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)
