Same genes, different jobs

Science · Organisms & Life Processes · ages 14-16

Name ______________________ Date ____________

What can embryonic stem cells turn into?
- Only blood cells
- Almost any cell type
- Only skin cells
What is differentiation?
- Unspecialised cells gaining a job by switching genes
- Cells losing genes they do not need
- Cells splitting into smaller cells
Every cell in your body holds the same genes.
Circle one: True False
What turns genes on or off inside a cell?
- Extra chromosomes arriving
- The cell wall pressing in
- Transcription factors binding near DNA
Two cells look different but carry the same genes. How?
- One cell lost half its genes
- Different genes are switched on in each
- One cell copied extra genes
Where do adult stem cells live, and what do they do?
- Blood, carrying oxygen
- Bone marrow, replacing nearby blood cells
- Brain, thinking new thoughts
Plant meristem cells and animal adult stem cells both keep dividing to supply new cells.
Circle one: True False
A clinic offers embryo-based treatment and a critic objects. Which pair fits?
- Use: replace damaged cells. Objection: embryos were destroyed
- Use: copy whole people. Objection: waiting lists grow
- Use: stop ageing. Objection: needles hurt

Answer key

For grown-ups. Fold this page away before handing over the rest.

Almost any cell type · Embryonic stem cells are pluripotent, so almost any cell type is possible.
Unspecialised cells gaining a job by switching genes · Differentiation switches on job genes while every cell keeps the full set.
True · Daughters inherit the full set. Only the switched-on genes differ.
Transcription factors binding near DNA · Transcription factors bind near DNA and switch genes on or off.
Different genes are switched on in each · Same book, different chapters: each cell reads the genes its job needs.
Bone marrow, replacing nearby blood cells · Adult stem cells are multipotent and replace only their neighbours, as in bone marrow.
True · Meristem at root and shoot tips and adult stem cells both feed nearby growth.
Use: replace damaged cells. Objection: embryos were destroyed · A real use is replacing damaged cells, and a real objection concerns destroyed embryos.