Exam 1 Vocab Flashcards
Level of biological organization:
Atoms to molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, biomes, biosphere
Theory:
An explanation of an aspect of the natural world and universe that has been repeatedly tested with the scientific method
Hypothesis:
A proposed explanation based on limited evidence
Null hypothesis:
The hypothesis is not the explanation
Independent variable
Not affected by the experiment, value does not change
Dependent variable
Changes with the experiment/ what is being tested
Control:
Provides a baseline for the experiment
Treatment groups
The item or subject that is manipulated
X- axis
Independent variable
Y-axis
Dependent variable
DNA
Deoxyribonucleic acid, stores genetic information, sugar-phosphate base
Watson & Crick
Used X-ray crystallography to determine that DNA was a double helix with antiparallel strands. Used the chargaff rule to determine nucleotides, determined nucleotides are linked through hydrogen bonding
Franklin & Wilkins
Researchers who helped Watson & Crick
RNA
Ribonucleic acid: a messenger that carries genetic information from DNA to the proteins in a cell
Hershey-Chase Experiment
Used the presence of phosphorous in DNA and sulfur in proteins ti confirm that DNA is the genetic material, not protein
Polymer
Any large molecule composed of small repeating units (monomers) bonded together
Nucleotides
A molecule consisting of a five carbon sugar, one or more phosphate groups, and a nitrogenous based
Nitrogenous base
Nitrogen containing biological compounds that form nucleosides
Purines
A class of double ringed nitrogenous bases found in nucleotides (Adenine, guanine)
Pyrimidine
A class of single-ringed nitrogenous bases found in nucleotides (Cytosine, uracil, thymine)
Sugar-phosphate backbone
The portion of the DNA double helix that provides structure and support to the molecule
Complementary base pairing
The association between specific nitrogenous based of nucleic acids stabilized by hydrogen bonding
Phospodiester linkage
Chemical linkage between adjacent nucleotides in DNA and RNA. Forms when the phosphate group of one nucleotide condenses with the hydroxyl group on the sugar of another nucleotide
Anti-parallel double helix
Describes the opposite orientation of nucleic acid strands that are hydrogen bonded to one another
Histone proteins
A member of a class of positively charged (basic) proteins associated with DNA in the chromatin of eukaryotic cells
Chromosome
Gene- carrying structure consisting of a single long molecule of double stranded DNA and associated proteins
DNA replication
The process of producing two identical replicas of DNA from the original DNA molecule
Semi-conservative
The way DNA replicates, with each strand of an existing DNA molecule serving as a template to create a new complementary DNA strand
Replication bubble
An unwound and open region of DNA where DNA replication occurs
Replication fork
The Y shaped site where a double-stranded molecule is DNA is separated into two single strands for replication and on which DNA synthesis occurs
Origin of replication
A particular sequence in a genome at which replication is initiated
Template strand
A strand of RNA or DNA used to make a new, complementary strand via complementary base pairing
Non-template strand
The strand of DNA that is not transcribed during synthesis of RNA
Leading strand
The new strand of DNA that is synthesized in one continuous piece in a direction that follows the replication fork
Lagging strand
The new strand of DNA that is synthesized discontinuously (as a series of short pieces that are later joined) in a direction moving away from the replication fork
DNA polymerase
An enzyme that catalyzes the synthesis of DNA
Central dogma
The scheme for information flow in in the cell (DNA transcription RNA translation PROTEIN)
Transcription
The process that uses a DNA template strand to produce complementary RNA
Translation
The process by which a polypeptide is synthesized from information in codons of messenger RNA
mRNA
Messenger RNA, carried information from DNA to proteins
Ribosome
A large macro molecular machine that synthesized proteins by using the genetic information encoded in mRNA
Triplet
A code in which a “word” of three letters encodes one piece of information
Codon
A sequence of 3 nucleotides in DNA or RNA that codes for an amino acid or a stop signal for protein synthesis
Amino acid
A small organic molecule with a central carbon atom bonded to an amino acid group, a carbonyl group, a hydrogen atom, and a side chain
Protein
A macromolecule consisting of one or more polypeptide chains
Polypeptide
A chain typically consisting of 50 or more amino acids linked together by peptide bonds
Enzyme
A protein catalyst used by living organisms to increase the rate of biological reactions
Start codon
The AUG triple in mRNA where protein synthesis begins; codes for the amino acid methionine
Stop codon
Any of the three mRNA triplets (UAG, UGA, or UAA) that cause the termination of protein synthesis
Base pair wobble
A pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules
Gene
A section of DNA that contains the regulatory sequences and coding information for the transcription of one or more related RNA molecules, some of which encode polypeptides
Loci/locus
A gene’s physical location on a chromosome
Chromatin
The complex of DNA and proteins, mainly histones, that compose eukaryotic chromosomes.
Homologous chromosome
In diploid organisms, a member of a pair of chromosomes that are similar in size, shape, and gene content
Sister chromatid
The paired, double stranded DNA copies of a recently replicated chromosome. Connected tightly at the centromere and eventually separate during anaphase of mitosis or meiosis II
Centromere
The region of a replicated chromosome where the two sister chromatic a are joined most tightly. The kinetochore is formed during the M phase
Karyotype
The distinctive appearance of all the metaphase or prometaphase chromosomes in an individual, including the number of chromosomes, their length, and their banding patterns
Diploids
A cell or organism with two sets of chromosomes
Haploid
A cell or organism with one set of chromosomes
Gene expression
The entire set of processes, including transcription and translation, that convert the information in DNA into a product of a gene, most commonly a protein, that contributes to the phenotype of a cell organism
Genotype
The alleles of a gene present in a given individual
One gene, one enzyme hypothesis
The theory that each gene directly produces a single enzyme
Phenotype
The detectable traits of an individual
Alleles
A particular version of a gene
Dominant allele
An allele whose phenotypic effect is observed when it is present in homozygous or heterozygous form
Recessive allele
An allele whose phenotypic effect is observed only in homozygous individuals
Homozygous
Having two identical alleles of a gene
Heterozygous
Having two different alleles of a gene
Mutation
Any permanent change in the hereditary material of an organism
Point mutation
A mutation that results in a change in or an insertion or deletion of a single base pair in DNA
Silent mutation
A mutation that changes the sequence of a codon without changing the amino acid that is specified
Missense mutation
A point mutation that changes one amino acid for another within a protein
Nonsense mutation
A point mutation that converts an amino-acid-specifying codon into a stop codon
Frameshift mutation
The addition or deletion of one or a few base pairs in a coding sequence that shifts the reading frame of the mRNA
Chromosome mutation
Any change in the chromosome number, or the change in the composition of individual chromosomes as a result of inversions, translocations, deletions, or duplications during cell division
Chromosome deletion
The loss of part of a chromosome
Chromosome duplication
A chromosome abnormality that occurs when there is an extra copy of genetic material on the short arm
Chromosome inversion
A chromosome rearrangement in which a segment of a chromosome is reversed end to end
Chromosome translocation
When a chromosome breaks and the fragmented pieces reattach to different chromosomes
Gregor Mendel
The father of genetics
Blending inheritance
The theory that offspring inherit a blend of the parents genes
Model organism
An organism selected for scientific study based on its features that make it easy to work with
Pure breeding/true breeding lines
A strain that produces offspring identical to the parents when mates within the strain
Genetic cross
The purposeful mating of two individuals resulting in the combination of genetic material in offspring
Hybrids
The offspring of parents from two different strains
Parental generation
The adults used in the first experimental cross of a breeding experiment
F1
The first set of offspring
F2
The second set of offspring
Monohybrid cross
The mating between two homozygous parents that differ in alleles of one gene
Particulate inheritance
Discrete particles are passed from parents to offspring
Principle of segregation
A hybrid between two parents different in a set of characters posses both parental factors which subsequently segregate
Gamete
A haploid reproductive cell that ca fuse with another haploid reproductive cell of the opposite sec to for a diploid zygote
Punnet square
A squared diagram used to predict the genotypes of a particular cross or breeding experiment
Independent assortment
The concept that each pair of hereditary elements segregates independently of alleles of other genes during meiosis
Dependent assortment
Null hypothesis to independent assortment
Mendelian inheritance
Patterns of how traits are passed from parent to offspring that follow the law of segregation, the law of dominance, and the law of independent assortment
Dihybrid cross
A mating between two homozygous parents that differ in alleles of two different genes
Linked genes
A physical association between two genes because they are on the same chromosome
Meiosis 1
The first cell diction of meiosis in which synapsis, crossing over, and independent assortment occur
Meiosis 2
The second cell division of meiosis, in which sister chromatids are separated from each other
Maternal chromosome
The chromosome coming from the mother
Paternal chromosome
The chromosome coming from the father
Daughter cell
The result of a single dividing parent cell
Independent assortment of chromosome
Genes independently separate from one another when reproductive cells develop
Crossing over
The swapping of genetic material
Random fertilization
There is a random chance that each egg and sperm will join one another
Genetic recombination
The exchange of genetic material between different organisms which leads to production of offspring
Population
A distinct group of individuals
Variation
Various differences between biological species and individuals
Gene pool
The stock of different breeding genes in an interbreeding population
Allele frequency
The frequency of an allele in a population
Equilibrium
The condition of achieving balance
Hardy-Weinberg equilibrium
A state of agreement between observed allele frequencies in a population and allele frequencies found by the hardy-Weinberg principle
Modern synthesis of evolution
The unified theory of evolution based on Mendelian genetics and Darwinian evolution
Evolution
Any change in the heritable characteristics of a population
Migration/gene flow
The introduction of genetic material from one population to another through migration
Genetic drift
Variation in allele and genotypic frequencies in a population
Founders effect
The reduction in genetic variation
Bottleneck effect
A sharp reduction of a population due to things like natural disasters
Admixed population
When a populations members possess recent ancestry from two or more sources
Non-random mating
Any mating in a population where crosses between the various types of individuals do not occur in the frequencies that are expected by chance
Positive assortative mating
Organisms choose to mate with similar organisms
Negative assortative mating
Organism choose to mate with organisms different from themselves
Inbreeding
Breeding between related individuals
Homozygosity
The possession of two identical alleles
Heterozygosity
Having two different alleles of a gene
Inbreeding depression
The decline in average fitness that takes place when homozygosity increases and heterozygosity decreased in a population due to inbreeding
Genetic rescue
A mitigation strategy designed to restore genetic diversity and reduce extinction risks in small, isolated and frequently inbred populations
Typological thinking
Classifies things only in terms of the types they belong and view variation as abnormal
Plato and the “perfect essence”
Claimed every organism was an example of a perfect essence, or type, created by god, and these types were unchanging
Aristotle and the “great chain of being”
Species were fixed types organized into a sequence based on increased size and complexity
Jean-Baptiste Lamarck
Developed the law of use and disuse and the law of inheritance of squired characteristics
Use and disuse hypothesis
More frequent use of organs strengthens, develops, and enlarges then
Inheritance of acquired characteristics hypothesis
All the acquisitions or losses on individuals are preserved and carried onto offspring
Charles Darwin
Described variation among individuals in a populations, across different populations of the same species, and across closely related species
Artificial selection
The identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations
Natural selection
A process through which individuals with certain characteristics survive and reproduce at a higher rate because of those characteristics
Fitness
The ability of an organism to survive and reproduce compared to other individuals in the population
Four requirements of evolution
Variation, inheritance, struggle for existence, differential survival and reproduction
Mechanisms of evolution
Mutation, gene flow, genetic drift, and selection
Directional selection
Individuals at one phenotypic extreme are favored
Stabilizing selection
Individuals with an intermediate phenotype are favored
Disruptive selection
Individuals at both phenotypic extremes are favored
Heterozygous advantage
When the heterozygous phenotype has a higher fitness than either homozygous dominant or recessive genotypes
Adaptation
A characteristic of an organism that improves its fitness
“Just-so” stories
A story that purports to explain how evolution happens but is just a theoretical explanation lacking evidence
Sexual selection
Selection because of preference by one sex for certain characteristics in individuals of another sex
Mate choice
Intersexual selection
Mate competition
Intrasexual selection
Intrasexual selection
Individuals of the same sex compete with each other to obtain mates
Intersexual selection
Selection of an individual if one sex for mating by an individual of another sex
Sexual dimorphism
Where the sexes of the same species exhibit different characteristics
Bateman-Trivers hypothesis
Variances in matings and reproductive success are greater among the sex with “cheaper” gametes and in greater abundance
