B Cells Flashcards
What is the cytoskeleton composed of?
- Microfilaments - made of actin, help the cell move and contract during cytokinesis.
- Microtubules - made of globular tubulin proteins that form tubes. Determine cellular shape and act as tracks for organelle movement.
- Intermediate fibres - give cells strength.
What are the functions of the cytoskeleton?
- Supports cell.
- Holds organelles in place.
- Allows cells to change shape during endocytosis and exocytosis.
- Facilitates movement of organelles.
- Makes up centrioles.
What is the structure and function of centrioles?
- Made of microtubules.
- Assemble and organise spindle fibres during cell division.
Structure and function of the flagella
- Tail-like extensions that detect changes in the cell’s environment and help the cell move.
- In eukaryotes they have a 9 + 2 arrangement of microtubules, and are thicker than flagella in prokaryotes .
Structure and function of cilia
Hair-like extensions that move particles that surround the cell by beating rhythmically.
Structure and function of the rough endoplasmic reticulum
- Made of folded membranes, with ribosomes attached to the membrane.
- Some proteins produced by ribosomes are converted to glycoproteins.
- Packages proteins and glycoproteins made by ribosomes into vesicles.
Structure and function of smooth endoplasmic reticulum
- Made of a folded membrane.
- Secretes lipids and carbohydrates, which are packaged into vesicles.
Structure and function of Golgi apparatus
- Made of a folded membrane.
- Vesicles from the rough and smooth ER bind to the Golgi apparatus. It modifies these molecules and then packages them into vesicles.
- When the Golgi apparatus fills vesicles with enzymes, it forms lysosomes (that contain digestive enzymes - lysozymes - which break down cell walls of bacteria that invade cells).
Structure of mitochondria
- Contains an outermsmbrane, and an inner membrane that forms cristae.
- Matrix contains ribosomes and mitochondrial DNA.
What is the cell wall composed of?
In plants and algae: cellulose
In fungi: chitin
In bacteria: peptidoglycan
Function of the vacuole
- Keeps cells turgid.
- Stores sugars and amino acids as an energy source.
Structure of chloroplasts
- Contain a double-membraned envelope.
- Filled with thylakoids, which are stacked to form grana.
- Thylakoids contain the pigment chlorophyll (essential for photosynthesis).
- Grana sit in a fluid called storm, which contains ribosomes, DNA and starch grains.
What are prokaryotic cells?
Single-celled organisms that don’t contain membrane bound organelles (don’t contain a nucleus).
Compare a eukaryotic cell and a prokaryotic cell (eg. bacteria)
- Similarities: contain a cytoplasm, cell-surface membrane, and non membrane-bound organelles, such as ribosomes.
- Differences: 80S ribosomes vs 70S ribosomes, prokaryotes contain a peptidoglycan cell wall and circular DNA in the cytoplasm, bacteria have an outer capsule to prevent excessive water loss.
What are viruses?
- Non, living acellular parasitic particles.
- Made of DNA or RNA wrapped in a protein coat (capsid).