Unit 7 Study Guide Biology 1 Honors

Asexual Reproduction

Reproduction with one parent.

Sexual Reproduction

Reproduction with two parents.

Fertilization

Process where a sperm and egg cell come together.

Zygote

A cell formed when two gametes come together.

Homologous Chromosomes

Pairs of chromosomes that can have different alleles for the same trait.

Sister Chromatids

Identical copies of a chromosome, having the same alleles.

Haploid

A cell containing one set of chromosomes.

Diploid

A cell containing two sets of chromosomes.

Gamete

A reproductive cell; specifically, an egg or sperm cell.

Meiosis

Cell division process to make gametes.

Mitosis

Cell division that produces two identical daughter cells.

Genetic Variation

Differences in DNA among individuals, important for species survival.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis.

Independent Assortment

The random distribution of maternal and paternal chromosomes into gametes.

Nondisjunction

The failure of chromosomes to separate properly during meiosis.

Monosomy

Condition where there is one less chromosome than normal.

Trisomy

Condition where there is one extra chromosome.

Homologous Chromosomes vs Sister Chromatids

Homologous chromosomes have different alleles, sister chromatids are identical.

Gregor Mendel

Famous for the laws of segregation and independent assortment in genetics.

Gene

A piece of DNA with instructions for making specific proteins.

Allele

One of multiple variations of a gene.

Phenotype

The physical characteristics of an organism.

Genotype

The genetic makeup of an organism.

Homozygous

Having two identical alleles for a trait.

Heterozygous

Having two different alleles for a trait.

Dominant Allele

An allele that can mask the effects of another allele.

Recessive Allele

An allele that can be masked by a dominant allele.

Punnett Square

A tool used to predict the probability of an outcome in genetics.

Incomplete Dominance

A blending of traits, such as red and white flowers producing pink.

Codominance

Both alleles are equally expressed, like AB blood type.

Multiple Alleles

A gene with three or more alleles, such as the ABO blood group.

Polygenic Trait

Traits determined by two or more genes, like eye color.

Autosomes

Chromosomes numbered 1-22 in humans that do not determine sex.

Sex Chromosomes

Chromosomes that determine an individual's sex (XX or XY).

Sex-Linked Trait

Characteristic determined by genes on sex chromosomes.

Sex-Linked Traits in Males

More common as males have only one X chromosome.

Karyotype

A picture of an individual's chromosomes used for diagnosis.

Gamete Formation

Involves meiosis to create haploid cells for fertilization.

Advantages of Asexual Reproduction

Only needs one parent and can be quicker.

Disadvantages of Sexual Reproduction

Requires two parents and can be slower.

Advantages of Sexual Reproduction

Creates genetic variation among offspring.

Disadvantages of Asexual Reproduction

No variation can lead to vulnerability to disease.

Meiosis I

first division in meiosis where homologous chromosomes separate, resulting in two diploid cells

Meiosis II

second division in meiosis where sister chromatids separate, resulting in four haploid cells