Chapter 1: What is life? Flashcards
(30 cards)
What are the five characteristics of life?
complex/dynamic
organized/self-sustaining
cellular
information-based (genetics)
can adapt/evolve
What are the four top elements in the human body?
hydrogen (63%)
oxygen (25.5%)
carbon (9.5%)
nitrogen (1.4%)
Why is oxygen and hydrogen so common?
The ubiquity of water.
Why is carbon used more frequently if silicon is more plentiful?
Carbon is more stable than silicon, making carbon-based a better fuel than silicon-based molecules.
* Carbon is soluble in water, whereas silicon is not. Once carbon is mixed with oxygen, it is permanently out of circulation.
What are the four basic macromolecles?
Nucelid acids, carbohydrates, lipids, proteins
What are characterisitcs of hydrocarbons?
Non-polar
Hydrophobic (not soluble in water)
Generally, not very reactive
What are proteins composed of and what are their function?
Composition: Amino acids
Function: enzymes, structure
What are carbohydrates composed of and what are their function?
Composition: sugars
Function: energy, structure, play a role in cell-to-cell interactions
What are fats/lipids composed of and what are their function?
Composition: hydrocarbons
Function: energy, structure, contains polar groups
What are RNA/DNA composed of and what are their function?
Composition: nucleotides
Function: genetic information
Of the four classes of biomolecules, which is NOT a biopolymer? Why?
Fats/Lipids.
They lack repeating units of the same molecule/atom, called monomers.
Describe nucleic acid function and construction
Stores and transfers information.
Linear model constructed of four building blocks of nucleotides.
What is a nucleotide made of?
- A nitrogenous base
- Ribose or deoxyribose sugar ring
- Phosphate group
What do amino acids (monomers) make?
Peptides and proteins.
What do monosaccharides (simple sugars) make?
Carbohydrates (polysaccharides)
Describe lipids
Lipid molecules consist mainly of repeating units called fatty acids.
- Double bond = unsaturated
- Single bond = saturated, very polar
Why is life predominantly carbon-based in biological systems?
Carbon forms stable and versatile covalent bonds with other elements.
Describe DNA
- A polymer of two polynucleotide strands wrapped in a right-handed double helix.
- Has a sugar (deoxyribose) phosphate backbone.
- Bases pair via hydrogen bonding. A-T and G-C.
- Carries the genetic information (genes) of an organism.
How many strands of DNA and RNA?
DNA: double helix, one strand of DNA
RNA: single strand, nucleotide
Nucleotides are monomers of what and what do they do?
DNA and RNA
The information content of DNA is the sequence of nucleotides linked together by phosphodiester linkages.
Describe RNA
- A polymer of polynucleotide strands.
- Has a sugar (ribose) phosphate backbone. The sugar component of the ribonucleotides contains an additional hydroxyl (—OH) group.
What are the three types of RNA
- Messenger RNA
- Transfer RNA
- Ribosomal RNA
What is the main function of lipids?
Crucial signal molecules and important stage of energy.
What is the main function of carbohydrates?
An important fuel source, most common is simple sugar glucose
