DNA, RNA, Protein Synthesis, and Cell Division

Vocabulary terms and definitions covering DNA and RNA structures, protein synthesis (transcription and translation), mitosis, and meiosis from the lecture transcript.

Deoxyribonucleic Acid (DNA)

A nucleic acid organized into 46 chromosomes in humans that stores genetic information within the cell nucleus.

Nucleotide

The distinctive monomer building block of nucleic acids, consisting of a five-carbon pentose sugar, a phosphate group, and a nitrogenous base.

Deoxyribose

The specific five-carbon pentose sugar found in DNA nucleotides that forms part of the alternating sugar-phosphate backbone.

Nitrogenous Base

A nitrogen-containing ring structure in a nucleotide that stores genetic information, categorized as purines or pyrimidines.

Purines

A group of double-ring nitrogenous bases found in DNA and RNA, consisting of adenine (A) and guanine (G).

Pyrimidines

A group of nitrogenous bases with a single fused carbon ring, which includes cytosine (C), thymine (T), and uracil (U).

Double Helix

The structural shape of DNA described as a twisted ladder or spiral staircase, formed by two complementary molecular strands.

Complementary Base Pairing

The specific hydrogen bonding between a purine and a pyrimidine across opposite DNA or RNA strands, such as adenine with thymine/uracil and cytosine with guanine.

Ribonucleic Acid (RNA)

A single-stranded nucleic acid containing ribose sugar and the nitrogenous base uracil instead of thymine.

mRNA (Messenger RNA)

The type of RNA synthesized from DNA during transcription that carries genetic code for protein production to the cytoplasm.

rRNA (Ribosomal RNA)

The RNA component that contributes to the structure and functional machinery of ribosomes.

tRNA (Transfer RNA)

The RNA molecule that delivers specific amino acids to the ribosome during translation by matching its anticodon to an mRNA codon.

Ribose

The five-carbon pentose sugar constituent found in RNA nucleotides.

Uracil

The pyrimidine base unique to RNA that replaces thymine to complementarily pair with adenine.

Gene

A specific coded region contained within DNA that holds the instructions to synthesize an RNA molecule and produce a protein.

Codon

A unique triplet sequence of bases on an RNA molecule that specifies a particular amino acid in protein synthesis.

Transcription

The process in the nucleus where an enzyme reads a DNA gene segment to produce a complementary messenger RNA (mRNA) molecule.

RNA Polymerase

The enzyme responsible for transcription that splits the DNA double helix and links complementary RNA nucleotides into an RNA strand.

Pre-mRNA

The immature initial RNA transcript produced in eukaryotic cells before non-coding regions are removed.

Exons

The functional, coding portions of a pre-mRNA gene transcript that remain spliced together to code for a protein.

Introns

The non-coding segments of a pre-mRNA molecule that are cut out and removed during mRNA processing.

Translation

The process occurring in the cytoplasm where ribosomes read mRNA triplets to assemble amino acids into a polypeptide chain.

Anticodon

A three-base sequence located on a tRNA molecule that pairs complementarily with a corresponding mRNA codon.

Mitosis

The nuclear division process that duplicates and splits genetic material to yield two genetically identical daughter cells for tissue growth and repair.

Cytokinesis

The division of the cell cytoplasm occurring at the end of cell division to physically separate one cell into two distinct cells.

Zygote

The single initial cell formed when a sperm cell fertilizes an egg cell, containing a full set of 46 chromosomes.

Prophase

The initial stage of mitosis where DNA condenses into visible chromosomes, the nuclear envelope disintegrates, and spindle fibers form.

Spindle Fibers

Microtubule structures produced by centrioles that attach to chromosomes to divide genetic material during cell division.

Metaphase

The stage of mitosis where condensed chromosomes align along the cell equator.

Anaphase

The stage of mitosis where sister chromatids are pulled apart by spindle fibers toward opposite mitotic poles.

Telophase

The final stage of mitosis where separated chromosomes cluster at opposite ends, nuclear envelopes reform from rough ER, and DNA relaxes into chromatin.

Chromatin

The loosened, less compacted structural state of DNA present in non-dividing cells or reformed during telophase.

Meiosis

A specialized cell division process occurring in the ovaries or testes that reduces chromosome numbers by half to create gametes with 23 chromosomes.

Gamete

A reproductive sex cell (sperm or egg) containing 23 chromosomes, produced through meiosis for sexual reproduction.