L1 - eukaryotic cell structure

• Chromatin: a complex of dna and proteins (histones), which condenses to form a chromosome during cell division
• Nanometre: one thousandth of a micrometer
• Micrometre: one millionth of a metre, it’s the standard unit for measuring cell dimensions
• Undilipodia: longer hair-like extensions that stick our from the surface of eukaryotic cells. Each one contains 2+9 microtubules. Can be used to move wholes cells
• Flagellin: a spiral of protein that’s attached to a hook in the flagella of prokaryotes
• Histone: proteins that dna tightly coiled around to form chromosomes
• Smooth endoplasmic reticulum: a series of membrane-bound flattened sacs. No ribosomes attached. Involved with lipid metabolism or membrane formation
• Golgi apparatus: membrane-bound organelle of eukaryotic cells. Modifies proteins made at RER into glycoproteins, packages proteins for secretion outside the cells, makes lysosomes, in plant cells secretes carbohydrates to make cell walls
• Vesicles: a membrane bound sac found in cells and used to transport materials around the cell
• Endoplasmic reticulum: a series of membrane-bound flattened sacs extending from the outer nuclear envelope through the cytoplasm
• Rough endoplasmic reticulum: a series of membrane-bound flattened sacs. Ribosomes are attached to the outer surface. Involved in the synthesis of proteins
• Chromosomes: a linear dna molecule wrapped around histone proteins found in the nucleus. Visible at prophase of cell division
• Nucleolus: a small dense spherical structure in the nucleus of a cell during interphase, it produces ribosomal rna and sub units
• Cilia: short extensions of eukaryotic cells, typically 2-10um long and 0.25um in diameter. Used for locomotion or moving fluids or mucus over a surface
• Flagella: projections from prokaryotic cells made of a spiral of protein called flagellin, and attached by a hook to a protein disc at the base. They are used in movement
• Plasma membrane: the cell’s outer membrane made up of two layers of phospholipids with embedded proteins. It separates the contents of the cell from its outside environment, and it regulates what enters and exits the cell
• 1000nm = 1um

  1000um = 1mm

  1000mm = 1m
• The basic unit of all living things is the cell, but not all cells are the same
• All cells fall into 2 major classes: eukaryotic and prokaryotic
• Eukaryotic cells: have membrane bound intracellular organelles. All plants, animals, fungi and protocists (eg. amoeba)
• Prokaryotic cells: have no true nucleus or membrane bound organelles. Eg. bacteria
• Utrastructure: the “fine” or detailed structure of a cell as revealed by the electron microscope
• Chemical reactions: fundamental processes of life require enzymes and specific reaction conditions. They take place in the cytoplasm
• The cytoplasm is divided into many membrane bound compartments in eukaryotic cells called organelles
• Organelles compartmentalise the cellular functions to provide distinct environments for specific cellular reactions to take place
• A number of organelles are common to all eukaryotic cells but some are only specific to plant cells
• Advantages of membrane bound organelles:

  -potentially harmful enzymes can be isolated inside an organelle, so the rest of the cell won’t be damaged

  -they contain enzymes within the organelles; so enzymes are close to the reaction site (more efficient)

  -increased surface area for reactions to take place

  -reaction rate can be controlled by membranes allowing reactants into organelle