Biology 9th grade quick flashcards

This is for biology test 4

Allele

Different forms of a gene for a trait.

Amino acid

Building block of proteins.

Body (somatic) cell

Any cell in the body except sperm or egg cells.

Centromere

Part of a chromosome where sister chromatids are joined.

Centriole

Organelle that helps organize spindle fibers during cell division.

Chromatin

Uncoiled DNA and protein found in the nucleus.

Codominance

Both alleles show equally in the phenotype (e.g., AB blood type).

Crossing over

Exchange of genetic material between homologous chromosomes during meiosis I.

Diploid (2n)

Cell with two sets of chromosomes (one from each parent).

Dominant

Allele that shows its effect even if only one copy is present.

Equator (metaphase plane)

Middle region of the cell where chromosomes line up during metaphase.

Fertilization

Joining of sperm and egg to form a zygote.

Gamete

Sex cell (sperm or egg) with half the number of chromosomes.

Genotype

The genetic makeup (letters) of an organism.

Haploid (n)

Cell with one set of chromosomes (gametes).

Heterozygous

Having two different alleles for a trait (Tt).

Homologous

Chromosomes that have the same genes in the same order.

Homozygous

Having two identical alleles for a trait (TT or tt).

Incomplete dominance

Blending of traits (e.g., red + white = pink).

Independent assortment

Genes separate randomly during meiosis.

Inheritance

Passing of traits from parents to offspring.

Karyotype

Picture of chromosomes arranged in pairs.

Meiosis

Cell division that produces four haploid sex cells.

Meiosis I

First division where homologous chromosomes separate.

Meiosis II

Second division where sister chromatids separate.

Monohybrid cross

Genetic cross involving one trait.

Nondisjunction

Failure of chromosomes to separate properly during meiosis.

Pedigree

Family tree showing inheritance of a trait.

Phenotype

Physical appearance of a trait.

Polygenic

Trait controlled by many genes (e.g., height, skin color).

Probability

Likelihood that a specific event will occur.

Punnett square

Chart used to predict genetic outcomes.

Recombination

Mixing of genes due to crossing over.

Recessive

Allele that is hidden when a dominant allele is present.

Sex cells (gametes)

Sperm (male) and egg (female) cells.

Sex-linked inheritance

Traits controlled by genes on sex chromosomes.

Sexual reproduction

Reproduction involving two parents; produces variation.

Sister chromatids

Identical copies of a chromosome joined at the centromere.

Spindle fibers

Threads that pull chromosomes apart during cell division.

Zygote

Fertilized egg cell; first cell of a new organism.