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