all of the chemical reactions that occur within the cells of living things
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homeostasis
the relatively constant and self-correcting internal environment of a living organism
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adaptive traits
all organisms have these traits which help them survive and reproduce in their natural environment
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atom
a unit of matter that cannot be broken down by ordinary chemical means
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tissue
a group of similar cells that perform the same function
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organ
a structure with two or more tissues working together to perform the same function
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organ system
at least two organs working together to perform a function
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organism
an individual living thing
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population
all individuals of the same species living in a distinct geographic area
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community
all individuals of any species living together in a geographic area, they can potentially interact with each other
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ecosystem
a community and its physical environment
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biosphere
the part of Earth where life exists
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science
an approach to answering questions through systematic documentation and experimentation
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scientific method
a series of steps used to gather information and reach conclusions. the first step is making careful observations and asking questions.
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hypothesis
a testable prediction/educated guess/answer to a question
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controlled experiment
An experiment in which one variable is tested using two groups. One group is a the control group, while the other is the experimental group.
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independent variable
the one variable that is manipulated in a controlled experiment
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bacteria
a domain including unicellular prokaryotic organisms that do not tend to live in extreme environments
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archaea
a domain including unicellular prokaryotic organisms that tend to live in extreme environments
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eukarya
a domain including eukaryotic organisms whose cell(s) contain a membrane-bound nucleus and organelles
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kingdoms
domain eukarya is split up into four of these (protists, fungi, plants, and animals)
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inductive reasoning
reasoning that involves the accumulation of facts to form a conclusion or hypothesis
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deductive reasoning
reasoning that involves making a hypothesis and then drawing more specific conclusions from it
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placebo
a substance made to look like the drug being tested, but that has no effect (sugar-pill)
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double-blind study
this occurs which neither researchers nor participants know which group is receiving treatment
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matter
anything that takes up space and has mass
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element
a pure form of matter containing only one kind of atom
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isotopes
atoms that have the same number of protons but differ in the number of neutrons
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radioisotopes
unstable, radiation-emitting isotopes which can be dangerous and/or useful, depending on context
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compound
two or more elements that are chemically combined
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covalent bond
a chemical bond that forms when two or more atoms share electrons in their outer shells
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molecule
a chemical structure consisting of at least two atoms held together by covalent bonds
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ion
an atom or group of atoms that carries either a positive or negative electrical charge
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ionic bond
a chemical bond formed when one or more electrons are transferred from one atom to another. the resulting attraction is due to oppositely charged ions (one positive and one negative)
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hydrogen bond
the attraction between a slightly positively charged hydrogen atom of one water molecule and a slightly negatively charged oxygen atom of another water molecule
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acid
anything that releases hydrogen ions (H+) when placed in water (result\=pH less than 7)
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base
anything that releases hydroxide ions (OH-) when placed in water (result\=pH greater than 7)
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pH
a measure of hydrogen ion concentration in a solution
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buffers
substances that prevent pH values from changing dramatically
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macromolecules
large organic molecules found in living things
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polymers
chains of monomers
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monomers
building blocks of polymers
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carbohydrates
sugars and starches that provide fuel for the body. the polymers of monosaccharide monomers
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oligosaccharides
chains of a few monosaccharides joined together by dehydration synthesis
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polysaccharide
a complex carbohydrate that forms when monosaccharides join together in long chains
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lipids
compounds, such as fats, that do not dissolve in water
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triglycerides
polymers made of three fatty acids bonded to glycerol. examples are fats and oils
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saturated fatty acid
fatty acid with only single bonds linking the carbons in its tail. known as the less healthy fatty acid
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unsaturated fatty acid
fatty acid with one or more double bonds linking the carbons in its tail. known as the healthier fatty acid
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phospholipid
molecule that forms a bilayer in cell membranes, consists of a hydrophilic head and hydrophobic tail
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protein
a polymer made of monomers called amino acids
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amino acids
building blocks (monomers) of proteins
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peptide
short chain of amino acids
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polypeptide
long chain of amino acids
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enzymes
substances (almost always proteins) that speed up chemical reactions
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nucleotides
the monomers of nucleic acids (DNA and RNA)
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ATP
adenosine triphosphate, the energy currency of the cell
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adenine
the base that pairs with thymine in DNA and uracil in RNA
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guanine
the base that pairs with cytosine in DNA and RNA
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organelle
a tiny cell structure that carries out a specific function within the cell
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plasma membrane
a selectively permeable phospholipid bilayer forming the boundary of the cells
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cytoplasm
a jelly-like fluid inside the cell in which the organelles are suspended
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simple diffusion
a form of passive transport that does not involve the aid of a carrier protein
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facilitated diffusion
a form of passive transport that is aided by transport proteins
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passive transport
the movement of a substance across the concentration gradient, which does not require energy
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active transport
the movement of a substance against the concentration gradient, which requires energy
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osmosis
passive transport (diffusion) of water across a selectively permeable membrane
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hypertonic
if a cell is in a \_______ solution, the concentration of solutes outside the cell is higher than the concentration inside the cell. the cell will lose water and shrink
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hypotonic
if a cell is in a \________ solution, the concentration of solutes inside the cell is higher than the concentration inside the cell. the cell will gain water and swell
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isotonic
if a cell is in a \_______ solution, the concentration of solutes is equal inside and outside of the cell. the cell will maintain water and shape
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endocytosis
in this process, a region of the plasma membrane engulfs the substance to be ingested and then pinches off from the rest of the membrane, forming a vesicle
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vesicle
small membrane-bound sac that functions in moving products into, out of, and within a cell
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phagocytosis
"cell eating," in which the cell engulfs large particles or bacteria
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pinocytosis
"cell drinking," in which the cell engulfs droplets of fluid
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exocytosis
the process by which large molecules leave cells. a vesicle from inside the cell fuses with the plasma membrane and spills its contents into the extracellular fluid
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nucleus
the organelle which contains almost all of the cell's genetic information
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nuclear envelope
a double membrane that surrounds the nucleus and separates it from the cytoplasm
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chromosomes
genetic information within the nucleus is organized into these threadlike structures made of DNA and associated proteins
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nucleolus
a specialized region within the nucleus that forms and disassembles during the course of the cell cycle
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ribosome
the organelle which is the site where protein synthesis begins
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endoplasmic reticulum
part of an extensive network of channels connected to the nuclear envelope and certain organelles
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smooth endoplasmic reticulum
lacks ribosomes and functions in detoxifying alcohol and other drugs, and producing phospholipids which contribute to membranes
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rough endoplasmic reticulum
studded with ribosomes which synthesize proteins, which contribute to membranes
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golgi complex
a cell organelle that consists of a series of interconnected, flattened membranous sacs. it processes and packages proteins
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lysosome
roughly spherical organelle that digests substances imported from outside the cell and destroys old or defective cell parts
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mitochondria
the site of cellular respiration that provides the energy that cells need
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cytoskeleton
a network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement
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anabolic pathways
metabolic pathways that consume energy to build complicated molecules from simpler ones
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catabolic pathways
metabolic pathways that release energy by breaking down complex molecules into simpler compounds
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cellular respiration
the oxygen-requiring pathway by which cells break down glucose to make a total of 36 ATP. consists of 4 phases: glycolysis, transition reaction, citric acid cycle, and electron transport chain
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glycolysis
the first phase of cellular respiration, which begins by splitting glucose into smaller sugars, yielding 2 ATP. the only phase which occurs in the cytoplasm
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transition reaction
the phase of cellular respiration that links glycolysis and the citric acid cycle, occurs in the mitochondria, and yields 0 ATP
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citric acid cycle
the third phase of cellular respiration, which yields 2 ATP and occurs in the mitochondria
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electron transport chain
the final phase of cellular respiration, which yields 32 ATP and occurs in the mitochondria
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fermentation
the breakdown of glucose without oxygen, which yields only 2 ATP in the entire process
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zygote
the cell formed by the union of an egg and a sperm
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meiosis
the type of cell division that gives rise to gametes
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mitosis
the type of cell division that results in identical body cells