgi Apparatus
• Center of manufacturing, processing, packaging
and shipping
• Enzymes here attach carbohydrates and lipids to
proteins
• After the ER makes the proteins, they move into
the Golgi Apparatus where they are modified
• From the Golgi Apparatus , modified proteins are
moved to their destinations
Lysosomes
• Small organelle filled with hydrolytic enzymes that cell uses to digest macromolecules. Important in phagocytosis • Acidic interior (pH-5) • Also functions to break down lipids, carbohydrates and proteins from food into particles that could be utilized by the rest of the cell • Debris removal of worn out organelles
Vacuoles
• Membrane bound sacs • Temporary storage areas for food water, enzymes and waste • Special types – Contactile –pumps out excess water in single celled water dwelling organisms (ex-aquatic protists, such as protozoans) – Central- large vacuole found in plants used for water storage
Chloroplasts
• Plant cells • Shaped like lenses • Double membrane • Use energy from sunlight to make energy-rich food molecules in a process known as photosynthesis Light energy + 6H 2 O + 6CO 2 ---- C 6 H 12 O 6 6O 2 +
Mitochondria
• Organelles that release energy from stored food molecules-Cellular respiration • Power house of the cell; ATP is made here • Energy released from the mitochondria is used by the cell for growth, development and movement
6O 2 + C 6 H 12 O 6 --------
6CO 2 + 6H20 +Energy
Centrioles
• Organelles made of microtubules and are involved in cell division • Animal cells only
Peroxisomes
• Specialized compartment bound by single membrane • Similar to lysosomes (contains enzymes) • Generation and degradation of H202 (hydrogen peroxide) to protect cell from it’s toxic effects
Cytoskeleton
• Microfilaments thinnest, made of protein, help cells change shape • Intermediate fibers Varied,rope-like, tension bearing • Microtubules Largest, anchorage and movement
Role of Cytoskeleton
• Extensions of plasma membrane –
Cilia
–
Flagella
– Both have 9 +2 microtubule arrangement except at base, which has 9 triplets-
Basal Body
• Identical in structure to
centriole
Cytoplasm
• Everything between the plasma membrane and the nuclear envelope • Semifluid (cytosol) with organelles suspended in it • Protoplasm=cytoplasm+nucleoplasm (inside nucleus)
Cell Junctions
• See Handout and/or book • Plant cells – Plasmodesmata- junctions between plant cells (walls) • Animal cells ~Tight junctions ~Anchoring junctions (desmosomes) ~Communicating (Gap) *Know exp of each!
• Cytology • Histology • Cytosol