Chapter 1: The Fundamental Units of Life Flashcards
What is Cell Theory?
All existing cells come from preexisting cells
What is the main function of Peroxisomes?
Remove hydrogen peroxide from cells
What is the main function of cytoskeletons?
protein filaments that Helps cells move and keep their shape, and facilitates organelle movement.
What’s the major advantage of electron microscopy?
What’s the major function of the Golgi Apparatus?
-Synthesis of some cell wall polysaccharides in plants
- Modification of secreted proteins
Which of the following is NOT a function of the Golgi apparatus?
Synthesis of the majority of membrane phospholipids
If you wanted to study the detailed internal membrane structure of a chloroplast, what kind of microscopy would be most appropriate?
Electron
Animal cells contain mitochondria whereas plant cells do not - instead they have chloroplasts.
False
What do eukaryotic cells have that prokaryotes lack?
a nucleus and membrane-bound organelles
Oxidation reactions
are always accompanied by a reduction reaction
Which four elements make up 96% of the weight of living organisms?
carbon, hydrogen, nitrogen, and oxygen
Atoms form covalent bonds with each other by
sharing electrons
On the basis of weight, which is most abundant in a living bacterial cell?
Water
In water, hydrogen bonds can form between which of the following?
a hydrogen atom of one water molecule and an oxygen atom of another
The reaction amino acids → polypeptide is an example of a spontaneous reaction
False
A condensation reaction involves the cleavage of a covalent bond by the addition of a water molecule.
False
A hydrolysis reaction involves the cleavage of a covalent bond by the addition of a water molecule.
True
Cells contains the following four major families of small organic molecules: sugars, fatty acids, amino acids, and nucleotides.
True
For a reaction to occur spontaneously..
- Free energy must be released
- Products have a lower energy than reactants
- The reaction is energetically favorable
- ∆G is negative
Consider the following peptide: Met-Ile-Leu-Ala-Phe-Ile-Val-Leu
Overall, this peptide is likely to be
Hydrophobic and uncharged
Why? Because the peptides were all nonpolar amino acids. Nonpolar means they are hydrophobic and they had no charge.
Which of the following molecules is likely to be amphipathic?
fatty acid
Hydrogen bonds can only form between atoms of a polypeptide backbone, not between side chains.
False
By what mechanism(s) can an enzyme lower the reaction’s activation energy?
- Positioning of substrates to favor the reaction
- Straining bonds within the bound substrate
- Rearrangement of electrons in the substrate
- Formation of a covalent bond between substrate and enzyme
- All of the above
All of the above
An α-helix is held together by
hydrogen bonds between atoms in the polypeptide backbone
Which technique would be most appropriate for the purification of a protein based on its charge?
ion exchange chromatography
Regulation of proteins typically involves a conformational change in the protein structure.
True
A protein phosphatase adds a phosphate group to a protein to regulate its activity.
False
Allosteric regulation of enzymes requires binding of a regulatory molecule to the active site.
False
In feedback inhibition, an enzyme acting early in a reaction pathway is inhibited by a late product of that pathway.
True
What’s referred to as the Central Dogma?
The flow of information in a cell: DNA–>RNA–>PROTEIN
What is the major advantage and disadvantage of light microscopy?
Advantages: Can distinguish cell structures
Disadvantages: Light, the wavelengths, limits the fineness of details.
What is the major advantage and disadvantage of electron microscopy?
Advantages: Allowed us to see the finest of details on cells, such as the structures of the endoplasmic reticulum.
Disadvantages: The process of preparing samples can’t look at living cells.
What evidence supports the endosymbiotic origins of mitochondria and chloroplasts?
mitochondria—the organelles that generate energy in eukaryotic cells—are thought to have evolved from aerobic bacteria that took to living inside the anaerobic ancestors of today’s eukaryotic cells.
chloroplasts—have evolved from photosynthetic bacteria that long ago found a home inside the cytoplasm of a plant-cell ancestor. aerobic eukaryotic cell
How prokaryotic and eukaryotic cells are defined?
Prokaryotes: rod, corkscrewed and spherical shaped, few micrometers long; have a tough protective cell wall surrounding plasma membrane. Single celled organisms
contains: cytoplasm and DNA
ex. bacteria and archaea
Eukaryotes: plants animals and fungi are formed from eukaryotes . Contains nucleus that stores DNA inside a nuclear envelope
What’s the major function of mitochondria?
harness the energy from the oxidation of food molecules, such as sugars, to produce adenosine triphosphate, or ATP
consumes oxygen and releases CO2 in the course of this activity, the entire process is called cell respiration—essentially, breathing at the level of a cell.
What’s the major function of chloroplasts?
found in the cells of plants and algae, but not in the cells of animals or fungi.
carry out photosynthesis—trapping the energy of sunlight in their chlorophyll molecules and using this energy to drive the manufacture of energy-rich sugar molecules. In the process, they release oxygen as a molecular by-product.
What’s the major function of the endoplasmic reticulum?
site where most cell-membrane components, as well as materials destined for export from the cell
secrets proteins(ribosomes translate RNA into protein)
What is the major function of peroxisomes?
Why do scientists study model organisms?
biologists have become dedicated to studying a few chosen species, pooling their knowledge to gain a deeper understanding than could be achieved if their efforts were spread over many different species.
