Chapter 2 Cells

• cells


  basic structural and functional units of all living organisms

  vary in size, shape and are microscope
• cell theory


  all organisms are made up of cell, which are basic units of life and arise from pre-existing cells
• combined and coordinated action of our cells result to:


  structure of human body and the way it functions
• cells must be satisfied to:


  function normally
• cell membrane


  outer boundary of cell

  separates cell contents from environment outside

  controls what is able to enter and leave

  very thin
• cytoplasm


  parts of cell within cell membrane, includes jelly-like fluid and organelles suspended in it
• organelles


  structures suspended in cytoplasm that carry out particular functions
• cytosol


  liquid part of cytoplasm

  complex mixture of water and dissolved substances

  most metabolic reactions occur

  controlling osmotic pressure of cell

  flow chemicals into and out of cell
• cytoskeleton


  internal scaffolding of protein fibres within cytoplasm
• microtubules


  hollow rods that keep organelles in place or move them around the cell
• microfilaments


  move materials around cytoplasm or move whole cell
• inclusions


  chemical substances occurring in granules or liquid droplets in cytoplasm

  haemoglobin, pigment melanin
• nucleus


  largest organelle in cell

  contains genetic info and controls structure of cell and way it function
• nuclear membrane


  separates nucleus from cytoplasm

  double membrane, seperate by a space
• nuclear pores


  gaps in nuclear membrane

  allows large molecules, messenger RNA, to enter and leave nucleus
• nucleolus


  inside the nucleus

  plays part in manufacturing proteins
• endoplasmic reticulum (ER)


  network of channels formed by pairs of parallel membrane

  provide surface for chemical reactions

  channels store or transport molecules
• lysosomes


  formed from Golgi body

  contain digestive enzymes that break down large molecules

  join with vesicles and break down material inside vesicle

  digest worn out organelles
• ribosomes


  at the ribosome amino acids join together to form proteins

  suspended in cytoplasm or attached to ER
• Golgi apparatus (body)


  flattened membranes stacked one upon another

  modify proteins and package them for secretion from cell
• protein travel path


  proteins produced at ribosomes pass through channels of ER to Golgi body
• vesicles


  sacs of liquids containing proteins formed from edges of Golgi body membrane
• mitochondria


  double membrane

  cellular respiration occurs

  folding creates large surface area where chemical reactions take place

  make energy available for cell activity
• mitochondria membranes


  smooth outer membranes surrond mitochondrion

  crusted (inner membrane) arranged in series of folds that extend into interior of organelle
• why is fluid mosaic model called fluid mosaic


  membrane is fluid bc molecules which it is made new constantly changing positions

  mosaic bc composed of many different kinds of molecules
• main structure of membrane


  composed of phospholipid molecules
• phospholipid molecules


  lipid molecules containing a phosphate group
• bilayer


  phospholipid arranged in two layers

  each molecule has hydrophilic head and hydrophobic tail
• what is embedded in bilayer

  cholesterol and protein molecules
• why are cholesterol and protein molecules important for bilayer


  function integrity and stability of membrane
• types of protein molecules

  receptor proteins, channel proteins, carrier proteins, cell identity markers
• osmosis


  diffusion of solvent (water) through differentially permeable membrane in order to balance concentration of another substance
• how water does osmosis


  water will move from an area where solute, such as sugar, is low concentration to an area where solute is high in concentration
• function of cell membrane

  acts like physical barrier

  regulates passage of materials

  sensitive to changes

  helps support cell
• transport across cell membrane

  allows certain ions and molecules to pass through but restricts movement of others

  transport is controlled

  occurs by diffusion, facilitated transport and vesicular transport
• passive process


  does not use energy

  diffusion, facilitated transport
• active transport


  uses cell energy in form of adenosine triphosphate ATP

  vesicular transport
• simple diffusion


  process of substance moving along concentration gradient in solution or across semi-permeable membrane without use of membrane proteins
• diffusions occurs for what state of molecules

  gases and liquids bc molecules are in constant movement
• concentration gradient


  difference in concentration brings about diffusion