Biology paper 1

• Typical animal cell


  nucleus

  Mitochondria

  Cytoplasm

  Cell membrane

  Ribosomes
• Nucleus


  -Controls cell activity

  -Contains genetic material
• Cytoplasm 


  Most of chemical reactions take place
• Cell membrane


  controls what goes in and out the cell
• Mitochondria 


  where areobic respiration takes place
• Ribosomes 


  proteins are synthesised
• Plant cell


  Nucleus

  Cell membrane

  Cytoplasm

  Ribosomes

  Mitochondria

  Permanent vacuole

  Cell wall

  Chloroplasts
• Cell wall


  made of cellulose, strengthens the cell
• Permanent vacuole


  filled with cell sap, supports the plant
• Chloroplasts


  Absorb light to make food by photosynthesis
• Eukaryotic


  Plant, animal and fungal cells
• Prokaryotic


  Bacterial cell
• Differences between prokaryotic and eukaryotic

  Prokayotic cells - much smaller

  - Genetic material is not enclosed in a nucleus

  -DNA in a single DNA loop

  - Plasmids

  -No mitochondria/chloroplasts
• Bacteria cells what are the roles mitochondria and chloroplasts taken over by


  cytoplasm
• Bacteria cells 


  -May be more than one flagella

  -Plasmids are present

  -Moves genes from one cell to another
• Flagella 


  Tail like structures that move the bacteria cell
• typical plant cell size

  0.1mm
• typical animal cell size

  0.02mm
• prokaryotic cell size


  0.002mm
• metres in um


  1*10^6
• metres in nm


  1*10^9
• Resolution


  the ability to see two or more objects as seperate objects
• Two types of microscopes

  light

  electron
• What is the difference in how to microscopes work

  electron microscopes passes electrons instead of light
• RP-microscopes


  -Place a tissue sample on a microscope slide

  -Add a few drops of sustainable stain

  -Lower a coverslip onto the tissue

  -Place slide on stage, focus the cells using lowest power objective lense

  -Use coarse adjuestment knob to bring the stage just below the lense

  -Refocus the image by slowly turning the coarse knob and then turning the fine adjustment knob for a clear image

  -To get a higher magnification adjust the objective lense, then readjust the stage coarse and fine knob
• Risks


  Make sure the illumination isn't too bright

  Use a scale line by focusing on the mm division of the rular
• Magnification equation


  size of image/real object size
• what are chromosomes made of

  DNA
• Cell cycle


  -Cell grows tp increase number of subcellular structures

  -DNA is copied and new chromosomes made

  -Mitosis

  -Each cell grows and makes new subcellular structures
• Mitosis


  -One set of chromosomes are pulled to each end of cell

  -Nucleus divides

  -Cytoplasm and cell membranes divide to form two identical cells
• Why is cell division by mitosis important

  -Growth and development

  -Reparing damaged tissue

  -Asexual reproduction
• Where are stem cells found

  -Human embryos

  -Some organs and tissues
• Embryonic stem cells


  -From human embryo

  -Differentiate into all types of cells
• Adult stem cells


  found in bone marrow

  Differentiate into certain types of cells

  -Capacity to divide is limited
• Use of stem cells

  -Used to treat conditions where cells are damaged/not working properly

  -Eg, paralysis, diabetes

  -Replaces damaged cells
• Theraputic cloning


  -Cloned embryo of patient made and used as a source for stem cells
• Why is theraputic cloning useful

  -Cloned embryo won't be rejected as it is from patient's body
• Why are there concerns surrounding theraputic cloning

  -Transfer of viral infection

  -No guarantee of success

  -Difficulty finding suitable stem cell donors

  -Difficulty storing and obtaining patients embryonic stem cell

  -Would have been collected before birth

  -Mutations cultured for generations, some behave like cancer cells
• Ethical issues with theraputic cloning

  -Is it right to destroy embryos, when they have a potential for life

  -What stage should an embryo be treated as a person
• Where are stem cells found in plants

  meristem