Genetics Test #2 Review for Mississippi State University

Hemizygous

Having one allele of a given gene.

Pedigree Analysis

Squares represent males; circles represent females.

Temperature Dependent Sex Determination

Temperature influences sex of developing eggs.

Autosomal Recessive Trait

Trait expressed only when homozygous recessive.

Zygotene Stage

Homologous chromosomes pair during Prophase I.

Mitochondrial Inheritance

Mitochondria inherited from mother only.

DNA Packaging Steps

Nucleosome, solenoid, loop, rosette, coil, chromatid.

Probability of Offspring Traits

Calculate using Punnett squares and multiplication.

Mitosis Phase for DNA Replication

DNA is replicated during Interphase S phase.

Equational Division

Type of division occurring during Mitosis.

Endosperm and Zygote

Mature seed has 3n endosperm, 2n zygote.

Types of Chromosomes

Autosomes and sex chromosomes are two types.

Normal Human Genotype

Male: XY, Female: XX.

Mass of DNA After Interphase

DNA mass doubles to 4.0 x 10^5 µg.

Genotypic Ratio

Ratio of offspring genotypes from crosses.

Prophase I Steps

Leptotene, zygotene, pachytene, diplotene, diakinesis.

Probability of Chick Traits

Calculate using combinations of offspring traits.

Cross-over Events

Occur between non-sister chromatids during meiosis.

Meiosis Division Types

Reductional in Meiosis I, equational in Meiosis II.

Oogenesis Progression

Oogonium -> primary oocyte -> secondary oocyte -> ovum.

First Meiotic Division

Occurs from secondary oocyte to ovum.

Polar Body Formation

First polar body with primary oocyte; second with secondary oocyte.

Mitosis vs. Meiosis

Mitosis is equational; meiosis is reductional.

Parthenogenesis Example

Beltsville small white turkeys and honey bees.

Drosophila Melanogaster Female

A = 3 autosomes.

X Chromosome Ratio Model

Determines sex based on X chromosome count.

Autosomes

Non-sex chromosomes in an organism.

Mary Lyon Hypothesis

X chromosome inactivation in female mammals.

Aneuploid

Abnormal number of chromosomes in a cell.

Drosophila Melanogaster

Model organism for genetic studies.

Intersex

Organism with both male and female characteristics.

Metamale

Male with an excess of X chromosomes.

Holandric Trait

Trait linked to Y chromosome only.

Spermatogenesis

Process of sperm cell development.

Barr Body

Inactivated X chromosome in female cells.

Calico Cats

Typically female cats with multicolored fur.

Sex-influenced Traits

Traits expressed differently in males and females.

Reciprocal Cross

Crosses between different sexes to study inheritance.

Bivalents

Paired homologous chromosomes during meiosis.

Megaspore

Haploid spore that develops into female gametophyte.

Diploid Microspore Mother Cell

Cell that undergoes meiosis to form pollen.

Chromosomal Count in Humans

Humans have 23 pairs of chromosomes.

X Chromosome Size

X chromosome is larger than Y chromosome.

Probability in Genetics

Likelihood of specific offspring combinations.

Sex-linked Traits

Traits associated with genes on sex chromosomes.

Spermatogonium

Diploid cell that produces sperm cells.

Secondary Spermatocyte

Haploid cell formed after first meiotic division.

Primary Spermatocyte

Diploid cell undergoing meiosis to form sperm.

Fertile Male

Male capable of producing viable offspring.

Infertile Male

Male unable to produce viable offspring.

Egg

Female gamete produced in ovary.

Fertility Ratio

Proportion of fertile offspring from a cross.