Bio exam 4

Meiosis

A type of cell division that produces gametes with half the number of chromosomes.

Diploid

A cell or organism with two complete sets of chromosomes, one from each parent (2n).

Haploid

A cell with half the number of chromosomes, typical of gametes (n).

Germ cells

Specialized cells that undergo meiosis to produce gametes, such as sperm and eggs.

Somatic cells

All non-reproductive cells in an organism that divide by mitosis.

Homologous chromosomes

Chromosome pairs from each parent that are similar in shape, size, and genetic content.

Sister chromatids

Identical copies of a chromosome that are connected by a centromere.

Crossing over

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Chiasmata

The points where homologous chromosomes exchange genetic material during crossing over.

Independent assortment

The random distribution of homologous chromosome pairs during metaphase I of meiosis.

Aneuploid gametes

Gametes that have an abnormal number of chromosomes due to nondisjunction.

Turner’s Syndrome

A condition where a female has only one X chromosome, leading to underdeveloped female characteristics.

Down syndrome

A genetic disorder caused by the presence of an extra copy of chromosome 21 (trisomy 21).

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate during meiosis.

Meiosis I

The first stage of meiosis, characterized by the separation of homologous chromosomes.

Meiosis II

The second stage of meiosis, where sister chromatids separate into individual chromosomes.

Gametes

Reproductive cells (sperm and eggs) produced through meiosis.

Nuclear envelope

The membrane that surrounds the nucleus, which re-forms during telophase of meiosis.

Trisomy 21

An extra copy of chromosome 21 leading to Down syndrome.

Klinefelter Syndrome

A genetic condition in males caused by an extra X chromosome, leading to infertility.

Meiosis vs. Mitosis

Meiosis results in four non-identical haploid cells and includes synapsis and crossing over; mitosis produces two identical diploid cells.

Patterns of Inheritance

The ways traits are passed from parents to offspring, including dominant, recessive, codominant, and incomplete dominance patterns.

Dominant allele

An allele that masks the effect of a recessive allele in heterozygous individuals.

Recessive allele

An allele that is only expressed in a homozygous condition and is masked by a dominant allele.

Codominance

A form of inheritance in which both alleles in a heterozygote are fully expressed.

Incomplete dominance

A pattern of inheritance where the phenotype of a heterozygote is intermediate between the phenotypes of the homozygotes.

Transcription

The process by which the information in DNA is copied into messenger RNA (mRNA).

RNA polymerase

The enzyme responsible for synthesizing RNA from a DNA template during transcription.

mRNA

Messenger RNA that conveys genetic information from DNA to the ribosome for protein synthesis.

Translation

The process of synthesizing proteins from the mRNA sequence, occurring at ribosomes.

Ribosomes

Cellular structures that facilitate the translation of mRNA into proteins.

tRNA (transfer RNA)

Molecules that transport amino acids to the ribosome during translation, according to the codon sequence in mRNA.

Codon

A sequence of three nucleotides in mRNA that specifies a particular amino acid.

Anticodon

A sequence of three nucleotides in tRNA that pairs with the corresponding codon in mRNA.

Genotype

The genetic constitution of an individual, encompassing all alleles inherited from both parents.

Phenotype

The observable characteristics or traits of an individual resulting from the interaction of its genotype with the environment.