Biology 192 Flashcards
Lipids
Hydrophobic molecules composed mainly of hydrogen, carbon, and oxygen atoms. Function is insulation and long term energy storage.
Triglycerides
A glycerol molecule linked to 3 fatty acids
Saturated fatty acids
All the carbons in the hydrocarbon chain form single bonds (C—C)
Monounsaturated fatty acids
Contain one C=C bond
Polyunsaturated fatty acids
Contain two or more C=C double bonds
Phospholipids
Similar structure to triglycerides, but the third —OH group is linked to a phosphate group instead of a fatty acid. Form a bilayer with the hydrophilic heads facing outward and the hydrophobic tails facing inward
Amino acids
Composed of a carbon atom, called the alpha carbon, that’s linked to an amino group (—NH2) and a carboxyl group (—COOH).
Peptide bond
The covalent bond formed between a carboxyl group and an amino group
Polypeptide
The molecule formed when multiple amino acids are joined by peptide bonds
Proteome
The complete protein composition of a cell or organism
Metabolism
The sum of the chemical reactions by which cells produce the materials and utilize the energy necessary to sustain life
Rough ER
Studded with ribosomes. Its functions are protein sorting, insertion of membrane proteins, and glycosylation (the attachment of carbohydrates to lipids and proteins)
Smooth ER
Its functions are metabolism, storage of Ca, and lipid synthesis and modification
Golgi
Consists of a stack of flattened membranes. Its functions are protein sorting, processing (enzymes modify certain proteins and lipids), and secretion
Lysosomes
Break down macromolecules
Vacuoles
Storage containers; contain enzymes that break down macromolecules
Mitochondria
Semiautonomous organelle that makes ATP
Peroxisomes
Catalyze various chemical reactions. Breaks down hydrogen peroxide, which can be dangerous to the cell, into water and oxygen
Chloroplasts
Semiautonomous organelle that captures light energy and uses it to synthesize organic molecules like glucose
Population
A group of the same species in an area
Community
All populations in an area
Ecosystem
Community of all living and non-living things
Biosphere
Regions of earth and atmosphere supportive of life
Homeostasis controls:
Body temperature, fluid balance, pH, electrolyte balance
Selective breeding
An artificially imposed version of natural selection
Random assortment
Variety in nature
Natural selection
Organisms with characteristics best suited to survival live to pass on these traits to later generations
Spontaneous mutations
Occasional errors in copying DNA will cause new forms of traits to appear
Tissues
Groups of cells of the same type
Organs
Structure made of different tissues
Organ system
Groups of organs working together
Aristotle
Developed the first classification system. He had two groups: plants and animals
Linnaeus
Father of Taxonomy. Created the classification system we use today.
3 Major Domains
Archaea, bacteria, animals
4 Major Kingdoms
Protista, fungus, plants, animals
Protists
Mostly unicellular eukaryotes divided into seven broad groups
Horizontal gene transfer
Genetic exchange between different organisms of the same generation. Only occurs in bacteria.
Discovery based science
Collection of data. Goal is to gather information. Often leads to hypothesis testing.
Scientific Method Experimentation (aka Hypothesis testing)
Observations are made. A testable hypothesis tries to explain andpredict outcomes. Experiments are conducted to determine if predictions are correct. Data are analyzed. The hypothesis is supported or rejected.
Variable
A factor that could change the outcome of an experiment (if changed)
Independent Variable
The one variable that is changed during an experiment
Constants
All the potential variables that do not change
Control
The set up in an experiment in which the independent variable is missing or held at a standard level
Dependent variable
The recorded data (the measured observation that was affected by the independent variable)
Magnification
Ratio between the size of an image produced by a microscope and its actual sizs
Resolution
Ability to observe two adjacent objects as distinct from one another’s
Resolution of human eye
0.1 mm
Electron microscope
Uses a beam of electrons and magnets. Resolution is 0.1 nm.
Transmission electron microscopy
Beam of electrons transmitted through the sample
Scanning electron microscopy
Sample coated with heavy metal. Beam scans surface to make 3D image.
Prokaryotic cells. Inside the plasma membrane
Cytoplasm, nucleotide region, ribosomes.
Prokaryotic cells. Outside the plasma membrane.
Cell wall, glycocalyx, pili, flagella
Plasma membrane
Membrane that controls movement into and out of the cell.
Cytosol
Site of many metabolic pathways
Nucleus
Area where genetic material is held and expressed
Nuclear envelope
Double membrane that encloses the nucleus
Nuclear pore
Passageway for molecules into and out of the nucleus
Nucleolus
Site for ribosome production (rRNA)
Ribosome
rRNA subunits. Site of protein manufacture in cells.
Atomic mass
Total mass of protons + total mass of neutrons
Atomic number
Number of protons in an atom of the element. Protons define the element. Every atom of an element has the same number of protons.
Isotope
Atoms of an element that have more or fewer neutrons than most atoms of that element.
Anion
Gain of electrons. Negatively charged ion.
Cation
Loss of electrons. Positively charged ion.
Orbitals
Certain regions around the nucleus that have a high probability of finding the electron. Each orbital can hold up to 2 electrons.
Valence shells
Outermost layers of electrons
Ionic bond
Force of attraction between two ions. Electrons are transferred, forming ions that are attracted to each other. Ionic compounds are called salts. They dissociate in water forming electrolyte solutions
Covalent bond
Electrons are shared to fill valence shells.
Polar covalent bonds
The unequal distribution of electrons in the molecule. Water has polar covalent bonds. Ions and molecules with polar covalent bonds are hydrophilic.
Hydrogen bonds
Hold polar molecules together. A d+ hydrogen atom from one polar molecule is attracted to a d- atom from another polar molecule
Cohesion
Molecules of water “stick together.” Surface tension.
Adhesion
Molecules of water adhere to other surfaces
Acids
Molecules that release hydrogen ions in solution
Bases
Lower the hydrogen ion concentration
C-O, C-N H-O, and H-N bonds
Polar covalent bonds. O and N form polar bonds with C or H.
Dehydration synthesis
Monomer to polymer; water is removed in the process
Hydrolysis
Polymers to monomers; water is used in the process
Functional groups
Groups of atoms with special chemical features that affect the function of its molecule
4 types of organic molecules/macromolecules
Carbohydrates, nucleic acids, lipids, proteins
Carbohydrates
Supply of chemical energy; structural support. Composed of carbon, hydrogen, and oxygen atoms.
Nucleic acids
Keeper of genetic information; template for proteins
Monosaccharides
Simplest sugars. Hexoses: glucose, fructose, galactose. Pentoses: ribose, deoxyribose
Disaccharides
Sucrose, lactose, maltose
Polysaccharides
Plants: starch (energy storage), cellulose (plant support). Animals: glycogen (energy storage), chitin (animal exoskeleton)
Three parts of nucleotides
Ribose or deoxyribose, phosphate functional group, purine or purimadine
Phosphodiester bonds
Monomers are held together in a polymer chain by strong covalent bonds. Sugar of one nucleotide bonded to the phosphate group of the next. Forms the sugar-phosphate backbone.
Purines
Adenine or guanine. Double ring
Pyrimadines
Thymine or cytosine. Single ring
Gene
A segment of DNA carrying a code of instructions for the cell in making a certain protein
mRNA
Copies the DNA code
rRNA
Forms the ribosome where polypeptide chains are made using the mRNA guide
tRNA
Brings amino acids to the ribosome to be added to a growing polypeptide chain
Function of steroids
Hormones, vitamins, cholesterol. 4 interconnected rings of carbon atoms. Usually insoluble in water.
Function of waxes
Protection from water
Membrane proteins
Proteins can be embedded in membrane (integral) or attached to it
Factors that increase fluidity
Short fatty acid chains; unsaturated fatty acids
Factors that decrease fluidity
Long fatty acid chains; saturated fatty acids; presence of cholesterol
Passive transport
Does not require energy expenditure; goal is to achieve equilibrium of concentration across membranes
Characteristics of molecules that diffuse
Small, uncharged, and nonpolar (O2 and CO2)
Diffusion
Occurs when a substance moves from a region of high concentration to a region of lower concentration
Facilitated diffusion
A transport protein provides a passageway for a substance to diffuse across a membrane (i.e. glucose through membrane channels that open with insulin)
Osmosis
Water diffuses across a membrane through aquaporins from the hypotonic compartment into the hypertonic compartment
Categories of passive transport
Diffusion; facilitated diffusion; osmosis
Isotonic
When the solute concentrations are equal on both sides of the plasma membrane
Hypertonic
The solute concentration outside the cell is higher than the solute concentration inside the cell
Hypotonic
The solute concentration outside the cell is lower than the solute concentration inside the cell
Crenation
A cell in a hypertonic solution shrinks because water exits the cell
Osmotic lysis
A cell in a hypotonic solution swells and may rupture because it takes in water
Active transport
Requires use of energy. Goal is not equilibrium of concentration across membrane.
Categories of active transport
Use of transporter proteins (uniporter, symporter, antiporter) for ions such as Na+ and K+; bulk transport (exocytosis, endocytosis)
Uniporter
Transporter protein that binds a single ion or molecule and transports it across the membrane
Symporter
Transporter protein that binds two or more ions or molecules and transports them in the same direction
Antiporter
Transporter protein that binds two or more ions or molecules and transports them in opposite directions
Exocytosis
Material inside the cell is packaged into vesicles and then excreted into the extracellular environment
Endocytosis
The plasma membrane folds inward to form a vesicle that brings substances into the cell
The first law of thermodynamics
Energy cannot be created or destroyed, but it can be transferred and transformed
Second law of thermodynamics
Any energy transfer or transformation from one form to another increases the degree of disorder of a system (entropy)
Entropy
A measure of the randomness of molecules in a system
Enthalpy
H. The total energy
Free energy
G. The usable energy
Exergonic reactions
Spontaneous. DeltaG is negative. Free energy is released during product formation. Catabolic reaction.
Endergonic reactions
Not spontaneous. DeltaG is positive. Requires the addition of free energy. Anabolic reaction.
Energy
The ability to promote change or do work
Kinetic energy
Energy of movement
Potential energy
The energy that a substance possesses due to its structure or location (i.e. concentration gradients, chemical energy in chemical bonds)
Activation energy
The energy required to initiate a chemical reaction
Active site
Location in an enzyme where the chemical reaction takes place
Substrate
The reactant molecules that bind to an enzyme at the active site and participate in the chemical reaction.
Induced fit mechanism
Interaction also involves conformational (shape of enzyme) changes
Lock and key mechanism
For substrate binding—only the right key (substrate) will fit in the lock (enzyme)
Competitive inhibition
Phenomenon in which a substrate molecule is prevented from binding to the active site of an enzyme by a molecule that is very similar in structure to the substrate
Non-competitive inhibition
Inhibitor binds to an allosteric site on the enzyme and changes the shape of the active site, preventing the substrate from binding to the enzyme
