Cellular Level of Organization: Protein Synthesis, Cell Cycle, and Cell Division

A complete set of vocabulary flashcards covering key terms and definitions regarding protein synthesis, DNA replication, cell cycle phases, and mitosis.

Transcription

The process occurring in the nucleus where RNA nucleotides are used to make a complementary mRNA copy of a DNA gene strand.

Translation

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

Messenger RNA (mRNA)

A single-stranded coding RNA molecule that serves as a transcript of a gene and carries genetic information from the nucleus to the cytoplasm.

Transfer RNA (tRNA)

A folded, T or L-shaped RNA molecule featuring an anticodon at one end and a specific amino acid attachment site at the other end.

Ribosomal RNA (rRNA)

A globular RNA component of ribosomes that reads mRNA sequences and translates them to form proteins.

Genome

The complete set of DNA present within a cell.

Proteome

The complete set of proteins synthesized by a cell.

Gene

A segment of DNA that provides the code or recipe required to make a protein.

Gene Expression

The synthesis of proteins based on gene instructions, dictating the structure and functions of a cell.

Structural Proteins

Proteins that form physical cellular components and framework, such as transport channels, receptors, ID markers, fibers, and microtubules.

Functional Proteins

Proteins that actively direct chemical processes and cellular actions, such as enzymes and hormones.

Anabolic Reactions

Metabolic biochemical reactions that use smaller units to build larger products, such as DNA replication and protein synthesis.

Catabolic Reactions

Metabolic reactions that break down molecules to release energy, such as using glucose to produce ATP.

Codon

A sequence of $3$ consecutive nucleotides on an mRNA strand that specifies a particular amino acid during translation.

Anticodon

A sequence of $3$ nucleotides on a tRNA molecule that complements a specific codon on the mRNA.

Peptide Bond

A covalent bond formed through dehydration synthesis that links successive amino acids together in a protein chain.

Primary Structure

The first level of protein structure, defined by the specific number, kind, and sequence of amino acids in a chain.

Secondary Structure

The second level of protein structure, formed by folding and twisting of an amino acid chain into an $\alpha$-helix or $\beta$-pleated sheet.

Tertiary Structure

The third level of protein structure, consisting of a globular three-dimensional structure held together by disulfide bonds, hydrogen bonds, and other attractive forces.

Quaternary Structure

The fourth level of protein structure, composed of two or more folded polypeptide chain clusters.

Somatic Cell

A general term for any body cell excluding germ cells, containing $2$ copies of each chromosome.

Homologous Chromosomes

A pair of matching chromosomes in a diploid cell, with one copy inherited from each parent.

Diploid

The chromosomal state of human somatic cells containing $23$ homologous pairs of chromosomes, totaling $46$ individual chromosomes.

Interphase

The non-dividing phase of the cell cycle consisting of $G_1$, S, and $G_2$ phases, during which the cell grows and duplicates its DNA.

$G_1$ Phase

The first growth phase (gap 1) of interphase, in which the cell grows and carries out normal metabolic functions.

S Phase

The synthesis phase of interphase, during which DNA replication occurs to produce $92$ sister chromatids from $46$ chromosomes.

$G_2$ Phase

The second growth phase (gap 2) of interphase, in which the cell continues growth and prepares for cell division or mitosis.

Helicase

The enzyme that untwists and unzips double-stranded DNA by breaking base pairing to expose template strands for replication.

DNA Polymerase

The enzyme that synthesizes new complementary DNA strands by adding free nucleotides along the template strands.

Sister Chromatids

Two identical copies of a replicated chromosome attached together at a central region called the centromere.

Centromere

The constricted region of a chromosome that joins two sister chromatids together and serves as an attachment site during mitosis.

Prophase

The first stage of mitosis, during which chromatin condenses into visible chromosomes, centrioles move to opposite poles forming spindle fibers, and the nuclear envelope disappears.

Metaphase

The second stage of mitosis, during which sister chromatids align along the metaphase plate in the middle of the cell.

Anaphase

The third stage of mitosis, during which centromeres break and sister chromatids separate toward opposite poles of the cell.

Telophase

The final stage of mitosis, in which two new nuclei reform around chromosomes at opposite poles as chromosomes return to chromatin form.

Cytokinesis

The process following nuclear division that splits the cytoplasm to produce two distinct daughter cells.

Karyotype

An ordered visual arrangement or photograph of an individual's complete set of chromosomes arranged in homologous pairs.