Eukaryotic Cells Flashcards
What does eukaryotic cells mean?
That each cell has a nucleus and membrane-bound organelles
Types of eukaryotic cells
Plants, animals, algae and fungi
What is the function of the nucleus?
•Contains DNA arranged in chromosomes, with genes that code for the primary structure of polypeptides
•Site of mRNA production for protein synthesis is transcription
•Production of rRNA to make ribosomes for protein synthesis
•Location of semi-conservative replication
What is the nuclear envelope in a nucleus?
A double membrane that surrounds the nucleus which controls entry and exit of substances. Compartmentalises reactions that occur
What are the nuclear pores in a nucleus?
Allows passage of large molecules such as mRNA. 3000 pores, each 40-100 nm in diameter
What is the chromatin in the nucleus?
Linear DNA which is protein histone bound that condensed into visible chromosomes during nuclear divisions
What is the nucleolus in the nucleus?
A small, spherical region within the nucleoplasm. Manufactures rRNA and ribosomes. 1 nucleolus in each nucleus
What is the function of mitochondria?
Where ATP is synthesised by aerobic respiration
What is the purpose of a double membrane in mitochondria?
2 membranes that control entry and exit of molecules in and out of the mitochondria
What is the cristae in the mitochondria?
Extensions that form folds of the inner membrane, providing a large surface area for enzymes to hydrolyse and carry out condensation reactions
What is the outer membrane in the mitochondria?
Shields the mitochondria from any foreign substances
What is the inner membrane of the mitochondria?
A membrane that folds in on itself creating a larger surface area
What is the matrix in the mitochondria?
The liquid part that contains proteins, lipids, mitochondrial (circular) DNA and 70s ribosomes. Mitochondrial DNA and ribosomes allow mitochondria to make its own proteins for respiration
What is the use of mitochondria?
For cells that are metabolically active and require large quantities of ATP (have many mitochondria)
•Slow-twitch muscle cells = long distance running contractions
•Small intestine epithelial cells = active transport needed during absorption of glucose and amino acids
What is the function of the rough endoplasmic reticulum?
In places of the outer membrane of a nucleus ,it is continuous with the rough endoplasmic reticulum
•On outer surface are ribosomes to synthesise proteins
•Provide a large surface area for protein synthesis
•Packages proteins into vesicles and transports them to the golgi apparatus to be modified
-Found in cells that make lots of proteins
What type of cells require or have lots of rough endoplasmic reticulum?
Cells which make lots of proteins, secreting extra cellular enzymes or plasma B cells secreting antibodies
What is the function of the smooth endoplasmic reticulum?
It lacks ribosomes on its outer surface and often more tube-like in appearance
•Synthesise, store and transport lipids e.g. Combine glycerol and fatty acids
•Synthesise, store and transport carbohydrates
Packages triglycerides and carbohydrates into vesicles and transports them to the Golgi to be modified
What kind of cells have extensive smooth endoplasmic reticulum?
Cells that produce large quantities of carbs such a liver cells, glycogen
What is the function of the golgi apparatus?
•Proteins and lipids made in smooth and rough ER are passed through the golgi in a strict sequence
•Sorts and modified proteins by adding carbohydrates or lipids onto them forming glycoproteins and glycolipids
Modified proteins and packaged into vesicles, pinched off from where the golgi cisternae ends
•Also forms lysosomes
What type of cells require extensive golgi?
Cells that package lots of molecules for export: commonly large amounts of protein e.g. enzyme secreting gland cells in the digestive system or antibody producing plasma cells in the immune system
What happens after the vesicles are released from the golgi?
Move towards and fuse with the cell surface membrane, releasing their contents via exocytosis
What are lysosomes?
•Contain and release hydrolytic enzymes (protease and lipase). They contain lysozymes, enzymes that hydrolyse the walls of certain bacteria
•Roughly 1um diameter
•Lysosomes isolate hydrolytic enzymes from the rest of the cell before releasing them, preventing any unwanted breakdown of cell ultrastructure
What is the function of lysosomes?
•Fuse with foreign materials ingested by phagocytic cells (a type of white blood cell involved in the immune response) and then release its hydrolytic enzymes
•Release enzymes to the outside of the cell (extra cellular enzymes via exocytosis) to hydrolyse and breakdown dead organic molecules outside of the cell
•Breakdown damaged and worn out organelles, useful molecules they are made from can reused
•Completely breakdown cells after they have died (autolysis)
What is exocytosis?
Something going outside of the cell
