A Tour of the Cell PDF 2022

CHAPTER 6 A Tour of the Cell YOU MUST KNOW Three differences between prokaryotic and eukaryotic cells. The structure and function of organelles common to plant and animal cells. The structure and function of organelles found only in plant cells or only in animal cells. 2 TYPES OF...

CHAPTER 6 A Tour of the Cell YOU MUST KNOW Three differences between prokaryotic and eukaryotic cells. The structure and function of organelles common to plant and animal cells. The structure and function of organelles found only in plant cells or only in animal cells. 2 TYPES OF CELLS: 1. Prokaryotes: Domain Bacteria & Archaea 2. Eukaryotes (Domain Eukarya): Protists, Fungi, Plants, Animals A PROKARYOTIC CELL (BACTERIA) PROKARYOTE VS. EUKARYOTE “before” “kernel” “true” “kernel” No nucleus Has nucleus and nuclear DNA in a nucleoid envelope Cytosol Cytosol No organelles other Membrane-bound than ribosomes organelles with Small size specialized structure/function Primitive Much larger in size i.e. Bacteria & Archaea More complex i.e. plant/animal cell MITOCHONDRIA Function: site of cellular respiration Double membrane: outer and inner membrane Cristae: folds of inner membrane; contains enzymes for ATP production; increased surface area to ↑ ATP made Matrix: fluid-filled inner compartment CHLOROPLASTS Function: site of photosynthesis Double membrane Thylakoid disks in stacks (grana); stroma (fluid) Contains chlorophylls (pigments) for capturing sunlight energy ENDOSYMBIONT THEORY Mitochondria & chloroplasts share similar origin Prokaryotic cells engulfed by ancestors of eukaryotic cells Evidence: ⚫ Double-membrane structure ⚫ Have own ribosomes & DNA ⚫ Reproduce independently within cell CYTOPLASM Region between the nucleus and plasma membrane Watery matrix is called the cytosol Cytoplasm includes the cytosol and the embedded organelles Found in all living things! PLASMA MEMBRANE Likely the first cell structure as it provides a barrier between the organism and its extracellular environment Made of a bilayer phospholipids with embedded proteins Found in all living things We will study this more in depth next week! NUCLEUS Function: control center of cell Contains DNA Surrounded by double membrane (nuclear envelope) ⚫ Continuous with the rough ER Nuclear pores: control what enters/leaves nucleus Chromatin: complex of DNA + proteins; makes up chromosomes Nucleolus: region where ribosomal subunits are formed NUCLEUS NUCLEUS Contains DNA Function: control center of cell Surrounded by double membrane (nuclear envelope) ⚫ Continuous with the rough ER Nuclear pores: control what enters/leaves nucleus Chromatin: complex of DNA + proteins; makes up chromosomes Nucleolus: region where ribosomal subunits are formed RIBOSOMES Function: protein synthesis Composed of rRNA + protein Large subunit + small subunit Types: 1. Free ribosomes: float in cytosol, produce proteins used within cell 2. Bound ribosomes: attached to ER, make proteins for export from cell ENDOMEMBRANE SYSTEM: Regulates protein traffic & performs metabolic functions ENDOPLASMIC RETICULUM (ER) Network of membranes and sacs Types: 1. Rough ER: ribosomes on surface Function: package proteins for secretion, send transport vesicles to Golgi, make replacement membrane 2. Smooth ER: no ribosomes on surface Function: synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca2+ CHECK YOUR UNDERSTANDING In which cells would you have more smooth ER? Why? ENDOPLASMIC RETICULUM (ER) GOLGI APPARATUS Function: synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes Series of flattened membrane sacs (cisternae) ⚫ Cis face: receives vesicles ⚫ Trans face: ships vesicles 2007-2008 More Resources LYSOSOMES Function: intracellular digestion; recycle cell’s materials; programmed cell death (apoptosis) Contains hydrolytic enzymes VACUOLES Function: storage of materials (food, water, minerals, pigments, poisons) Membrane-bound vesicles Eg. food vacuoles, contractile vacuoles Plants: large central vacuole -- stores water, ions Parts of plant & animal cell p 108-109 PLANT CELLS Cell wall: protect plant, maintain shape ⚫ Composed of cellulose Plasmodesmata: channels between cells to allow passage of molecules  Plant Cells Only Animals Cells Only Central vacuoles Lysosomes Chloroplasts Centrioles Cell wall of cellulose Flagella, cilia Desmosomes, tight and Plasmodesmata gap junctions Extracellular matrix (ECM)