Eukaryotic Cells

• Eukaryotic - Are Complex, have a “true” nucleus and include plants, animals, fungi and protists
• Cell Wall: Rigid structure surrounding a plant cell made of fibres of cellulose held together by a matrix of protein and hemicellulose, supports the cell, maintaining both turgidity and shape - prevents bursting under osmotic pressure
• Centrioles: Small hollow cylinders containing rings of microtubules in 9 triplets (always found in pairs), they synthesise spindle fibres during mitosis and is involved in the separation of chromosomes during cell division
• Chloroplasts: Very large oval-shaped organelle surrounded by a double membrane it has a series of stacked membranes inside called thylakoid membranes also a matrix, DNA, and ribosomes - similar theory to mitochondria
• Chlorophyll acts like solar panels and absorbs light - attached to the thylakoid membranes - site of photosynthesis
• Chloroplast Diagram

  A) Outer Membrane

  B) Inner Membrane

  C) Thylakoid Membrane

  D) Granum (Thykaloid Stack)

  E) Stalked Particles (ATP Synthase)

  F) Starch Grains

  G) Storma

  
• Cilia: Small, hair-like structures found on the surface of some cell membranes, made of microtubules in a 9+2 arrangement and can contract and move/waft substances across the cell surface (found in trachea and oviducts)
• Flagella: Like cilia but longer and contract to make cell move e.g. sperm
• Golgi Body: Series of flattened tubes and vesicles in stacks - receives transport vesicles containing polypeptides/proteins from RER and lipids from SER
• Golgi Body 2: Involved in processing and packaging new proteins and lipids e.g glycoproteins, lysosomes - improves and adds final touches - forms secretory vesicles to transport proteins to the cell surface membrane for secretion (exocytosis) or to other parts of the cell
• Lysosomes: Round Organelle with no clear internal structure containing digestive enzymes (mostly hydrolases in an acidic solution), involved in the breakdown (hydrolysis) of large molecules and worn-out cells and abundant in secretory cells and phagocytic white blood cells (macrophages and neutrophils)
• Mitochondria: Very large, oval-shaped organelle with a double membrane - inner one folded into cristae with iron-containing protein complexes, inside is the matrix containing respiratory enzymes, mitochondrial DNA, and ribosomes
• Mitochondria 2: Site of aerobic respiration, only inherited from your mother - The theory: the original mitochondria a “bacteria” that was absorbed
• Mitochondria Diagram:

  A) Outer Membrane

  B) Inner Membrane

  C) Christa (fold)

  D) Matrix

  E) Stalked Particles (ATP Synthase)

  F) Ribosomes

  G) DNA

  
• Nucleolus: Made of DNA, RNA, and proteins; there may be one or two nucleoli present - synthesis and assembly of ribosomes
• Nucleur Envelope: Double membrane with (nucleur) pores, the outer membrane is continuous with RER and often has ribosomes on the surface - pores allow large molecules to pass in and out (e.g. RNA) - not DNA as it is unneeded outside the nucleus and when wrapped around histones is too bulky to fit
• Nucleus: Contains Linear DNA which is associated with proteins called histones (DNA + Histones = Chromatin) - controls the cell's activities using the proteins synthesised from the genetic code on the DNA
• Plasma Membrane: Made of mainly phospholipids which form a bilayer with other molecules attached - Controls the entry/exit of molecules, makes the cell partially permeable
• Ribosomes: 80s Size, smallest and complex organelle - not membrane-bound - has two subunits, the large and the small; both are made of roughly equal quantities of protein and ribosomal (rRNA), they can be free in the cytoplasm or bound to the ER and the site of protein synthesis
• Rough Endoplasmic Reticulum (RER): Similar to SER but also has ribosomes attached to its surface - involved in protein synthesis and secretion - found in abundance in rapidly growing cells and enzyme-secreting cells (next to the nucleus to increase efficiency)
• Smooth Endoplasmic Reticulum (SER): A dense system of flattened membrane tubes that contain a fluid-filled space (Cisternae) - site of lipid and steroid synthesis and processing - found in abundance in... Liver Cells, Intestinal Epithelial Cells, Adrenal Cortex, and Skin Sebaceous Glands
• Vacuole (Large, permanent): Membrane-bound sacs containing dilute solutions (called tonoplast), most cells have small ones but plant cells have a large permanent vacuole - it fills most of the cell and contains cell sap, helping to maintain the plant’s turgidity