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Same genes, different jobs

Science · Organisms & Life Processes · ages 14-16

Name ______________________ Date ____________

What can embryonic stem cells turn into?
- Only blood cell types, such as red and white cells
- Almost any specialised cell type in the human body
- Only the cell types found in their original tissue
What is differentiation?
- Cells becoming specialised as their gene activity changes
- Cells losing unused genes when they take specialised jobs
- Cells copying DNA, then dividing into two identical cells
Every cell in your body holds the same genes.
Circle one: True False
Which proteins can increase or decrease transcription by binding to DNA?
- Proteins that cut unused genes out of chromosomes
- Proteins that add genes as cells take on new jobs
- Transcription factors that bind to regulatory DNA
A muscle cell and a nerve cell carry the same genes but make different sets of proteins. What explains this?
- They discard different genes from their chromosomes
- They use different genes to make different proteins
- They gain extra chromosomes to suit each cell's job
Which description fits blood-forming adult stem cells?
- In mature red blood cells, taking oxygen from lungs to tissues
- In bone marrow, producing several specialised blood cell types
- In brain nerve cells, receiving signals from other nerve cells
Plant meristems and animal adult stem cells can supply new cells without every stem cell dividing all the time.
Circle one: True False
Which pair correctly names a medical use of adult stem cells and an objection to collecting embryonic stem cells?
- Restore blood-cell production; object because embryos deserve protection
- Restore blood-cell production; object since stem cells cannot specialise
- Repair any organ; object because adult stem cells come only from embryos

Answer key

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

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Almost any specialised cell type in the human body · Embryonic stem cells are pluripotent. Their possible specialised cell types are not limited to blood or one tissue.
Cells becoming specialised as their gene activity changes · Differentiation gives cells specialised structures and functions through changes in gene activity. Making more cells by division is a different process.
False · The statement includes mature human red blood cells. They have no nucleus and do not retain the full gene set, so every is too broad.
Transcription factors that bind to regulatory DNA · Transcription factors bind to regulatory DNA and can increase or decrease the copying of a gene's information into RNA.
They use different genes to make different proteins · Different gene activity lets cells with the same genes make different proteins. Those proteins help the cells perform different jobs.
In bone marrow, producing several specialised blood cell types · Blood-forming stem cells in bone marrow are multipotent. They produce several related blood cell types, which can travel around the body.
True · Both can supply new cells through division. This ability does not require every stem cell to divide continuously.
Restore blood-cell production; object because embryos deserve protection · Adult blood-forming stem-cell transplants can restore blood-cell production. Some people object to embryo destruction because they believe embryos deserve protection.