Topic 1 Flashcards
What are the characteristics common to all lifeforms?
Organization (made of cells), energy use, response to environment, homeostasis, growth, reproduction, adaptation/evolution.
Why are information transmission, energy transfer, and evolution considered basic to life?
Information (genetic) transfer enables continuity; energy transfer is essential for metabolism; evolution allows adaptation.
What is homeostasis, and what happens if it fails?
Homeostasis maintains internal balance. Without it, an organism’s systems may fail, resulting in illness or death.
How does evolution depend on transfer of information?
Genetic information transfer underlies inheritance, enabling evolution; evolution selects for beneficial information transfers.
How do viruses fit into the definition of life?
Viruses have genetic material and can evolve but lack metabolism and cannot reproduce outside a host. Thus, they’re not fully considered alive.
What evidence does DNA provide for evolution?
DNA sequences show similarities among species, indicating common ancestry and evolutionary change.
When did life arise on Earth?
About 3.5–4 billion years ago.
What is a stromatolite and why is it important?
Stromatolites are layered fossil structures from ancient cyanobacteria, providing evidence of early life and photosynthesis.
What are two main hypotheses for the origin of life?
Primordial soup (organic molecules in early oceans) and hydrothermal vent hypotheses (life at deep-sea vents); also the RNA world hypothesis.
What makes water critical to life?
Cohesion, high specific heat, ice floats, excellent solvent properties.
Why is water an excellent solvent?
It’s a polar molecule, enabling it to dissolve other polar substances and ions.
What enables water molecules to bond with each other?
Hydrogen bonds form due to water’s polarity.
What property allows ice to float and why is that important?
Ice is less dense than liquid water, allowing it to float and insulate aquatic ecosystems.
What are the four main elements in living organisms?
Carbon, hydrogen, nitrogen, oxygen.
Why is carbon so fundamental to life?
Carbon can form four covalent bonds, enabling the formation of diverse organic molecules.
What type of bond holds atoms together in water, and what type of force holds water molecules together?
Covalent bonds within water molecules; hydrogen bonds between molecules.
What did Stanley Miller’s experiment demonstrate?
That organic molecules could form under early Earth conditions, indicating life’s emergence followed physical and chemical laws.
What is a macromolecule?
A very large molecule, such as protein, DNA, or polysaccharide, formed by the polymerization of smaller subunits called monomers.
What is the monomer and bond of carbohydrates?
Monomer: monosaccharide; Bond: glycosidic linkage.
Starch vs. cellulose - what is the main difference relevant to digestion?
Starch has α-glycosidic bonds (digestible by humans); cellulose has β-glycosidic bonds (not digestible by humans).
What is the monomer and bond of proteins?
Monomer: amino acid; Bond: peptide bond.
List levels of protein structure.
Primary: sequence, Secondary: local folding (α-helix, β-sheet), Tertiary: 3D shape, Quaternary: multiple polypeptides.
What causes protein denaturation?
Factors such as pH, temperature, or chemicals disrupt non-covalent interactions (hydrogen bonds, ionic, hydrophobic).
What is the monomer and backbone bond of nucleic acids?
Monomer: nucleotide; Bond: phosphodiester bond in the sugar-phosphate backbone.
Directionality of nucleic acids—what do 5’ and 3’ mean?
5’ and 3’ refer to the carbon numbers in the sugar, indicating the direction of nucleotide addition.
What is the basic structure and function of a lipid?
Mostly hydrophobic molecules including fats (glycerol + fatty acids), function in energy storage & membranes.
What is the main structural difference between saturated and unsaturated fatty acids?
Saturated = no double bonds, Unsaturated = one or more double bonds (causing kinks).
Name the three domains of life.
Bacteria, Archaea, Eukarya.
How do Bacteria differ from Archaea?
Cell wall composition, membrane lipids, gene and ribosome structure.
What is peptidoglycan, and where is it found?
A polysaccharide with amino acid cross-links found in bacterial cell walls.
How does penicillin target bacteria without harming animal cells?
It inhibits peptidoglycan synthesis, which animal cells do not have.
What distinguishes eukaryotes from prokaryotes?
Eukaryotes have a nucleus and membrane-bound organelles; prokaryotes do not.
What is the endosymbiotic theory?
Mitochondria and chloroplasts evolved when ancestral eukaryotic cells engulfed prokaryotic cells.
List three pieces of evidence supporting endosymbiosis for mitochondria/chloroplasts.
Double membranes, own circular DNA, and independent replication.
Difference between plant and animal cells?
Plant: cell wall, chloroplasts, large vacuole; Animal: lysosomes, centrioles, no cell wall.
What is the cytoskeleton composed of?
Microtubules, microfilaments, and intermediate filaments.
What is the ‘fluid mosaic model’?
Model describing membranes as a fluid phospholipid bilayer with embedded proteins.
What is the role of cholesterol in membranes?
Maintains membrane fluidity and stability.
Compare facilitated diffusion and active transport.
Facilitated diffusion: passive, down concentration gradient; Active transport: requires energy, against gradient.
What is the main difference between mitosis in eukaryotes and cell division in prokaryotes?
Eukaryotes: mitosis (multiple linear chromosomes); prokaryotes: binary fission (single circular chromosome).
What are the phases of mitosis?
Prophase, metaphase, anaphase, telophase.
What is a cyclin-dependent kinase (CDK)?
Enzyme that controls cell cycle progression at checkpoints by phosphorylating target proteins.
What is the evolutionary advantage of sexual reproduction during unfavorable conditions?
Increases genetic diversity, enhancing adaptability.
Define ‘macromolecule’
A large molecule formed by joining smaller molecules, e.g., proteins, nucleic acids, carbohydrates.
What is ‘homeostasis’?
Maintaining a stable internal environment.
What is ‘enzyme’?
Biological catalyst, usually a protein, that speeds up chemical reactions in organisms.
What is ‘osmosis’?
Diffusion of water across a selectively permeable membrane.
What is ‘chromatin’?
DNA and protein complex that package DNA into chromosomes.
