Bio Paper 2

• Description of nucleus


  Large organelle surrounded by a nuclear envelope which contains pores. the nucleus contains chromatin (which is made from DNA and proteins and a structure called the nucleolus.
• What is the function of nucleus ?


  Controls the cells activities by controlling the transcription of DNA. DNA contains instructions to make proteins. Pores allow substances to move between the nucleus and cytoplasm. The nucleolus makes ribosomes
• Description of lysosome


  A round organelle surrounded by a membrane with no clear internal structure
• What is the function of the lysozyme?


  Contains digestive enzymes which are used to digest invading cells or break down worn components of the cell
• Describe a ribosome


  A very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum. It is made up of proteins and RNA. No membrane
• What is the function of a ribosome?


  Function of ribosome ?Site where proteins are synthesised
• Describe the RER


  A system of membrane bound flattened sacs. the surface is covered with ribosomes
• What is the function of the RER?

  Folds and processes proteins that have been made at the ribosomes
• Describe the SER


  Description of smooth endoplasmic reticulum ?a system of membrane bound flattened sacs but with no ribosomes
• What is the function of the SER?

  Function of smooth endoplasmic reticulum ?synthesises and processes lipids
• Describe the Golgi apparatus


  A group of fluid filled membrane bound flattened sacs. formed by the fusion of vesicles from the ER
• What is the function of the Golgi apparatus?

  It processes and packages new lipids and proteins. it also makes lysosomes
• Describe the mitochondria


  Description of mitochondria ?Double membrane- inner one is folded to form a structure called cristae. inside is the matrix which contains enzymes involved in respiration
• What is the function of the mitochondria?

  Function of mitochondria ?site of aerobic respiration, where ATP is produced. found in large numbers in cells that are very active and require a lot of energy.
• Describe the centriole


  small hollow cylinders made of microtubules. found in animal cells but only some plant cells
• What is the function of the centriole?

  Involved with the separation of chromosomes during cell division
• What type of proteins do ribosomes make?

  Ribosomes on the rER make proteins that are excreted or attached to the cell membrane. Free ribosomes in the cytoplasm make proteins that stay in the cytoplasm.
• What happens once the new proteins are made ?

  They enter into the rER and are folded and processed. Then they are transported to the Golgi apparatus in vesicles. The vesicles fuse to form the flattened sacs of the Golgi and the Golgi further processes the proteins. The proteins enter more vesicles and are transported around the cell
• What is found in the cytoplasm in prokaryotic cells?

  No membrane bound organelles and has smaller ribosomes than in eukaryotic cell
• What is the flagellum?

  long hair like structure that rotates to make the prokaryotic cell move. not all prokaryotes have a flagellum and some have more than one
• What is circular DNA?

  Long coiled up strand of DNA that is not attached to any histone proteins
• What is a plasmid?


  Small loops of DNA that aren't part of the main circular DNA molecule. contain genes for things like antibiotic resistance
• What is a mesosome?

  inward folds in the plasma membrane (thought to be artifacts of cell staining and preparation)
• What is a capsule?

  Made up of secreted slime. helps protect bacteria from attack by cells of the immune system and prevents dehydration
• What is the Pilli?


  Short hair like structure. helps prokaryotes stick to other cells and can be used to transfer genetic material between cells
• What is the cell wall in prokaryotes made of?

  Support the cell and prevents it from changing shape. made of murein glycoprotein or peptidoglycan
• What is the function of the plasma membrane?

  Mainly made of lipids and proteins. controls the movement of substances into and out of the cell
• Description and function of the cell wall?

  rigid structure, mainly made of cellulose, that surrounds and supports plant cells.
• Description and function of the middle lamella

  outermost layer of the cell. acts as an adhesive, sticking adjacent plant cells together. it gives the plant stability
• Description and function of the plasmodesmata

  channels in the cell walls that link adjacent cells together, allows transport of substances and communication between cells
• Description and function of the pits

  regions in the cell wall where the wall is very thin. arranged in pairs so a pit in one cell is lined up with the pit in the adjacent cell. allows transport of substances between cells
• Description and function of the chloroplast

  small flattened structure. has a double membrane and membranes inside called thylakoid membranes. thylakoid membranes are stacked up in some parts to form grana. grana are linked together by lamellae (thin pieces of thylakoid membrane). Site of photosynthesis
• Description and function of the amyloplast

  small organelle enclosed by a membrane. stores starch granules and converts the starch back to glucose for release when the plant requires it
• Description and function of the vacuole and tonoplast


  vacuole is a compartment surrounded by a membrane called a tonoplast. vacuole contains cell sap which is made up of water, enzymes, minerals and waste products. vacuoles keep cells turgid - stops plants from wilting. also involved in the breakdown and isolation of unwanted chemicals in the cell. tonoplast controls what enters and leaves vacuole
• Why is water a polar molecule?

  Oxygen is more electronegative than Hydrogen so there is a slight difference in charge between the atoms.
• Why does water remain a liquid over a wide range of temperatures?

  Hydrogen bonding holds water molecules together and collectively they make water very stable
• Why is water cohesive?

  the delta positive H is attracted to the delta negative O. This helps water to flow so it is good at transporting substances
• Why is water a good solvent?

  Polar molecules and ionic substances dissolve in water because water is dipolar. The forces of attraction between the delta positive H and the delta negative O are stronger than the ionic bonds so the ions become hydrated and completely surrounded by water molecules
• Describe the structure of alpha glucose, with diagram


  six carbon atoms/CHO elements only/OH below on C1
• Describe the structure of beta glucose, with diagram

  six carbon atoms/CHO elements only/OH above on C1