BIO Exam #3 Mitosis & Meiosis Terminology

This set of flashcards covers key vocabulary and concepts related to mitosis, meiosis, transcription, and translation as described in the provided lecture notes.

Chromatid

One half of a duplicated chromosome; sister chromatids are identical copies.

Centromere

The region of a chromosome where sister chromatids are joined and spindle fibers attach.

Spindle fibers

Microtubules that help separate chromosomes during mitosis and meiosis.

Homologous chromosomes

Pairs of chromosomes, one from each parent, that are similar in size and gene content.

Crossing over / recombination

Exchange of genetic material between homologous chromosomes during prophase I of meiosis.

Synapsis

The pairing of homologous chromosomes during prophase I.

Diploid (2n)

A cell with two sets of chromosomes (e.g., body cells in humans have 46 chromosomes).

Haploid (n)

A cell with one set of chromosomes (e.g., gametes in humans have 23 chromosomes).

Independent assortment

The random distribution of homologous chromosomes during metaphase I of Meiosis.

Cytokinesis

The division of the cytoplasm, resulting in two daughter cells.

Interphase

The cell growth phase where DNA is replicated (includes G1, S, and G2 phases).

Prophase

Stage of mitosis where chromosomes condense, spindle forms, and the nuclear envelope breaks down.

Metaphase

Stage of mitosis where chromosomes align at the cell equator.

Anaphase

Stage of mitosis where chromatids are pulled to opposite poles.

Telophase

Stage of mitosis where nuclear membranes reform and chromosomes decondense.

Gametes

Reproductive cells (sperm or egg) formed via meiosis, each haploid.

Nondisjunction

Failure of chromosomes to separate properly; can lead to genetic disorders.

Mitosis vs Meiosis

Mitosis produces identical diploid cells for growth and repair; Meiosis produces genetically diverse haploid gametes.

Okazaki fragments

Short sequences of DNA synthesized discontinuously on the lagging strand during DNA replication.

RNA polymerase

The enzyme that synthesizes RNA from a DNA template during transcription.

Promoter / TATA box

A DNA sequence where RNA polymerase binds to initiate transcription.

mRNA (messenger RNA)

Carries genetic instructions from DNA in the nucleus to ribosomes for protein synthesis.

tRNA (transfer RNA)

Transfers specific amino acids to the ribosome, matching mRNA codons with its anticodon.

Splicing / Exons / Introns

Splicing is the removal of introns and joining of exons in pre-mRNA; exons are coding regions.

5’ cap / Poly-A tail

5’ cap is added for stability; Poly-A tail prevents degradation.

Operon (lac operon)

A unit of gene expression in prokaryotes that includes a promoter, operator, and genes.

Repressor / Inducer

Repressor is a protein that prevents transcription; Inducer inactivates the repressor, allowing transcription.

Enhancer / Silencer

Enhancer increases gene transcription; Silencer represses gene transcription.

Epigenetics

Heritable changes in gene expression without changes to the DNA sequence, such as DNA methylation.

Chromatin (euchromatin vs. heterochromatin)

Euchromatin is loosely packed and transcriptionally active; Heterochromatin is densely packed and inactive.

Ribosome (large and small subunits)

A complex made of RNA and proteins facilitating translation.