Mutations + Meiosis Vocab

Cellular Error

Incorrect synthesis of strands during DNA replication or transcription

Metabolism

Build of up of toxic byproducts in cells (like oxygen!), which reacts with the nucleic acids

External Causes

UV radiation, carcinogens, and certain preservatives

Viruses

Certain viruses inject their own nucleic acids into host DNA

Point Mutations

one nucleotide is replaced with another, maintaining the length of the mRNA strand

Silent Point Mutations

usually occurs in the 3rd position of the codon (wobble position). Does not impact the identity of the amino acid

Missense Point Mutations

changes the identity of the amino acid

Nonsense Point Mutations

changes the codon to a stop codon

Frameshift Mutation

one nucleotide is added or removed, changing the length of the mRNA strand

Insertion

a nucleotide is added into the mRNA sequence, creating new codons

Deletion

a nucleotide is removed, creating the new

Meiosis

a type of cell division that reduces the chromosome number by half and produces genetically diverse sex cells.

Reductive division

a form of cell division in which the daughter cells have fewer chromosomes than the parent cell.

Gametes

sex cells produced through meiosis; in animals these are sperm and eggs, in plants pollen, and in fungi spores.

Diploid (2n)

a cell containing two copies of each chromosome, one inherited from each parent; humans have 46 chromosomes arranged in 23 pairs.

Haploid (n)

a cell containing one copy of each chromosome; human gametes have 23 chromosomes.

Zygote

a diploid cell formed when two haploid gametes fuse during fertilization

Homologous chromosomes

pairs of chromosomes with the same genes but possibly different versions of those genes, one from each parent

Sister chromatids

identical copies of a chromosome joined at the centromere after DNA replication

Tetrad

a structure formed during prophase I when homologous chromosomes pair up, consisting of four chromatids

Genetic variation

differences in DNA among individuals of the same species, providing an evolutionary advantage

Crossing over

the exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I

Recombinant chromosomes

chromosomes containing a mixture of genetic material from both parents due to crossing over

Independent assortment

the random alignment of homologous chromosome pairs during metaphase I, leading to genetically unique gametes

Nondisjunction

the failure of chromosomes to separate properly during meiosis, resulting in abnormal chromosome numbers

Trisomy

a condition in which a cell has three copies of a specific chromosome

Monosomy

a condition in which a cell has only one copy of a specific chromosome

Down syndrome

a non-fatal genetic condition caused by trisomy 21

Klinefelter syndrome (XXY)

a genetic condition caused by an extra X chromosome in individuals typically assigned male at birth

Turner syndrome (Monosomy X)

a genetic condition caused by having only one X chromosome

S phase

the stage of the cell cycle during which DNA is replicated

Prophase

the stage of cell division in which chromatin condenses into chromosomes and the nuclear membrane breaks down

Metaphase

the stage in which chromosomes line up at the metaphase plate.

Anaphase

the stage in which chromosomes or chromatids are pulled to opposite poles of the cell

Telophase

the stage in which chromosomes decondense and nuclear membranes reform

Cytokinesis

the division of the cytoplasm that creates separate daughter cells

Meiosis I

the first division of meiosis in which homologous chromosomes separate, reducing the cell from diploid to haploid

Meiosis II

the second division of meiosis in which sister chromatids separate, producing four genetically unique haploid cells

Mitosis

a type of cell division that produces two genetically identical diploid daughter cells used for growth and repair