Gene Expression and Cell Specialization
Introduced| English |
|---|
| differentiation/ˌdɪfəˌrenʃɪˈeɪʃn/ |
| stem cell/stem sel/ |
Same DNA, very different cells
- A nerve cell, a muscle cell, and a red blood cell look nothing alike.
- Yet every one of them carries the exact same DNA.
- How can identical instructions build such different cells?
- The answer lies in which genes each cell switches on.
Differentiation
- Early cells are unspecialized; over time they become specialized.
- This process is called differentiation 分化.
- A cell takes on a specific shape and job — carrying oxygen, contracting, signalling.
- Once specialized, it usually keeps that role for life.
Differentiation is the process by which a cell…
Differentiation is a cell becoming specialized — a muscle cell, a nerve cell, and so on.
Different genes, different cells
- Every cell has the same genes but expresses a different set.
- A muscle cell switches on contraction genes; a red blood cell switches on haemoglobin genes.
- This is why cells with identical DNA end up so different.
- Specialization is about gene expression, not different DNA.
How can cells with the same DNA become so different?
Every cell has the same genes but switches on a different set — this is differential gene expression.
A specialized cell keeps all its genes, but only expresses some of them.
Specialization comes from switching genes on and off, not from losing genes.
Stem cells
- A stem cell 干细胞 has not yet specialized.
- It can still develop into many different cell types.
- Your body uses stem cells to grow and to repair damage.
- As a stem cell differentiates, it locks in a particular pattern of gene expression.
Which cell expresses which genes?
Sort each specialized job by the cell type whose genes are switched on to do it.
An unspecialized cell that can develop into many cell types is a ____ cell.
A stem cell has not yet specialized, so it can still become many different cell types.
Select all true statements about cell specialization.
Cells keep all their genes; they just do not express the unused ones. The other three are correct.
Specialized cells do not throw away the genes they are not using. A muscle cell still carries the haemoglobin gene — it just keeps it switched off. Every cell holds the full genome; specialization is which genes are expressed.
A red blood cell versus a neuron:
- Both start with the same complete DNA.
- The red blood cell switches on haemoglobin genes and even loses its nucleus to carry more oxygen.
- The neuron instead grows a long axon and switches on signalling genes — same genome, opposite jobs.
Cells with identical DNA become different through differentiation, expressing a different set of genes. A muscle cell and a nerve cell run different genes from the same genome. A stem cell is unspecialized and can still become many cell types. Specialization is about gene expression, not gene loss.