Unit 5: Genetics Vocab
DNA
A giant molecule consisting of the sugar deoxyribose, phosphates and nitrogen bases; contains the coded genetic information
Punette Square
A grid system used to predict possible combinations of genes due to random fertilization
Pure-bred
A phenotype (trait) resulting from homozygous genes from the offspring of true breeding
Gene
A portion of DNA which codes a specific hereditary trait
Hypothesis
A proposed explanation for an observation which has not been experimentally tested
Gamete
A reproductive cell produced by the male or female parent, which contains the haploid number of chromosomes
X Chromosome
A sex chromosome; in human males only one is present and in females two are present
Centromere
A structure on the chromosome that holds a pair of chromatids together during replication
Meiosis
A type of cell division used to produce gametes and there is a reduction in the chromosome number from the diploid to the haploid number
Gene Pool
All of the genes present in a specific population
Law
An explanation for events which is supported by the results on many experiments by a large number of investigations
Rh factor
An inherited protein found on the surface of the red blood cell membrane
Mutation
A change in the genetic information code
Y Chromosome
A sex chromosome found in males; influencing the degree of maleness
Diploid
Both members of a pair of chromosomes are present
F1 Generation
First filial generation; the first generation from a given class
Cotyledon
First leaf or leaves produced from the seed
Sex-linked
Genes that are located in the sex chromosome
Gene Frequency
How the common gene is in the population
Oogenesis
Process of development of haploid female gametes.
Turner's Syndrome
(XO) An abnormality in females where on of the sex chromosomes is missing leaving a total of 45 chromosomes; produced by nondisjunction
Klinefelter's Syndrome
(XXY) An abnormality affecting males where there is an extra X chromosome due to nondisjunction
If you have two coins, the probability of both coming up heads from a flip of each is_____ .
25
Deoxyribose
A five-carbon sugar
Tetrad
During metaphase I the two pairs of chromatids of the homologous pair of chromosomes come together; crossing over can occur at this time
Tetrad
During metaphase I the two pairs of chromatids of the homologous pair of chromosomes comes together; crossing-over can occur at this time.
Nondisjunction
Failure of chromosomes to segregate during the formation of gametes, resulting in extra or a shortage of chromosomes in the gamete
Dominant
In a pair of genes, one may prevent the allele from being expressed
Principle of Segregation
Members of a gene pair separate during meiosis and are found in separate gametes
Pedigree
The ancestral history of an individual; a chart showing the history of a trait in the family
Chromosome Theory
The behavior of chromosomes explains the inheritance of genes
Pollination
Transfer of pollen, male gamete, in plants to the stigma which contains the female gamete
The calculation of probabilities is based on ______events.
random
Probabilities are expressed as a number between 0 and 1
true
Trait
A genetic characteristic of the idividual
Down's Syndrome
A genetic disorder caused by the presence of a third copy of chromosome 21
DNA
A giant molecule consisting of sugar deoxyribose, phosphates and nitrogen bases; contain the coded genetic information
Allele
Alternative forms for a specific gene (either dominant or recessive)
Sickle-Cell Anemia
An hereditary form of anemia
Incomplete Dominance
The blending of two traits in a heterozygous individual
Test Cross
The breeding of an individual which possesses the dominant trait to a homozygous recessive for that trait
Genotype
The genes present in an organism
One-gene-one-enzyme concept
The genetic code of the gene is responsible for the production of a specific enzyme, which regulates the metabolic pathways in the cell during meiosis; the combination of chromosomes in a gamete is due to chance.
Self-Fertilization
The organism, which possesses both male and female gametes, brings the two genetically identical gametes together to produce offspring
Using the group of cards just described in this section, the probability of drawing a red five is:_____ . (four colors, 1-14 of each)
1/56
The probability of a yellow-seed plant (YY) forming a Y gamete is_____ % because the principle of segregation - one_____ of each gene pair goes to a____ ; it only has "Y" alleles.
100,
The second generation phenotypes resulting from the cross of true-breeding monohybrid pollination will display a ratio of:
3:1
The probability of having the combination of one head and one tail when flipping two coins is_____ .
50
If you have a heterozygous yellow-seed plant (Yy), the probability of forming a "Y" gamete is _____. The probability of forming a "y" gamete is _____. This follows the principle of segregation.
50 ,50
When flipping a coin, the chance that it will come up a head is_____ . If you flip the coin a second time, the chance that it will come up a head again is_____ . Let us say that you have had 25 heads come up in 25 consecutive flips. If you flip the coin one more time, the chance of coming up with a head is_____
50, 50, 50
Chromosome
A "thread-like" molecule in the nucleus, composed of DNA. A chromosome possesses one allele for a given trait, therefore chromosomes occur in pairs. Each originates from the male and female gamete (parent)
Crossing Over
A condition where non-sister chromatid of homologous chromosomes exchange genes
Chromatid
A double-stranded chromosome following replication attached by a centromere
Holandric Gene
A gene located on the Y chromosome in XY species
Recessive
A gene or trait which is masked when a dominant allele is present
Hemophelia
A hereditary condition for bleeding due to the inability to clot properly
Guanine
A nitrogen base found in DNA and RNA; normally pairs with cytosine
Cytosine
A nitrogen base found in DNA and RNA; pairs normally with guanine
Thymine
A nitrogen base found in DNA; normally pairs with adenine.
Adenine
A nitrogen base occurring in DNA and RNA; pairs normally with thymine
RNA
A nucleic acid similar to DNA using ribose for the sugar and the nitrogen base uracil in place of thymine.
Spindle Fibers
A number of threadlike filaments formed between poles of the cell during cell division to which the centromeres of chromosomes attach; used to pull chromosomes apart and segregate them during anaphase.
Hybrid
An offspring from a cross between parents which has different phenotypes for a specific trait
Autosome
Any pair of chromosomes other than the sex chromosome
Dihybrid Cross
Breeding of individuals which have two genes for two different characteristics
Haploid
One member of a pair of homologous chromosomes is present, such as in a gamete
Sex-Chromosomes
One of the chromosomes which determine the sex of the individual
Nitrogen Base
One of the three major types of chemicals making up a nucleotide in DNA; either guanine, cytosine, adenine, or thymine; the sequence of three codes for an amino acid
Polar Body
One of three small cells produced during oogenesis, each contain the haploid number of chromosomes.
Heterozygous
Refers to a pair of genes from a specific trait in an organism which are different
Homozygous
Refers to a pair of genes in an organism which are identical in the way they influence a trait
F2 Generation
Second Filial generation; the second generation resulting from interbreeding or fertilization from other F1 members
Monohybrid Cross
The breeding of two organisms which differ in a single trait
Probability
The chance that a given event will occur usually expressed between the number 0 (will not occur) and 1 (the event will occur)
Nucleotide
The combination of phosphate, sugar and nitrogen bases in DNA or RNA; the combination of
Codominance
The condition in heterozygotes where both members of an allelic pair contribute to phenotype producing a mixture of phenotypic traits
Theory
The form of the hypothesis after it has been tested and found to be supported by the data collected as the explanation for the observation
Sickel-Cell Trait
The heterozygous condition which is generally phenotypically indistinguishable for normal person; in conditions of low oxygen some cells sickle. An example of incomplete dominance and environmental influence on gene expression.
Phenotype
The outward appearance of the organism which is the product of gene action
P1 Generation
The parental generation for a given cross
Linkage
The presence of different genes on the same chromosome
True-Breeding
The process of crossing two organisms, both having homozygous genes for the same trait
Spermatogenesis
The production of haploid male gametes by the male parent.
Prophase I
The stage in the first meiotic division where the doubled chromosomes become visible and nuclear membrane disappears.
Metaphase I
The stage in the first meiotic division where the homologous chromosomes line up as a pair, forming a tetrad of chromatids, at the equator of the cell
Metaphase II
The stage in the second meiotic division where the chromatid pair lines up at the equator of the cell..
Anaphase II
The stage in the second meiotic division where the sister chromatids of a chromosome split and migrate to opposite poles
Telophase I
The stage of the first meiotic division where the cell divides into two cells each containing one member of each pair of homologous chromosomes.
Telophase II
The stage of the second meiotic division when the cell divides into two cells with each being haploid; these cells become the gametes.
Anaphase I
The stage on the first meiotic division when the homologous chromosomes move to opposite poles but the sister chromatids remain together
Population Genetics
The study of a hereditary trait in a large population
Deviation
Variation from the predicted values
Multiple Alleles
Where more than two alternatives for a gene exist
Genetics experiments on the breeding of plants or animals are based on the laws of_____ .
probability
The probability of two independent events occurring together is the_____ of the probability of each event occurring separately.
product
