SBI 3UC Zk

They are single-celled organisms, and they lack membrane-bound organelles. (no organized nucleus, vacuoles etc.) Examples include bacteria, archaea and blue-green algae PROKARYOTIC CELLS

CELL STRUCTURE Cilia

1. Cell surface membrane (plasma membrane): controls which materials enter and leave the cell, either by active or passive. It is selectively permeable. 2. Cell wall: Rigid or semi-rigid wall surrounding plasma membrane. Contains pores to allow passage of materials in & out. The cell wall supports cell and provides shape. STRUCTURES

Plasmid: Small circular pieces of naked DNA in addition to main chromosome of prokaryote cells. Nucleoid: Region of prokaryote cytoplasm where main chromosome and plasmid are found. Naked DNA - DNA is not bound to proteins (like histones) to reduce the amount of space they take up. STRUCTURES

Mesosome: Internal membrane connected to the cell surface membrane. It increases the area available to make ATP (cell energy). It may also aid the replication of DNA and cell division. MESOSOME

Pili- are thin protein tube, found outside of the plasma membrane. Attachment pili (fimbriae) – allow prokaryotes to stick to surfaces Conjugation pili (sex pili) – few in number, but longer than attachment pili. They build a bridge between cells and allow an exchange of plasmids. PILI

Cytoplasm: Contains enzymes for catalyzing chemical reactions of metabolism. Contains ribosomes and naked DNA. Ribosome: Sites of protein synthesis (scattered throughout cytoplasm rather than in rough ER). Prokaryotes contain 70S ribosomes comprised of a large 50S and a small 30S subunit. Flagellum: One to many threadlike, motile structures (locomotion). Slime capsule: Layer of thick, jellylike polysaccharides surrounding some prokaryote cells to aid in protection. STRUCTURES

Prokaryotic cells divide by BINARY FISSION They double their chromosome number and then split in half DIVISION

PROKARYOTIC CELLS The photo above shows a cross-section through a prokaryotic cell. Can you identify any of the parts?

1. Photosynthesis- Blue-green algae convert light energy into chemical energy (food) 2. Nitrogen Fixation- Nitrogen-fixing bacteria convert gaseous nitrogen from air into nitrogen compounds. (rhizobium) 3. Fermentation- Some bacteria convert sugars to lactic acid or into alcohol in order to obtain energy. The latter 2 chemicals are then released. METABOLIC ACTIVITY (NICHES) OF PROKARYOTIC CELLS

Eukaryotes have compartmentalized cell structure. Symbiosis: two organisms live closely together Endosymbiosis: one organism lives inside another (like bacteria live inside of us) EUKARYOTIC CELLS

It is thought that chloroplasts and mitochondria were originally free-living prokaryotic cells which gradually became able to live and reproduce within a larger cell. The larger cell provided protection and in some cases food to the prokaryote, while the smaller prokaryotic cell (which became the chloroplasts & mitochondria) provided an energy supply to the larger cell. THEORY OF ENDOSYMBIOSIS

a. mitochondria and chloroplasts surrounded by double membrane b. mitochondria and bacteria have similar size c. mitochondrial ribosomes resemble bacterial ribosomes d. mitochondria and chloroplast DNA is circular like bacteria e. mitochondria divides by simple fission like bacteria EVIDENCE

Organelles: Any discrete structure within a cell which has a specific function. Organelles a) are each surrounded by a plasma membrane. b) separate and compartmentalize chemical reactions in time and space (They organize reactions so they can be more efficient.). c) are only found in all eukaryotic cells (They do not exist in prokaryotes.). Intracellular: found inside the cell (within cytoplasm). Extracellular: found on outside cell membrane. ORGANELLE'S

1) Plasma membrane: Outer surface of animal cells. Phospholipid bilayer. Controls entry & exit of molecules. Phospholipid bilayer (polar head=hydrophilic; non-polar tails =hydrophobic) EUKARYOTIC ORGANELLES

2) Nucleus: information center of cell. Largest organelle, readily visible. Nuclear envelope: double membrane layer, restricts passage of molecules. Chromosomes: contain heredity information (made of DNA & proteins). Nucleolus: in center of nucleus- manufactures ribosomes. NUCLEUS

3) Endoplasmic reticulum: Tubules for transport and synthesis of large organic molecules. Often continuous with nuclear envelop. Organizes cell interior. a) Rough ER (rER): Manufacture proteins for export ENDOPLASMIC RETICULUM

Ribosomes: globular proteins that assist in protein synthesis (80S). Can be free floating or on RER b) Smooth ER (sER): Lack ribosomes so they have a smooth surface. Synthesize carbohydrates and lipids. Associated with detoxification. RIBOSOMES

Lysosomes: vacuole containing digestive enzymes. Functions: a. Enzymes catalyze breakdown of macromolecules b. Alter internal pH c. Digest worn-out cell components d. Digest pathogens engulfed by WBC's e. Participate in selective cell death LYSOSOMES

Mitochondria: Provides chemical energy (ATP) for cell Double membrane Possesses own DNA: produces own RNA (ribosomes) Capable of replication MITOCHONDRIA

Chloroplasts: organelle that performs photosynthesis (trap light energy in plants). Occur in plants and algae. Double membranes. Possess own DNA, produce own RNA (ribosomes). CHLOROPLAST

Flagella and Cilia: motility Flagella: long microtubule strands, locomotion Cilia: short microtubule strands. Locomotion, pass fluids, react to sound waves FLAGELLA AND CILIA

Golgi Apparatus: Modification, packaging & distribution of finished macromolecules (carbohydrates & lipids) GOLGI APPARATUS

Membrane bound organelles for storage of macromolecules, water, or cellular wastes. VACUOLES

IDENTIFY STRUCTURES IN LIVER CELL

Organelles Found only in Plant Cells: Chloroplasts (not found in plant cells found in roots, or cells found in the dark interiors of stems or branches) Large Central Vacuole (not commonly found in animal cells) TYPICAL PLANT

Rigid outer layer of plant cells. Made of cellulose microfibrils. Barrier to pathogens, provides support/shape Plasmodesmata- narrow passages through the cell wall to allow exchange with neighbouring cytoplasm CELL WALL

Palisade cells are responsible for photosynthesis because they contain chloroplasts. Sugars, gases and water are able to diffuse in/out of the cell APPLICATION: PALISADE MESOPHYLL

COMPARISONS…

Anything outside the cell membrane Cellulose microfibrils- The plant cell wall gives the cell a lot of strength and prevents it from bursting under high pressure as it is made up of cellulose arranged in groups called microfibrils. Glycoproteins- in their extracellular matrix which are involved in the support, movement and adhesion of the cell. EXTRACELLULAR COMPONENTS

Exocrine pancreas: that part of the pancreas that excretes through a duct, consisting of the pancreatic acini, which produce pancreatic juice and secrete it into the duodenum to aid in protein digestion.pancreatic acinipancreatic juice APPLICATIONS: EXOCRINE PANCREAS

COMPARISONS

Cells - Building blocks of all life. Tissues - Group of similar cells. (nervous tissue, cardiac tissue, skeletal muscle tissue) Organs - Several types of tissues grouped together to help do a certain function. (heart, brain, liver) Organ Systems - Several different organs working together to perform the same job. (Ex: esophagus, stomach, small intestine etc. are part of the digestive system) Organism - Many different organ systems that work together to make one living thing. ORGANIZATION OF CELLS IN MULTICELLULAR ORGANISMS

Next week bell ringer; You will be given 1 min per station. At each station you will be given an image or a function of an organelle/organism and need to recognize what you are looking at. In lieu of unit test! Helpful website- BELL RINGER