Unit 1 of Genetics: Genetic Inheritance

Genes

A segment of DNA that codes for a protein (ie: the gene for eye color)

Character

A heritable feature (ie: flower color)

Variant

A different form of a gene or trait (ie: blue vs brown eyes)

Allele

Different versions of a gene (ie: A or a for seed color)

Trait

An observable characteristic (ie: tall plant)

Polypeptide

A chain of amino acids (ie: insulin chain)

Protein

Folded polypeptide(s) with a function (ie: hemoglobin)

Transcription

Making RNA from DNA (ie: mRNA for insulin)

Translation

Making protein from mRNA (ie: ribosome builds insulin)

Histones

Proteins DNA wraps around (ie: H1, H2A)

Nucleosomes

DNA and histone bundle; beads on a string

Chromatin

DNA and proteins in the relaxed form (ie: interphase DNA)

Centromere

Region joining sister chromatids (ie: constriction in X-shaped chromosome)

Karyotype

Chromosome picture of an organism (ie: human 46, XX)

Chromosome

DNA molecule with genes (Ie: chromosome 21)

Chromatids

Identical DNA copies in the duplicated chromosome (ie sister in mitosis)

Sister Chromatids

Two identical copies joined at centromere

Duplicated Chromosomes

A chromosome with two sister chromatids

Homologous Chromosomes

Pair of chromosomes (one from each parent). (ie: chromosome 1 from mom and dad)

Homologs

Another term for Homologus Chromosomes

Autosomes

Non-sex chromosomes (ie: 1-22 in humans)

Sex Chromosomes

Chromosomes that determine sex (ie: X and Y)

Monad

single chromosome (unduplicated)

Dyad

A duplicated chromosome (2 chromatids)

Tetrad

4 chromatids from homologous pair in meiosis

Haploid (n)

One set of chromosomes (ie: sperm and egg)

Diploid (2n)

Two sets of chromosomes (ie: human somatic cells)

Aneuploid

Wrong number of chromosomes (ie: Down Syndrome-Trisomy 21)

Euploid

Correct number of chromosomes (ie: humans have 46)

Polyploid

More than 2 full sets (ie: triploid seedless watermelon)

Tetraploid

4 sets of chromosomes (ie in some plants)

Nondisjunction

chromosomes fail to separate (ie trisomy 21)

Meiosis

division of making gametes (n)

Mitosis

division of making identical cells (2n)

Meiosis I

Homologs separate

Meiosis II

Sister chromatids separate

Somatic Cells

Body cells (not sex) (ie: skin cell)

Gametes

Sex cells (haploid only) (ie: sperm and egg)

Sex Cells

Same as gametes

Genotype

Genetic makeup (ie: Aa)

Phenotype

Physical trait (ie: purple flowers)

Homozygous

Same alleles (ie: AA or aa)

Heterozygous

Different alleles (ie: Aa)

Dominant

Allele shows when present (ie: A for purple; AA is purples as is Aa)

Recessive

Hidden unless both alleles are present (ie aa for white flowers)

Law of Segregation

Allele pairs separate in gamete formation

Independent Assortment

chromosomes sort randomly during meiosis

Crossing Over

exchange of DNA between homologs in meiosis I

Prophase I

homologs pair and crossing over occurs

Metaphase I

homologous pairs align at equator of cell

Myoglobin

1 chain protein

Hemoglobin

4 chain protein

Antibody

4 chain protein, where 2 are heavy and the other two are light

Duplication

extra gene segment

Deletion

missing gene segment

Inversion

segment is flipped

Translocation

segment moves to another chromosome

Insertion

extra DNA added

Derivative Chromosome

the chromosome is structurally rearranged