Eukaryotic cell

• What is the cell surface membrane made of?

  Phospholipid bilayer with interactions between hydrophilic heads and hydrophobic tails. There are also proteins embedded in this bilayer
• What do the phospholipids in the membrane do?

  They allow lipid-soluble substances to enter and leave the cell. They prevent water-soluble substances from entering and leaving the cell. Also, it allows for the membrane to be flexible
• What are the 2 main types of proteins in the cell-surface membrane?

  Integral proteins = pass all the way through the bilayer

  Peripheral proteins = stay on one side of the membrane
• What molecule controls the fluidity of the membrane?

  Cholesterol
• What does the nucleus do?

  It contains the cell's DNA.
• What are the features of a nucleus?

  Nuclear envelope, nucleoplasm, chromatin and a nucleolus
• What is the nuclear envelope?

  A double membrane (2 phospholipid bilayers). The outer membrane has ribosomes on its surface and an extension of endoplasmic reticulum.
• What do the nuclear pores on the nuclear envelope do?

  Allows the passage of large molecules, such as mRNA, out of the nucleus via diffusion
• What is the nucleoplasm?

  A jelly-like material (the cytoplasm of the nucleus)
• What is chromatin?

  Loose stands of DNA in the nucleoplasm
• What is the nucleolus?

  A small, round region in the nucleoplasm. This is the site of RNA and ribosomes synthesis, and there can be more than one in a nucleus.
• What are the two types of ribosomes?

  80S ribosomes = only in eukaryotic cells, the larger of the two

  70S ribosomes = only in prokaryotic cells, slightly smaller than 80S
• What do ribosomes do?

  They are a big subunit, and a smaller subunit. They then separate to allow mRNA through, and then separate again to allow tRNA through to make a protein (in short, protein synthesis)
• What is Golgi apparatus?

  Fluid filled, flattened and curved sacs (in the shape of a Wi-Fi symbol), with vesicles surrounding the edges
• What does Golgi apparatus do?

  They modify the proteins and lipids produced by the endoplasmic reticulum, by adding non-protein and protein components to them. They then 'sort' these proteins and lipids to the correct places. Example being a glycoprotein
• How are the modified proteins/lipids sorted to the correct places?

  They are transported in the Golgi vesicles (that have 'pinched off' from the cisternae) to the cell's surface. These vesicles then fuse with the cell-surface membrane and release the contents inside.
• Golgi apparatus produce secretory enzymes and forms lysosomes.
• What are the two types of endoplasmic reticulum (ER)?

  Rough ER and smooth ER
• What is the difference between rough ER and smooth ER?

  Rough ER and smooth ER both have cisternae. However, only rough ER has ribosomes attached to it
• What is rough ER used in?

  Protein synthesis (using its ribosomes)
• What is smooth ER used in?

  The synthesis and storage of lipids
• What are lysosomes?

  Vesicles produced by Golgi apparatus, containing hydrolytic enzymes
• How many enzymes are there in a single lysosome?

  50 max
• What are phagosomes?

  Vesicles that contain foreign material to be digested. They are produced due to phagocytosis
• What are peroxisomes?

  Vesicles that are involved in the production of phospholipids and cholesterol
• What do lysosomes do?

  Break down waste materials and organelles. However, they don't last long themselves
• Extracellular matrix

  Network of collagen fibres and glycoproteins. It strengthens the cell-surface membrane, and plays a role in the differentiation of stem cells.
• What is a centrosome?

  2 centrioles (tube-like structures) that are perpendicularly positioned to each other
• What do centrosomes do?

  They produce structural proteins, such as microtubules. These microtubules make up the cytoskeletons that give cells specific shapes. Also, they produce spindle fibres for cell division
• What are mitochondrion?

  An oval-shaped organelle that has its own DNA and its own ribosomes
• What is the double membrane of the mitochondrion?

  It controls passage of molecules. The folded internal membrane (cristae) increases surface area.
• What is the mitochondrial matrix?

  It contains enzymes needed for aerobic respiration
• What are chloroplasts?

  Disc-shaped organelles that play a role in photosynthesis
• What is the chloroplast envelope?

  Double membrane which controls the passage of molecules
• What are grana? (singular = granum)

  Stacks of thylakoids
• What are thylakoids?

  Disk-like structures that contain chlorophyll
• What do grana do?

  Grana is where the 1st stage of photosynthesis occurs
• What is the stroma?

  Fluid-filled matrix (a chloroplast's cytoplasm basically)
• What does the stroma do and what does it contain?

  The stroma is where the 2nd stage of photosynthesis occurs. It contains starch grains, ribosomes and loops of chloroplast DNA
• What is the vacuole?

  A fluid-filled sac bound by a single membrane called the tonoplast