Chapter 9 (Study Guide)

Front 1

Gametes

Back 1

A sex cell, a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zigote.

Front 2

Fertilization

Back 2

The union of the nucleus of a sperm cell w/ the nucleus of an egg cell, producing a zigote.

Front 3

Zigote

Back 3

The diploid fertilized egg, which results from the union of a sperm cell nucleus and an egg cell nucleus.

Front 4

Tetrad

Back 4

A pair set of homologous c’somes, each composed of 2 sister chromatids. Tetrads form during the prophase 1 of meiosis, when crossing over may occur

Front 5

Crossing Over

Back 5

The exchange of segments of between chromatids from homologous c’somes during synapsis in prophase 1 of meiosis; also the exchange of segments between of DNA molecules in prokariotes.

Front 6

Independent Assortment

Back 6

The process of random segregation and assortment of chromosomes during anaphase I of meiosis resulting in the production of genetically unique gametes.

Front 7

Genetics

Back 7

The scientific study of heredity. Modern genetics began w/ the work of Gregor Mendel in the 19th century.

Front 8

Alleles

Back 8

Its a version of a gene. Each diploid has two versions(alleles) of a gene

Front 9

Homozygous

Back 9

It's an organism that has 2 identical alleles for a gene.

Front 10

Heterozygous

Back 10

An organism that has 2 different alleles for a gene.

Front 11

Trait

Back 11

A variant of a character found in a population such as purple or white flowers in pea plants

Front 12

Gene

Back 12

A selection of DNA that codes for a protein. "A recipe"

Front 13

Phenotype

Back 13

Describes an organism’s physical trait.
(e.g purple or white flowers)

Front 14

Genotype

Back 14

Describes an organism’s genetic make up. (eg PP, Pp, RR ,Rr).

Front 15

Punnet Square

Back 15

A diagram used in the study of inheritance to show the result of random fertilization.

Front 16

Dominant vs Recessive

Back 16

The DOMINANT allele determines an organism’s appearance, while the RECESSIVE has no noticeable effect on the organism’s appearance.

Front 17

Codominant

Back 17

Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles. (expression of both alleles)

Front 18

Incomplete Dominance

Back 18

A type of inheritance in which the phenotype of a heterozygote (Aa) is intermediate between the phenotypes of the two types of homozygotes (AA) & (aa)

Front 19

Polygenic Inheritance

Back 19

The additive effects of two or more gene loci on a single phenotypic characteristics. (skin color)

Front 20

Pleitropy

Back 20

The control of more than one phenotypic characteristics by a single gene. (e.g Albanism)

Front 21

Sex Linked Trait

Back 21

A trait genetically determined by an allele located on the sex c’some. (e.g Color blindness is a sex-linked trait whose alleles are recessive and are located on the X c’some.

Front 22

Autosome

Back 22

A c’some not directly involved in determinig the sex of an organism ( in mammals for example, other c’some other than X & Y).

Front 23

Trisomy

Back 23

3 of a set of c’somes (2n+1) It causes down syndrome

Front 24

Nondisjunction

Back 24

An accident of meiosis or mitosis in which a pair of homologous c’somes or a pair of sister chromatids fail to separate at anaphase.

Front 25

Chromosomal Deletion

Back 25

A deletion occurs a piece of a c’some breaks and some genetic material is lost. It can be large or small, and occur anywhere.

Front 26

Karyotype

Back 26

A display of micrographs of the metaphase c’somes of a ccell., arranged by size and centromere position. Karyotypes may be used to identify certain chromosomal abnormalities.

Front 27

Amniocentesis

Back 27

A technique for diagnosing genetics defects while a fetus is in the uterus.