Cell Biology: Translation, Cell Division, Genetics, and Cancer

Comprehensive vocabulary flashcards covering translation, ploidy, meiosis stages, mitosis, the cell cycle, checkpoints, cancer biology, and genetics from lecture notes.

Codon

A sequence of $3$ nucleotides on mRNA that corresponds to a specific amino acid monomer during translation.

Translocation

The step in translation where the ribosome moves along the mRNA, reading one codon at a time and shifting everything over so tRNA can enter.

Transgenic Organism

An individual organism that contains DNA and genes from two or more different species.

Pharming

The process of using genetically modified animals to produce pharmaceutical drugs.

Somatic Cells

Body cells containing homologous pairs of chromosomes ($2n$).

Gamete Cells

Sperm or egg cells used exclusively for sexual reproduction, carrying half of each homologous pair of chromosomes.

Homologous Pair of Chromosomes

Two pieces of DNA that carry genes for the same trait, with one chromosome inherited from the mother and one from the father.

Karyotype

A picture of an individual's chromosomes used to identify homologous pairs and determine sex.

Ploidy

The number of individual pieces of DNA present for each chromosome position.

Diploid

A cell condition characterized by having homologous pairs of chromosomes, representing $2$ pieces of DNA for each chromosome position (symbolized as $2n$).

Haploid

A cell condition characterized by having half of each homologous pair of chromosomes, representing $1$ piece of DNA for each position (symbolized as $1n$ or $n$).

Tetrad

A structure composed of $4$ pieces of DNA, formed by a copied homologous pair of chromosomes with two sister chromatids held very close together.

Crossing Over

The swapping of genes between homologous pairs of chromosomes that occurs exclusively when DNA is in tetrad form, generating genetic variation.

Dyad

A sister chromatid pair comprising $2$ pieces of DNA held together by a centromere, which may have swapped genes during crossing over.

Interkinesis

An intermission-like resting stage between meiosis 1 and meiosis 2 during which the cell builds more energy for the second round of division.

Anaphase 1

The stage of meiosis 1 where microtubules tear homologous tetrads apart into dyads and move them to opposite sides of the cell.

Anaphase 2

The stage of meiosis 2 where microtubules tear dyads apart into individual chromosomes in the cytoplasm.

Telophase 2

The stage of meiosis 2 where new nuclei form around individual chromosomes followed by cytokinesis, yielding $4$ non-genetically identical haploid cells.

Chromatin

The loose, uncondensed form of DNA that appears grainy under a microscope and has a smooth-edged nuclear outline.

Sister Chromatids

Two genetically identical, separate pieces of DNA formed after replication and held together by a centromere.

Centromere

A protein band that holds two sister chromatids together.

Centriole

Small chunks of microtubules that act like anchors for spindle fibers to attach during cell division.

$G_1$ Phase

The interphase stage lasting $5\text{--}6\text{ hours}$ where the cell doubles in size by making extra cytoplasm and organelles, containing a checkpoint to verify resources before division.

$S$ Phase

The interphase stage lasting $10\text{--}12\text{ hours}$ in human cells where all DNA is replicated.

$G_2$ Phase

The interphase period lasting $4\text{--}6\text{ hours}$ where DNA condenses into chromosomes, sister chromatids are formed, and a checkpoint ensures all DNA replicated correctly.

Metaphase (Mitosis)

The longest stage of mitosis (lasting approximately $20\text{ minutes}$) where microtubules align sister chromatids in the center of the cell and pass a checkpoint before separation.

Anaphase (Mitosis)

The shortest stage of mitosis where microtubules tear sister chromatids into individual chromosomes and pull them to opposite sides of the cell.

Cytokinesis

The physical separation of the cytoplasm, membrane, and organelles that divides one enlarged cell into two genetically identical daughter cells.

Binary Fission

Bacterial cell division where one cell divides into two genetically identical cells faster than eukaryotes because there is no nuclear membrane to dissolve or spindle apparatus to form.

Dysplastic Cell

A cell that cannot be identified as part of the tissue or organ from which it was taken.

Benign Tumor

Cancerous cells that have been actively dividing but remain confined within a discrete tumor structure.

Malignant Tumor

A tumor composed of cancerous cells that readily divide and spread to other parts of the body.

Angiogenesis

The process where a malignant tumor stimulates the growth of veins and capillaries directly into the tumor structure.

Metastasis

The invasion of other tissues by cancerous cells, causing those surrounding cells to lose their identity and become cancerous.

Proto-oncogenes

Normal genes that signal cells to divide and maintain their identity, which can become permanently stuck on when mutated.

Oncogenes

Mutated forms of proto-oncogenes that remain permanently activated, driving uncontrolled cell division like a stuck gas pedal.

Tumor Suppressor Genes

Genes, such as BRCA1 and BRCA2, that stop cell division or trigger apoptosis (cell death), acting as cellular brakes.

Taxol

A chemotherapy drug derived from the Pacific yew tree that prevents microtubules from shortening, blocking chromatid separation and arresting cells in metaphase.

Mutation

A change in the nucleotide sequence of DNA that affects protein structure and function and gives rise to new alleles.

Allele

An alternative or different version of a gene, created through DNA mutations.