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D2.2.5 (HL)—Genome, transcriptome, proteome

Genome, transcriptome and proteome distinguish inherited DNA information from expressed mRNA and dynamic protein output in cells over time and conditions.

Syllabus
First assessment 2025
Objective
D2.2.5
Level
HL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper1
Typical marks1

Common command terms

  • State
  • Calculate
  • Explain

Scoring notes

Common mistake
Assuming the genome and proteome are identical in all tissues.

Recent exam appearances

May 2023Paper1 ["HL"] · TZ27[ 1 ]D2.2.5 (HL)—Genome, transcriptome, proteome
November 2019Paper1 ["HL"] · TZ06[ 1 ]D2.2.5 (HL)—Genome, transcriptome, proteome
May 2019Paper1 ["HL"] · TZ27[ 1 ]D2.2.5 (HL)—Genome, transcriptome, proteome
November 2014Paper3 ["HL"] · TZ04(c)[ 1 ]D2.2.5 (HL)—Genome, transcriptome, proteome
November 2014Paper3 ["HL"] · TZ04(b)[ 1 ]D2.2.5 (HL)—Genome, transcriptome, proteome

Coverage 2014–2023 · Updated 16 Jul 2026

Genome, Transcriptome and Proteome Describe Different Layers

HL only
Layer What it contains How it changes
genome the complete DNA information of a cell relatively stable across most somatic cells
transcriptome all RNA transcripts present in a cell or tissue at a stated time changes with cell type, signals and developmental stage
proteome all proteins present in a cell, tissue or organism at a stated time changes through translation, modification, location and degradation

The genome supplies possible information. The transcriptome records which regions are being expressed as RNA now. The proteome records the protein products actually present after further regulation.

The transcriptome and proteome must be tied to a sample and time. Neither is a permanent list of everything the genome could produce.

A Shared Genome Can Produce Distinct Cell Identities

HL only

Cells produced from the same zygote usually share the same genome, but regulatory states make different subsets of that genome accessible and active.

Same underlying genome Different active output Functional consequence
insulin gene present abundant insulin mRNA and protein in pancreatic β cells blood-glucose regulation
collagen genes present high collagen expression in many connective-tissue cells extracellular support
ion-channel genes present neuron-specific channel and receptor profile electrical signalling

regulatory state → selected transcriptome → selected proteome → specialized structure and function

A cell type does not normally lose every gene it does not use. Inactivity and absence are different claims.

Epigenetic Regulation Balances Memory with Resetting

HL only

shared genome → cell-specific regulatory and epigenetic state → cell-specific transcriptome → cell-specific proteome → differentiated structure and function

Process What remains continuous? What can change?
mitosis in a differentiated lineage much of the expression state reversible tags and regulatory inputs
environmental response DNA base sequence usually remains signalling, transcription and sometimes epigenetic marks
gamete and early-embryo reprogramming genome and selected imprints most parental epigenetic patterns are reset

For any epigenetic claim, ask where the tag is, how it changes access or protein binding, whether it persists through mitosis or gametes, and whether the evidence shows correlation or causation.

Genome, transcriptome, proteome

HL only

[ 1 ]

Which statement correctly describes genome and proteome?

Concept essentials

  • The genome is the complete genetic information.
  • The transcriptome is the set of RNA transcripts expressed at a time.
  • The proteome is the set of proteins produced at a time.
  • Different tissues can share a genome but have different proteomes.