Topic 1 Flashcards
(166 cards)
1
Q
What are the characteristics common to all lifeforms?
A
Organization (made of cells), energy use, response to environment, homeostasis, growth, reproduction, adaptation/evolution.
2
Q
Why are information transmission, energy transfer, and evolution considered basic to life?
A
Information (genetic) transfer enables continuity; energy transfer is essential for metabolism; evolution allows adaptation.
3
Q
What is homeostasis, and what happens if it fails?
A
Homeostasis maintains internal balance. Without it, an organism’s systems may fail, resulting in illness or death.
4
Q
How does evolution depend on transfer of information?
A
Genetic information transfer underlies inheritance, enabling evolution; evolution selects for beneficial information transfers.
5
Q
How do viruses fit into the definition of life?
A
Viruses have genetic material and can evolve but lack metabolism and cannot reproduce outside a host. Thus, they’re not fully considered alive.
6
Q
What evidence does DNA provide for evolution?
A
DNA sequences show similarities among species, indicating common ancestry and evolutionary change.
7
Q
When did life arise on Earth?
A
About 3.5–4 billion years ago.
8
Q
What is a stromatolite and why is it important?
A
Stromatolites are layered fossil structures from ancient cyanobacteria, providing evidence of early life and photosynthesis.
9
Q
What are two main hypotheses for the origin of life?
A
Primordial soup (organic molecules in early oceans) and hydrothermal vent hypotheses (life at deep-sea vents); also the RNA world hypothesis.
10
Q
What makes water critical to life?
A
Cohesion, high specific heat, ice floats, excellent solvent properties.
11
Q
Why is water an excellent solvent?
A
It’s a polar molecule, enabling it to dissolve other polar substances and ions.
12
Q
What enables water molecules to bond with each other?
A
Hydrogen bonds form due to water’s polarity.
13
Q
What property allows ice to float and why is that important?
A
Ice is less dense than liquid water, allowing it to float and insulate aquatic ecosystems.
14
Q
What are the four main elements in living organisms?
A
Carbon, hydrogen, nitrogen, oxygen.
15
Q
Why is carbon so fundamental to life?
A
Carbon can form four covalent bonds, enabling the formation of diverse organic molecules.
16
Q
What type of bond holds atoms together in water, and what type of force holds water molecules together?
A
Covalent bonds within water molecules; hydrogen bonds between molecules.
17
Q
What did Stanley Miller’s experiment demonstrate?
A
That organic molecules could form under early Earth conditions, indicating life’s emergence followed physical and chemical laws.
18
Q
What is a macromolecule?
A
A very large molecule, such as protein, DNA, or polysaccharide, formed by the polymerization of smaller subunits called monomers.
19
Q
What is the monomer and bond of carbohydrates?
A
Monomer: monosaccharide; Bond: glycosidic linkage.
20
Q
Starch vs. cellulose - what is the main difference relevant to digestion?
A
Starch has α-glycosidic bonds (digestible by humans); cellulose has β-glycosidic bonds (not digestible by humans).
21
Q
What is the monomer and bond of proteins?
A
Monomer: amino acid; Bond: peptide bond.
22
Q
List levels of protein structure.
A
Primary: sequence, Secondary: local folding (α-helix, β-sheet), Tertiary: 3D shape, Quaternary: multiple polypeptides.
23
Q
What causes protein denaturation?
A
Factors such as pH, temperature, or chemicals disrupt non-covalent interactions (hydrogen bonds, ionic, hydrophobic).
24
Q
What is the monomer and backbone bond of nucleic acids?
A
Monomer: nucleotide; Bond: phosphodiester bond in the sugar-phosphate backbone.
25
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.
26
What is the basic structure and function of a lipid?
Mostly hydrophobic molecules including fats (glycerol + fatty acids), function in energy storage & membranes.
27
What is the main structural difference between saturated and unsaturated fatty acids?
Saturated = no double bonds, Unsaturated = one or more double bonds (causing kinks).
28
Name the three domains of life.
Bacteria, Archaea, Eukarya.
29
How do Bacteria differ from Archaea?
Cell wall composition, membrane lipids, gene and ribosome structure.
30
What is peptidoglycan, and where is it found?
A polysaccharide with amino acid cross-links found in bacterial cell walls.
31
How does penicillin target bacteria without harming animal cells?
It inhibits peptidoglycan synthesis, which animal cells do not have.
32
What distinguishes eukaryotes from prokaryotes?
Eukaryotes have a nucleus and membrane-bound organelles; prokaryotes do not.
33
What is the endosymbiotic theory?
Mitochondria and chloroplasts evolved when ancestral eukaryotic cells engulfed prokaryotic cells.
34
List three pieces of evidence supporting endosymbiosis for mitochondria/chloroplasts.
Double membranes, own circular DNA, and independent replication.
35
Difference between plant and animal cells?
Plant: cell wall, chloroplasts, large vacuole; Animal: lysosomes, centrioles, no cell wall.
36
What is the cytoskeleton composed of?
Microtubules, microfilaments, and intermediate filaments.
37
What is the 'fluid mosaic model'?
Model describing membranes as a fluid phospholipid bilayer with embedded proteins.
38
What is the role of cholesterol in membranes?
Maintains membrane fluidity and stability.
39
Compare facilitated diffusion and active transport.
Facilitated diffusion: passive, down concentration gradient; Active transport: requires energy, against gradient.
40
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).
41
What are the phases of mitosis?
Prophase, metaphase, anaphase, telophase.
42
What is a cyclin-dependent kinase (CDK)?
Enzyme that controls cell cycle progression at checkpoints by phosphorylating target proteins.
43
What is the evolutionary advantage of sexual reproduction during unfavorable conditions?
Increases genetic diversity, enhancing adaptability.
44
Define 'macromolecule'
A large molecule formed by joining smaller molecules, e.g., proteins, nucleic acids, carbohydrates.
45
What is 'homeostasis'?
Maintaining a stable internal environment.
46
What is 'enzyme'?
Biological catalyst, usually a protein, that speeds up chemical reactions in organisms.
47
What is 'osmosis'?
Diffusion of water across a selectively permeable membrane.
48
What is 'chromatin'?
DNA and protein complex that package DNA into chromosomes.
49
50
What is biology?
The scientific study of organisms, both living and after death, with the goal of discovering and understanding the underlying unity as well as the amazing diversity of complex processes that make up life.
51
What are acids?
A substance that can release a proton in solution.
52
What is adhesion?
The binding of one cell or substance to another.
53
What is aerobic metabolism?
Occurring in the presence of oxygen; requiring or using oxygen.
54
What is anaerobic metabolism?
Occurring without the use of molecular oxygen, O2.
55
What are anions?
A negatively charged ion.
56
What are atoms?
The smallest unit of a chemical element. Consists of a nucleus and one or more electrons.
57
What are bases?
(1) A substance that can accept a hydrogen ion in solution. (Contrast with acid.) (2) In nucleic acids, the purine or pyrimidine that is attached to each sugar in the sugar–phosphate backbone.
58
What are biomes?
A major division of the ecological communities of Earth, characterised primarily by distinctive vegetation and annual patterns of temperature and precipitation.
59
What is the biosphere?
All regions of Earth and Earth's atmosphere in which organisms can live.
60
What is a buffer?
A substance that can transiently accept or release hydrogen ions and thereby resist changes in pH.
61
What are cations?
An ion with one or more positive charges.
62
What is a cell?
The simplest structural unit of a living organism. In a multicellular organism, many individual cells serve as the building blocks of tissues and organs.
63
What is a chemical bond?
An attractive force stably linking two atoms.
64
What is a chemical reaction?
The change in the composition or distribution of atoms of a substance, with consequent alterations in properties.
65
What is cohesion?
The tendency of molecules (or any substances) to stick together.
66
What is a community?
A group of species living together at the same place and time.
67
What is a compound?
(1) A substance made up of atoms of more than one element. (2) Made up of many units, as in the compound eyes of arthropods.
68
What is a covalent bond?
A chemical bond based on the sharing of electrons between two atoms.
69
What is an ecosystem?
The organisms of a particular community together with the physical and chemical environment in which they live.
70
What is electronegativity?
The tendency of an atom to attract electrons when it occurs as part of a compound.
71
What are electrons?
A subatomic particle outside the nucleus carrying a negative charge and very little mass.
72
What is an element?
A substance that cannot be converted to a simpler substance by ordinary chemical means.
73
What is energy?
The capacity to do work or move matter against an opposing force. The capacity to accomplish change in physical and chemical systems.
74
What is Eukarya?
The formal taxonomic name for eukaryotes.
75
What is evolution?
The process by which living organisms change over time through changes in the genome.
76
What is evaporation?
The transition of water from the liquid to the gaseous phase.
77
What is homeostasis?
The maintenance of a steady state, such as a constant temperature, by means of physiological or behavioural feedback responses.
78
What is a hydrogen bond?
A weak electrostatic bond which arises from the attraction between the slight positive charge on a hydrogen atom and a slight negative charge on a nearby oxygen or nitrogen atom.
79
What does hydrophilic mean?
Having an affinity for water.
80
What does hydrophobic mean?
Having no affinity for water. Uncharged and non-polar groups of atoms are hydrophobic.
81
What is a hydrophobic interaction?
A weak chemical interaction caused when molecules that are not attracted to water interact to exclude water.
82
What is an ionic bond?
An electrostatic attraction between positively and negatively charged ions.
83
What are isotopes?
Isotopes of a given chemical element have the same number of protons in their nuclei (and thus are in the same position on the periodic table) but differ in the number of neutrons.
84
What are liposomes?
A spherical structure contained by a membrane of phospholipids. Can be used to deliver drugs to cells.
85
What is mass?
A measure of the quantity of matter present; the greater the mass, the greater the quantity of matter.
86
What is a membrane?
A phospholipid bilayer forming a barrier that separates the internal contents of a cell from the nonbiological environment or enclosing the organelles within a cell. The membrane regulates the molecular substances entering or leaving a cell or organelle.
87
What is metabolism?
The sum total of the chemical reactions that occur in an organism, or some subset of that total.
88
What is a mole?
A quantity of a compound whose weight in grams is numerically equal to its molecular weight expressed in atomic mass units. Avogadro’s number of molecules: 6.023 × 10^23 molecules.
89
What is molecular weight?
The sum of the atomic weights of the atoms in a molecule.
90
What are neutrons?
One of the three fundamental particles of matter (along with protons and electrons), with mass slightly larger than that of a proton and no electrical charge.
91
What does non-polar mean?
Having electric charges that are evenly balanced from one end to the other. (Contrast with polar.)
92
What are nucleic acids?
A compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.
93
What is the nucleus?
The centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains chromosomes.
94
What are organ systems?
An interrelated and integrated group of tissues and organs that work together in a physiological function.
95
What is an organism?
An individual animal, plant, or single-celled life form.
96
What are organs?
A body part composed of different tissues integrated to perform a distinct function.
97
What is oxidation?
The relative loss of electrons in a chemical reaction; either outright removal to form an ion, or the sharing of electrons with substances having a greater affinity for them, such as oxygen. Most oxidations, including biological ones, are associated with the liberation of energy.
98
What is an oxidation-reduction reaction?
A reaction in which one substance transfers one or more electrons to another substance.
99
What is pH?
The negative logarithm of the hydrogen ion concentration; a measure of the acidity of a solution. A solution with pH = 7 is said to be neutral; pH values higher than 7 characterise basic solutions, while acidic solutions have pH values less than 7.
100
What is a phospholipid bilayer?
The basic structural unit of biological membranes; a sheet of phospholipids two molecules thick in which the phospholipids are lined up with their hydrophobic “tails” packed tightly together and their hydrophilic, phosphate-containing “heads” facing outward.
101
What is photosynthesis?
The metabolic processes carried out by green plants and some microorganisms by which visible light is trapped and the energy used to synthesise compounds such as ATP and glucose.
102
What does polar mean?
Referring to a molecule with separate and opposite electric charges at two ends, or poles; the water molecule (H2O) is the most prevalent example.
103
What is a product?
A molecule that results from the completion of a chemical reaction.
104
What are prokaryotes?
Unicellular organisms that do not have nuclei or other membrane-enclosed organelles; this includes the Bacteria and Archaea.
105
What are proteins?
Any of a class of nitrogenous organic compounds that have large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, etc., and as enzymes and antibodies.
106
What are protocells?
A self-organised sphere of lipids proposed as a stepping-stone to the origin of life.
107
What are protons?
(1) A subatomic particle with a single positive charge. The number of protons in the nucleus of an atom determines its element. (2) A hydrogen ion, H+.
108
What are reactants?
A chemical substance that enters into a chemical reaction with another substance.
109
What is reduction?
The gain of electrons by a chemical reactant.
110
What is a reversible reaction?
A chemical transformation that can occur in either direction, so that reactants become products and vice versa.
111
What is a solute?
A substance that is dissolved in a liquid to form a solution.
112
What is a solvent?
The liquid in which a substance (solute) is dissolved to form a solution.
113
What is a solution?
A liquid and its dissolved solutes.
114
What is specific heat?
The amount of energy that must be absorbed by a gram of a substance to raise its temperature by one degree centigrade. By convention, water is assigned a specific heat of one.
115
What are tissues?
A group of similar cells organised into a functional unit; usually integrated with other tissues to form part of an organ.
116
What are van der Waals forces?
Weak attractions between atoms resulting from the interaction of the electrons of one atom with the nucleus of another. This type of attraction is about one-fourth as strong as a hydrogen bond.
117
What are the four classes of biological macromolecules?
Proteins, carbohydrates, lipids, and nucleic acids
118
What are the most abundant elements in living organisms?
Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur
119
What experiment disproved spontaneous generation of microbes?
Louis Pasteur’s swan-neck flask experiment
120
What is a gene?
A DNA sequence that codes for a specific protein or functional RNA
121
What property of water makes it a good solvent for polar molecules?
Its polarity and ability to form hydrogen bonds
122
What is an isotope?
Atoms of the same element with different numbers of neutrons
123
What is the central dogma of molecular biology?
DNA → RNA → Protein
124
What cellular process produces genetic diversity in meiosis?
Crossing over and independent assortment of homologous chromosomes
125
What 3 components make up a nucleotide?
A phosphate group, a five-carbon sugar, and a nitrogenous base
126
Name one trace element essential to most life.
Iron (Fe), Iodine (I), Zinc (Zn), Flourine (F), etc.
127
What is homeostasis?
The maintenance of a constant internal environment
128
What is the function of mitochondria?
Site of cellular respiration and ATP production
129
Describe a controlled experiment.
An experiment in which only one variable is manipulated, and all others are kept constant
130
What are enzymes?
Proteins that catalyze biochemical reactions
131
What is the monomer of proteins?
Amino acids
132
What does pH measure?
The concentration of hydrogen ions in a solution
133
Which bond joins monosaccharides to form polysaccharides?
Glycosidic bond
134
What is a buffer?
A solution that minimizes changes in pH when acids or bases are added
135
What is a hypothesis?
A tentative explanation that can be tested through experiments and observations
136
What are prokaryotic cells?
Cells without a nucleus or membrane-bound organelles (bacteria, archaea)
137
What chemical bond is the strongest in biology?
Covalent bond
138
What is the main function of ribosomes?
Protein synthesis
139
What is the function of the Golgi apparatus?
Modifies, sorts, and packages proteins and lipids
140
What is passive transport?
Movement of molecules across a membrane without energy input (diffusion, osmosis, facilitated diffusion)
141
What is the basic structure of a biological membrane?
Phospholipid bilayer with embedded proteins
142
What is a mutation?
Any change in the DNA sequence
143
What is photosynthesis?
The process by which plants, algae, and some bacteria convert light energy to chemical energy (glucose)
144
What labs are used to assemble proteins?
Ribosomes
145
What’s the function of lysosomes?
Digest and recycle cellular waste, damaged organelles, and macromolecules
146
What is a population?
A group of individuals of the same species living and interbreeding in the same area
147
What is endosymbiosis?
Theory that mitochondria and chloroplasts originated as free-living prokaryotes engulfed by an ancestral eukaryotic cell
148
What is the semi-permeable property of the cell membrane?
Allows some molecules to cross more easily than others
149
What are autotrophs?
Organisms that produce their own food from inorganic sources (like plants via photosynthesis)
150
What is a phospholipid?
A lipid containing a phosphate group; forms cell membranes
151
What are the stages of mitosis in order?
Prophase, prometaphase, metaphase, anaphase, telophase
152
What is necrosis?
Accidental or pathological death of cells due to injury or toxins
153
What is apoptosis?
Programmed cell death; a controlled, energy-dependent process
154
What is an oncogene?
A mutated gene that promotes uncontrolled cell division (cancer)
155
What is a tumor suppressor gene?
A gene that codes for proteins that inhibit cell division or cause apoptosis (e.g., p53, RB)
156
What does a kinase do?
Enzyme that adds a phosphate group to a molecule (phosphorylation)
157
What is the restriction point (R) in the cell cycle?
The point in G1 where the cell commits to DNA replication and division
158
What are cyclin-dependent kinases (CDKs)?
Protein kinases that control cell cycle progression, only active when bound to cyclins
159
What is binary fission?
Asexual reproduction method used by prokaryotes—cell divides into two
160
What is the G0 phase?
Non-dividing, resting phase some cells enter from G1
161
Describe the difference between mitosis and meiosis.
Mitosis creates two genetically identical diploid cells; meiosis produces four genetically unique haploid cells
162
What is independent assortment?
The random distribution of homologous chromosome pairs to daughter cells during meiosis I
163
What is nondisjunction?
The failure of chromosomes to separate properly during cell division, leading to aneuploidy
164
What is cytokinesis?
Division of the cytoplasm to form two separate cells after mitosis or meiosis
165
What is chromatin?
The complex of DNA and proteins that makes up eukaryotic chromosomes
166
What is the function of the cytoskeleton?
Provides structural support, shapes the cell, and mediates intracellular transport and cell movement
