Studying Cells Flashcards
What is the function of the nucleus? (2)
- Contains genetic material/DNA
- Controls cell activity
What is the function of the mitochondria? (2)
- Site of aerobic respiration
- ATP production
What is the function of the rough endoplasmic reticulum? (3)
- Encrusted in ribosomes
- Site of protein synthesis
- Transports and stores proteins within the cell
What is the function of the smooth endoplasmic reticulum? (1)
- Site of lipid synthesis
What is the function of the ribosomes? (1)
- Site of protein synthesis
What is the function of the golgi apparatus? (2)
- Sorts, modifies and packages proteins and triglycerides
- Produces vesicles
What is the function of lysosomes? (2)
- Contains digestive enzymes
- Digests worn out organelles
What is the function of the cell surface membrane? (3)
- Made of a phospholipid bilayer
- Controls what enters and leaves the cell / selectively permeable
- Can be folded to increase surface area
What is the function of chloroplasts? (2)
- Contains thylakoids, stacked into granum
- Site of photosynthesis
What is the cell wall in algae and plants made from?
Cellulose
What is the cell wall in bacteria made from?
Murein / Peptidoglycan
What is the cell wall in Fungi made from?
Chitin
What is the function of a capsule? (2)
- Protects cell from immune systems
- Aids bacteria sticking together
What is the function of plasmid? (2)
- Circular DNA
- Contains antibiotic resistance genes
What is the function of the cell wall? (2)
- Provides rigid shape / structure
- Stops osmotic lysis
What is the function of flagellum? (1)
- Allows movement
Eukaryotic cells produce and release proteins. Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells. (5)
- DNA in nucleus is code (for protein)
- Ribosomes / RER produce protein
- Mitochondria produce ATP (for protein synthesis)
- Golgi body sorts, packages and modifies protein into vesicles
- Vesicles transport protein
- Vesicles fuse with cell membrane
Compare and contrast eukaryotic and prokaryotic cells (5)
COMPARISONS
1. Nucleotide structure is identical
2. Nucleotides joined by phosphodiester bonds
3. DNA in mitochondria is similar to DNA in prokaryotes
CONTRASTS
4. Eukaryotic DNA is longer whereas prokaryotic DNA is shorter
5. Eukaryotic DNA contains introns whereas prokaryotic DNA does not contain introns
6. Eukaryotic DNA is linear whereas prokaryotic DNA is circular
7. Eukaryotic DNA is associated with histones whereas prokaryotic DNA is not associated with histones
State three differences between DNA in the nucleus of a plant cell and DNA in a prokaryotic cell (3)
Plant Vs Prokaryote
1. Associated with histones vs not associated with histones
2. Linear vs circular
3. No plasmids vs plasmids
4. Introns vs no introns
5. LongER vs shortER
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. (4)
- Cholera bacterium is prokaryote
- Does not have a nucleus
3 and 4. any two from: no membrane-bound organelles/ no mitochondria/ no golgi/ no no endoplasmic reticulum - Small/ 70s ribosomes
6 and 7. any two from: capsule/ flagellum/ plasmid/ cell wall
Name 2 structures found within a eukaryotic cell that cannot be identified using an optical microscope (2)
- Mitochondrion
- Ribosome
- Endoplasmic reticulum
- Lysosome
- Cell - surface membrane
Describe how the student could have used an eyepiece graticule to determine the mean diameter of stomata (3)
- Measure each stomata using an eye piece graticule
- Calibrate the eyepiece graticule against a stage micrometre
- Take at least 5 measurements and calculate a mean
Give one advantage of using a TEM rather than a SEM. (1)
- Higher resolution
- Higher magnification
OR - Allows internal details to be seen
Give one advantage of using a SEM rather than a TEM. (1)
- Thin sections don’t need to be prepared
- Can have 3D images
Explain the advantages and limitations of using a TEM to investigate cell structure. (5)
ADVANTAGES
1. Small objects can be seen
2. TEM has high resolution
3. Electron wavelength is shorter
LIMITATIONS
4. Cannot look at living cells
5. Must be in a vacuum
6. Thin specimen required
7. Preparation may create artefacts
Name 2 structures found within a eukaryotic cell that can be identified using a transmission electron microscope (2)
- Mitochondrion
- Ribosome
- Endoplasmic Reticulum
- Lysosome
- Cell - surface membrane
Describe how you could make a temporary mount of a piece of a plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope. (4)
- Add a drop of water to the microscope slide
- Get a thin section of plant tissue and float on the drop of water
- Stain with KI solution
- Lower the cover slip using a mounted needle to avoid air bubbles
Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold, buffered, isotonic solution. Explain the solution was
a) isotonic
b) ice cold
c) buffered
a) prevents osmosis so organelle doesn’t burst/shrivel
b) reduce enzyme activity so organelles are not digested
c) maintain a constant pH so proteins don’t denature
Describe and explain how cell fractionation and centrifugation can be used to isolate mitochondria from a suspension of animal cells. (5)
- Cell homogenisation to break open cell and release organelles
- Filter to remove debris
- Use isotonic solution to prevent osmotic damage
- Keep cold to reduce enzyme activity
- Use buffer to maintain pH and prevent protein denaturation
- Use centrifuge and spin at high speed to separate nuclei and heavy organelles
- Re-spin at highER speed to get mitochondria in pellet
- Observe pellet with microscope to identify mitochondria
Describe the structure of a phospholipid molecule and explain how phospholipids are arranged in a plasma membrane. (3)
- Glycerol joined to two fatty acid tails and phosphate group joined to glycerol on opposite side
- Phospholipid has hydrophilic head and hydrophobic fatty acid tails
- Arrange to form a phospholipid bilayer
