Studying Cells 2.1 Flashcards
What are Ribosomes the site of?
Site of protein synthesis
What is the function of the Nucleus?
Contains genetic material/DNA
Controls cell activity
What is the function of the Mitochondria?
Site of aerobic respiration;
ATP production
What is the function of the Smooth Endoplasmic Reticulum?
Site of Lipid Synthesis
What is the function of the Rough Endoplasmic Reticulum?
Ribosomes embedded;
Site of protein synthesis;
Transports and stores proteins within the cell
What is the function of the Golgi apparatus?
Modifies/packages proteins;
Products vesicles
What is the function of Lysosomes?
Contains digestive enzymes;
Digests worn out/damaged organelles (autolysis)
What is the function of the cell surface membrane?
Phospholipid Bilayer;
Selectively permeable so controls what enters the cell;
Double folded bilayer to increase SA
What is the function of Chloroplasts?
Contains thylakoids, stacked into Granum;
Site of photosynthesis
What is the function of a (prokaryotic) Capsule?
Protects cell from immune systems;
Helps bacteria to stick together; (bacteria has a capsule but no cell wall/membrane)
What is the function of a Plasmid?
Circular DNA (not enclosed in histones);
Contains antibiotic resistant genes
What is the function of the (cellulose/peptidoglycan) cell wall?
Provides rigid shape/structure;
Stops osmotic lysis (cell bursting from excess water)
B - What is the function of Flagellum?
Allows movement/propulsion
Eukaryotic cells produce and release proteins. Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells.
- DNA in nucleus (genome) codes for all proteins/amino acids;
- Ribosomes embedded in RER produce/translate protein;
- Mitochondria produce ATP (for protein synthesis)
- Golgi apparatus package/modify; OR Carbohydrate/Glycoproteins produced by Golgi;
- RER transports vesicles;
- Vesicles fuse with cell surface membrane.
Compare and contrast Eukaryotic and Prokaryotic cells (3+, 7-)
Compare
1. Nucleotide structure is identical;
2. Nucleotides joined by phosphodiester bond;
OR Deoxyribose joined to phosphate in sugar phosphate backbone;
3. DNA in mitochondria/chloroplasts is similar to prokaryotic DNA
4. Mitochondria, chloroplasts (EUK) & bacteria (PRO) all contain 70S ribosomes.
Contrast
4. Eukaryotic DNA is longer;
5. Eukaryotic DNA contains introns, prokaryotic does not;
6. Eukaryotic DNA is linear, prokaryotic DNA is circular;
7. Eukaryotic DNA is associated with histone proteins, prokaryotic DNA is not.
8. Cellulose (EUK plant cell) vs Peptidoglycan cell wall;
(8. Prokaryotes may have a capsule/slime polysaccharide layer and one or more plasmids)
B - What is the function of the plasmid?
A small, circular double-stranded DNA molecule that replicates independently in the cytoplasm;
Provides bacteria with antibiotic resistance.
State 3 differences between the DNA in the nucleus of plant cells and prokaryotic cells.
Plant DNA -> Prokaryotic DNA
- Associated with histone proteins -> No histones;
- Linear -> Circular;
- No plasmids -> Plasmids
- Introns -> No introns
- Longer -> Shorter
The structure of a cholera bacterium is different from the structure of an epithelial cell from the ileum (S.I).
Describe how the structure of a cholera bacterium is different (7)
- Cholera bacterium is a prokaryote;
- Does not have a nucleus/nuclear envelope/has free DNA in cytoplasm/has circular plasmid.
3 and 4 - Any two from:
No membrane-bound organelles/no mitochondria/no Golgi/no Endoplasmic reticulum;
5. Smaller ribosomes (70s)
6 and 7 - Any two from:
Capsule/flagellum/plasmid/cell wall.
Give one advantage of using a Transmission Electron microscope (TEM) rather than a Scanning Electron microscope (SEM)
- Higher resolution so smaller organelles viewed;
- Higher (maximum) magnification;
- Penetrates sample cells (internal organelles viewed)
- Shorter electron wavelength (penetrates cell)
Give one advantage of using an SEM rather than a TEM
- Thin sections/specimen does not need to be prepared;
- 3D image;
- Shorter preparation time;
(4. Fine focused beam of electron/Costs less)
Scientists use optical microscopes and transmission electron microscopes to investigate cell structure. Explain the advantages and limitations of using a TEM to investigate cell structure.
Advantages
1. High resolution so small objects can be seen;
2. Shorter electron wavelength
Limitations
3. Cannot look at living cells (abiotic);
4. Must be in a vaccum;
5. Specimen must be sliced thin;
6. Preparation may create artefact (false image)
Scientists isolated mitochondria from liver cells. They broke the cells open in an ice-cold, buffered and isotonic solution. Explain why.
Ice-cold - reduces enzyme activity SO organelles not damaged/digested
Isotonic - prevents osmotic lysis (no net movement of water) SO cell does not burst/shrivel
Buffered - maintains a constant pH SO no proteins denature
What is the plasmodesmata?
Gaps in the cellulose cell membrane of (eukaryotic) plant cells for cell-cell communication.
What is the tonoplast?
Semi-permeable Membrane around plant cell vacuole (that regulates the movement of ions around the cell)
Scientists use optical microscopes and transmission electron microscopes to investigate cell structure. Explain the advantages and limitations of using a TEM to investigate cell structure.
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 Must cut section / thin specimen;
7 Preparation may create artefact;
Give one advantage of using an SEM rather than a TEM
• Thin sections do not need to be
prepared
• shows surface of specimen
• can have 3-D images;
Give one advantage of using a TEM rather than a SEM
- Higher resolution;
- higher (maximum) magnification / higher detail (of image);
OR - Allows internal details / structures within (cells) to be seen cross section to be taken;
