Glossary Making Cells and Proteins

Cell Cycle and Mitosis Glossary

A-C

• Abscission – The final separation of daughter cellsThe basic structural and functional units of life. at the end of cytokinesis.
• Anaphase – A stage in mitosis or meiosis where sister chromatids or homologous chromosomes separate.
• Apoptosis – Programmed cell death, an essential process for growthAn increase in size and number of cells. and developmentThe process of growth and differentiation..
• Cell cycle – The sequence of events in a cell’s life, including growth, DNA replication, and division.
• Centromere – The region of a chromosome where sister chromatids attach and spindle fibers bind.
• Chromatin – DNA and associated proteinsLarge molecules made of amino acids with various functions in the body. in a loose, uncondensed form inside the nucleusThe control center of the cell that contains DNA and directs cellular activities..
• Chromosome – A condensed structure of DNA that carries genetic information.
• Cleavage furrow – The indentation in the cell membrane that forms during cytokinesis in animal cells.
• Cyclins – Regulatory proteins that control the progression of the cell cycleThe sequence of events in a cell’s life, including growth, DNA replication, and division..
• Cytokinesis – The division of the cytoplasmThe gel-like substance within a cell that contains organelles and cytosol. to form two daughter cells after mitosis or meiosis.

D-G

• Diploid – A cell with two sets of chromosomes, one from each parent (2n).
• DNA helicaseAn enzyme that unwinds and separates DNA strands during replication. – An enzyme that unwinds and separates DNA strands during replication.
• DNA ligaseAn enzyme that joins Okazaki fragments and seals breaks in the DNA backbone. – An enzyme that joins Okazaki fragments and seals breaks in the DNA backbone.
• DNA polymeraseAn enzyme that synthesizes new DNA strands by adding nucleotides to a template. – An enzyme that synthesizes new DNA strands by adding nucleotidesThe building blocks of nucleic acids. to a template.
• Gap 1 (G1) phase – The first growth phase of the cell cycle before DNA replication.
• Gap 2 (G2) phase – The second growth phase before mitosis, preparing for cell division.
• Growth factor – A signaling molecule that stimulates cell division and differentiation.
• G-zero (G0) phase – A resting or non-dividing phase of the cell cycle.

H-L

• Histone – A protein that DNA wraps around to form nucleosomes, aiding in chromosome packaging.
• Homologous chromosome – A pair of chromosomes (one from each parent) that have the same genes but may carry different alleles.
• Interphase – The phase of the cell cycle in which the cell grows, performs its functions, and replicates DNA.
• Karyotype – A visual representation of an organism’s chromosomes arranged in pairs.
• Kinetochore – A protein structure on the centromereThe region of a chromosome where sister chromatids attach and spindle fibers bind. where spindle fibers attach during cell division.

M-Q

• Metaphase – A stage of mitosis where chromosomes align at the metaphase plateThe imaginary plane in the center of the cell where chromosomes line up during metaphase..
• Metaphase plate – The imaginary plane in the center of the cell where chromosomes line up during metaphaseA stage of mitosis where chromosomes align at the metaphase plate..
• Mitosis – The division of a cell’s nucleus into two identical daughter nucleiClusters of neurons in the CNS responsible for processing information..
• Mitotic spindle – The structure made of microtubules that separates chromosomes during mitosis.
• Nucleosome – A unit of DNA wrapped around histone proteins.
• Prophase – The first stage of mitosis where chromatinDNA and associated proteins in a loose, uncondensed form inside the nucleus. condenses into visible chromosomes.

R-Z

• Replication fork – The Y-shaped region where DNA is unwound and replicated.
• S phaseThe DNA synthesis phase of the cell cycle where chromosomes are replicated. – The DNA synthesis phase of the cell cycle where chromosomes are replicated.
• Semiconservative replication – The process in which DNA is copied, producing two moleculesGroups of atoms bonded together. with one old strand and one new strand.
• Sex cell (gamete A haploid reproductive cell (sperm or egg).) – A haploid reproductive cell (sperm or egg).
• Sex chromosome – The X or Y chromosome that determines biological sex.
• Sister chromatid – One of two identical copies of a duplicated chromosome.
• Somatic cells – Any body cell that is not a reproductive cell.
• Spindle fiber – Microtubules that separate chromosomes during mitosis.
• Supercoil – The coiling of chromatin into highly condensed chromosomes.
• Telophase – The final stage of mitosis where nuclear envelopes reform around separated chromosomes.

Protein Synthesis Glossary

A

• Adenine – A purineA type of nitrogenous base with a two-ring structure (adenine and guanine). nitrogenous baseA component of nucleotides that includes adenine, guanine, cytosine, thymine (DNA), and uracil (RNA) found in DNA and RNA, pairs with thymine (DNA) or uracil (RNA).
• Allele – Different versions of a gene that determine specific traits.
• Amino acidA substance that releases hydrogen ions (H⁺) in solution. – The building block of proteins, linked together by peptide bondsBonds that link amino acids in proteins..
• Anticodon – A sequence of three nucleotides on tRNA that pairs with a codon on mRNA.
• Autosome – A chromosome that is not a sex chromosomeThe X or Y chromosome that determines biological sex., the same in both males and females.

B–E

• Base pairing – The specific hydrogen bonding between complementary bases (A-T, C-G in DNA).
• Base triplet – A sequence of three DNA nucleotides that codes for an amino acidThe building blocks of proteins, consisting of an amino group, carboxyl group, and side chain..
• Codon – A three-nucleotide sequence on mRNA that codes for a specific amino acid.
• Cytosine – A pyrimidineA type of nitrogenous base with a single-ring structure (cytosine, thymine, and uracil). nitrogenous baseA substance that accepts hydrogen ions (H⁺) or releases hydroxide ions (OH⁻). that pairs with guanine in DNA and RNA.
• Deoxyribose – The five-carbon sugar found in DNA nucleotides.
• Double helix – The twisted-ladder structure of DNA molecules.
• Elongation – The phase of DNA replication, transcription, or translationThe process of converting mRNA into a protein. in which the molecule is lengthened.

G-L

• Genetic code – The set of rules by which DNA sequences are translated into proteins.
• Genome – The complete set of genetic material in an organismA living individual made up of cells..
• Guanine – A purine nitrogenous base that pairs with cytosineA pyrimidine nitrogenous base that pairs with guanine in DNA and RNA. in DNA and RNA.

• Initiation – The beginning phase of DNA replication, transcription, or translation.
• Intron – A non-coding sequence in DNA that is removed during mRNA processing.
• Large ribosomal subunit – The larger part of a ribosome that helps form peptide bonds during translation.

M-N

• Molecular chaperone – A protein that helps other proteins fold correctly.
• mRNA (messenger RNA) – RNA that carries genetic instructions from DNA to the ribosome.
• Mutation – A change in DNA sequence that can affect gene function.
• Nitrogenous base – A component of nucleotides that includes adenineA purine nitrogenous base found in DNA and RNA, pairs with thymine (DNA) or uracil (RNA)., guanine, cytosine, thymine (DNA), and uracil (RNA).
• Nucleotide – The basicA solution with a pH above 7, having a lower concentration of H⁺ ions. building block of DNA and RNA, consisting of a sugar, phosphate group, and nitrogenous base.

P-R

• Phosphate group – A chemical group in nucleotides that helps form the sugar-phosphate backbone The structural framework of DNA and RNA. of DNA and RNA.
• Post-translational modification – Chemical changes made to proteins after translation to activate or regulate them.
• Purine – A type of nitrogenous base with a two-ring structure (adenine and guanine).
• Pyrimidine – A type of nitrogenous base with a single-ring structure (cytosine, thymine, and uracil).
• Regulatory protein – A protein that controlsVariables that remain constant to ensure a fair test. gene expression by binding to DNA or other molecules.
• Ribose – A five-carbon sugar found in RNA.
• RNA polymeraseAn enzyme that synthesizes RNA from a DNA template. – An enzyme that synthesizes RNA from a DNA template.
• rRNA(ribosomal RNA) – RNA that forms part of the ribosome and helps in protein synthesis. (ribosomal RNA) – RNA that forms part of the ribosome and helps in protein synthesis.

S-T

• Secretory vesicles – Membrane-bound sacs that store and transport proteinsBind hormones for transport in the blood. to be secreted.
• Small ribosomal subunit – The smaller part of a ribosome that binds to mRNA to start translation.
• Start codon – The codon (AUG) that signals the beginning of translation.
• Stop codon – A codon that signals the end of translation (UAA, UAG, UGA).
• Sugar-phosphate backbone – The structural framework of DNA and RNA.
• Termination – The final phase of transcription or translation where the process stops.
• Thymine – A pyrimidine nitrogenous base found only in DNA, pairs with adenine.
• Transcription – The process of copying DNA into RNA.
• Translation – The process of converting mRNA into a protein.
• Transport vesicles – Membrane-bound sacs that move substances within the cell.
• tRNA (transfer RNA) – RNA that carries amino acids to the ribosome during translation.