BSC 2011 Exam 3 Vocab

Sexual Reproduction

The process in which each parents passes one set of genes to offspring via haploid gametes

Gametogenesis

The process of making gametes from diploid starting cells (spermatocytes or oocytes)

Sister Chromatids

The two identical DNA copies formed after S-phase (joined at centromere), separate during anaphase II

Homologous chromosomes

Consists of two chromosomes (1 from each parent) with the same genes but different versions (alleles)

Independent assortment

The random orientation of homologous pairs during Metaphase I. Produces many possible gamete combos

Crossing Over

When chromatids of homologous chromosomes break and rejoin, exchanging segments and producing recombinant chromatids. Occurs during Prophase I.

Chiasma

The physical point where chromatids of homologous chromosomes cross during Prophase I

Meiosis

Cell division that creates haploid gametes from diploid cells: mixes up genes (genetic variation), separates homologous pairs (reduce chromosome number)

Prophase I

Homologous chromosomes pair; Crossing over occurs; chiasmata form

Metaphase I

Homologous pairs line up; independent assortment occurs

Anaphase I

Homologous chromosomes (not sister chromatids) separate

Telophase I / Cytokinesis

Two haploid cells form

Blending Inheritence

An early and incorrect theory that offspring traits are intermediate blends of parent traits

Discrete Inheritence

Mendel’s correct explanation that traits are determined by separate, particulate factors (genes) that do not blend and are passed intact from each parent

Traits

Physical characteristics of an organism that can be compared across parents and offspring (eg. pea color)

True-breeding

A line of organisms that, when crossed with others of the same line, always produce offspring that look like the parents

Hybrid

An offspring produced by crossing two different true-breeding lines

Cross

A controlled mating between two selected parents to observe inheritance patterns

Parent (P) Generation

The original true-breeding parents used in the first cross

First filial (F1) Generation

The offspring produced from crossing the P generation (hybrids)

Second filial (F2) Generation

The offspring produced by crossing members of the f1 generation