Unit 2- Genetic Processes Bio Test Review

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Heredity

Back 1

the passing traits from parents to offspring

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Genetics

Back 2

the branch of biology dealing with heredity and the variation of inherited characteristics

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DNA (deoxyribonucleic acid)

Back 3

-a molecule that carries genetic information in cells

- the set of instruction to make a protein

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Gene

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A segment of a DNA molecule that codes for a particular trait; found at a specific location on a chromosome

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Locus

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the location of a gene on a chromosome

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Polyploid

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Having more than two sets of a chromosome; many plants are polyploids (as opposed to diploid or haploid)

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Asexual reproduction

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the production of offspring from a single parent; the genetic makeup of the offspring is identical to that of the parent

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Sexual reproduction

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the production of offspring from the fusion of two sex cells (usually from two different parents); the genetic makeup of the offspring is different from that of either parent

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Fragmentation

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a method of asexual reproduction in which a piece or body fragment of the parent organism develops into a mature individual

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Mitosis

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the process by which a eukaryotic cell divides the genetic material in its nucleus into two new identical nuclei

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Interphase

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the portion of the cell cycle between mitotic divisions when the genetic material (in the form of chromatin) is duplicated

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Chromatin

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the tangled strands of DNA and protein within a eukaryotic nucleus

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Sister chromatid

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the identical copy of a single chromosome that remains attached to the original chromosome at the centromere

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Cytokinesis

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the process in which a eukaryotic cell divides its cytoplasm into the new daughter cells

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Cloning

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the process of producing one individual that is genetically identical to another, using a single cell or tissue

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Gamete

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a sex cell; includes sperm cells in males, and egg cells in females

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Fertilization

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the formation of a zygote by the joining together, or fusion, of two gametes

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Zygote

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A cell produced by the fusion of two gametes

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Ova

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A female sex cell (egg cells)

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Meoisis

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A two-stage cell division in which the resulting daughter cells have half the number of chromosomes as the parent cell; results in the formation of gametes or spores

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Homologous chromosomes

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matching pairs of chromosomes, similar in size and carrying information for the same genes

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Tetrad

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a pair of homologous chromosomes, each with two sister chromatids

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Synapsis

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the physical pairing up of homologous chromosomes during prophase 1 of meoisis

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Crossing over

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the exchange of chromosome segments between homologous pairs during synapsis

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Gametogenesis

Back 25

the production of gametes (sex cells) in animals

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Spermatogenesis

Back 26

the production of mature sperm cells

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Oogenesis

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the production of mature egg cells

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Karyotype

Back 28

the chromosomes of an individual that have been sorted and arranged according to size and type

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Non-disjunction

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the failure of homologous chromosomes to move to opposite poles of the cell during meiosis; results in an abnormal number of chromosomes in the daughter cell

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trisomy

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A chromosomal abnormality in which there are three homologous chromosomes in place of a homologous pair

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Monosomy

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a chromosomal abnormality in which there is a single chromosome in place of a homologous pair

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Down syndrome

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-trisomy 21

- three copies of chromosome number 21

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maternal inheritance

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a type of inheritance in which a zygote formed from two gametes inherits cytoplasmic DNA from only the female gamete

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paternal inheritance

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a type of inheritance in which a zygote formed from two gametes inherits cytoplasmic DNA from only the male gamete

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trait

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particular version of a characteristics that is inherited, such as hair colour of blood type

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true-breeding organism

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an organism that produces offspring that are genetically identical for one or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits

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Hybrid

Back 37

the offspring of two different true-breeding plants

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cross

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the successful mating of two organisms from distinct genetic lines

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P generation

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the parent plants used in the cross

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F1 generation

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the offspring of a P-generation cross

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F2 generation

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offspring of an F1-generation cross

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Monohybrid

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the offspring of two different true-breeding plants that differ in only one characteristic

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Monohybrid cross

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a cross designed to study the inheritance of only one trait

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Law of segregation

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a scientific law stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only one copy of each gene to their gametes because the genes separate during gamete formation

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Allele

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a specific form of a gene

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Homozygous

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describes an individual that carries two of the same alleles for a given characteristic

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Heterozygous

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describes an individual that carries two different alleles for a given characteristic

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Genotype

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the genetic makeup of an individual

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Phenotype

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an individual's outward appearance with respect to a specific characteristic

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dominant allele

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the allele that, if present, is always expressed

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recessive allele

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the allele that is expressed only if it is not in the presence of the dominant allele, that is, if the individual is homozygous for the recessive allele

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Punnett square

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a diagram that summarizes every possible combination of each allele from each parent; a tool for determining the probability of a single offspring having a particular genotype

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Test cross

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a cross used to determine the genotype of an individual expressing a dominant trait

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Complete dominance

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a situation where an allele will determine the phenotype, regardless of the presence of another allele

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Incomplete dominance

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a situation where neither allele dominates the other and both have an influence on the individual; results in partial expression of both traits

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Codominance

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a situation where both alleles are expressed fully to produce offspring with a third phenotype

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pedigree

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a diagram of an individual's ancestors used in human genetics to analyze the Mendelian inheritance of a certain trait; also used for selective breeding of plants and animals

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Autosomal inheritance

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inheritance of alleles located on autosomal (non-sex) chromosomes

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Sex-linked

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describes an allele that is found on one of the sex chromosomes, X or Y, and when passed on to offspring is expressed

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X-linked

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phenotypic expression of an allele that is found on the X chromosome

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Y-linked

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phenotypic expression of an allele that is found on the Y chromosome

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mutation

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a change in the genetic code of an allele; the change may have a positive effect, a negative effect, or no effect

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dihybrid cross

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a cross that involves two genes, each consisting of heterozygous alleles

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law of independent assortment

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if genes are located on separate chromosomes, they will be inherited independently of one another

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Discontinuous variation

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when the expression of the products of one gene has no bearing on the expression of the products of a second gene

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Continuous variation

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when the product of one gene is affected by the product of another gene, the gene products may be additive, or one product may negate another product

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Additive allele

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an allele that has partial influence on a phenotype

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Nucleotide

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the repeating unit in DNA; it comprises a deoxyribose sugar, a phosphate group, and one of the four nitrogenous bases

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Complementary base pairing

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pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand; adenine pairs with thymine, guanine pairs with cytosine

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Point mutation

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a small-scale change in the nitrogenous base sequence of a DNA; the mutation may be beneficial, harmful, or neutral (having no effect on the organism)

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Chromosome mutation

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an error that involves an entire chromosome or a large part of a chromosome

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Spontaneous mutation

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an error that involves an entire chromosome or a large part of a chromosome

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Induced mutation

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a mutation that occurs because of exposure to an outside factor; second-hand smoke increases the chance of developing lung cancer

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Antibiotic resistance

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describes strains of bacteria that are no longer susceptible to the effects of antibiotics; are sometimes called "superbugs" and are prevalent in hospital settings

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transposon

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a specific segment of DNA that can move along or between the chromosomes

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transposition

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the process of moving a gene sequence from one part of the chromosome to another part of the chromosome

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microarray

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a small membrane or glass slide that has been coated in a predictable and organized manner with a genomic sequence

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human genome

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the sequence of DNA nitrogenous bases found on the 23 sets of chromosomes in humans

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coding DNA

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a region of DNA that contains a sequence of nucleotides that will be expressed; a gene

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non-coding DNA

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a region of DNA that does not count a sequence of nucleotides that will be expressed

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functional genomics

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the study of the relationship between genes and their function

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model organism

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an organism that can be used to study biological functions of another organism, due to its genetic similarity

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restricting enzyme

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a molecule that has the ability to cut DNA at a specific site; different restriction enzymes recognize and cut different sites

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recombinant DNA

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a fragment of DNA consisting of nucleotide sequences from at least two different sources

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kinetochore

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a complex of proteins associated with the centromere of a chromosome during cell division, to which the microtubules of the spindle attach

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frameshift mutation

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a genetic mutation caused by insertion or deletion of a number of nucleotides in a DNA sequence that is not divisible by three

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Epigenesis

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the theory, now generally held, that an embryo develops progressively from an undifferentiated egg cell.

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Pangenesis

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a disproven hypothetical mechanism of heredity in which the cells throw off particles that collect in the reproductive products or in buds so that the egg or bud contains particles from all parts of the parent.

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Filial generation

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a generation in a breeding experiment that is successive to a parental generation—compare f1 generation, f2 generation.