Topic 2

• Eukaryotic cells


  Contain a nucleus and other membrane-bound organelles
• eukaryotic vs prokaryotic cells

  • Prokaryotic cells are cells without a nucleus.
  • Eukaryotic cells are cells that contain a nucleus.
  • Eukaryotic cells have other organelles besides the nucleus, which allow eukaryotic cells to carry out more functions than prokaryotic cells can. This allows eukaryotic cells to have greater cell specificity than prokaryotic cells.

  The only organelles in a prokaryotic cell are ribosomes.

  All cells, whether prokaryotic or eukaryotic, share these four features:1. DNA2. Plasma membrane3. Cytoplasm4. Ribosomes

  
• What three things do plant cells have that animal cells do not?

  Cellulose cell wall, vacuole, chloroplasts
• What are the two key differences between plant and fungal cells?

  Their cell walls are made of chitin, not cellulose and they don't have chloroplasts because they don't photosynthesise
• What are the chloroplasts like in algal cells?

  Often different shapes and sizes: for example, some algae have one large chloroplast rather than several smaller ones
• Which organelles have a double membrane?

  Nucleus, chloroplasts and mitochondria
• Description of cell surface membrane


  Membrane found on the surface of animal cells and below the cell wall of other cells. Made mainly of phospholipids and protein
• Function of cell surface membrane

  Regulates the movement of substances into and out of the cell. It also has receptor molecules on it which allow it to respond to chemicals like hormones
• Description of nucleus


  Large organelle surounded by double membrane which contains pores. Contains chromosomes ad one or more nucleoli
• Function of nucleus


  Controls the cells activities by controlling the transcription of DNA and contains instructions to make proteins. It also contains a nucleolus which makes ribosomes
• Description of mitochondria


  Oval shaped with a double membrane - the inner one is folded to form cristae. Inside is the matrix which contains enzymes controlling respiration

  
  

  inner membrane is where oxidative phosphorylation occurs
• Function of mitochondria


  The site of aerobic respiration and responsible for producing most of the ATP in a cell. Active cells which require a lot of energy will have many of these
• Description of chloroplasts


  Found in plant and algal cells. Surrounded by a double membrane, with thlakoid membranes inside the organelle. Thylakoid membranes stack up into grana, joined by lamellae
• Function of chloroplasts


  The site where photosynthesis takes place. Some parts of photosynthesis happen in the grana, others in the stroma (a thick fluid found in chloroplasts)
• Description of golgi apparatus

  A group of fluid filled, membrane bound flattened sacs. Vesicles are often seen at the end of sacs
• Function of golgi apparatus

  Processes and packages new lipids and proteins
• Description of golgi vesicles


  Small fluid-filled sac produced by the golgi apparatus
• Function of golgi vesicles

  Stores and transports lipids and proteins make by the golgi apparatus either within the cell or out of the cell
• Description of lysosomes


  A round organelle surrounded by a membrane, with no clear internal structure. It's a type of golgi vesicle
• Function of lysosomes


  Contain digestive hydrolytic enzymes called lysozymes. Can be used to digest invading cells or break down and work out components of the cell
• Description of ribosomes


  Small organelle found attatched to rough endoplasmic reticulum or free in the cytoplasm. Made from proteins and RNA, doesn't have a membrane
• Function of ribosomes


  The site where proteins are made
• Description of rough endoplasmic reticulum

  A system of membranes enclosing a fluid filled space. The surface is covered in ribosomes
• Function of rough endoplasmic reticulum

  Folds and processes proteins that have been made at the ribosomes
• Description of smooth endoplasmic reticulum

  Similar to rough endoplasmic reticulum, but with no ribosomes
• Function of smooth endoplasmic reticulum

  Synthesises and processes lipids
• Description of cell wall

  Surrounds plant, algal and fungal cells. Made from cellulose in plants and algae, and chittin in fungi
• Function of cell wall


  Supports cells and prevents them from changing shape
• Description of vacuole


  Organelle in cytoplasm, contains cells sap. Surrounded by a membrane called a tonoplast
• Function of vacuole


  Helps to maintain pressure inside the cell and keeps it rigid, preventing wilting. Also involved in the isolation of unwanted chemicals
• Prokaryotes definition


  Single celled organisms
• Difference between prokaryotic cells and eukaryotic cells

  Prokaryotic cells are much smaller and simpler
• Capsule


  Made of secreted slime and helps to protect the bacteria from attack by cells of the immune system
• Cell wall in prokaryotes

  Made of murein (a glycoprotein), this supports the cell and prevents it from changing shape
• Cell surface membrane in prokaryotes

  Like in a eukaryotic cell, this is made out of mainly lipids and proteins and it controls the movement of substances into and out of the cell
• What three things do many prokaryotic cells have that eukaryotic cells do not?

  One or more plasmids, a capsule surrounding the cell, one or more flagella
• Plasmids definition


  Small loops of DNA that aren't part of the main circular DNA molecule which contain genes for things like antibiotic resistance, and can be passed between prokaryotes
• DNA of a prokaryotic cell

  No nucleus, instead they have a single circular DNA molecule that is free in the cytoplasm and is not associated with proteins
• Process by which bacteria replicate

  Binary fission
• Stages of binary fission

  1. Circular DNA and plasmids replicate.

  
  

  DNA loop only replicated once, but plasmids can be replicated lots of times.

  
  

  2. Cell gets bigger and the DNA loops move to opposite poles of the cell.

  
  

  3. Cytoplasm begins to divide and new cell wall begins to form

  
  

  4. Cytoplasm divides and two new cells are produced

  
  

  each daughter cell has a variable number of copies of the plasmids and one copy of the circular DNA