B1

• Eukaryotic cells

  • DNA is enclosed in a nucleus
  • animal and plant cell
  • cytoplasm
  • cell membrane
• Prokaryotic cells

  • no nucleus
  • smaller
  • bacteria cells
  • single DNA loop
  • cell wall and membrane
  • cytoplasm
• order of magnitude

  10x more than the one before
• cytoplasm

  watery solution where chemical reactions take place
• cell membrane is a selectively permeable barrier that controls the movement of substances in and out of the cell
• mitochondria

  aerobic respirations
• ribosomes

  smaller than mitochondria

  sites of protein synthesis
• plant cells

  regular shape

  packed of green structures
• chloroplasts

  plant cells

  site of photosynthesis

  chlorophyll
• cell wall

  plant cell

  cellulose strengthens cell
• vacuole

  plant cell

  cell sap

  gives the plant its shape
• animal cells

  most are specialised

  they have adaptations

  when cells become specialised it is called differentiation
• sperm cell

  job is to join a egg to fertilised

  half genetic information

  long tail to swim

  contain enzymes so they can digest egg outer layer
• nerve cell

  send electrical impulses around the body

  axon carries impulses around the body

  axon is covered in myelin which speeds up transmission

  synapses allow impulses to pass

  dendrites increase surface area for easier connection
• muscles cells

  contract

  contains protein cells

  mitochondria for energy

  create muscle tissue
• plant cells

  most are specialised

  adaptations to help with there function

  this is called differentiation
• root hair cells

  covered in hair to increase surface area and absorb water effectively

  do no have chloroplast
• xylem cells

  plant stem

  tubes carry water from root to leaves

  thick walls made for lignin

  end walls have been dissolved for easier water movement

  no internal structure
• phloem cells

  carry dissolved sugars

  phloem vessel cell has no nucleus and limited cytoplasm

  sieve plates (pores)

  mitochondria and companion cell provide energy
• light microscopes

  limited magnification and resolution
• electron microscope

  high magnification and resolution
• body cells

  contain two of each chromosome

  23 pairs of chromosomes

  chromosomes carry genes
• mitosis

  1. DNA replicates, grows and copy's structure
  2. one set of chromosomes are pulled to each side of the cell and the nucleus divides
  3. cytoplasm and cell membraned divide
• mitosis functions

  essential for growth and development

  takes place when an organism repairs itself

  during asexual reproduction
• stem cells in animals

  undifferentiated cell which can give rise to more cells

  useful in medicine
• stem cells in plants

  roots and buds contain meristem tissue which can differentiate

  useful for cloning
• diffusion is the net movement of particles from an area of high concentration to an area of low concentration
• urea diffuses out of cells
• larger surface area means a greater rate of diffusion
• osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• after osmosis in a cell the cell will expand so the sell becomes turgid
• if cell is in a concentrated solution the water moves out of the cell so it shrinks and this is called flaccid
• active transport

  particles are moved against the concentration gradient

  requires energy from respiration