organelles

Nucleus

  • double membrane

  • contains linear DNA molecules packaged inside and contained

  • nucleolus is the site of ribosome production

  • It coordinates the cells activities such as growth, protein synthesis and cell division

Ribosome

  • No membrane

  • Found in both prokaryotes and eukaryotes

  • Can be free floating in cytosol or attached to rough endoplasmic reticulum

  • Site of protein synthesis

  • Composed of ribosomal RNA (rRNA) and folded protein

  • Contain a large and small subunit

Rough endoplasmic reticulum

  • AKA RER

  • Connected, flattened sacs, coating with ribosomes

  • Located close to nucleus

  • Site of protein production and modification

Smooth endoplasmic reticulum

  • Tubular, connected, flattened sacs that do not have ribosomes

  • Synthesises lipids for the cell, such as phospholipids for the plasma membrane

Golgi apparatus (or golgi body)

  • Stacked flattened sacs

  • Site of protein, packaging, modification and exporting

  • Secretory vesicles are associated with or bud from the golgi apparatus

Lysosome

  • membrane bound organelle

  • Contains digestive enzymes

  • Breaks down worn out cell parts, cell waste or toxins

  • Breaks down viruses and bacteria that invade the cell

Vacuole

  • membrane bound organelles

  • important in plants for maintaining structural intergrity

  • can be found in animals, fungi, bacteria and protists

  • used for water and solute storazge

  • can also take in wastes

Vesicle

  • membrane bound organelle

  • stores substances such as hormones and enzymes

  • involved in transporting substances into and out of a cell plasma membrane through endocytosis or exocytosis

Cytoskeleton

  • protein filaments from nucleus to plasma membrane

  • maintains the shape, organelles place and transport of vesicles within the cell

Cell wall

  • provides tensile strength against mechanical and osmotic stress

  • found in plant, bacterial and fungal cells

  • composed of cellulose in plant cells

  • partially permeable (only some things can get through it)

  • gives structure to cells

Plasma membrane

  • semi-permeable membrane seperating the intracellular and extracellular environments

  • transports nutrients into the cell and toxic wastes out of the cell

  • glycoproteins and glycolipids allow for interactions with other substances or cells

  • contains a phospholipid bilayer with hydrophilic (water loving) and hydrophobic (water hating) tails

  • channel proteins embedded in the plasma membrane allow large molecules to move in and out of the cell

  • small molecules like oxygen, carbon dioxide and water can diffuse across the membrane

Mitochondrion (singular, the powerhouse of the cell)

  • site of adenosine triphosphate (ATP) production in the cell

  • aerobic (in the presence of oxygen) respiration produces ATP

  • have a double membrane

Mitochondria (plural) structure and function

  • highly folded inner membrane surrounded by an outer membrane

  • has its own DNA: mitochondrial DNA (mtDNA) and ribosomes

  • inter-membrane space, the mitochondrial matrix, facilitates cellular respiration

  • only involved in aerobic (in the presence of oxygen) cellular respiration

Aerobic cellular respiration

  • cellular respiration is the process whereby a cell breaks down glucose to produce energy in the form of ATP

  • when in the presence of oxygen, it is aerobic

  • when oxygen is absent, it is anaerobic

glucose + oxygen → carbon dioxide + water + energy

C₆H₁₂O₆ + 60₂ → 6CO₂ + 6H₂O + 36 ATP

Chloroplasts

  • found in plants and algal cells

  • there is an inner and outer membrane

  • contains its own DNA in nucleoids

  • the fluid within the chloroplast is called stroma

  • grana (granum=singular) are made up of stacks of thylakoids

  • thylakoid membranes contain chlorophyll pigments to absorb light which energies reactions

  • all of these structures enable photosyntheses, a process converting light and inorganic molecules into organic molecules

Photosynthesis

  • the product of photosynthesis is glucose

  • glucose is used by mitochondria for energy for the cell

  • excess glucose in plants not used for energy, is stored as starch

  • carbon dioxide + water → sunlight → glucose + oxygen

  • 6CO₂ + 6H₂O → chlorophyll → C₆H₁₂O₆ + 6O₂