Meiosis and Genetics Vocabulary Flashcards

Vocabulary flashcards covering meiosis, inheritance, and genome concepts from the lecture.

haploid

A cell with one set of chromosomes (n); in humans, 23 total. Gametes are haploid.

diploid

A cell with two sets of chromosomes (2n); in humans, 46 total (23 pairs) in somatic cells.

gamete

A haploid reproductive cell (sperm or egg) produced by meiosis that fuses with another gamete during fertilization.

zygote

The diploid cell formed when two haploid gametes fuse; the first stage of a new organism.

meiosis

Cell division that reduces chromosome number from diploid to haploid, producing gametes; includes meiosis I and meiosis II.

meiosis I

First division of meiosis; separates homologous chromosomes, reducing chromosome number and producing two haploid cells.

meiosis II

Second division of meiosis; separates sister chromatids in each haploid cell to form four haploid gametes.

prophase I

Meiosis stage where chromosomes condense, homologous chromosomes pair (synapsis), and crossing over occurs.

synapsis

Pairing of homologous chromosomes during prophase I to facilitate crossing over.

crossing over

Exchange of genetic material between non-sister chromatids of homologous chromosomes, increasing genetic diversity.

independent assortment

Random orientation of homologous chromosome pairs during metaphase I, creating diverse gametes.

tetrad

Structure formed when paired homologous chromosomes align during prophase I (two chromosomes, four chromatids).

sister chromatid

Two identical copies of a chromosome connected at the centromere until they are separated in cell division.

homologous chromosomes

Pairs of chromosomes of the same type, one from each parent, containing the same genes in the same order.

allele

A variant form of a gene; can be dominant or recessive.

genotype

The allele combination for a gene (e.g., AA, Aa, aa) present in an individual.

phenotype

The observable traits or characteristics resulting from the genotype and environment.

homozygous

Two identical alleles for a gene (e.g., AA or aa).

heterozygous

Two different alleles for a gene (e.g., Aa).

dominant

Allele that masks the presence of a recessive allele in a heterozygote; usually represented with uppercase letters.

recessive

Allele that is masked by a dominant allele in a heterozygote; needs two copies to express in classic dominance.

codominance

Both alleles are fully expressed in the phenotype (e.g., AB blood type shows both A and B antigens).

incomplete dominance

Heterozygote shows an intermediate phenotype between the two alleles (e.g., red x white -> pink flowers).

polygenic inheritance

Traits controlled by more than one gene, often producing a spectrum of phenotypes.

Punnett square

A grid used to predict offspring genotypes and phenotype probabilities from parental genotypes.

ABO blood type alleles

I^A, I^B, and i; I^A and I^B are codominant; i is recessive; combinations determine blood type (A, B, AB, O).

karyotype

A visual arrangement of an individual's chromosomes used to assess number and structure.

germline cells

Cells that give rise to gametes and undergo meiosis to produce haploid gametes.

oogenesis

Meiosis-based production of female gametes (ova/eggs).

spermatogenesis

Meiosis-based production of male gametes (sperm).

Down syndrome

Trisomy 21; three copies of chromosome 21; the most common viable chromosomal abnormality.

Turner syndrome

Monosomy X (only one X chromosome in a female); typically leads to nonfunctional ovaries and infertility.

Klinefelter syndrome

XXY male genotype; extra X chromosome; often infertile and may have reduced secondary male characteristics.

sex-linked inheritance

Traits encoded on the X chromosome; often more common in males due to having only one X chromosome.

genome

The complete set of genetic material in an organism or cell.

epigenetics

The study of heritable changes in gene expression not caused by changes in DNA sequence; involves epigenome modifications.