Cells A1 Flashcards
What’s the difference between a eukaryotic and prokaryotic cell?
(give examples of both)
- eukaryotes have a nucleus (plants, algae, animal, protozoan, fungi)
- prokaryotes do not have a nucleus (bacteria, blue-green algae, archaea)
What is the function of the ribosomes?
protein synthesis (70s and 80s)
What is the function of nucleus?
- contains DNA
- controls cell activity
What is the function of the mitochondria?
- site of respiration (folder to form cristae)
- ATP production (matrix is its cytoplasm)
What is the function of smooth endoplasmic reticulum?
site of lipid synthesis
What is the function of rough endoplasmic reticulum?
- encrusted in ribosomes
- site of protein synthesis
What is the function of Golgi apparatus?
- modifies/packages/sorts proteins
- modifies/processes triglycerides
- combines triglycerides with proteins
- packages for release/forms vesicles
What is the function of the cell surface membrane?
- made of phospholipid bilayer
- controls what enters the cell/is selectively permeable
- can be folded to increase surface area
What is the function of lysosomes?
- contains digestive enzymes
- digests worn out organelles (autolysis) (phagocytes contain them)
Function of chloroplasts?
- contain thylakoids, staked into granum
- site of photosynthesis
- traps light energy and converts it to chemical energy
Function of capsule?
- protects from immune system
- aids bacteria sticking together
Function of plasmid?
- circular DNA
- contains antibiotic resistant genes
Function of cell wall?
- provides structure
- stops osmotic lysis
Function of flagellum?
allows movement / propulsion
Describe the difference between eukaryotic and prokaryotic cells.
Eukaryotic cells have:
1. DNA is linear and associated with proteins
2. contains membrane bound organelles eg.(mitochondria, Golgi apparatus, RER, SER, lysosomes)
3. Has nucleus / DNA contained within nuclear membrane
4. contains larger / 80s ribosomes
5. do not have capsule or flagella
The structure of a cholera bacterium is different from the structure of an epithelial cell from the small intestine.
Describe how the structure of a cholera bacterium is different.
- cholera bacterium is prokaryote
- does not have nucleus / has free DNA in cytoplasm / has loop of DNA
3 and 4 any two from:
- no membrane bound organelles / no mitochondria / no Golgi / no ER - small ribosomes only
6 and 7 any two from
- capsule / flagellum / plasmid / cell wall etc
Give one advantage of using a SEM rather than a TEM.
Thin sections do not need to be prepared / shows surface of specimen / can have 3D images
Explain the advantages and limitations of using a TEM to investigate cell structure.
advantages:
1. small objects can be seen
2. TEM has a high resolution
3. wavelength of electrons shorter
limitations:
1. cannot look at living cells
2. must be in a vacuum
3. must cut section / thin specimen
4. preparation may create artefact
Explain why a solution was made…
- isotonic
- ice cold
- buffered
isotonic - prevent osmotic (no net movement of water so organelle does not burst (lysis) or shrivel)
ice cold - reduce / prevent enzyme activity so organelles are not digested/damaged
buffered - maintain constant PH so proteins don’t denature
Describe and explain how cell fractionation can be used to isolate mitochondria from a suspension of animal cells.
Any 5 from…
1. cell homogenisation to break open cells and release organelles
2. filter to remove large debris/whole cells
3. use isotonic solution to prevent damage of mitochondria/organelles by osmosis
4. keep cold to reduce damage to organelles by enzymes
5. use buffer to maintain PH and prevent protein/enzyme denaturing
6. use differential centrifuge (at lower speed/1000g) to separate nuclei/cell fragments/heavy organelles
7. re-spin supernatant after nuclei pellet removed, at higher speed to get mitochondria pellet at bottom
8. observe pellet with microscope to identify mitochondria
List the order of organelles in a cell from densest to least dense, for cell fractionation experiment.
- nucleus (1st pellet)
- mitochondria, chloroplast (2nd pellet)
- ribosomes (3rd pellet - least dense)
What is homogenisation?
breaking apart the tissue/cell to release organelles into solution
What are microvilli?
- finger like projections
- which increase SA of a cell membrane
- found in the epithelial cells in the small intestine
What are centrioles?
- function in mitosis
- from a network of spindle fibres across the cell onto which the chromosomes attach
- these fibres pull the chromosomes/chromatids apart
- these are ONLY found in animal cells
Name the components of a palisade cell ultrastructure.
Ribosomes, SER, RER, nucleus, large central vacuole, starch grain, cell wall, cell membrane, Golgi apparatus, chloroplast, vacuole membrane, mitochondrion, cytoplasm
Define the term turgid.
When a plant is so full of water that it can be used for structural support, due to the cell walls preventing it bursting eg. the stem
Name the differences between a plant and animal cell.
Plant/Animal cell
1. cellulose cell wall surrounding membrane / no cell wall
2. chloroplasts present / no chloroplasts
3. large central vacuole / no large central vacuole
4. carbohydrates stored as starch / carbohydrates stored as glycogen
Describe the function of granum.
stack of thylakoid membranes.
Describe the function of thylakoid membrane.
contains chlorophyll for photosynthesis
Describe the function of stroma.
fluid filled matrix
some of the photosynthesis reactions occur here
Describe the function of starch grains.
the energy storage molecule in plants
Describe the function of DNA and ribosomes in the chloroplast.
chloroplasts have their own DNA and ribosomes to make enzymes needed for photosynthesis
What is a bacterial cell wall made of?
murein / peptidoglycan
What do viruses have and not have compared to prokaryotic cells?
do have:
1. RNA
2. capsid (prokaryotes don’t have this)
don’t have:
3. ribosomes
4. organelles
One advantage of TEM over SEM?
- higher resolution
- higher (maximum) magnification
OR - allows internal details (structures within cells) to be seen / cross section to be taken
What is the equation to find out actual size?
Actual size = image size ÷ magnification
What produces ATP in a prokaryotic cell?
Mesosomes
What is the fungal cell wall made of?
Chitin
What is a fungul cell wall made of?
Chittin