Unity of Life - Chapter 1 Flashcards
What does the unity of life reveal?
All organisms arise from a common ancestor.
Which naturally occurring elements make up 98% of the atoms in an organism?
oxygen, hydrogen, and carbon
What reaction using biological fuels provides the energy to power the cell?
combustion, the reaction of oxygen with biological fuels to produce carbon dioxide and water
Why is carbon compared to silicon? Why is carbon better suited for life compared to silicon?
Although silicon is much more plentiful in the Earth’s crust and can form 4 covalent bonds, carbon-carbon bonds are stronger than silicon-silicon bonds.
- Carbon’s stronger bonds are more stable, enabling the building of large molecules.
- More energy is released when carbon-carbon bonds undergo combustion, making it a better fuel.
- After combustion, carbon dioxide remains in biochemical circulation due to being readily soluble in water and its ability to exist as a gas.
Why is carbon dioxide in biochemical circulation? Why isn’t silicon?
It is readily soluble in water and can exist as a gas. In contrast, silicon is insoluble after combustion, causing it to permanently remain out of circulation.
What are proteins?
biological macromolecules composed of linear array of 20 amino acids joined by peptide bonds to form long, unbranched polymers that fold into specific 3D structures to facilitate biochemical functions
What are nucleic acids?
biological macromolecules constructed of 4 nucleotides that store and transfer information in the cell
Name some of the functions of proteins.
- Catalysis as enzymes
- Transmission of signals as signal molecules and receptors
- Structural
- Mobility
- Defense against environmental dangers
Describe the structure of a nucleic acid.
five-carbon sugar (either deoxyribose or ribose) attached to a heterocyclic ring structure (a base) and a phosphoryl group
What are the two differences in DNA and RNA’s composition?
- Thymine is used in DNA and uracil is used in RNA.
- Ribose contains an additional hydroxyl group than deoxyribose.
What are the four deoxyribonucleotides?
adenine, cytosine, guanine, and thymine
How is information contained in DNA?
contained in the sequence of nucleotides linked together by phosphodiester linkages
How is mRNA different from DNA?
mRNA is an RNA and is frequently broken down after use. DNA is conserved to store information.
How do the sizes of proteins, lipids, and nucleic acids compare?
Lipids are much smaller. Proteins and nucleic acids can have weights of thousands-millions g mol^-1, lipids generally have a molecular weight of 1300 g mol^-1.
What allows the development of the inside and outside of a cell?
Lipids’ dual nature (hydrophobic and hydrophilic regions)
What are lipids?
a biological macromolecule with hydrophobic and hydrophilic regions that allow the formation of barriers; serves as a storage form of energy and a signal molecule
What are carbohydrates?
a biological macromolecule that serves as fuel and can be used for cell-cell recognition and interaction
How is glucose stored in animals? In plants?
as glycogen in animals
as starch in plants
Describe the structure of glycogen.
Glycogen is a branched polymer composed of glucose molecules.
What is the central dogma?
What is replication? What catalyzes it?
the process of copying the genome
DNA polymerases
What are the discrete units DNA is packaged into?
genes
What is transcription?
process of transcribing DNA into RNA to make its information accessible, catalyzed by RNA polymerase
What defines the function of a tissue or cell?
The selective transcription of certain genes
How are membranes organized?
Membranes are lipid bilayers with two layers of lipids organized with hydrophobic chains interacting with each other between hydrophilic head groups that interact with the environment.
What allows the plasma membrane to be selectively permeable?
Proteins embedded or attached to the membrane that permit the entry and exit of certain molecules and information.
Describe the secretory pathway.
- Proteins are transported into the lumen of the ER during translation.
- Inside the lumen, the protein folds into a final 3D structure with help from chaperones and are often modified (with addition of carbohydrates).
- The proteins are then put on regions of the RER lacking ribosomes, which bud off as transport vesicles and travel into the Golgi complex.
- After fusing with the Golgi, the proteins are further processed and sorted to different fates.
- A vesicle filled with proteins for secretion buds off the Golgi, forming a secretory granule, which is directed towards the plasma membrane.
- After receiving a signal, the secretory granule undergoes exocytosis by fusing with the plasma membrane and dumping its cargo into the extracellular environment.
