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Bio midterm 3
| Term | Definition |
|---|---|
| nerves | long fibers made up of specialized cells and supportive tissue that transmits signals through the nervous system |
| spinal cord | major collection of nerves which extends from the base of the brain down to the lower back and is contained in and protected by spinal column |
| central nervous system (CNS) | brain and spinal cord |
| peripheral nervous system (PNS) | nerves that travel from spinal cord to distant body sites; includes all nervous tissue outside brain + spinal cord leading to + from our limbs and organs |
| neurons | highly specialized cells of the nervous system that generate electrical signals in the form of action potentials |
| cell body | the part of a neuron that contains the nucleus and most of the cell's other organelles |
| dendrites | branched extensions from the cell body of a neuron, which receive incoming information |
| axon | the long extension of a neuron that conducts electrical signals away from the cell body toward the axon terminal |
| axon terminals | the tips of an axon, which communicate with the next cell or cells in the pathway |
| sensory neurons | receive info from the external world and internally and transmit it to CNS |
| motor neurons | neurons that control the contraction of skeletal muscle; transmit info from CNS to muscle cells signaling them to contract or relax |
| effector | cells or tissues that respond to info relayed from a sensor |
| action potential | an electrical signal that travels down a neuron, caused by ions moving across the cell membrane |
| myelin | a fatty substance that insulates the axons of neurons and facilitates rapid conduction of action potentials |
| glial cell | supporting cells of the nervous system, some of which produce myelin |
| cerebellum | located in the rearmost portion of the brain, controls movement, coordination, and balance |
| brain stem | base of brain; coordinates involuntary (automatic) actions like reflexes, heart rate, digestion, and breathing |
| diencephalon | located above the brainstem, regulates homeostatic functions like body temp., hunger, thirst, sex drive; contains hypothalamus |
| cerebrum | largest part of brain; sits on top; has two portions the outer and inner |
| cerebral cortex | outer part of the cerebrum; more advances brain functions, including perception + thinking; gives us our distinct personalities and most human characteristics |
| limbic system | a set of brain structures that is stimulated during pleasurable activities and which is involved in addiction; "pleasure center" "reward system" |
| dopamine | a chemical messenger that is involved in conveying a sense of pleasure in the brain |
| neurotransmitter | a chemical signaling molecule released by a neuron to transmit a signal to a neighboring cell |
| synapse | the site of transmission of a chemical signal from a neuron to another cell; consists of axon terminal, the small gap between two cells, and protein receptors |
| synaptic cleft | the physical space between the neuron and cell with which it is communication |
| proteins | a macromolecule made up of repeating subunits called amino acids, which determine the shape and function of a protein |
| amino acids | the building blocks of proteins; there are 20 different amino acids |
| gene | a sequence of DNA that contains the info to make at least one protein |
| gene expression | the process of using DNA instructions to make proteins |
| hydrophobic amino acid chain | tend to clump together away from water |
| hydrophilic amino acids | face out toward water |
| beta sheets | a folded structure found in many proteins but present at a much higher frequency than silk |
| regulatory sequence | "on/off switch" for a gene; determines when, where, and how much protein is produced from a gene |
| coding sequence | the sequence of nucleotides in a gene that determines the identity of a protein; it specifies order/sequence of amino acids |
| transcription | the process of using DNA to make a messenger RNA (mRNA) copy of the gene (carried out by RNA polymerase) |
| messenger RNA (mRNA) | the RNA copy of an original DNA sequence made during transcription; RNA is another type nucleic acid but one that is single stranded rather than double stranded |
| translation | the process of using this mRNA copy as a set of instructions to assemble amino acids into a protein |
| RNA polymerase | the enzyme that carries out transcription; copies a strand of DNA into a complementary strand of mRNA |
| codon | a sequence of 3 main mRNA nucleotides that specifies a particular amino acid; ex. GGU specifies amino acid glycine |
| transfer RNA (tRNA) | each tRNA molecule serves as a kind of adapter, with one end binding to a specific amino acid and the other end binding to the mRNA codon for that particular amino acid |
| anticodon | the part of tRNA molecule that binds to a complimentary mRNA codon |
| start codon | in eukaryotes codes for methionine; first codon of a coding sequence; tells ribosome to start translating and add more amino acids |
| stop codon | there are three; tell the ribosome to stop translating and not add any more amino acids to the growing chain |
| genetic code | the set of rules dictating which mRNA codons specify which amino acids |
| transgenic | organisms that have been genetically modified to contain genes from another species |
| recombinant gene | a genetically engineered gene that contains portions of genes not naturally found together |
| vector | the carrier DNA molecule |
| genetic engineering | altering or manipulating the DNA of organisms by modern laboratory techniques |
| genetically modified organisms (GMOs) | organisms whose genomes have been altered through modern genetic engineering techniques, sometimes to contain new genes |
| gene therapy | replacing a defective human gene with a healthy one |
| hemoglobin | the oxygen-carrying protein in red blood cells |
| beta-globin | protein that makes up one part of the hemoglobin molecule; A-T base pair in original version of beta-globin gene is changed to T-A base pair |
| mutation | a change in the nucleotide sequence of a DNA molecule |
| point mutation | alters a single nucleotide; may or may not alter the amino acid sequence of a protein depending on where it occurs |
| missense mutations | point mutations that change the amino acid sequence of a protein (change one nucleotide to another, different amino acid sequence results) |
| silent mutations | point mutation; those that do not change the protein sequence (change one nucleotide to another but no change in amino acid sequence) |
| frameshift mutations | one or more DNA nucleotides may be inserted/deleted from genes, shifting the reading frame of that gene (changing where a codon begins and ends |
| nonsense mutation | type of point mutation; change one nucleotide, introduces early stop codon |
| insertion mutation | type of frameshift mutation; insert one or more nucleotides and shifts reading frame of every codon after the insertion |
| deletoin mutation | type of frameshift mutation; delete one or more nucleotides and shifts reading frame of every codon after the deletion |
| inversion mutation | type of rearranged mutation; group of DNA nucleotides are flipped to read in reverse order, different amino acid sequence in this location |
| translocation mutation | type of rearranged mutation; move segments of DNA from one chromosome to another, fusing portions of different genes together |
| mutagens | physical or chemical agents that cause mutations |
| gene editing | a way to change the sequence of a gene |
| CRISPR (clustered regularly interspaced short palindromic repeats) | a kind of molecular scissors that bacteria use to chop up viruses and thereby defending themselves from infection |
| somatic cells | nonreproductive cells of the body |
| germ cells | those that develop into sperm or eggs |
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