| Proof for Davson-Danielli model? | 1. Chemical analysis of plasma membranes showed that they were made of phospholipid and protein
2. Evidence showed that the membranes of red blood cells had enough phospholipid to make an area twice as large
3. Experiments showed the membrane was creating a barrier to some substances, they thought it could be protein |
| Proof for Singer-Nicholson model? | 1. Freeze etched micrographs showed globular proteins in the middle of the membrane
2. Analysis of membrane protein showed parts of their surface were hydrophobic, so they would have to be within the bilayer
3. Fluorescent antibody tagging showed that membrane proteins tagged with red and green eventually fused after 40 mins, showing the fluidity of membranes |
| How does cytokinesis happen in plants and in animals? | In animal cells, a cleavage furrow forms using actin and myosin (contractile proteins) and is pinched off to form the two genetically identical cells. In plant cells, vesicles fuse at the equator to create a new membrane that will ultimately join the preexisting membrane of the daughter cell, and pinch off. |
| What does the cell theory state? | All living things are made of cells, all cells come from pre-existing cells, cells are the smallest unit of life |
| What's the correct order in the unit scale? How do you convert between units? | m, mm, μm, nm, pm. If you want to make a unit smaller, you multiply by 1000, if you want to make it bigger, you divide by 1000 |
| Do the procedures necessary | 2.a) M= I/A : M= 63mm/8μm (conversion) : M= 63mm/0.008mm : M = 7875×
b) I = MxA : I= 7875x 5μm : I= 39 375 μm OR 39.375 mm
c) A= I/M: A= 23mm/7875 : 0.0029 mm (remember that anytime they ask for the ACTUAL size of a diagram, you have to measure the organism displayed on the diagram with the ruler, to get I) |
| What are some exceptions to the cell theory and why? | Striated muscle fiber: they have multiple nuclei and are very large
Aseptate fungi: no divisions (septa) and many nuclei
Acetabularia: only one nucleus for a very large organism |
| Why is surface are to volume ratio important? | It impacts the efficacy of the exchange of substances in and out the cell, and it regulates heat loss and use within the cell. Because both heat and substances accumulate in the cell faster than they can be lost across the membrane if the ratio is too small |
| How do you get the SA/V ratio ? | SA: length x width x number of sides
V: length x width x length
*simplify the results *the greater the ratio the most effective movement in and out of cells |
| Compare and contrast the functions of life in paramecium and chlamydomonas | Nutrition: Paramecium ingests smaller organisms through endocytosis, whereas Paramecium makes its own food through photosynthesis
Growth: Paramecium increases in size and dry mass after ingesting organic matter and minerals, whereas chlamydomonas increases in dry mass through the absorption of minerals
Excretion: Paramecium excretes CO2 from cell respiration, chlamydomonas excretes oxygen from photosynthesis
Response: Paramecium uses cilia to swim away from objects, chlamydomonas uses its eyespot and its flagella to swim towards light
Homeostasis: both organisms use contractile vacuoles to expel excess water through their membranes
Reproduction: both organisms can reproduce sexually or asexually
Metabolism: both have enzymes that catalyze reactions inside their cells |
| What is a tissue? | A group of cells specialized to carry out the same function |
| What is euchromatin and heterochromatin? What is their significance to specialized cells? | Euchromatin are the expressed genes in a cell whereas Heterochromatin are the unexpressed genes in a cell. The expression of some genes and not others leads to the specialization of a cell, because all cells carry the same set of genes |
| Why are stem cells of such high interest to researchers? | Because they produce copious amounts of cells and they're not fully differentiated |
| Name benefits and disadvantages of embryonic, umbilical cord, and adult stem cells | Embryonic
-Capacity to differentiate into any cell
-embryo dies though
-more chance for tumor formation and rejection of an adult patient
Umbilical Cord
-limited amount
-less differentiation potential
-easily obtained and stored
-fully compatible with individual later on in life
-umbilical cord is discarded either way
Adult
-fully compatible with adult's tissue
-less chance of a malignant tumor forming
-harder to obtain
-less capacity to differentiate
-adult does not have to die |
| Compare and contrast light and electron microscopes | They both magnify an image, and they both work based on wavelengths of light. However, an electron micrograph uses a beam of electrons (2-12 pm) and a light microscope uses visible light (400-700nm), so the shorter wavelength of the electron microscope gives it a higher resolution. Dead or alive organisms can be seen under a light microscope, but only dead ones in an electron. Light mic: resolution 0.2 micrometers magnification 500x, electron mic: 1 nm, resolution 500,000x |
| What should you include in a diagram of a palisade mesophyll cell? | Vacuole, chloroplasts with grana and double membrane, mitochondria with double membrane, nucleus, cell wall, plasma membrane, LABEL diagram |
| What should you include in a diagram of an E. coli cell? | Nucleoid (genophore), plasmid, plasma membrane, cell wall, slime capsule, pili, flagella, free ribosomes, LABEL diagram |
| What should you include in a diagram of a pancreatic exocrine gland cell? | Nucleus with nucleolus and nuclear pores, rER, lysosomes, ribosomes, secretory granules por abajo, Golgi App nearby, mitochondria (double membrane), plasma membrane, LABEL diagram |
| Where are ribosomes and lysosomes made? | ribosomes in nucleolus and lysosomes in RER |
| What are some benefits of having membrane-bound organelles? | The enzyme and substrates are more highly concentrated, movement of substances is facilitated within the cell (such as the vesicles that bud off from the rER to the Golgi) and no other enzymes disrupt the process |
| What is an example of secretory proteins? | antibodies |
| What is the structure of a mitochondrion in a eukaryote? | Inner membrane is called cristae, it has two membranes. It is filled with a fluid called Matrix which contains 70s ribosomes like prokaryotes, and it also has circular DNA like a prokaryote |
| What should you include in a diagram of the phospholipid bilayer? | phosphate hydrophilic heads, hydrocarbon hydrophobic tails, integral proteins, peripheral proteins, glycoprotein, channel protein, cholesterol |
| What makes the phospholipid bilayer so stable? | The attraction between the hydrophilic head and hydrophobic tails |
| Why is cholesterol important in the bilayer? | It regulates membrane fluidity by reducing it. It makes it less easy for hydrophilic substances such a sodium or hydrogen ions to pass through, and thats important because there has to be a concentration difference across the membrane |
| Some functions of membrane proteins? | Neurotransmitter receptor between pre and postsynaptic cells - acetylcholine receptor
Hormone receptor - insulin
Channel for facilitated diffusion
cell to cell adhesion to form tight junctions between cells in tissues |
| What is the importance of the universality of the genetic code? | Since all 64 codons mean the same for all organisms, it serves as evidence to show that all organisms evolved from the same group of cells |
| Explain the endosymbiotic theory | It is thought that it happened at least two times. The first time, an anaerobic organism took in an aerobic bacterium. The smaller, aerobic cell existed inside a vesicle in the cytoplasm of the larger cell, and reproduced at the same rate. Eventually, the bacterium turned into mitochondria and the larger cell into a heterotrophic eukaryote (animal). Then the second time, a heterotrophic cell took in a photosynthetic bacterium, and eventually the bacterium turned into chloroplasts and the larger cell into an autotrophic plant. Chloroplasts and mitochondria are very alike prokaryotes; both have 70s ribosomes to synthesize their own proteins, they reproduce like cells, they have naked circular DNA, and a double membrane which is what you would expect when a cell is taken in as a vesicle |
| What are the 4 theorized steps for the creation of cells from non-living matter? | 1. Scientists simulated Earth's atmosphere billions of years ago by passing electrical charges through hydrogen, methane and ammonia. Carbon compound and amino acids necessary for life were produced.
2. To turn those carbon compound into polymers, it is thought that energy from deep sea vents was taken. It's where there is hot water gushing out, and where reduced inorganic chemicals such as iron sulphide could be found.
3. To make plasma membranes, a bilayer was formed, where amphipathic carbon compounds assembled vesicles to resemble a plasma membrane
4. RNA instead of DNA might've been used to pass on genetic material, since RNA is self replicating, serves as a catalyst and also stores genetic material |
| Proof for Davson-Danielli model? | 1. Chemical analysis of plasma membranes showed that they were made of phospholipid and protein
2. Evidence showed that the membranes of red blood cells had enough phospholipid to make an area twice as large
3. Experiments showed that some substances couldn't pass through the membrane, so proteins were thought to create that barrier |
| New evidence for Singer-Nicholson model? | 1. Freeze etched micrographs showed globular proteins in the center of the bilayer
2. Analysis of membrane proteins showed that parts of them were hydrophobic, and therefore they would have to be within the bilayer
3. Fluorescent antibody tagging of membrane proteins showed how they fused together after 40 mins, showing the fluidity of membranes |
| What are two processes that only happen in the cell during interphase? | Protein synthesis in the cytoplasm and DNA replication in the nucleus |
| How does cytokinesis happen in plants and in animals? | In animal cells, a cleavage furrow forms using actin and myosin (contractile proteins) and is pinched off to form the two genetically identical cells. In plant cells, vesicles fuse at the equator to create form tubular structures. These create a new membrane that will ultimately join the preexisting membrane of the daughter cell, and pinch off. |
| How do tumors form? | Oncogenesis results from several mutations to an oncogene, which is a set of genes involved in controlling the cell cycle |
| How is the cell cycle controlled? | Proteins called kinases bind to enzymes called cyclin dependent kinases, which attach phosphate groups to other proteins in the cell in charge of carrying out tasks specific to their respective phase of the cell cycle. |
| Do mitochondria and chloroplasts increase during interphase? | YESSS |
