2A - Cell Structure and Division Flashcards
What are prokaryotic cells?
- single cell organisms
- don’t have membrane-enclosed internal compartments
- don’t have a nucleus
What are eukaryotic cells?
- multi cellular organisms
- have membranes
- with a nucleus
- e.g. animal cells, plant cells, algae and fungi
What organelles do plant cells have that animal cells don’t have?
- cellulose cell wall
- plasmodesmata
- vacuole
- chloroplasts
What is the difference between plant and fungal cells?
- cell walls are made of chitin
- don’t have chloroplasts
What does the cytoplasm do?
- contains enzymes for glycolysis
- contains sugars, salts, amino acids, nucleotides for metabolic reactions
What is the nucleus and what does it do?
- largest organelle surrounded by nuclear envelope
- pores control exits of substances
- nucleolus makes ribosomes
What is the mitochondria and what does it do?
- aerobic respiration takes place
- release ATP from carbohydrates, lipids etc
- large surface area (double membrane)
- permeable outer membrane
What are ribosomes and what do they do?
- smallest, most numerous organelles
- protein synthesis
- free in cytoplasm
- can be attached to RER, make exported proteins
What is the endoplasmic recticulum and what does it do?
- series of membrane channels
- synthesise and transport materials
- RER transports proteins to Golgi body
- SER has no ribosomes, processes lipids
What is the Golgi body and what does it do?
- series of flattened membrane vesicles
- transport proteins from RER to cell membrane
What are lysosomes and what do they do?
- membrane bound vesicles formed from RER
- contain proteins
- break down unwanted chemicals
- fuse with vacuole to digest
What is the cytoskeleton and what does it do?
- network of protein fibres
- transport, support and mobility
What does the undulipodium do and what is it?
- long tail used for mobility
- extension of membrane
- short (cilia) and long (flagellum)
What are microvilli and what do they do?
- small extensions
- found in epithelial cells of intestine and kidney
- increase SA for absorption
What is the cell membrane and what does it do?
- thin, flexible layer
- separates content from outside environment
- controls entry and exits of materials
What organelles do prokaryotic cells have?
- Cytoplasm
- Ribosomes (smaller)
- Nucleoid
- DNA
- Plasmid
- plasma membrane
- cell wall
- capsule
- flagellum
What does the capsule do and what is it?
- thick polysaccharide layer outside of cell wall
- sticks cells together
How do prokaryotic cells replicate?
- binary fission
How do viruses replicate?
- use host cells
- attachment proteins bind to receptor proteins
What happens in cell fractionation?
- cut tissue in cold isotonic buffer
- grind tissue in a blender to open cells
- filter to remove insoluble tissue
- centrifuge at low speed
- centrifuge at medium speed
- centrifuge at high speed
- centrifuge at very high speed
What is the tissue cut in a cold isotonic buffer?
- cold slows enzyme reactions
- isotonic prevents osmosis
- buffer stops pH changes
What happens during Gap Phase 1 in mitosis?
- cell grows and new organelles are made
What happens during Synthesis in mitosis?
- cell replicates DNA, ready to divide by mitosis
What happens during Gap Phase 2 in mitosis?
- cell keeps growing
- proteins needed for cell division are made
What happens during Prophase in mitosis?
- chromosomes condense
- centrioles move to opposite sides of the cell
- nuclear envelope starts to break down
What happens during Metaphase in mitosis?
- chromosomes line up in the middle of the cell
- attach to spindle fibres
What happens during Anaphase in mitosis?
- centromeres divide, separating sister chromatids
- spindles contract
- chromatids reach opposite ends of the spindle
What happens during Telophase in mitosis?
- chromatids uncoil
- nuclear envelope forms around each group of chromosomes
- cytokinesis (cytoplasm divides)
